SU1468406A3 - Versions of milling cutter for round holes - Google Patents

Abstract

Each tooth (18,20) of the cutter (10) is formed with a radially outer cutting edge (38) and at least alternate teeth (18) are formed with radially extending, circumferentially staggered inner and outer cutting edges (34, 35 or 36:38). The bottom face of each tooth (18, 20) is formed with oppositely radially inclined inner and outer back-off clearance faces (56,58) which intersect in a downwardly extending crest (60) which intersects the radially outer cutting edge (38). The outer back-off faces (58) of alternate teeth (18) are vertically relieved relative to the outer back-off faces (58) of the intermediate teeth (20), and the inner back-off faces (56) of the intermediate teeth (20) are vertically relieved relative to the inner back-off faces (56) of the alternate teeth (18) a distance greater than the chip load at which the cutter is operated, so that the outer cutting edges (38) of alternate teeth (18) cut a chip (68) (Figure 7) only on an inner portion thereof and the outer cutting edges (38) of the intermediate teeth (20) a chip (64) only on an outer portion thereof. When each tooth (18, 20) has a single inner cutting edge (35, Figures 8-14) the inner back off faces may be relieved in that teeth (18) cut a chip on the outer part of the edge (35) only and teeth (20) on the inner part only. <IMAGE>

Description

cutters on the side of the front surface of one of the teeth in FIG. 11, the same, bottom view, plan; FIG. 12 is a partial view of a tooth followed by a tooth shown in FIG. ten; in fig. 13 - the same, bottom view, plan; on ymgo 14 - the entry of two consecutive teeth of the cutter into the workpiece

The milling cutter (FIGS. 1-7) includes a body 1 and a shank 2. The body 1 is the shape of an inverted cup having a side wall 3. The lower end of the side wall 3 along its periphery is made with a plurality of circumferentially spaced cutting teeth: one group of teeth is indicated 4, and the other - 5. They are interconnected so that the tooth 5 is located between successive teeth 4. Around the outer periphery of the cutter near each tooth is directed upward spiral groove 6 "The sequentially arranged spiral grooves 6 are separated by a ribbon 7 on the outside the periphery of the cutter. The front edge of each ribbon 7 is made with a narrow edge 8. Parts of the side wall 3 of the cutter between the teeth 4 and 5 contain cores 9. Each includes a circumferentially front side wall 10 and a rear side circumferentially 11. Each tooth 4 and 5 of the cutter can have up to three cutting edges 12-14. However, the milling cutter shown in FIG. 1-7, has only two cutting edges. The cutting edge 14 is divided into two parts 15 and 16. The cutting edge 14 is located at the lower end of the rear surface 17 of the inner cavity 18. The upper end of the cavity 18 is tilted radially outward in the upward direction (as shown surface 19).

Each tooth is made only with two cutting edges, and the internal cutting edge 20 is located throughout the entire core 9. There is no reason that the internal cutting 1 of the clamp 20 corresponds in width to the thickness of the core 9, approximately half or slightly more wall thickness milling. Since the inner cutting edge 20 is located across the entire width of the cutter, it is only necessary to provide one groove 18 between successive teeth.

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The outer rear surfaces of the 21 teeth 4 are vertically ground, and the internal rear surfaces of the 22 teeth 5 are similarly ground. Thus, the ridges 23 of consecutive teeth are dentate along the radius, as in the indicated embodiment. However, in the embodiment shown in FIG. 1-7, where the inner cutting edge 20 is located throughout the entire thickness of the cores 9, the inner rear surfaces of the 22 teeth 4 are laminated. These rear surfaces are flared upward only on a part of the schiria, namely on the inner part along the radius. This divides the inner cutting edges 20 of the teeth 4 into a radially inner portion 24 and a radially outer portion 25. The rear surfaces 22 of the teeth 4 are thus ground out, but their entire circumference, resulting in the rear surfaces 22 being divided into two parts 26 and 27 (line division between them - the ridge is designated 28).

From the cutting edge 13, the intersection line 28 is desirable to be separated radially inward from the safety seal 29 by a distance of one-fourth to one-half the thickness of the core 9. As a result, the desired size is obtained by using the inner cutting edges. Since parts of the internal rear surfaces 26 of the teeth 5 are laminated, long. obtaining the required cutting effect (it is necessary that parts of the surface 26 of the teeth 4 should be more relieved, preferably two or three times more to sew the stitches from the back surfaces of the teeth 5. For example, if the back surfaces of the 21 teeth 5 are relieved by about 0.010 inch The backing degree of the backs of the surfaces 27 of the teeth 4 should be approximately 0.020-0.030 inches along the inner periphery of the cutter.

The cutting action of the milling cutter is best illustrated in the perspective views of FIG. 7. The inner cutting edges of consecutive teeth cut chips having a width smaller than the width of the cutting edge 20. Since parts of the back surfaces 27 of each tooth 4 are ground (4g. 5 and 6), it follows that radially outer

part of the cut; the edges 20 on each tooth 4 cut the chips designated 30 and the radially part of the cutting edges 20 on each tooth 5 gives chips 31. The width of the chips 30 and 31 depends on the radial position of the intersection line 28. Since the inner radially the chips 31 must move along the radius a greater distance in order to reach the groove 6 of the milling cutter, it is desirable that the chips 31 have a width smaller than the chips 30. Thus, as shown in FIG. 7, where intersection line 28 is separated from zagotech 29 by distance, approximately equal to one third thickness of core 9, chips 3 are significantly narrower than chips 30.

Another modification of the present invention is depicted in FIG. 8-14. In it, each tooth 4 and 5 can have up to three cutting edges 12-14. The cutting edge 12 is located at a distance forward in rotation of the cutting edge 13, and the latter is located at a distance forward in the direction of rotation from the cutting edge 14. The cutting edge 12 is located at the lower end of the rear surface 17 of the inner depressions 18 formed in the core 9. The upper end of the cavity 18 is tilted radially outward in the upward direction (as shown by the surface 19). The cutting edge 13 is located at the lower end of the rear surface 32 of the secondary depression 33, which is also formed in the core 9 directly adjacent to the depression 18. The upper end of the secondary depression 33 turns upwards radially outwards (as shown by the surface 34) above the depression 18. The cutting edges 12 and 13 are separated by a circumferentially distributed bobbin 35 at the lower end of the radially inner surface of the hollow 33. The cutting edge 14 is located at the lower end of the adnei side wall 11 of the groove b and back away from the cutting edge 1 3 behind the safety device 36 at the lower end of the anavage 6.

The bottom surface of each tooth is complete with two backed surfaces 37 and 38. In the working condition of the cutter there is a radially internal

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the rear surface 37 is inclined relative to the axis and relative to the radius inward, and the radially outer surface 38 is inclined relative to the axis upward and relative to the radius outward. In addition, each of these back surfaces is inclined upward from the corresponding cutting edges in the circumferential direction to a slight degree, say 8-10, deflected radially to at an angle (-3) - (- 2525),

The chuck is necessary for the 1 ° back angle for re-edges when rotating the cutter. The two rear surfaces 37 and 38 intersect, giving the ridge 39, which intersects with the radially cutting outer edge 14, at the intersection of the downward direction, divided it into the radially wrist part of the edge 15 and the radially inner part of the edge 16, the radial tilt of the front surface 38 lies within about 5-35 relative to the horizontal and preferably

is approximately W.

Internal rear surface 37

horizontally, preferably at an angle of 15 °. As a result of tilting the back surfaces 37 and 38 in the radial and circumferential directions, the cutting edges 12-14 not only form teeth around the circumference, but also form teeth in the vertical direction when viewed from the front surface tooth.

When using the specified cutter chips, cut cutting edges 12 and 13, already the depth of the grooves 6 and

therefore easy to enter the grooves. However, when the cutting edge 14 cuts off the chips along its full width, then after cutting it expands and tends to tighten between the shoulder 36 and the wall of the hole being cut. The purpose of the present invention is to eliminate this tightening effect by ensuring that each outer edge 14 is cut.

chips having a width less than the width of the edge 14,

Thus, the ridge on the tooth x 4 is located radially inward relative to the ridge 39 on the tooth x 5. The radially stepped ridges 39 on

successive teeth x threads in- kggs due to the fact that on each tooth 4, the back surface 38 is sloped in the vertical direction

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radially upward relative to the back surface 38 of each tooth 5. This in itself leads to the fact that the ridge 39 of each tooth 4 is located radially inward relative to the ridge 39 of each tooth 5. In accordance with the present invention, the back surface 37 of each tooth 5 is similarly extended along its entire radial extent upward with respect to the back surface 37 of each tooth A. Gating the back surfaces 37 of the teeth 5 shifts the ridges 39 radially outward from the ridges 39 to the tooth x 4 in addition.

The degree of relief of these rear surfaces in the vertical direction is not significant. neither, but in any case it should be greater than the required theoretical load of chips on each tooth. For example, if a six-tooth milling cutter moves forward by. O, O, 12 inches per turn, the theoretical chip load: ki per tooth is 0.002 inches. Thus, if the theoretical load of the chips on each tooth is 0.002 inches, then the back surfaces 37 and 38 should be routed in the vertical direction for a distance greater than the length. In practice, if it is admissible that a chip load of 0.002 inch is the normal minimum load 1; oh chip at which the mill can work, and that the load. chips of about 0.005 dpi is the normal maximum chip load at which this type of round cutter operates, then vertical backing on the rear surfaces 37 and 38 should be in the range of 0.003-0.012 dcm. However, with large heavy milling machines, the speed under chi must be such as to create a chip load that is substantially larger than 0.005 inches, then the cutting may reach 0.020 inches. In practice, it is desirable for: to cinch these surfaces by an amount approximately equal to 0.007-0.010 inches, preferably by an amount approximately equal to 0.009 inches. As can be seen, the maximum degree of relief is associated with the angles of radial inclination of the back surfaces and with the width of the outer cutting edge, as a result

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which, in the presence of patching, the ridge 39 still crosses the outer cutting edge 14, and not the intermediate cutting edge 13.

It is highly desirable to ground the inner and outer rear surfaces so that the ridges of consecutive teeth are located approximately on. equal distances x radially from the radial center line of the groove. When the ridges are positioned in this way, the outer cutting edges of the consecutive teeth cut chips of approximately the same width, which is only slightly wider than half the depth of the groove. B. As a result, all chips have a maximum clearance in the grooves 6,

FIG. 14a, a milling cutter is presented in a position in which the cutting edge 13 only began to penetrate the upper surface of the workpiece and therefore cut the narrow chips 40 from the upper surface of the workpiece. In this position, the cutting edge 14 of the odd-numbered tooth has not yet touched the workpiece, and the lower point of the cutting edge 12 is about to touch the workpiece. When the milling cutter rotates one tooth pitch and moves axially from the position shown in FIG. 14, and the cutting edge 14 of the even tooth cuts into the workpiece, creating chips 41. The cutting edges 12 and 13 on the specified tooth are vertically sharpened for a distance exceeding the theoretical load of the shavings generated by the axial feed speed, and thus the cutting edge 13 is actually located at a distance above the groove created before this corresponding edge 13 of the odd tooth.

-In the next increment of rotation

and axial movement of the milling cutter (Fig. 14, c), the chips 40 produced by the cutting edge 13 of the odd tooth are relatively thick, since this cutting edge is not vertically built, but the cutting edge 12 of the same tooth cuts the chips, denoted by 42. radially the inner part of the cutting die 14 on an odd tooth begins cutting and creates chips 43. When the tool rotates one more increment (4 mg. 14 g), the radially outer part of the cutting edge .14 cuts a wider and deeper

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the groove than the 14-even tooth previously cut by the edge, resulting in chips 41 wider and thicker than the chips obtained by the inside of the cutting edge 14 of the previous tooth. Since the edges 12 and 13 of the next tooth are vertically extended to a distance greater than the load of the chips, they are located at a distance above the bottom of the groove formed by the corresponding modes of the odd teeth. FIG. 14, d shows the cutting action of the next odd tooth after an additional increment of rotation and feed. Cutting edges 12 and 13 now cut chips 40 and 41, but only the radially internal part of the cutting Kpot-i-ki 14 is effective, with the result that the chips 43, which are cut by it, are wider than the chips, cut by the internal part of the cutting edge 14 of an odd tooth.

Although the chips 40 and 41 correspond in width to the cutting edges of 13 and 12, respectively, and even though these chips expand somewhat immediately after their formation, they tend to be drawn into the mill if they are relatively narrow, since after the formation of chips 42, it is radiated outwards into the adjacent groove 6 by the upper surface 19 of the cavity 18. Similarly, after the formation of chips 40, it is directed radially outwards to the adjacent groove 6 by the upper surface 34 of the secondary depression 33. The cutting edges 12 and 13 are guided into the adjacent groove 6 immediately after formation, and since the radial depth of the groove 6 greatly exceeds the width of the shavings 40 and 42, they usually move gently up along the groove without encountering obstacles.

After all the cutting edges have penetrated into the workpiece (FIG. 14, cc), each of the cutting portions 15 and 16 gives shavings of menichi shichiriny than the width of the cutting edge 14. Thus, the radially outer portion of the edge 14 on each second tooth cuts the chips 41, and the radially inner part of each cutting edge passes the interstitial point. Tooth x cuts the chips 43. Therefore, since each of the shavings 41 and 43 are of radial depth

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grooves 6, these chips move freely along the grooves.

Since the back surfaces 37 and 38 are alternately vertically vertical, as indicated, to a degree greater than the theoretical load of the chip, it is obvious that after all the teeth have penetrated into the workpiece, all the chips are relatively thick and have an actual maximum thickness exceeding the theoretical load of the chip. When the chips are relatively thick, they tend to remain 15 with mostly straight rather than tightly twisted, therefore, they do not tend to overlap with other chips and therefore move more easily up the grooves of the cutter. In addition, since all rear surfaces 38 are inclined to the horizontal at a relatively small angle, preferably at an angle of about 10, the chips cut first by the hem portion 25–15 are directed mainly up the groove rather than radially inwards towards the radially the inner surface of the grooves. This facilitates the unrestricted free movement of all the chips formed by the cutting edges up the grooves.

When the movement of the chips from the cutting edges up along the grooves occurs unchecked, a twisting mo- ny. 35 cop and feed effort required

The dp of driving the milling cutters is greatly reduced. In addition, since the cutting edges remain sharp and because the chips do not stick to the wall of the hole being cut, the quality of the surface that is obtained turns out to be much higher than 30.

0

the quality of the surface obtained by means of known cutters.

In accordance with the invention, the cutting action is performed by cutting edges 12 and 13 of only even teeth. Since the cutting edges 12 and 13 of the teeth 5, (namely,

0 even teeth in implementation) do not perform cutting, cutting edges 12 and 13 on these teeth x may not be done at all; | This is easy to do by completely grinding each tooth 5 by

g its width, as shown by the dotted radial line 44 in FIG. 9 and 11. In this case, the inner cutting edges 12 and 13 have only the tooth 4. When the tooth 5 is made with only one outer cutting edge U, the circumference of each tooth 5 around the circumference is relatively small, and since each tooth 5 cuts only one narrow the chip, the adjacent groove 6 may be significantly narrower than the grooves adjacent to the teeth 4, which must be passed through three narrow chips. In this way,

when the tooth 5 is made with only one cutting edge, a greater number of teeth can be made on the cutter of a predetermined diameter. With the increase in the number of teeth not only

The cutter is stronger, but the cutting speed increases at the same surface speed. Moreover, since only a part of the cutting edges on each tooth is actually cutting, the remaining parts are easily filled with cooling fluid flowing down the channel in the cutter shank due to whereby the heat generated during cutting is easily dispersed.

Claims (7)

1. A milling cutter for round holes, comprising a body having a generally circular cylindrical side wall with a series of cutting teeth, spaced apart from each other around a circumference around its lower end, a number of grooves formed upward around the side wall its lower end, each tooth being connected to the next adjacent tooth with a circumferentially extending core located near the inner periphery of the side wall, the cores alternating radially with grooves, each of which has spaced the circumferential front and rear side walls and the circumferential inner wall forming the radial outer surface of the core, characterized in that, in order to increase the productivity and durability of the cutter by improving chip breaking, every second tooth of the latter has a radially inner cutting edge , the hollows on the core are located upward from each of the inner edges and extend radially outward into the adjacent groove, all the teeth have radially outer cutting edges, which are formed by the lower end of the back wall of the adjacent groove, the radially outer cutting edge of each second tooth is made stepped circumferentially back from the inner cutting edge of the tooth relative to the direction of rotation of the cutter, each tooth has a radially inner rear surface tilted down and radially outwards , and a radially external back surface, inclined downwards and radially inwards, which, at the intersection, form a ridge, extending mainly around the circumference and an outer cutting edge that divides at the front end onto a radially outer part and a radially inner part, the radially outer posterior surfaces of each second tooth are made upwardly radiated relative to the radially outer surfaces of the intermediate teeth located between each second teeth, and the radially inner posterior surface of the intermediate tooth performed backed up relative to the outer rear surfaces of each of the second teeth. 2. The milling cutter according to claim 1, wherein the inner and outer posterior surfaces are ground over the entire radius thereof with the possibility of placing the crests of each second tooth radially inward from the crown of the intermediate teeth. 3. The milling cutter according to claim 1, in accordance with clause 1, so that the intermediate teeth are made with internal cutting edges similar to the cutting edges of the second teeth. 4. in accordance with claim 1, of which is. the size of the inner parts of the inner posterior surfaces of each second tooth is greater in height, what is the height of the inner posterior surfaces of the tooth teeth. 5. A milling cutter in accordance with Clause 4, which means that the degree of backing of the radially inner parts of the trailing posterior surfaces of each second tooth on the inner periphery of the milling cutter is 2-3 times more than the filling of the inner hind surfaces. surfaces of intermediate teeth on the inner periphery of the cutter. 6. A milling cutter according to claim 2, characterized in that the inner and outer rear surfaces are assembled with the possibility of assigning each second and intermediate teeth along a radius to a distance equal to the radial center line of the grooves. 7. A milling cutter for round holes, comprising a housing having a generally circular cylindrical wall with a series of cutting teeth located at a distance from each other circumferentially around its lower end, a series of grooves made up around the side wall from its lower end, each tooth being connected to the following one; the circumference of the core, located near the inner periphery of the side wall, the cores alternating radially with grooves, each of which has anterior and posterior side walls spaced around the circumference and an circumferentially inner circumferential wall the outer surface of the core, characterized in that, in order to increase the productivity and durability of the cutter by improving chip breaking, each second tooth is filled at its core with three radially adjacent cutting edges, namely: a radially inner cutting edge, a radially intermediate cutting edge and radially the outer cutting edge, where the intermediate cutting edge is located along the circumference with a ledge directed backwards relative to the inner edge and forward relative to the outer cutting edge in the course of rotation of the cutter, the core being made with a second recess directed upward from the intermediate cutting edge and radically opening the adjacent groove, each tooth is made with an outer rear surface and an inner rear surface, which, at the intersection, form a ridge that dissects the outer cutting edge a radially inner part and a radially outer part, each second tooth being made with a rounded outer back surface relative to the outer back surface of the intermediate tooth, and each intermediate tooth is filled with a back internal surface relative to the inner back surface of each second tooth and each intermediate tooth It has only one cutting edge, which is located from the outer to the inner periphery of the cutter, where the inner radial part of the single cutting K15 BOM aspolagaets over the inner cutting edge of each second tooth. Priority points: 09/27/82 in paragraphs 1, 2, 6, 7; 12.08.83 pp. 3, 4, 5. X  .J F r5 7v 23 Fig.z p a js yy phage.7 If " s ftsg.o 3 corner I I t w g gz / u. 77 to 19 18 36 czig 11 6 36