JP6539831B2 - Trochoidal gear - Google Patents

Description

  The present invention relates to a trochoidal gear and a reduction gear including the same, and a method, an apparatus and a program for manufacturing the trochoidal gear.

  One type of gear is a trochoidal gear having a tooth profile along a trochoidal curve. Trochoid gears have advantages such as achieving smooth rolling contact as compared to other gears, for example, involute gears, and are used in various applications such as reduction gears and pumps. Such a trochoid gear can be processed using a cutting tool such as an end mill numerically controlled by a computer (see Patent Document 1).

Japanese Patent Laid-Open No. 2002-98219

  By the way, the present inventors noticed that there were the following problems in manufacturing a trochoid gear while moving the cutting tool relative to the work by numerical control. That is, when processing with such numerical control is performed, data of the target tooth shape is given to the computer in advance, and control is made to move the end mill or the work along this, but in this case, it is finally manufactured The shape of the tooth base of the trochoid gear tends to be shallower than the target tooth shape (see FIG. 14). This is considered, in part, because the cutting resistance increases from the tip of the tooth to the bottom of the tooth. And, if the root of the tooth is shallowly formed in this way, problems such as interference with other parts may occur when assembling the gear as a part into a finished product.

  The present invention has been made in view of the above problems, and relates to a trochoidal gear having a tooth shape closer to a target tooth shape, a reduction gear including the same, and a method, an apparatus and a program for manufacturing the trochoidal gear.

  The trochoid gear according to the first aspect of the present invention comprises tooth tips and tooth bottoms alternately. The trochoid gear controls the cutting tool to move along the first trochoid curve at the time of formation of the tooth top portion relative to the cutting surface of the workpiece, and at the time of formation of the tooth bottom portion, the first trochoid It has a tooth profile formed by controlling to move along the offset curve drawn on the tooth bottom side of the curve.

  The trochoid gear according to a second aspect of the present invention is the trochoid gear according to the first aspect, wherein the offset curve is a second trochoid curve that describes a sharper curve than the first trochoid curve.

  The trochoid gear according to the third aspect of the present invention is the trochoid gear according to the first aspect or the second aspect, wherein the offset curve is a parameter for determining the curvature of the trochoid curve from the shallow portion to the deep portion of the root portion. It is a curve drawn by changing it so that the curvature may become larger as it goes.

  The trochoid gear according to a fourth aspect of the present invention is the trochoid gear according to the third aspect, wherein the parameter changes according to a quadratic function of pressure angle.

  The trochoid gear according to a fifth aspect of the present invention is the trochoid gear according to the third aspect, wherein the parameter changes in accordance with a linear function of pressure angle.

  A reducer according to a sixth aspect of the present invention includes the trochoidal gear according to any one of the first to fifth aspects.

A method of manufacturing a trochoidal gear according to a seventh aspect of the present invention is a method of manufacturing a trochoidal gear having tooth tips and tooth bottoms alternately, and includes the following steps (1) and (2).
(1) forming the tooth top portion on the cutting surface by controlling the cutting tool so as to move along the first trochoid curve relative to the cutting surface of the work;
(2) The cutting surface is controlled by moving the cutting tool relative to the cutting surface along an offset curve drawn closer to the bottom of the tooth than the first trochoid curve. Forming the tooth bottom;

  An apparatus for manufacturing a trochoidal gear according to an eighth aspect of the present invention is an apparatus for manufacturing a trochoidal gear having tooth tips and tooth bottoms alternately, and includes a cutting tool and a control unit. The cutting tool cuts the tooth top and the tooth bottom on a cutting surface of a workpiece. The control unit controls the cutting tool to move along the first trochoid curve at the time of formation of the tooth top portion relative to the cutting surface, and the first trochoid at the time of formation of the tooth bottom portion. Control is made to move along the offset curve drawn on the tooth bottom side of the curve.

A manufacturing program of a trochoidal gear according to a ninth aspect of the present invention is a manufacturing program of a trochoidal gear having tooth tips and tooth bottoms alternately, and has a computer execute the following steps (1) and (2) .
(1) forming the tooth top portion on the cutting surface by controlling the cutting tool so as to move along the first trochoid curve relative to the cutting surface of the work;
(2) The cutting surface is controlled by moving the cutting tool relative to the cutting surface along an offset curve drawn closer to the bottom of the tooth than the first trochoid curve. Forming the tooth bottom;

  According to the present invention, in manufacturing the trochoid gear, the locus of relative movement of the cutting tool with respect to the cutting surface of the workpiece follows the first trochoid curve at the tip of the tooth and the first trochoid curve at the root of the tooth It is controlled to follow an offset curve drawn on the bottom side of teeth. That is, at the tooth bottom where cutting resistance is considered to be large, the cutting tool is controlled to move deeper than the first trochoid curve. As a result, the actually formed tooth profile has a shape close to the first trochoid curve not only at the tip of the tooth but also at the bottom of the tooth. Therefore, it is possible to obtain a trochoidal gear having a tooth profile closer to the target tooth profile.

It is a sectional view of a drive provided with a reduction gear concerning one embodiment of the present invention. It is the sectional view on the AA line of FIG. FIG. 1 is an enlarged sectional view of a transmission. It is an expanded sectional view which shows the carrier pin and the other example of the fixing method. It is an expanded sectional view which shows the carrier pin and the other example of the fixing method. It is a perspective view which shows the carrier pin and the other example of a roller. It is the perspective view (a) and sectional drawing (b) of the chamfering process of the edge part of an external gear. It is sectional drawing which shows the other example of a needle bearing. It is sectional drawing which shows the other example of a needle bearing. It is sectional drawing which shows the other example of a needle bearing. It is sectional drawing which shows the other example of a needle bearing. It is sectional drawing which shows the other example of a needle bearing. It is a perspective view which shows the other example of an external gear. The figure explaining the problem of the prior art at the time of formation of a trochoid tooth profile. It is a block diagram which shows the structure of the manufacturing apparatus of an external gear. It is a graph which shows the epitrochoid parallel curve which represents the tooth profile of an epitrochoid gear. It is the elements on larger scale of FIG. It is a graph showing the correction coefficient of an epitrochoid parallel curve.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment in which a trochoid gear according to the present invention and a reduction gear having the same are applied to a drive device provided with a motor will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the drive device, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, and FIG. 3 is an enlarged cross-sectional view of the transmission of FIG.

  As shown in FIG. 1, the drive device according to the present embodiment includes a reduction gear 1 and a motor 2, which are integrally connected. With this configuration, the rotational force transmitted from the motor 2 through the input shaft 31 is decelerated by the reduction gear 1 and output from the output shaft 32. In the following, for convenience of explanation, the motor side (right side) of FIG. 1 may be described as the front end side or the front side, and the reduction gear side (left side) may be described as the rear end side or the rear side. Moreover, the rotation axis of the input shaft 31 and the output shaft 32 may be referred to as an axis X, and this direction may be referred to as an axial direction. First, the reduction gear 1 will be described.

  As shown in FIGS. 1 to 3, the speed reducer 1 is provided with a casing 11 for accommodating a reduction mechanism, and an input shaft 31 to which a rotational force is applied by a motor 2 is connected to the tip end side of the casing 11. ing. The casing 11 includes a disc-shaped first support plate 111 disposed on the tip end side, and a disc-shaped second support plate 112 disposed on the rear end side with a diameter smaller than that of the first support plate 111. , Are arranged in parallel. A cylindrical outer cylinder 113 is disposed between the two support plates 111 and 112, and is connected to the two support plates 111 and 112 by bolts 114. Specifically, a plurality of through holes 1131 extending in the front-rear direction are formed at predetermined intervals on the outer peripheral edge of the outer cylinder 113, and both the support plates 111 and 112 are also penetrated so as to correspond thereto. Holes 115 and 116 are formed. Then, the bolt 114 inserted into the through hole 115 from the surface on the tip end side on the first support plate 111 side is screwed into the female screw formed in the through hole 116 of the second support plate 112, thereby the first support The plate 111, the outer cylinder 113, and the second support plate 112 are integrally connected to form a casing 11. Thus, a cylindrical internal space is formed in the casing 11, and the speed reduction mechanism is accommodated.

  A central through hole 117 is formed at the center of the first support plate 111, and the input shaft 31 is inserted through the central through hole 117 via the bearing 121. The front end of the input shaft 31 is rotatably connected to the internal space of the motor 2 as described later, and the rear end is splined to the eccentric 4 as described later.

  Next, the speed reduction mechanism housed in the casing 11 will be described. As shown in FIG. 3, the speed reduction mechanism includes a first carrier 5 disposed on the front end side of the internal space of the casing 11 and a second carrier 6 disposed on the rear end side. The first carrier 5 is formed in a disk shape, and is rotatably supported in the inner space by a first bearing 51 disposed between the outer peripheral surface thereof and the inner peripheral surface of the outer cylinder 113. Further, a first flange portion 52 protruding radially outward is formed on the outer peripheral surface on the tip end side of the first carrier 5, and the first flange portion 52 engages with the first bearing 51 from the tip side. doing. On the other hand, the second carrier 6 is also configured in the same manner, and is disposed at the rear end side of the inner space with an interval between the second carrier 6 and the first carrier 5. Then, similarly to the first carrier 5, it is rotatably supported in the inner space by a second bearing 61 which is formed in a disk shape and is disposed between the outer peripheral surface thereof and the inner peripheral surface of the outer cylinder 113. It is done. In addition, a second flange portion 62 protruding radially outward is formed on the outer peripheral surface on the rear end side of the second carrier 6, and the second flange portion 62 is formed on the second bearing 61 from the rear end side. It is engaged.

  An output shaft 32 is connected to a rear end surface of the second carrier 6 so as to rotate together with the second carrier 6. The output shaft 32 protrudes to the outside from a central through hole 118 formed at the center of the second support plate 112 of the casing 11. Further, a bearing 119 is provided on the inner peripheral surface of the central through hole 118, and the output shaft 32 is supported by the central through hole 118 via the bearing 119. The first and second bearings 51 and 61 can be configured by ball bearings or the like.

  The first carrier 5 and the second carrier 6 are connected by a plurality of carrier pins 7 formed in a cylindrical shape. Hereinafter, the carrier pin 7 and the connection structure thereof will be described. In the reduction gear according to the present embodiment, as shown in FIG. 2, four carrier pins 7 are provided at every 90 degrees around the axis line X of the reduction gear. As shown in FIG. 3, each carrier pin 7 is provided with a cylindrical main body 71, and a small diameter portion 72 is formed on the front end side of the main body 71, and cylindrical on the rear end side of the main body 71. The large diameter portion 73 is formed. The small diameter portion 72 is formed in a cylindrical shape having a diameter smaller than that of the main body portion 71, and a male screw is formed on the outer peripheral surface. The large diameter portion 73 is formed in a cylindrical shape having a diameter larger than that of the main body portion 71.

  The second carrier 6 is formed with a through hole 63 for receiving the main body portion 71 of the carrier pin 7 and the large diameter portion 73. The through hole 63 includes a first diameter portion 631 having an inner diameter substantially the same as the outer diameter of the main body portion 71, and a second diameter portion 632 having an inner diameter substantially the same as the outer diameter of the large diameter portion 73. The first diameter portion 631 and the second diameter portion 632 are continuously formed in this order from the tip end side. On the other hand, in the first carrier 5, a through hole 53 for receiving the main body portion 71 of the carrier pin 7 and the small diameter portion 72 is formed. The through hole 53 includes a first diameter portion 531 having an inner diameter substantially the same as the outer diameter of the small diameter portion 72, and a second diameter portion 532 having an inner diameter substantially the same as the outer diameter of the main body 71. The first diameter portion 531 and the second diameter portion 532 are continuously formed in this order from the tip end side.

  Next, fixation of the carrier pin 7 and the carriers 5 and 6 will be described. First, the small diameter portion 72 of the carrier pin 7 is directed to the front end side, and is inserted into the through hole 63 from the rear end surface side of the second carrier 6 and then inserted into the through hole 53 of the first carrier 5. And, when the large diameter portion 73 of the carrier pin 7 is disposed in the second diameter portion 632 of the through hole 63 of the second carrier 6, the front end portion of the small diameter portion 72 from the front end side of the through hole 53 of the first carrier 5 Is supposed to protrude. Next, the nut 33 is screwed onto the male screw of the small diameter portion 72 protruding from the through hole 63 of the first carrier 5 and tightened. Thus, both carriers 5 and 6 are integrally connected via the plurality of carrier pins 7.

  When the nut 33 is tightened, a force acts on the first carrier 5 to move to the rear end side, and a force acts on the second carrier 6 to move to the front end side. However, since the first flange portion 52 is provided on the first carrier 5 and engaged with the first bearing 51 from the front end side, the rearward movement of the first carrier 5 is restricted. Similarly, since the second flange portion 62 is provided on the second carrier 6 and engaged with the second bearing 61 from the rear side, the forward movement of the second carrier 6 is restricted.

  As shown in FIG. 3, a cylindrical eccentric body 4 extending along the axis X is disposed between the two carriers 5 and 6. The eccentric body 4 includes a small diameter front end portion 41 formed on the front end side and a small diameter rear end portion 42 formed on the rear end side. Further, between the front end portion 41 and the rear end portion 42, two eccentric portions eccentric to the axis line X, that is, a first eccentric portion 43 and a second eccentric portion 44 are formed. Here, the first eccentric portion 43 is disposed on the front end side, and the second eccentric portion 44 is disposed on the rear end side.

  The front end portion 41 of the eccentric body 4 is inserted into a through hole 54 formed at the center of the first carrier 5, and is rotatably supported by a bearing 55 disposed on the rear end side of the through hole 54. On the other hand, the rear end portion 42 of the eccentric body 4 is inserted into a through hole 64 formed at the center of the second carrier 6, and rotatably supported by a bearing 65 disposed on the tip end side of the through hole 64. ing. Thereby, the eccentric body 4 is rotatable with respect to both the carriers 5 and 6. Further, a recess 45 is formed at the tip of the tip end portion 41 of the eccentric 4, and the rear end of the input shaft 31 is inserted into the recess 45 and splined. Therefore, the eccentric body 4 rotates with the input shaft 31 around the axis X.

  The eccentric portions 43 and 44 of the eccentric body 4 are formed in a disk shape, and are integrally connected in the front-rear direction with a slight gap. As shown in FIG. 2, the axial center X1 of the first eccentric portion 43 and the axial center X2 of the second eccentric portion 44 are both eccentric from the axis line X of the reduction gear 1 and shifted 180 degrees around the axis line X It is placed in position.

  A first needle bearing 56 is disposed on the outer peripheral surface of the first eccentric portion 43, and the first external gear 8 is connected to the first eccentric portion 43 via the needle bearing 56. That is, a central through hole 81 is formed at the center of the first external gear 8, and the first eccentric portion 43 is disposed in the central through hole 81 via the first needle bearing 56. As shown in the enlarged view in FIG. 3, the first needle bearing 56 includes a plurality of cylindrical rollers 561 and an annular shell 562 that supports the rollers 561. The shell 562 has a cylindrical base portion 563 fixed along the inner peripheral surface of the central through hole 81 of the first external gear 8, and a plate shape extending radially inward from the front end and the rear end of the base portion 563. The first support 564 and the second support 565 are formed. The plurality of rollers 561 are arranged circumferentially along the base portion 563 and sandwiched between the first and second support portions 564 and 565, whereby movement in the front-rear direction is restricted. The plurality of rollers 561 are rotatably supported by the shell 562 and in contact with the outer peripheral surface of the first eccentric portion 43, whereby the first external gear 8 can rotate around the first eccentric portion 43. It has become.

  Next, the first external gear 8 will be described. Since the axial center X1 of the first eccentric portion 43 is eccentric from the axis X, when the first eccentric portion 43 rotates, the first external gear 8 eccentrically rotates. Further, as shown in FIG. 2, in the first external gear 8, four carrier pin through holes 82 into which the carrier pin 7 is inserted are formed between the center and the outer peripheral edge thereof. The carrier pin through holes 82 are larger than the carrier pin 7 and a roller 83 described later, and are formed every 90 degrees around the axial center of the first external gear 8. In each carrier pin 7, a cylindrical roller 83 is provided at a position passing through the carrier pin through hole 82. The roller 83 is disposed rotatably with respect to the outer peripheral surface of the carrier pin 7, the outer peripheral surface of the roller 83 contacts the inner peripheral surface of the carrier pin through hole 82, and the pressure from the inner peripheral surface is the roller It is transmitted to the carrier pin 7 through 83.

  Further, the external teeth 84 of the first external gear 8 have a trochoidal tooth shape defined by an epitrochoidal parallel curve.

  The external teeth 84 of the first external gear 8 configured as described above mesh with the internal gear 15 formed on the inner peripheral surface of the casing 11. The internal gear 15 will be described below. First, as shown in FIG. 2, on the inner peripheral surface of the outer cylinder 113 of the casing 11, a concave portion 151 having a circular arc shape in cross section is provided at a predetermined interval along the circumferential direction between the first bearing 51 and the second bearing 61. Is formed. A cylindrical internal tooth pin 152 extending in the front-rear direction is rotatably disposed in each recess 151, and a part of the outer peripheral surface of the internal tooth pin 152 extends radially from the inner peripheral surface of the outer cylinder 113. It protrudes inward. In this way, the internal tooth pin 152 protrudes from the inner peripheral surface of the outer cylinder 113 at a predetermined interval, whereby the inner peripheral surface of the outer cylinder 113 is formed with irregularities along the circumferential direction. Configure.

  On the other hand, the second needle bearing 66 is disposed on the outer peripheral surface of the second eccentric portion 44, and the second external gear 9 is connected to the second eccentric portion 44 via the second needle bearing 66. There is. The configurations of the second needle bearing 66 and the second external gear 9 are the same as those of the first needle bearing 56 and the first external gear 8, and thus detailed description will be omitted. A cylindrical roller 93 is provided at a position where each carrier pin 7 passes the carrier pin through hole 92 of the second external gear 9. Further, like the first external gear 8, the second external gear 9 is in mesh with the internal gear 15 of the outer cylinder 113 described above.

  Although the number of teeth of the first external gear 8 and the second external gear 9 is the same, it is smaller than the number of teeth of the internal gear 15. In the present embodiment, as an example, the number of teeth of both external gears 8 and 9 is 29, and the number of teeth of the internal gear (the number of internal tooth pins 152) is 30.

  Further, regarding the rollers 83 and 93 attached to the carrier pin 7, the roller 83 disposed in the through hole 82 of the first external gear 8 and the roller 93 disposed in the through hole 92 of the second external gear 9. And a plate-shaped first regulating plate 86 is disposed between them. The first restriction plate 86 is formed in a disk shape in which a through hole is formed, and the carrier pin 7 is inserted through the through hole. The first restricting plate 86 restricts the movement of the roller 83 in the front-rear direction.

  Similarly, a plate-like second regulation plate 96 is disposed between the roller 93 disposed in the through hole 92 of the second external gear 9 and the second carrier 6. The second restricting plate 96 is also formed in a disc shape in which a through hole is formed, and the carrier pin 7 is inserted through the through hole. The movement of the roller 93 in the front-rear direction is restricted by the second restriction plate 96. Such restriction plates 86 and 96 can also be provided between the roller 83 disposed in the through hole 82 of the first external gear 8 and the first carrier 5.

  Next, the motor 2 will be described. The motor 2 is attached to the input shaft 31 and accommodated in the motor housing 21. As shown in FIG. 1, the motor housing 21 has a cylindrical side portion 211 extending forward from the outer peripheral surface of the first support plate 111 of the casing 11, and a disk-like closing portion 212 closing the front end opening of the side portion. And. The stator 22 and the rotor 23 of the motor are accommodated in an internal space surrounded by the first support plate 111, the side surface portion 211 and the closing portion 212 of the casing 11. A bearing 213 is attached to the inner surface of the closing portion 212, and the tip of the input shaft 31 is rotatably attached to the bearing 213.

  Further, the stator 22 of the motor 2 is attached to the inner surface of the closing portion 212 so as to surround the input shaft 31. The stator 22 is formed in an annular shape so as to surround the periphery of the input shaft 31, and a coil 221 to which power is supplied is provided. On the other hand, the rotor 23 is fixed to the input shaft 31. More specifically, a pair of radially outwardly extending vanes 231 are attached to the rear end of the input shaft 31, and the tips of the vanes 231 extend forward and face the coils 221 of the stator 22. The plate-like support portions 232 are connected. A magnet 233 facing the coil 221 is attached to the radially inward surface of the support portion 232. With the stator 22 and the rotor 23 configured as described above, the rotor 23 rotates with the input shaft 31 around the stator 22 around the axis X.

  Next, the operation of the drive device configured as described above will be described. First, when the motor 2 is driven, the input shaft 31 rotates with the rotor 23. Since the input shaft 31 is splined to the eccentric 4, the eccentric 4 also rotates around the axis X together with the input shaft 31. When the eccentric body 4 rotates, the first external gear 8 performs eccentric oscillation rotation around the first eccentric portion 43. As a result, a phenomenon occurs in which the meshing positions of the first external gear 8 and the internal gear 15 are sequentially shifted. Then, the first external gear 8 rotates relative to the fixed internal gear 15 by the difference in the number of teeth with the internal gear 15. That is, the first external gear 8 rotates. Similarly, the second external gear 9 rotates eccentrically and rotates relative to the internal gear 15. Thus, the rotation components of the external gears 8 and 9 are transmitted to the carriers 5 and 6 through the carrier pins 7, and the output shaft 32 is rotated.

  In the present embodiment, the number of external teeth of each of the external gears 8 and 9 is 29, the number of internal teeth of the internal gear 122 (outer pin 129) is 30, and the difference in the number of teeth is 1 Therefore, for each rotation of the input shaft 31 (eccentric body 4), the external gears 8 and 9 are displaced (rotate by one tooth) with respect to the internal gear 15. Thereby, one rotation of the input shaft 31 is decelerated to 1/30 of the rotation of each of the external gears 8 and 9. The rotations of the input shaft 31 and the output shaft 32 are opposite to each other.

  Next, a method and an apparatus 10 for manufacturing the external gear 8 will be described. The external teeth 84 have an epitrochoidal tooth shape, and here it is described how the external teeth 84 are formed. The external gear 8 and the external gear 9 have the same shape, and the external gear 9 can also be manufactured by the same manufacturing method.

  FIG. 15 is a block diagram showing the configuration of the manufacturing apparatus 10 for the external gear 8. The manufacturing apparatus 10 is an NC machine tool such as an NC (numerical control) machining center or an NC milling machine, and has a cutting tool 12 and a computer 13 for numerically controlling the operation of the cutting tool 12 as shown in FIG. In the present embodiment, an end mill is mounted as the cutting tool 12. The manufacturing apparatus 10 is also equipped with a transport mechanism 14 such as an arm for moving the end mill 12 to an arbitrary position, and the computer 13 controls the operation of the transport mechanism 14 to accurately track the movement of the end mill 12. Can be controlled. The manufacturing apparatus 10 also includes a drive device 27 such as a motor for driving the end mill 12 to rotate, and the operation of the drive device 27 is also controlled by the computer 13. In FIG. 15, the broken lines are communication lines, and the solid lines represent mechanical connections. The computer 13 includes a control unit 26 including a CPU, and a storage device 18 configured by appropriately combining a ROM, a RAM, a hard disk, a flash memory, and the like. In the storage device 18, a control program 18a that executes an operation described below is installed from a storage medium 18b such as a CD-ROM and stored.

  In manufacturing the external gear 8, first, a workpiece 20 to be processed is prepared. The work 20 is a disk-like member having a circular outer peripheral surface 25, and the outer peripheral surface 25 is a cutting surface on which the external teeth 84 are formed. The workpiece 20 is set at a predetermined processing position of the manufacturing apparatus 10.

  Subsequently, tooth shape data defining the tooth shape of the processed external tooth 84 is stored in the storage unit 18. At this time, the tooth profile data can be calculated by the computer 13 of the manufacturing apparatus 10, or values calculated by another computer can be input to the storage device 18. This tooth profile data is used to identify the movement trajectory of the end mill 12. As described above, since the external gear 8 is an epitrochoidal gear, this tooth profile data is data representing an epitrochoid parallel curve H1 (see FIG. 16). Therefore, in the process of cutting the external gear 84 by the end mill 12, the control unit 26 reads out this tooth profile data from within the storage device 18, and moves the end mill 12 so as to move along the epitrochoidal parallel curve H1 indicated by this tooth profile data. Control.

  The epitrochoid parallel curve H1 switches to an epitrokoid curve of different curvatures bordering the transformation point P0. FIG. 17 is a partially enlarged view of the external gear 8 and the vicinity thereof. As shown in FIG. 2, the external gear 8 alternately has 29 tooth tips 184 and tooth bottoms 185 along the outer circumferential direction, and the conversion point P 0 shown in FIGS. It is a point that forms the boundary between the outline of the tooth tip 184 of the tooth 84 and the outline of the tooth bottom 185. Therefore, there are 29 × 2 = 58 conversion points P0. When the conversion point P0 is the outermost point on the outer periphery of the external gear 8 from the center of the external gear 8 as the outermost point P1, and the point closest to the center of the external gear 8 is the innermost point P2. , And between points P1 and P2.

The epitrochoid parallel curve is generally represented by the following formula. (Α, β) are coordinates representing a point on an epitrochoid parallel curve. Here, α is the coordinate of the horizontal axis in the orthogonal coordinate system on the plane, and β is the coordinate of the vertical axis.

Here, Rc ′ is the radius of the internal tooth pin 152, and (α ₀ , β ₀ ), cos θ and sin θ are represented according to the following equations.

Is a parameter for drawing an epitrochoid curve, .pi. Is a circle ratio, Rpc is a radius of a pitch circle of the internal tooth pin 152, and Zb is a number of the internal tooth pin 152. (In the present embodiment, 30), Za is the number of teeth of the external gear 8 (in the present embodiment, 29), and x is a correction coefficient. Moreover, it is a = Rpc (1-x) / Zb. The correction coefficient x is a parameter that determines the curvature of the epitrochoid curve, and the curvature of the epitrochoid curve decreases as the value increases, and the curvature of the epitrochoid curve increases as the value decreases. The correction coefficient x is represented by the following equation using Rpc and Rb. R b is the radius of the rolling circle in the model describing the epitrochoid curve.

  In the epitrochoidal parallel curve H1, the correction coefficient x is larger at the tooth tip 184 side, and the correction coefficient x is smaller at the tooth root 185 side (see FIG. 18). In other words, the epitrochoid curve H3 indicating the tooth shape of the tooth bottom 185 is a curve that draws a steeper curve than the epitrochoid curve H4 which is an extension of the epitrochoid curve H2 indicating the tooth shape of the tooth tip 184. In addition, the epitrochoid curve H2 of the tooth tip portion 184 is an epitrochoid curve with a constant correction coefficient x, and the epitrokoid curve H3 of the tooth root portion 185 is as the correction coefficient x goes from the conversion point P0 to the innermost point P2. It is an epitrochoid curve which becomes smaller gradually. In other words, in the epitrochoid curve H3 of the tooth bottom 185, the correction coefficient x decreases as going from the shallow portion to the deep portion of the tooth bottom 185.

  A curve H4 shown in FIG. 16 is an epitrochoid curve obtained by extending the epitrochoid curve H2 of the tooth tip 184, and the correction coefficient x thereof is the same as the correction coefficient of the epitrochoid curve H2. As can be seen from the figure, the epitrochoid curve H3 of the tooth bottom 185 is the inside of the epitrochoid curve H4 in which the epitrochoid curve H2 representing the shape of the tooth tip 184 is extended, ie, from the tooth tip 184 to the tooth bottom 185 It is offset to the tooth root 185 side along the direction to which it faces.

  The correction coefficient x of the epitrochoid curve H3 of the tooth bottom 185 changes in accordance with a quadratic function f (γ) of the pressure angle γ. FIG. 18 is a graph showing the correction coefficient of the epitrochoidal parallel curve H1 according to the pressure angle γ. Here, the pressure angle γ is a pressure angle of the epitrochoid curve H2 of the tip 184 and the epitrochoid curve H4 that is an extension thereof. The pressure angle γ is a function of α-axis (horizontal axis) coordinates, and can be expressed as γ (α). Therefore, the coordinates (α, β) of the point on the epitrochoid curve H3 calculate γ (α), based on which the value of the correction coefficient x = f (γ (α)) is calculated, and this correction coefficient It is obtained by substituting the value of x into the equation of the above equation 4 and substituting the values of cos θ and sin θ obtained here into the equation of the above equation 1. The function f (γ) can be appropriately determined as a quadratic function of γ, but in the present embodiment, the correction coefficient x at the conversion point P0 is x = 0.3, and the correction coefficient x at the innermost point P2 Is set to be x = 0.1. The correction coefficient x of the epitrochoid curve H2 of the tooth tip portion 184 is x = 0.3.

  By the above calculation, the epitrochoid parallel curve H1 can be determined. Then, if coordinate data (tooth shape data) of each point on the epitrochoidal parallel curve H1 is set in the manufacturing apparatus 10 as a control parameter, the control unit 26 selects the tooth shape of the shape represented by the control parameter according to the control program 18a. The operation of the end mill 12 can be controlled to cut. As a result, since the cutting resistance is relatively small at the time of cutting of the tooth top portion 184, a tooth profile along the epitrochoid curve H2 is formed on the outer circumferential surface 25 of the work 20. In addition, since the cutting resistance becomes relatively large when the tooth bottom 185 is cut, a tooth profile shallower than the epitrochoid curve H3 is formed, and as a result, a tooth profile close to the epitrochoid curve H4 is formed. That is, by using the coordinate data of the epitrochoid parallel curve H1 synthesized from the epitrochoid curves H2 and H3 as control parameters defining the trajectory of the end mill 12, a tooth profile substantially along the epitrochoid curves H2 and H4 is formed. Can.

  The position of the conversion point P0 can be set as appropriate, but is preferably at or near the inflection point of the curve connecting the epitrochoid curves H2 and H4. This is because the cutting resistance is considered to be largely changed near the inflection point. More quantitatively, the ratio of the distance from the inflection point to the conversion point P0 to the distance between the adjacent points P1 and P2 along the connecting curves H2 and H4 is preferably 0.2 or less, more preferably It is 0.1 or less, more preferably 0.05 or less. Further, the position of the conversion point P0 can be set to the middle point of the adjacent points P1 and P2 on the connection curves H2 and H4 or in the vicinity thereof. More quantitatively, the ratio of the distance from the midpoint to the conversion point P0 to the distance between the adjacent points P1 and P2 along the connection curves H2 and H4 is preferably 0.2 or less, more preferably It is 0.1 or less, more preferably 0.05 or less.

  As described above, according to this embodiment, the following effects can be obtained. That is, in manufacturing the epitrochoidal gears 8 and 9, the locus of the relative movement of the cutting tool 12 with respect to the cutting surface 25 of the work 20 follows the epitrochoidal curve H2 at the tip 184 and at the root 185 Is controlled to follow an offset curve H3 drawn on the tooth bottom side of the epitrochoid curve H4 which is an extension of the epitrochoid curve H2. That is, at the tooth root 185 considered to have a large cutting resistance, the cutting tool 12 is controlled to move the epitrochoid curve H2 to a position deeper than the extended epitrochoid curve H4. As a result, the actually formed tooth profile has a shape that substantially matches the epitrochoid curve (that is, the epitrochoid curve H4) having the same correction coefficient x as the epitrochoid curve H2 not only at the tooth tip 184 but also at the tooth bottom 185 It becomes. Therefore, it is possible to obtain a trochoidal gear having a tooth profile closer to the target tooth profile (connection curve H2, H4).

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning.

  For example, the carrier pin can be fixed in various manners, for example, as shown in FIG. As shown in the figure, in this example, the axial length of the first diameter portion 531 and the second diameter portion 532 of the through hole 53 of the first carrier 5 is adjusted, and an internal thread is formed on the first diameter portion 531. Form. Then, the male screw 72 of the carrier pin 7 is screwed into this female screw. Also by this, the carrier pin 7 can be firmly fixed to both the carriers 5 and 6, and there is no problem even if the above-mentioned thrust force acts. In addition, in the rear end surface of the large diameter portion 73 of the carrier pin 7, a tool concave portion 77 into which a tool such as a hexagonal wrench can be inserted is formed in order to rotate and screw the carrier pin 7.

  In addition, as shown in FIG. In this example, the axial length of the first diameter portion 531 and the second diameter portion 532 of the through hole 53 of the first carrier 5 is adjusted, and a plurality of axially extending in the inner circumferential surface of the first diameter portion 531 Form a ditch. On the other hand, no large diameter portion is provided at the rear end portion of the carrier pin 7 and a spline 79 is formed at the front end portion of the carrier pin 7 instead of the male screw. Thus, the tip end of the carrier pin 7 and the first diameter portion 531 of the first carrier 5 are splined. Further, a third flange portion 58 protruding radially outward is formed on the outer peripheral edge on the rear end side of the first carrier 5, and the first flange portion is eliminated.

  On the other hand, the first diameter portion 631 of the through hole 63 of the second carrier 6 corresponds to the main body portion 71 of the carrier pin 7, and the second diameter portion 632 has a smaller diameter than the first diameter portion 631. Adjust the lengths of the parts 631 and 632. In addition, a fourth flange portion 68 protruding radially outward is formed on the outer peripheral edge on the tip end side of the second carrier 6, and the second flange portion is eliminated. Further, a projection 16 for pressing the first bearing 51 is formed on the rear end side surface of the first support plate 111 of the casing 11, and a second bearing 61 is formed on the front end side surface of the second support plate 112. Form a projection 17 for pressing the

  According to the configuration as described above, by tightening the bolt 114 of the casing 11, the first support plate 111 and the second support plate 112 approach each other, whereby the bearings 51 and 61 approach each other. Thereby, the first bearing 51 presses the first carrier 5 rearward via the third flange portion 58, and the second bearing 61 presses the second carrier 6 forward via the fourth flange portion 68. As a result, since the carrier pin 7 is pressed from both sides in the axial direction by both carriers 5 and 6, it is firmly fixed to both carriers 5 and 6 and there is no problem even if the above-mentioned thrust force acts.

  The rollers 83, 93 of the carrier pin 7 are rotatably attached to the carrier pin 7, but in order to facilitate this rotation, they can be configured as follows. That is, as shown in FIG. 6A, a plurality of grooves 831 extending in the axial direction are formed in the inner peripheral surfaces of the rollers 83 and 93, and lubricating oil is supplied to the grooves 831. Alternatively, as shown in FIG. 6B, a plurality of grooves 78 extending in the axial direction may be formed on the outer peripheral surface of the carrier pin 7, and lubricating oil may be supplied to the grooves 78. By so doing, the rotation of the rollers 83, 93 becomes smooth, and the wear resistance of the rollers 83, 93 and the carrier pin 7 is improved. In addition, since the gap between the inner circumferential surface of the rollers 83 and 93 and the outer circumferential surface of the carrier pin 7 is filled with the lubricating oil, noise at the time of driving can also be reduced. Note that the groove 78 can have various modes, and can be formed, for example, in a screw shape. As a result, the number of grooves decreases, so the contact area between the two increases, and there is an advantage that the strength is improved.

  It is possible to chamfer the boundaries (hereinafter referred to as edge portions 88, 98) between the end surfaces of the front end side and the rear end side of the external gears 8, 9 and the tooth surfaces. If the edge portions 88 and 98 are sharp, they may be broken due to stress concentration. Although the method in particular of a chamfer is not limited, For example, as shown in FIG. 7, it can process by electrical discharge machining or electropolishing. Fig.7 (a) is a perspective view of a chamfering process, FIG.7 (b) is sectional drawing. As shown to the same figure, the recessed part 102 of circular-arc-shaped cross section is formed in the periphery of the lower end of the cylindrical tool 101. As shown in FIG. Then, the concave portion 102 is brought into contact with the edge portions 88, 98 of the external gear wheels 8, 9, and the tool 101 is moved along the edge portions 88, 98 of the external gear wheels 8, 9 while rotating around the axis Z. To go. At this time, the external gear wheels 8 and 9 are electrically connected to the positive electrode, and the tool 101 is electrically connected to the negative electrode, and a voltage is applied between the two. As a result, the edge portions 88 and 98 of the external gears 8 and 9 are polished in an arc shape by electric polishing and chamfered.

  The needle bearing according to the above-described embodiment can be attached to the center through holes 81 and 91 of the external gears 8 and 9 as follows so as not to slip out in the axial direction during its rotation. In the following, the configuration of both needle bearings is substantially the same, so the first needle bearing 55 will be described. First, as shown in FIG. 8, radially outward of the base 563 of the shell 562 for manufacturing reasons. The face of the is inclined. That is, the outer diameter of the base 563 of the shell 562 is reduced from the front to the rear. The needle bearing 55 is easily disengaged from the external gear 8 due to this shape. Then, the shell 562 in which the roller 561 is accommodated is press-fit from the front into the central through hole 81 of the first external gear 8 and fixed to the first external gear 8. Further, the rear end portion of the base portion 563 is fixed to the inner peripheral edge of the central through hole 81 of the first external gear 8 by, for example, welding 103.

  Further, as shown in FIG. 9, a flange portion 821 that protrudes radially inward is formed on the inner peripheral edge on the rear end side of the center through hole 81 of the first external gear 8. Then, the shell 562 is formed in the same manner as in FIG. 8, and the shell 562 in which the roller 561 is accommodated is press-fit from the front into the center through hole 81 of the first external gear 8. The shell 562 is fixed to the first external gear 8 by press-fitting and abuts on the flange portion 821 so that the rearward movement of the needle bearing 55 is restricted.

  Furthermore, as shown in FIG. 10, the inner peripheral surface of the center through hole 81 of the first external gear 8 is formed so that the inner diameter decreases from the front to the rear. Then, using the same shell 562 as in FIG. 8, press-fit into the central through hole 81 of the first external gear 8. Also in this case, the shell 562 is fixed to the first external gear 8 by press-fitting, and the inner peripheral surface of the central through hole 81 is inclined, so that the rearward movement of the needle bearing 55 is restricted.

  Further, in the shell 562, the roller 561 can be configured as follows in order to rotate the roller 561 smoothly. For example, as shown in FIG. 11, a through hole 5641 is formed in the support portion 564 of the shell 562 so that the lubricating oil can be easily introduced to the roller 561 from the through hole 5641. Alternatively, as shown in FIG. 12, the outer peripheral surface of each of the eccentric portions 43 and 44 of the eccentric body 4 is formed in an arc shape in cross section. That is, it is curved so as to protrude radially outward. Thus, a gap is formed between the front end side and the rear end side of the roller 561 and the outer peripheral surface of the eccentric portions 43 and 44, so that the lubricating oil can be easily introduced into the gap. According to the example shown in FIGS. 11 and 12, since the lubricating oil is sufficiently supplied to the roller 561, the rotation of the roller 561 can be made smooth and the wear resistance is improved.

  As shown in FIG. 13, a ring-shaped weight 105 can be attached to the peripheral edge of the central through hole 81 at the front and rear end faces of the external gears 8 and 9. Thereby, the following effects can be obtained. First, in the reduction gear 1, vibration may occur due to a decrease in balance during driving. In order to reduce this vibration, it is necessary to evenly distribute the load. As the method, there is a method of increasing the number of teeth of the external gears 8 and 9 to disperse the load acting on the tooth surface, but if doing this, the number of parts increases and the assemblability decreases. Therefore, as described above, by attaching the weight 105 near the center of the external gears 8, 9 with a bolt 106 or the like, it is possible to concentrate the mass near the center. As a result, the moment from the center of the external gear wheels 8 and 9 decreases, and the vibration can be reduced even if the balance is reduced.

  Although two external gears are provided in the above embodiment, the number may be one or three or more. Also, the number of carrier pins is not particularly limited.

  In the above embodiment, although the internal gear 15 is formed by providing an internal tooth pin, internal teeth can also be formed directly on the inner peripheral edge of the outer cylinder.

  In the above embodiment, the cutting tool 12 is moved, but the work 20 can also be moved (including rotation). Alternatively, both can be moved.

  Although the cutting tool 12 is an end mill in the above embodiment, the present invention is not limited to this example, and may be, for example, a milling cutter.

  In the above embodiment, the function f (γ) for determining the correction coefficient x of the epitrochoid curve H3 of the tooth bottom 185 is a quadratic function of the pressure angle γ, but the present invention is not limited to this example. The correction coefficient x of the epitrochoid curve H3 can follow an arbitrary function as long as it is set to be smaller than the correction coefficient x of the epitrochoid curve H2. For example, the correction coefficient x of the epitrochoid curve H3 may be a constant value. Further, the correction coefficient x of the epitrochoid curve H3 may be a linear function of the pressure angle γ which decreases from the shallow to the deep of the tooth bottom 185. However, in the case of the linear function, the epitrochoid parallel curve H1 may be sharply bent at a connection point (that is, the conversion point P0) between the epitrokoid curve H2 and the epitrokoid curve H3. In order to avoid this and to obtain a smoother epitrochoidal gear, it is preferable to determine the correction coefficient x according to the quadratic function of the pressure angle γ described in the above embodiment. If the epitrochoidal parallel curve H1 is smooth, the epitrochoid tooth shape finally formed is also smooth, the rotation of the external gear 8 is smooth, and the durability is improved.

  In the above embodiment, although the external gear wheels 8 and 9 are epitrochoidal gears and the method of manufacturing them has been described, the same method can be applied to the formation of other trochoidal tooth profiles.

  Moreover, the manufacturing method of the trochoid gear demonstrated in the said embodiment can be used not only for an external gear but for manufacturing any trochoid gear which has a trochoid tooth profile. For example, the present invention can be applied to the manufacture of an internal gear having a trochoidal tooth profile and a linear gear. Further, the present invention can be applied not only to the trochoidal gear used for a reduction gear, but also to the manufacture of a trochoidal gear to be incorporated into a trochoidal pump, a motor or the like.

  Further, the epitrochoidal parallel curve H1 described above can be used not only when manufacturing a gear by cutting, but also when manufacturing a gear by a creation method. That is, a trochoid curve in which the correction coefficient x on the tooth bottom side is smaller than that on the tooth tip side is obtained, and a gear having a tooth profile along this curve can be manufactured. Tools may be manufactured. And, a trochoid tooth profile of a gear manufactured by using such a tool such as a hobbing machine or a gear grinder roughly draws a trochoid curve with a constant correction coefficient x.

1 Reduction gear 8 1st external gear (trochoid gear)
9 2nd external gear (trochoid gear)
10 Manufacturing equipment 12 End mill (cutting tool)
20 Workpiece 25 Outer peripheral surface (cutting surface)
18a Manufacturing program 184 Epitochoidal curve (first trochoid curve) of tooth tip 185 bottom H2 tooth tip
Epitrochoid curve (offset curve, second trochoid curve) at the bottom of the H3 tooth
x correction factor (parameter that determines the curvature of the trochoid curve)
γ pressure angle

Claims (6)

A method of manufacturing a trochoidal gear having a tooth tip and a tooth root alternately, comprising:
By controlling the cutting tool to move along the first trochoid curve relative to the cutting surface of the workpiece, the tooth tip having a shape along the first trochoid curve is formed on the cutting surface. Step to
The cutting tool is moved relative to the cutting surface along a second trochoid curve which is drawn closer to the bottom of the teeth than the first trochoid curve and draws a steeper curve than the first trochoid curve . Forming the tooth root of the shape substantially along the first trochoid curve on the cutting surface by controlling
Method of manufacturing trochoidal gears. The second trochoid curve is a curve drawn by changing a parameter for determining the curvature of the trochoid curve so that the curvature becomes larger as it goes from the shallow part to the deep part of the tooth bottom.
A method of manufacturing a trochoidal gear according to claim 1 . Said parameters vary according to a quadratic function of pressure angle,
A method of manufacturing a trochoidal gear according to claim 2 . Said parameters vary according to a linear function of the pressure angle,
A method of manufacturing a trochoidal gear according to claim 2 . What is claimed is: 1. A manufacturing apparatus of a trochoidal gear having alternately a tooth tip having a shape along a first trochoidal curve and a tooth bottom having a shape substantially along the first trochoidal curve ,
A cutting tool for cutting the tooth top and the tooth bottom on a cutting surface of a workpiece;
The cutting tool, relative to said cutting surface, said controlled to move along the first trochoidal curve during the formation of the tip portion than said first trochoidal curve during the formation of the tooth bottom portion A controller which is drawn on the bottom side of the tooth and is controlled to move along a second trochoid curve which draws a curve steeper than the first trochoid curve ;
Production equipment for trochoidal gears. A manufacturing program of a trochoid gear having a tooth tip and a tooth bottom alternately, comprising
By controlling the cutting tool to move along the first trochoid curve relative to the cutting surface of the workpiece, the tooth tip having a shape along the first trochoid curve is formed on the cutting surface. Step to
The cutting tool is moved relative to the cutting surface along a second trochoid curve which is drawn closer to the bottom of the teeth than the first trochoid curve and draws a steeper curve than the first trochoid curve . Controlling the computer to execute the steps of: forming the tooth root of the shape substantially along the first trochoid curve on the cutting surface;
Trochoid gear manufacturing program.