JP2010025256A - Rolling screw device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling screw device which hardly causes damage even at high-speed operation and is long in service life. <P>SOLUTION: A ball screw is composed of a screw shaft 1, a nut 2, a plurality of rolling elements 3 freely rollingly loaded in a rolling element rolling passage 4 and a rolling element circulation member 6 containing a rolling body circulation passage 5. A tongue member 7 for scooping up and introducing into the rolling body circulation passage 5 the rolling element 3 reaching an endpoint of the rolling element rolling passage 4 by rolling in the rolling element rolling passage 4 is arranged in the vicinity of the end of both ends of the rolling body circulation passage 5 which is arranged in the endpoint of the rolling element rolling passage 4. The rolling element 3 is scooped up along a tangential direction and the lead angle direction of the rolling element rolling passage 4 in the endpoint of the rolling element rolling passage 4 when the nut 2 is viewed from an axial direction by the tongue member 7. The tongue member 7 is not mounted in the nut 2 and the rolling element circulation member 6, held between the screw shaft 1 and the rolling element circulation member 6, and loosely fitted to each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rolling screw device such as a ball screw and a roller screw.

  As a rolling screw device, a ball screw whose rolling element is a spherical ball and a roller screw whose rolling element is a roller having a cylindrical shape or a truncated cone shape are known. In a rolling screw device, a rolling element that rolls in a rolling element rolling path formed by a space between a screw groove of a screw shaft and a screw groove of a nut is connected to the rolling element rolling path by a rolling element circulation path. Relative linear movement between the screw shaft and the nut is smoothly performed by circulating from the end point to the start point. And the rolling element which reached the end point of the rolling element rolling path is scooped up by the tongue part distribute | arranged to the edge part of the rolling element circulating path, and it introduce | transduces in a rolling element circulating path.

  Such a rolling screw device is used for, for example, a machine tool feeding device. However, in recent years, the demand for speeding up of machine tools and the like has increased, and accordingly, the speed of the rolling screw device (that is, rolling elements) is increased. Speeding up the revolution speed). And in order to achieve the high speed of the rolling screw device, it is important to prevent the rolling screw device from being damaged even if the rolling member collides with the tongue when the rolling member is scooped up. It was. Therefore, the strength of the members constituting the tongue portion (for example, thickening of the members) and the rolling-up method of the rolling elements such that the force acting on the tongue portion is reduced (for example, the rolling elements are turned into rolling element rolling paths). The method of scooping up in the tangential direction) has been studied.

  In order to roll up the rolling element in the tangential direction of the rolling element rolling path, it is necessary to make the rolling element circulation path into a complicated shape, but the rolling element circulation member having a complex shape rolling element circulation path Since it is not easy to configure the rolling member with a metal material, the rolling element circulating member is configured with an injection molded product of a resin material or the like. As shown in FIG. 10, when the rolling element circulation member and the tongue portion are integrally formed of a resin material, the material of the entire rolling element circulation member is determined according to the tongue portion that requires strength. (For example, refer to Patent Document 1).

When the rolling element circulation member and the tongue portion are separate members, the tongue portion is fixed to the nut (see, for example, Patent Document 2). In that case, the impact force when the rolling element collides with the tongue portion is received by the fixing portion between the nut and the tongue portion. In addition, during high-speed operation, a force resulting from the rolling elements competing in the rolling element circulation path is also applied. Therefore, since the tongue portion needs to be made of a material having higher strength than the rolling element circulating member, the tongue portion is made of a scraped steel material or a sintered material. And the fixing | fixed part of the tongue part needed to be high intensity | strength to the extent which can receive the above-mentioned impact force.
JP 2005-83519 A JP 2005-351340 A

  However, since a force that presses radially inward due to the collision of the rolling elements acts on the tongue portion, a large force acts on a portion that supports the tongue portion. Therefore, a rolling screw device including a member in which a rolling element circulation member and a tongue portion are integrally formed as described in Patent Document 1, and a tongue portion as described in Patent Document 2 are fixed to a nut. In the rolling screw device, the portion other than the tip of the tongue portion tends to be easily damaged during high-speed operation. That is, in the case of the rolling screw device described in Patent Document 1, an upper portion of the tongue portion (corresponding to a portion that supports the tongue portion) among members in which the rolling element circulation member and the tongue portion are integrally formed. In the case of the rolling screw device described in Patent Document 2, the fixing portion of the tongue portion with the nut tends to be damaged.

Thus, since the part which supports or fixes a tongue part is easy to be damaged, it has become a big obstacle to the high speed of the rolling screw device. If the size and thickness of the portion that supports or fixes the tongue portion is increased, the strength of the portion can be improved. However, such means has a problem that the degree of freedom in design is reduced.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems of the conventional rolling screw device and to provide a long-life rolling screw device that is hardly damaged even at high speed operation.

  In order to solve the above problems, the present invention has the following configuration. That is, the rolling screw device according to the first aspect of the present invention includes a screw shaft in which a spiral groove is formed on the outer peripheral surface, and a screw groove facing the screw groove of the screw shaft is formed on the inner peripheral surface. And a plurality of rolling elements that are movably loaded in a spiral rolling element rolling path formed by a space between the screw grooves, and the rolling elements that are attached to the nut. Rolling element circulation member having a rolling element circulation path that circulates the rolling element by sending the rolling element rolling path from the end point to the starting point, and by the relative rotational motion of the screw shaft and the nut, In the rolling screw device in which the screw shaft and the nut are relatively linearly moved in the axial direction via rolling of the moving body, an end point of the rolling body rolling path among both ends of the rolling body circulation path In the vicinity of the end portion of the rolling element, the rolling element rolling path A tongue member that rolls up the rolling element that reaches the end point of the rolling element rolling path and introduces the rolling element into the rolling element circulation path is disposed, and the nut is viewed from the axial direction by the tongue member. The rolling element is scooped up along the tangential direction and the lead angle direction of the rolling element rolling path at the end point of the rolling element rolling path in the case of And it is not attached to the said rolling-element circulating member, It is pinched | interposed between the said screw shaft and the said rolling-element circulating member, It is characterized by the above-mentioned.

According to a second aspect of the present invention, there is provided the rolling screw device according to the first aspect, wherein the tongue member is integrally formed of resin and metal and is in contact with the screw groove. Is made of resin.
Furthermore, the rolling screw device according to claim 3 of the present invention is characterized in that in the rolling screw device according to claim 2, the resin is an oil-containing resin.

Furthermore, the rolling screw device of Claim 4 which concerns on this invention is a rolling screw device as described in any one of Claims 1-3. The front-end | tip part which contacts the said rolling element among the said tongue members is a corner | angular part. The tongue member is arranged so that the step is not curved and has a curved shape, and the step between the screw groove and the tip of the tongue member is 5% or less of the diameter of the rolling element. It is characterized by being.
Furthermore, the rolling screw device according to claim 5 according to the present invention is the rolling screw device according to any one of claims 1 to 4, wherein the rolling element circulation path is formed by an inner wall surface of a through hole formed in the nut. At least a part of which is configured.

  The rolling screw device of the present invention is not easily damaged even at high speed operation and has a long life.

An embodiment of a rolling screw device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a ball screw which is an embodiment of a rolling screw device according to the present invention. FIG. 2 is a cross-sectional view taken along the line AA of the ball screw of FIG. In the drawings used for the following description, the same or corresponding parts are denoted by the same reference numerals.
As shown in FIGS. 1 and 2, the ball screw of the present embodiment has a screw shaft 1 in which a spiral groove 1 a is formed on the outer peripheral surface, and a spiral groove 2 a on the inner peripheral surface. And a cylindrical nut 2 formed. The screw shaft 1 is inserted into the nut 2, the screw groove 1 a of the screw shaft 1 and the screw groove 2 a of the nut 2 face each other, and a spiral rolling element rolling path is formed by a space between the screw grooves 1 a and 2 a. 4 is formed. A plurality of rolling elements 3 (balls) are slidably loaded in the rolling element rolling path 4, and the nut 2 is screwed to the screw shaft 1 through the rolling elements 3.

  The nut 2 is formed with a hole 2b that communicates the outer peripheral surface and the inner peripheral surface, and a rolling element circulation member 6 (see FIG. 3) having a rolling element circulation path 5 is attached in the hole 2b. It has been. Then, the rolling element 3 that moves around the screw shaft 1 a plurality of times while moving in the rolling element rolling path 4 and reaches the end point of the rolling element rolling path 4 is arranged near one end of the rolling element circulation path 5. The tongue member 7 is rolled up, passes through the rolling element circulation path 5, and is sent to the starting point of the rolling element rolling path 4 by the tongue member 7 disposed in the vicinity of the other end of the rolling element circulation path 5. It has become.

  Thus, since the rolling element 3 rolling in the rolling element rolling path 4 is infinitely circulated by the rolling element circulation path 5, when the screw shaft 1 and the nut 2 are relatively rotated, The screw shaft 1 and the nut 2 continuously move relative to each other in the axial direction. In addition, in this embodiment, as shown also in FIG. 1, it has the structure which has two circulation circuits which consist of such a rolling element rolling path 4 and the rolling element circulation path 5. FIG.

Here, the rolling element circulating member 6 of FIG. 3 is configured by overlapping two parts as shown in FIG.
Further, the tongue member 7 is a slightly curved substantially rod-like member, and in the case of being disposed at the X and Y positions in FIG. 1, one end portion is obliquely cut from the end face toward the side face as shown in FIG. As a result, a tongue portion 7a is formed at the one end portion by colliding the rolling element 3 and scooping it up. The tongue member 7 is disposed between the screw grooves 1a and 2a with one end portion having the tongue portion 7a facing the rolling element rolling path 4 and the other end portion of the cut-out surface facing the rolling element circulation path 5. Thus, the rolling element rolling path 4 and the rolling element circulation path 5 are connected. On the other hand, in the case of the tongue member 7 arranged at the position Z in FIG. 1, as shown in FIG. 2, the tongue portions 7a are formed at both ends, and both tongue portions 7a are each of two circuit circulation circuits. It is responsible for scooping up one end of the.

  Moreover, the tongue member 7 is arranged so that the rolling element 3 reaching the end point of the rolling element rolling path 4 can be scooped up along the lead angle direction. Further, the tongue member 7 is configured such that when the rolling element 3 reaching the end point of the rolling element rolling path 4 is viewed from the axial direction, the rolling element rolling path 4 at the end point of the rolling element rolling path 4 is obtained. It is arranged so that it can be scooped up along the tangential direction. For this reason, even when the rolling element 3 collides with the tongue 7 a of the tongue member 7 when the rolling element 3 is scooped up, the force acting on the tongue member 7 is small.

  Further, the tongue member 7 is not fixed to the nut 2 and the rolling element circulation member 6, and is sandwiched between the screw shaft 1 and the rolling element circulation member 6, and the thread groove 2 a of the screw shaft 1 and the nut 2 and It is loosely fitted in a gap formed between the rolling element circulation member 7. Therefore, the force acting on the tongue member 7 due to the collision of the rolling elements 3 is sufficiently mitigated from being transmitted as an impact to the nut 2 and the rolling element circulation member 6.

For these reasons, even if the force that presses radially inward due to the collision of the rolling elements 3 acts on the tongue member 7, the portion that supports the tongue member 7 is not damaged. Therefore, this ball screw has a long life even when operated at high speed.
Further, the vibration of the tongue member 7 due to the collision of the rolling elements 3 is hardly transmitted to the rolling element circulation member 6 and the nut 2, and the tongue member 7 is not fixed and can move in the radial direction. This ball screw has low vibration and low noise because the force pressing inward is reduced.

Further, since the vibration of the tongue member 7 is hardly transmitted to the rolling element circulation member 6 and the nut 2, the rolling element circulation member 6 does not need to have high strength and has only a function of circulating the rolling element 3. Since it is good, it can be thinned. Therefore, the rolling element circulation member 6 can be efficiently disposed on the nut 2.
Furthermore, since a large-diameter rolling element can be used, the rated load can be increased. Furthermore, the processing cost can be reduced.

Such a ball screw can be suitably used for a machine tool feeding device (for example, a mold clamping mechanism of a mold clamping device incorporated in an electric injection molding machine or a press machine). However, the application of the rolling screw device of the present invention is not limited to the above.
Here, the tongue member 7 will be described in more detail. The length of the tongue member 7 (the length in the moving direction of the rolling element 3) is 1.5 times or more and 5 times the diameter of the rolling element 3 so that the posture of the tongue member 7 is stabilized between the screw grooves 1a and 2a. The following is preferable. Moreover, if the wing | blade part 7b extended along a longitudinal direction is provided in a both-sides part or one side part, and it accommodates in the clearance gap between the outer peripheral surface of the screw shaft 1 and the inner peripheral surface of the nut 2 (refer FIG.5, 6). The stability of the posture of the tongue member 7 can be further improved.

  Moreover, you may employ | adopt the positioning structure (refer FIG. 7) which prevents the tongue member 7 from moving along the moving direction of the rolling element 3 by the collision of the rolling element 3. FIG. That is, if the protrusion 7 c is provided on the outer surface of the tongue member 7 and inserted into the recess 10 formed in the nut 2, the tongue member 7 can be prevented from moving along the moving direction of the rolling element 3. However, the concave portion 10 and the projection 7c are not fitted and fixed, but are loosely fitted so as not to prevent the minute movement of the tongue member 7 in the radial direction. Since the force in the moving direction of the rolling element 3 received by the tongue member 7 due to the collision of the rolling element 3 is not so large, the tongue member 7 is prevented from moving along the moving direction of the rolling element 3 by the loose fitting as described above. can do.

  However, in the case of the tongue member 7 in which the tongue portion 7a is formed only at one end portion (the tongue member 7 arranged at the positions X and Y in FIG. 1), the balance of the acting forces cannot be taken, and the spiral direction Therefore, the tongue member 7 may be pressed by a pin 11 which is press-fitted into a hole provided in the nut 2 and attached as shown in FIG. 8 which is a BB cross-sectional view of the ball screw of FIG. Since this pin 11 receives only the force in the moving direction of the rolling element 3 acting on the tongue member 7, the impact force due to the collision of the rolling element 3 is relieved by the tongue member 7 coming into contact with the screw shaft 1 or the like. . On the other hand, in the case of the tongue member 7 (the tongue member 7 arranged at the position of Z in FIG. 1) in which the tongue portions 7a are formed at both ends, the tongue portions 7a at both ends are respectively responsible for the force by the rolling elements 3. Therefore, it is not necessary to provide the pin 11 or the like.

  Further, the material of the tongue member 7 is not particularly limited, but it is preferable that the tongue member 7 is integrally formed of resin and metal. Since the part which contacts the thread groove 1a and the rolling element 3 is preferably excellent in slidability and lubricity, it is preferable that the part is made of resin. If this resin is an oil-containing resin obtained by mixing a lubricating oil and a resin, extremely excellent lubricity can be obtained. The protrusion 7c of the positioning structure described above may be made of metal.

  Further, since the tongue portion 7a of the tongue member 7 is in contact with the rolling element 3, the tip portion thereof does not have a corner, and has a curved surface (for example, a cross section broken along the moving direction of the rolling element 3 is a circle). It is preferable that the shape is an arc. In order to smoothly roll up the rolling element 3, the step H formed between the thread groove 1 a and the tip of the screw shaft 1 is 5% or less of the diameter of the rolling element 3. The tongue member 7 is preferably disposed.

  Furthermore, in this embodiment, since almost no force is transmitted from the tongue member 7 to the rolling element circulation member 6, the rolling element circulation member 6 does not need to support the tongue member 7, and serves as a path for circulating the rolling element 3. It only has to have a function. Therefore, in this embodiment, the entire rolling element circulation path 5 is formed in the rolling element circulation member 6, but a part of the inner wall surface of the hole 2 b provided in the nut 2 is at least a part of the rolling element circulation path 5. (See FIG. 9). As a result, the size of the hole 2b provided in the nut 2 can be reduced as compared with the case where the entire rolling element circulation path 5 is formed in the rolling element circulation member 6 (the hole indicated by the dotted line in FIG. 9). In addition, interference between the thread groove 2a of the nut 2 and the rolling element circulation path 5 can be avoided, and the specification using a rolling element having a large diameter can be accommodated.

  In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, a ball screw having two circulation circuits has been described. However, the circulation circuit may be one circuit or three or more circuits. In the present embodiment, the ball screw is shown and described as an example of the rolling screw device. However, the rolling screw device of the present invention can be similarly applied to a roller screw whose rolling element is a roller.

It is a top view of a ball screw which is one embodiment of a rolling screw device concerning the present invention. It is AA sectional drawing of the ball screw of FIG. It is a perspective view of a rolling element circulation member. It is a perspective view of the parts which constitute a rolling element circulation member. It is a perspective view of a tongue member. It is sectional drawing explaining that the stability of the attitude | position of a tongue member can be improved with the wing | blade part of a tongue member. It is sectional drawing explaining the positioning structure of a tongue member. It is BB sectional drawing of the ball screw of FIG. It is sectional drawing explaining the rolling element circuit which the one part comprised by a part of inner wall surface of the hole provided in the nut. It is a perspective view of the rolling element circulation member of the conventional ball screw.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screw shaft 1a Thread groove 2 Nut 2a Thread groove 2b Hole 3 Rolling element 4 Rolling element rolling path 5 Rolling element circulation path 6 Rolling element circulation member 7 Tongue member 7a Tongue part

Claims (5)

A screw shaft in which a spiral groove is formed on the outer peripheral surface, a cylindrical nut in which a screw groove facing the screw groove of the screw shaft is formed on the inner peripheral surface, and a space between the two screw grooves A plurality of rolling elements loaded in a freely rolling manner on a spiral rolling element rolling path formed by the above, and attached to the nut, the rolling element is sent from the end point to the starting point of the rolling element rolling path A rolling element circulation member having a rolling element circulation path that circulates the rolling elements, and the screw shaft and the nut via the rolling of the rolling element by the relative rotational movement of the screw shaft and the nut. In the rolling screw device that is designed to move in a relative straight line in the axial direction,
Of the two ends of the rolling element circulation path, in the vicinity of the end arranged on the end point of the rolling element rolling path, the rolling element rolling path is rolled to the end point of the rolling element rolling path. The tongue member which scoops up the reached rolling element and introduces it into the rolling element circulation path is arranged,
By this tongue member, the rolling element is scooped up along the tangential direction and the lead angle direction of the rolling element rolling path at the end point of the rolling element rolling path when the nut is viewed from the axial direction. As well as
The rolling screw device according to claim 1, wherein the tongue member is not attached to the nut and the rolling element circulation member, and is loosely fitted between the screw shaft and the rolling element circulation member.   2. The rolling screw device according to claim 1, wherein the tongue member is integrally formed of a resin and a metal, and a portion in contact with the screw groove is formed of a resin.   The rolling screw device according to claim 2, wherein the resin is an oil-containing resin.   A tip portion of the tongue member that is in contact with the rolling element does not have a corner and is curved, and a step between the screw groove and the tip portion of the tongue member is formed on the rolling member. The rolling screw device according to any one of claims 1 to 3, wherein the tongue member is disposed so as to be 5% or less of the diameter.   The rolling screw device according to any one of claims 1 to 4, wherein at least a part of the rolling element circulation path is constituted by an inner wall surface of a through hole formed in the nut.

Images