JP2010058210A - Method of manufacturing rack, and the rack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve machining speed when machining a workpiece surface. <P>SOLUTION: On an outer peripheral edge portion 7 of a disc 6, a plurality of tooth form portions 8 is provided radially from the center of the disc 6 at intervals Z along the outer peripheral edge portion 7. A cutting hard tip 11 is provided on a rising front end surface 10 in a circumferential direction of the disc 6 of the teeth portions 8. An impact resisting member 12 is interposed between the rising front end surface 10 and the hard tip 11. By rotations of the disc 6, the cutting hard tip 11 intermittently hits on a tooth surface 19 of the rack 2 which is a workpiece, thereby cutting the tooth surface 19. Impact at that time can be absorbed to some extent by the impact resisting member 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a rack for a pinion and a rack.

  Conventionally, a combination of a pinion and a rack is used in a steering rack or the like that is used for steering a car in which a rack 22 is cut into a tie rod 21 and the tie rod 21 is directly operated by a pinion 23 directly connected to a handle as shown in FIG. Yes.

  A rack or other rack in such an automobile steering apparatus is formed by processing a steel material with a hob cutter or a broach cutter and arranging a plurality of tooth portions in parallel to form a rack body (for example, Patent Document 1), and further, a luxury vehicle, etc. In this case, the tooth surface of the tooth portion was quenched by induction hardening or the like to increase the hardness, and then the tooth surface was finished by grinding with a grindstone.

In addition to excellent rigidity and durability, hardened racks can be expected to have characteristics such as low vibration and low dust generation. It was a finished product. However, finishing by tooth polishing after quenching has been limited to some luxury cars. This is because finishing of the tooth surface after quenching has a high processing cost.
Japanese Utility Model Publication No. 62-11532

  As in the prior art, as a method of finishing the surface of a rack that has been hardened, it can be finished with high precision by using a grinding machine, but the grinding allowance for the workpiece is relatively small in the grinding machine. There was a limit to productivity.

  The problem to be solved is, for example, that the processing time for processing the surface to be processed is shortened.

  According to a first aspect of the present invention, in the manufacturing method of a rack in which the tooth body is formed by forming a rack body in which tooth portions are arranged side by side, an interval is provided along the outer periphery portion of the disk. A plurality of tooth profile portions projecting radially from the center of the disk, and a cutting hard tip is provided on the rising front end surface of the tooth shape portion in the circumferential direction of the disc, and the rising front end surface and the hard tip The rack manufacturing method is characterized in that the cutting finish is performed by a rotary cutter having an impact-resistant member interposed therebetween.

  The invention according to claim 2 is the rack manufacturing method according to claim 1, wherein the cutting hard tip is CBN or diamond.

  The invention according to claim 3 is the rack manufacturing method according to claim 1 or 2, characterized in that the impact-resistant member is high-speed tool steel or cemented carbide.

  The rack according to any one of claims 1 to 3, wherein the front surface portion of the cutting hard tip is provided on an imaginary radius line radially expressed from the center of the disk. It is a manufacturing method.

  The invention according to claim 5 is characterized in that the rising rear end surface of the tooth profile portion in the circumferential direction of the disk is formed to be inclined and lowered toward the rear. It is a manufacturing method of the described rack.

  According to a sixth aspect of the present invention, the center axis of the disk is parallel to the work surface of the workpiece, and the disk moves relative to the work surface so as to intersect the center axis. The rack manufacturing method according to any one of claims 1 to 5, wherein:

  The invention according to claim 7 is the rack according to any one of claims 1 to 6, wherein the tooth surface of the tooth portion is subjected to surface hardening treatment, and the tooth surface is cut and finished. It is a manufacturing method.

  The invention according to claim 8 is a rack characterized in that a rack for pinions is manufactured by the method for manufacturing a rack according to claims 1 to 6.

  According to the first aspect of the present invention, in the rack manufacturing method, the impact at the time of cutting is absorbed by the impact-resistant member by the rotating cutter, thereby reducing the deformation and breakage of the cutting hard tip and the tooth profile portion. Processing of objects can be performed at high speed.

  According to the second aspect of the present invention, it is possible to process a high-hardness workpiece subjected to the surface treatment with the cutting hard tip made of CBN or diamond.

  According to the invention of claim 3, optimal shock absorption can be performed.

  According to the fourth aspect of the present invention, the cutting hard tip can be brought into contact with the workpiece in a substantially perpendicular direction, so that cutting can be reliably performed.

  According to the invention of claim 5, the cutting force can be distributed and transmitted to the disk side, and the overall strength can be improved.

  According to invention of Claim 6, it can cut continuously along a workpiece.

  According to invention of Claim 7, the tooth surface which performed the surface hardening process can be cut-finished.

  According to invention of Claim 8, a rack can be provided at low cost.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below do not limit the contents of the present invention described in the claims. In addition, all the configurations described below are not necessarily essential requirements of the present invention.

  The figure shows Example 1, which shows a case of a cutting machine that processes a rack 2 in which the surface of the tooth portion 1 is quenched by high frequency. Then, as a pre-processing, the rack tooth portion 1 is cut by cutting the steel material before quenching to form the main body of the rack 2. Next, the tooth part 1 is finished by a high-speed rotation and high-speed feed with a rotary cutter described later.

  Next, the rotating cutter will be described. A rotation drive shaft 4 is provided in a horizontal axis parallel to the table 3 on a horizontal table 3 on which a workpiece, also called a workpiece, is placed. The rotating cutter 5 attached to the rotational drive shaft 4 is arranged on the outer peripheral edge 7 of the metal disk 6 with a plurality of tooth profile parts 8 at intervals Z along the outer peripheral edge 7 and the central axis 9 of the disk 6. And a cutting hard tip 11 is provided on the rising front end face 10 in the circumferential direction of the disk 6 of the tooth profile 8, and further between the rear face of the cutting hard tip 11 and the rising front end face 10. A shock-resistant member 12 for interfering with this is interposed. The hard cutting tip 11 and the impact resistant member 12 are bonded by the first brazing layer 13 as the first fixing means, and the impact resistant member 12 and the rising front end face 10 are the second fixing means. Bonded by the second brazing layer 14.

  For example, steel, for example, carbon steel for machine structure is used for the plate-like disk 6 on which the tooth profile 8 is integrally provided. Further, as the cutting hard tip 11, a thin plate tip to which ultra-hard CBN (cubic boron nitride) fine particles are fixed or a thin plate tip to which diamond fine particles are fixed is used. The impact resistant member 12 is made of a material having a hardness higher than that of the tooth profile portion 8 and a hardness lower than that of the cutting hard tip 11. In the embodiment, the impact resistant member 12 is formed of high speed tool steel or cemented carbide.

  Further, the rising rear end face 15 in the circumferential direction of the disk 6 of the tooth profile portion 8 is formed to be inclined and inclined downward.

  Further, the front surface portion 16 of the cutting hard tip 11 is substantially provided on a virtual radius line 17 that is radially expressed from the central axis 9 of the disk 6, and the rake angle A is formed at 0 to 5 degrees. The cutting edge angle B at the tip of the cutting hard tip 11 is 80 to 85 degrees and is retreated. Further, the clearance angle C following the land 18 of the cutting hard tip 11 is formed to be 5 to 10 degrees, and further, the first width D on the central axis 9 side of the disk 6 in the front surface portion 16, that is, the base end side. The second width E opposite to the central axis 9 of the disk 6 in the front face portion 16, that is, the second width E on the front end side, is smaller than the first width D of the front face portion 16 (D> E). The front surface of 16 is an isosceles triangle shape, and the sandwiching angle F on the tip side is formed from 0 to 90 degrees. By these, optimum cutting can be performed. The land 18 is formed by chamfering the edge of the front surface portion 16 of the cutting hard tip 11 only slightly obliquely.

  Further, the impact-resistant member 12 is also formed in a plate shape, and in the case of the embodiment, the first thickness G in the circumferential direction is larger than the second thickness H in the circumferential direction of the cutting hard tip 11. (G> H). The impact-resistant member 12 and the rising front end face 10 are formed so as not to protrude outside when projected rearward from the front face portion 16 of the cutting hard tip 11.

  Next, the operation of the above configuration will be described. The rack 2 from which the steel material has been cut out is quenched and the tooth surface 19 is subjected to surface hardening treatment. The rack 2 is attached to the table 3 in order to finish the tooth surface 19 of the rack 2 to a predetermined dimension. At this time, the width direction I of the tooth surface 19 and the central axis 9 intersect with each other, and in the embodiment, they are arranged so as to be orthogonal. Then, the rotational drive shaft 4 is rotationally driven, and from one side in the width direction I of the tooth surface 19 to the other side in the width direction I of the tooth surface 19 with the front surface portion 16 of the cutting hard tip 11 facing the one. When relatively moved, the cutting hard tip 11 hits the tooth surface 19 to cut the tooth surface 19. Further, the tooth surface 19 is intermittently cut by the next cutting hard tip 11 following the cutting hard tip 11 by rotating the rotation drive shaft 4.

  Thus, while rotating the cutter 5 for rotation and moving the cutter 5 for rotation and the rack 2 relatively, the width direction I of the tooth surface 19 can be finished. Then, by rotating the rotating cutter 5, a plurality of cutting hard tips 11 provided at intervals Z along the outer peripheral edge portion 7 abut on the tooth surface 19 on the outer peripheral edge portion 7 of the disk 6. In this case, the cutting hard tip 11 is intermittently brought into contact with the tooth surface 19 to receive a relatively large impact, and the cutting hard tip 11 is damaged or deformed. Although it is a concern, since the impact can be absorbed to some extent by the impact resistant member 12 located behind the cutting hard tip 11, deformation and breakage of the cutting hard tip 11 can be prevented.

  Processing examples will be described below. A rack body, which is a work material having a quenching hardness of HRC 55 degrees, was processed at a cutting allowance of 0.1 to 0.2 mm, a feed rate of 600 mm / min, and a peripheral speed of 200 m / min using the rotating cutter 5 having a diameter of 130 mm. As a result, both pitch accuracy and surface roughness achieved JIS 1-2 grade. And as a result of cutting the rack main body (length 1m) of the module 3 and verifying the life of the cutter 5 for rotation, it was possible to continue the processing without having to re-grind to a cutting length of 500m.

  As described above, in the above-described embodiment, the plurality of tooth profile portions 8 project radially from the center of the disk 6 at the interval Z along the outer peripheral edge portion 7 on the outer peripheral edge portion 7 of the disk 6. A hard tip 11 for cutting is provided on the rising front end face 10 in the circumferential direction of the disk 6 of the tooth profile 8, and an impact resistant member 12 is interposed between the rising front end face 10 and the hard tip 11, thereby The impact when the cutting hard tip 11 intermittently hits the tooth surface 19 by the rotation is absorbed by the impact resistant member 12 to some extent, so that the cutting hard tip 11 and the tooth profile portion 8 are not deformed or damaged, and the surface is cut. It is possible to finish the tooth surface 19 that has been subjected to the hardening treatment.

  In addition, the conventional rack grinder is usually installed in a temperature-controlled room, but in the above embodiment, it can be installed at room temperature, and the machining allowance per one time is larger than that of the grinder, so that the workpieces are arranged in parallel. They can also be processed at the same time.

  Further, by using CBN as the cutting hard tip 11, it is possible to ensure ultra-high hardness, and it is possible to reliably perform cutting even on the tooth surface 19 that has undergone surface hardening treatment.

  Furthermore, since the impact resistant member 12 is a high-speed tool steel or cemented carbide that is higher in hardness than the tooth profile portion 8 and lower than the hardness of the cutting hard tip 11, optimum shock absorption can be performed.

  In addition, since the front surface portion 16 of the cutting hard tip 11 is provided on the virtual radius line 17 that appears radially from the central axis 9 of the disk 6, the cutting hard tip 11 is formed in a direction substantially perpendicular to the tooth surface 19. Since it comes into contact, cutting can be performed reliably.

  Further, the rising rear end face 15 in the circumferential direction of the disk 6 of the tooth profile portion 8 is inclined and lowered toward the rear, so that the cutting resistance by the tooth face 19 is reduced by the cutting hard tip 11, the impact resistant member. 12, it is transmitted to the disk 6 side via the tooth profile part 8, but since the rising rear end face 15 is inclined rearward in the tooth profile part 8, the cutting resistance can be transmitted distributed to the disk 6 side, The overall strength can be improved.

  Further, the central axis 9 of the disk 6 is always parallel to the tooth surface 19 that is the work surface of the rack 2 that is the work, and the disk 6 is orthogonal to the central axis 9. By moving relative to the width direction I of the tooth surface 19, cutting can be performed continuously along the width direction I of the tooth surface 19.

  The rack 2 manufactured by the manufacturing method is manufactured at low cost.

  As described above, the method for manufacturing a pinion rack according to the present invention can be applied to various uses. For example, by arranging a plurality of the present invention coaxially like a hob cutter, the processing time can be shortened by, for example, 10 to 20 times compared to processing by a grinding machine.

It is a partially cutaway front view showing Example 1 of the present invention. FIG. It is the front view which expanded a part of principal part same as the above. FIG. It is a perspective view of a prior art.

Explanation of symbols

2 racks (workpiece)
6 Disc 7 Outer peripheral edge 8 Tooth profile 9 Center axis (center)
10 Front end face
11 Cutting hard tip
12 Impact resistant material
15 Rear end face
16 Front part
17 Virtual radius line
19 Tooth surface (machined surface)
Z interval

Claims (8)

  In the manufacturing method of a rack in which the tooth body is formed by forming the rack body side by side, and the tooth portion is cut, a plurality of tooth profile portions are provided on the outer peripheral edge portion of the disk at intervals along the outer peripheral edge portion. Projecting radially from the center of the disk, a cutting hard tip is provided on the rising front end surface of the tooth profile in the circumferential direction of the disk, and an impact resistant member is interposed between the rising front end surface and the hard tip. A method of manufacturing a rack, wherein the cutting finish is performed by a rotating cutter.   The rack manufacturing method according to claim 1, wherein the cutting hard tip is CBN or diamond.   The rack manufacturing method according to claim 1, wherein the impact resistant member is high-speed tool steel or cemented carbide.   The rack manufacturing method according to any one of claims 1 to 3, wherein a front surface portion of the cutting hard tip is provided on an imaginary radius line radially expressed from a center of the disk.   The manufacturing method of the rack according to any one of claims 1 to 4, wherein a rising rear end surface of the tooth profile portion in the circumferential direction of the disk is formed to be inclined and lowered toward the rear.   The center axis of the disk is parallel to a surface to be processed of the workpiece, and the disk moves relative to the surface to be processed so as to intersect the center axis. Item 6. The method for manufacturing a rack according to any one of Items 1 to 5.   The method of manufacturing a rack according to any one of claims 1 to 6, wherein a surface hardening treatment is performed on a tooth surface of the tooth portion, and the tooth surface is cut and finished.   The rack for pinions was manufactured by the manufacturing method of the rack of the said Claims 1-7.

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