JP2007083245A - Rack for steering device and producing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack for a steering device and a producing method therefor, wherein the rack is light weight and a metallic mold therefor has a simple shape and a long service life, and the exclusive working machine is unnecessary. <P>SOLUTION: When an outline of a rack tooth-shape in an intermediate forming process is formed; flat surfaces 13, 13 formed at both sides of the outer periphery in the crossing side at the right angle to the rack tooth-forming side of a rack blank 1 are restricted with the restricting surface 551 of a die 55, and since the blank material for rack blank 1 not flows to the outer peripheral side of the rack blank 1, the flowing of the blank material for rack blank 1 is effectively performed. When the outline of the rack tooth-shape in this intermediate forming process is formed, the blank material removed at the rack tooth-forming time flows in the inner diameter hole 12 of the rack blank 1, and since a gap is remained in this inner diameter hole, the metallic mold is not formed as the closed-state, and since the forming load can be made small, the metallic mold has the long service life. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steering device rack and a manufacturing method thereof, and more particularly to a steering device rack molded by a processing method using a mold and a manufacturing method thereof.

  As a method for manufacturing a rack by plastic working using a mold, there are manufacturing methods shown in Patent Documents 1 to 9.

  The rack manufacturing methods of Patent Document 1 and Patent Document 2 use a solid round bar rack material, and the excess wall removed at the time of rack tooth molding protrudes as a burr on the rack side, and this protruding burr is pressed or It is a rack manufacturing method that is deleted by machining. In the manufacturing methods of Patent Document 1 and Patent Document 2, an extra process for removing burrs is required, which increases the processing cost, and in order to discharge surplus as burrs to the side, As the pressure load increases, the material escapes to the burr side, so that the rack teeth are not sufficiently filled with the material.

  In the rack manufacturing method of Patent Document 3, a rack-shaped molded portion is previously processed into a thin shape by turning to a solid round bar rack material, and an escape absorbing portion that accommodates the surplus portion removed at the time of rack-tooth molding is provided. This is a rack manufacturing method in which burrs are not produced by forming in a multi-stage on the mold on the back side of the rack teeth. In the manufacturing method of Patent Document 3, since the shape of the mold is complicated and becomes a closed mold, the stress applied to the mold is increased, and the life of the mold is shortened. Rises.

  Moreover, since the rack manufacturing method of the said patent document 1-patent document 3 uses a solid round bar rack raw material, in order to make it lightweight, especially parts other than a rack tooth molding part are solid and heavy. In addition, it becomes necessary to perform drilling with a drill or the like, and the processing cost for drilling increases. In addition, since the rack material needs to be heated in order to sufficiently fill the rack teeth with the material, there is a problem that the accuracy of forming the rack teeth decreases.

  The rack manufacturing methods of Patent Document 4 to Patent Document 5 are methods of manufacturing a Y-shaped rack having a Y-shaped cross section perpendicular to the axis using a solid round bar rack material. In the rack manufacturing methods of Patent Document 4 to Patent Document 5, since the shape of the back side of the rack teeth is complicated, the rack guide for guiding the back side of the rack teeth (part 21 in FIG. 12 of Patent Document 4) Since the shape of the steering wheel becomes complicated, the steering device becomes expensive. In addition, in order to form the rack tooth portion into the Y shape, a large number of dies (six in Patent Document 5) in which the positional relationships are combined with each other are required, which increases the manufacturing cost of the dies. .

  Furthermore, the rack manufacturing methods of Patent Document 6 to Patent Document 9 are rack manufacturing methods in which a mandrel is press-fitted into an inner diameter hole of a hollow tubular rack material to mold a rack tooth profile. In the manufacturing methods of Patent Document 6 to Patent Document 9, since a large processing force is required for ironing by a mandrel, it is necessary to perform processing while exchanging a plurality of mandrels whose dimensions are changed little by little, and the processing time is long. In addition, since a dedicated processing machine is required, the manufacturing cost increases. Moreover, since the thickness of the bottom of the rack tooth is thin, there is a problem that the strength of the rack tooth is lowered.

JP-A-10-58081 Japanese Patent Laid-Open No. 2001-79639 Japanese Patent No. 3442298 JP 2004-34829 A US Patent No. 4571982 Japanese Examined Patent Publication No. 3-5892 Japanese Patent No. 2928427 US Pat. No. 6,575,009 JP 2002-178095 A

  An object of the present invention is to provide a steering device rack and a method for manufacturing the same, in which the rack is lightweight, the mold shape is simple, the life is long, and a dedicated processing machine is unnecessary.

  The above problem is solved by the following means. That is, the first invention uses a tubular rack material having an inner diameter hole, constrains both sides of the outer periphery of the rack material on the side orthogonal to the rack tooth forming side with a die, and has a punch having an approximate rack tooth profile. An intermediate forming step of forming an approximate rack tooth by pressing against the rack tooth forming portion on the outer periphery of the rack material, a die having a desired rack tooth shape, and a desired outer peripheral shape on the side facing the rack tooth forming side. By sandwiching and pressing the rack material that has undergone the intermediate forming process between the die and the die, the desired rack teeth can be formed while increasing the width between the outer peripheral sides on the side perpendicular to the rack tooth forming side of the rack material. And a sizing molding step for molding, and the rack teeth are molded by accommodating the material material excluded during the rack tooth molding in the inner diameter hole of the rack material. It is a manufacturing method of use rack.

According to a second aspect of the present invention, in the method for manufacturing the steering device rack of the first aspect,
A method for manufacturing a rack for a steering device, wherein the rack material is a hollow cylinder.

  According to a third aspect of the present invention, there is provided a steering device rack manufacturing method according to the first aspect of the present invention, as a pre-process of the intermediate forming step, both sides of the outer periphery of the rack material orthogonal to the rack tooth forming side are A method for manufacturing a rack for a steering apparatus, comprising an upsetting process of forming a flat shape over a forming length.

  According to a fourth aspect of the present invention, in the method for manufacturing a rack for a steering apparatus according to the first aspect, the constraining surfaces of the die that constrain both outer peripheral sides on the side perpendicular to the rack tooth forming side of the rack material press the punch. A method of manufacturing a rack for a steering apparatus, wherein the rack is formed in a taper shape that continuously reduces the width between both sides of the outer periphery in the direction in which the steering device is mounted.

  According to a fifth aspect of the invention, in the method for manufacturing a rack for a steering device according to the first aspect, the intermediate forming step is performed on the rack material with a punch having an approximate rack tooth shape having a smaller number of teeth than a desired number of teeth. The process is divided into a first half step of forming a rough rack tooth and a second half step of forming the remaining rack teeth and forming the same number of rough rack teeth as the desired number of teeth on the rack material. This is a method for manufacturing a steering device rack.

  According to a sixth aspect of the present invention, there is provided the steering device rack manufacturing method according to the fifth aspect of the present invention, wherein the punch having an approximate rack tooth shape having a smaller number of teeth than the desired number of teeth is provided every other desired number of teeth. The rack tooth profile is formed in the steering device rack manufacturing method.

  According to a seventh aspect of the present invention, there is provided the steering device rack manufacturing method according to the fifth aspect of the present invention, wherein the approximate rack tooth pressure angle is less than the desired number of teeth and the same number of teeth as the desired number of teeth. This is a method of manufacturing a rack for a steering device, which is larger than the pressure angle of the rack teeth.

  According to an eighth aspect of the present invention, in the method for manufacturing a rack for a steering device according to the first aspect, in the intermediate forming step, the approximate rack tooth pressure angle is smaller than the desired rack tooth pressure angle, A rack for a steering apparatus, wherein a tooth depth of a tooth is formed smaller than a desired rack tooth depth, and is expanded to a pressure angle and a depth of a desired rack tooth in the sizing molding step. It is a manufacturing method.

  A ninth invention is a steering device rack manufactured by the method for manufacturing a steering device rack according to any one of the first to eighth inventions.

  In the steering device rack manufacturing method and the steering device rack manufactured by the manufacturing method of the first to fourth inventions of the present invention, a tubular rack material having an inner diameter hole is used, and the rack teeth The material material removed during molding flows into the inner diameter hole and a void remains in the inner diameter hole, so that the mold does not become sealed and the molding load is small, so the mold life is long. Become. Further, since the molding load is small, it is possible to perform the molding in the cold, and the molding accuracy of the rack teeth is improved.

  In addition, since the material material excluded at the time of forming the rack teeth is accommodated in the inner diameter hole of the rack material, burrs are not generated in the formed rack, and the number of processing steps for removing the burrs is reduced. Moreover, since a tubular rack material is used, parts other than the rack tooth molding part are also reduced in weight.

  In addition, since the shape of the mold is simple and molding can be performed with a general-purpose press, the mold production cost and molding equipment cost are reduced, and a mandrel is not used, so that the processing time is short. Moreover, since no mandrel is used, the thickness of the bottom of the rack tooth is sufficiently secured, and the strength of the rack tooth is improved.

  Further, both sides of the outer periphery of the rack material orthogonal to the rack tooth forming side are constrained by a die, and a punch having an approximate rack tooth shape is pressed against the rack tooth forming portion on the outer periphery of the rack material to form an approximate rack tooth. An intermediate molding process is provided. Therefore, since the material material does not flow to the outer peripheral side of the rack material at the time of the rough rack tooth forming mold, the material material flows to the rack teeth effectively.

  Moreover, the width | variety between the outer peripheral both sides of the side orthogonal to a rack tooth shaping | molding side can be made narrower than the width | variety between the outer peripheral both sides of a desired rack tooth profile by the said intermediate | middle shaping | molding process. Therefore, it is easy to put the rack material into the sizing molding process, and even if the die used in the sizing molding process is a pair of upper and lower simple dies, burrs protrude from the outer periphery of the rack material. Therefore, the number of processing steps for removing burrs is reduced.

  Further, in the steering device rack manufacturing method and the steering device rack manufactured by the manufacturing method according to the fifth and sixth inventions of the present invention, the intermediate molding step has fewer teeth than a desired number of teeth. A step of forming approximate rack teeth on the rack material with a punch having a number of rack tooth shapes, and then forming the remaining rack teeth to form the same number of approximate rack teeth as the desired number of teeth on the rack material. It is divided into the process to do. Accordingly, the surface pressure when forming the rough rack teeth is increased, so that the material material is effectively flowed to the rack teeth.

  In the steering device rack manufacturing method and the steering device rack manufactured by the manufacturing method according to the seventh aspect of the present invention, the intermediate forming step has a rough number of teeth less than a desired number of teeth. The pressure angle of the rack teeth is set to be larger than the approximate pressure angle of the rack teeth as many as the desired number of teeth. Therefore, since the flow of the material of the latter half of the intermediate molding process is performed along the tooth surfaces of the rack teeth formed in the first half of the intermediate molding process, the stress required for molding is reduced. The flow of the material can be performed smoothly.

  In the steering device rack manufacturing method and the steering device rack manufactured by the manufacturing method according to the eighth aspect of the present invention, the approximate rack tooth pressure angle is set to a desired rack tooth in the intermediate forming step. The rack angle of the approximate rack teeth is smaller than the desired rack tooth depth, and is expanded to the desired rack tooth pressure angle and tooth depth in the sizing molding process. Yes. Therefore, since the molding pressure when molding the approximate rack teeth may be small, the rack teeth can be easily formed.

  Embodiments 1 to 4 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a process diagram showing a method of manufacturing a rack according to a first embodiment of the present invention, (1A) and (1B) are explanatory views showing rack materials, and (1A) is a left side view of (1B). is there. (2A), (2B) is explanatory drawing which shows the rack raw material after an upsetting process, (2A) is AA sectional drawing of (2B).

  FIG. 2 is a process diagram showing a post-process of FIG. 1, and (3A) and (3B) are explanatory views showing an intermediate forming process for forming a rough rack tooth (rack-processed rack tooth). FIG. 3B is a sectional view taken along line BB of (3B). (4A) and (4B) are explanatory views showing a sizing molding process for molding a desired rack tooth (a rack tooth for finishing), and (4A) is a sectional view taken along the line CC in (4B).

  FIG. 3 shows a structure of a mold for performing the upsetting process of the first embodiment. (1) is a longitudinal sectional view taken along a vertical plane passing through the rack axis and parallel to the rack axis. (2) is a DD cross-sectional view of (1). FIG. 4 shows the structure of a mold for processing the intermediate forming step of Example 1, (1) is a longitudinal sectional view taken along a vertical plane passing through the rack axis and parallel to the rack axis, (2) is EE sectional drawing of (1).

  FIG. 5 shows a structure of a mold for performing the processing of the sizing molding process of Example 1, wherein (1) is a longitudinal sectional view cut along a vertical plane passing through the rack axis and parallel to the rack axis; (2) is FF sectional drawing of (1).

  As shown in FIGS. 1 (1A) and (1B), the rack material 1 of the first embodiment is formed in a hollow cylindrical shape in which the outer periphery 11 and the inner diameter hole 12 have a circular cross section. As the shape of the rack material 1, in the first embodiment, both the outer periphery 11 and the inner diameter hole 12 are circular. However, the shape of the rack material 1 is not limited to a circular shape, and may be a tube having an arbitrary cross-sectional shape such as a rectangle or a polygon.

* Upsetting process As shown in the process diagram of FIG. 1, the rack manufacturing method of Example 1 is prepared by preparing a hollow cylindrical rack material 1 having a circular cross section as shown in (1A) and (1B). Then, upsetting is performed on the rack material 1, and as shown in (2A) and (2B), both sides of the outer periphery of the rack material 1 on the side orthogonal to the rack tooth forming side are aligned with the axis of the rack material 1. 3 is formed flat by the upsetting mold shown in FIG. 3 by the rack tooth forming length L in the direction.

  Due to the flattening in the upsetting process, flat surfaces 13 and 13 are formed on both sides of the outer periphery on the side orthogonal to the rack tooth forming side, and the width W1 between the flat surfaces 13 and 13 is the outer periphery of the rack material 1. 11 is shorter than the outer diameter D. Further, the height H1 between the outer peripheral both sides on the rack tooth forming side is higher than the outer diameter D of the outer periphery 11 of the rack material 1.

  The upsetting metal mold shown in FIG. 3 includes a flat plate-shaped upper mold holder 21 attached to the lower surface of a ram (not shown) that can be raised and lowered in a press machine, and a flat plate attached to the upper surface of a bed of press equipment. It is comprised from the lower mold | type holder 31 of a shape.

  On the lower surface of the upper mold holder 21, a backing plate 22, a punch plate 23, and a punch retainer 24 are stacked and fixed in this order from top to bottom. The backing plate 22 is accurately fixed to a desired position on the lower surface of the upper holder 21 by bolts 221 and knock pins 222.

  An upper punch 25 is fitted in the long groove 231 formed in the punch plate 23 and the long groove 241 formed in the punch presser 24. A spacer 26 is inserted between the upper surface of the upper punch 25 and the lower surface of the backing plate 22, and the upper punch 25 is fixed to the punch plate 23 by a punch presser 24.

  The punch press 24 is fixed to the punch plate 23 by bolts 242, and the integrated punch plate 23 and punch press 24 are positioned on the backing plate 22 by knock pins 243. Further, the left and right sides (FIG. 3B) of the punch plate 23 are pressed against the backing plate 22 by pressing plates 27 and 27 fixed to the lower surface of the upper mold holder 21 with bolts 271. Thus, the upper punch 25 is fixed to the backing plate 22 via the spacer 26 in the vertical direction.

  Further, on the upper surface of the lower mold holder 31, a backing plate 32, a punch plate 33, and a punch press 34 are stacked and fixed in this order from the bottom to the top. The backing plate 32 is fixed to the upper surface of the lower mold holder 31 at a desired position with a bolt 321 and a knock pin 322 with high accuracy.

  A lower punch 35 is fitted in the long groove 331 formed in the punch plate 33 and the long groove 341 formed in the punch presser 34. A spacer 36 is inserted between the lower surface of the lower punch 35 and the upper surface of the backing plate 32, and the lower punch 35 is fixed to the punch plate 33 by a punch press 34.

  The punch retainer 34 is fixed to the punch plate 33 by bolts 342, and the integrated punch plate 33 and punch retainer 34 are positioned on the backing plate 32 by knock pins 343. Further, both the left and right sides (FIG. 3B) of the punch plate 33 are pressed against the backing plate 32 by pressing plates 37, 37 fixed to the upper surface of the lower mold holder 31 with bolts 371. Thus, the lower punch 35 is fixed in the vertical direction to the backing plate 32 via the spacer 36.

  As shown in FIG. 3 (1), on the left side of the backing plates 22 and 32, a plate 28 is fixed to the lower surface of the upper mold holder 21 with bolts (not shown), and a plate 38 is illustrated on the upper surface of the lower mold holder 31. Not fixed by bolts. Guide bolts 281 and 381 are screwed into the plates 28 and 38, respectively, and the upper stripper 282 and the lower stripper 382 are movable in the vertical direction by being guided by the guide bolts 281 and 381, respectively.

  A spring 283 is inserted between the upper stripper 282 and the plate 28, and the upper stripper 282 is always biased downward by the spring 283. A spring 383 is inserted between the lower stripper 382 and the plate 38, and the lower stripper 382 is always urged upward by the spring 383.

  Further, as shown in FIG. 3A, a positioning block 39 is fixed to the upper surface of the lower mold holder 31 on the right side of the backing plate 32. When the rack material 1 is loaded into the upsetting mold shown in FIG. 3, the right end surface 14 of the rack material 1 comes into contact with the positioning block 39, and the position of the rack material 1 in the axial direction is positioned.

  Accordingly, when the rack material 1 is loaded into the upsetting mold shown in FIG. 3 and the ram of the press machine is lowered, the upper stripper 282 sandwiches the outer periphery 11 of the rack material 1 with the lower stripper 382. Therefore, the position of the rack material 1 in the upsetting mold shown in FIG. 3 is fixed.

  Subsequently, the outer periphery of the rack material 1 is pressed between the flat pressing surface 251 formed on the lower surface of the upper punch 25 and the flat pressing surface 351 formed on the upper surface of the lower punch 35, By performing upsetting, flat surfaces 13 and 13 having a width W1 are formed on both outer peripheral sides on the side orthogonal to the rack tooth forming side.

  When the upsetting is completed, the upper punch 25 is separated from the lower punch 5 and the pressing surface 251 on the lower surface of the upper punch 25 is separated from the flat surface 13 of the rack material 1 as the ram of the press machine is raised. At this time, the lower stripper 382 forcibly separates the rack material 1 from the lower punch 35 upward by the biasing force of the spring 383.

* Intermediate forming step Next, as shown in the intermediate forming steps of (3A) and (3B) in FIG. 2, the flat surfaces 13 and 13 of the rack material 1 are restrained by the die 55, and the punch 45 having an approximate rack tooth profile is formed. Is pressed against the rack tooth forming portion on the outer periphery of the rack material 1 to form rough rack teeth (roughly processed rack teeth). FIG. 4 shows the structure of the mold in this intermediate molding process.

  The intermediate molding process mold shown in FIG. 4 includes a flat plate-shaped upper mold holder 41 attached to the lower surface of a ram (not shown) that can be raised and lowered in a press machine, and a flat plate attached to the upper surface of a bed of press equipment. It is comprised from the lower mold | type holder 51 of a shape.

  On the lower surface of the upper mold holder 41, a backing plate 42 and a punch plate 43 are stacked and fixed in this order from the top to the bottom. The backing plate 42 and the punch plate 43 are accurately positioned at desired positions on the lower surface of the upper holder 41 by knock pins 431, and the punch plate 43 is fixed to the lower surface of the backing plate 42 by bolts 432.

  A punch 45 is fitted in the long groove 433 formed in the punch plate 43. A spacer 46 is fixed to the upper surface of the punch 45 by bolts 461, and the spacer 46 abuts on the lower surface of the backing plate 42, thereby restricting the vertical position of the punch 45. A rough rack tooth profile (roughly processed rack tooth profile) 451 is formed on the lower surface of the punch 45.

  On the upper surface of the lower mold holder 51, a backing plate 52, a die plate 53, and a die presser 54 are stacked and fixed in this order from the bottom to the top. The backing plate 52 is fixed to the upper surface of the lower mold holder 51 at a desired position with a bolt 521 and a knock pin 522 with high accuracy. A die 55 is fitted in the long groove 531 formed in the die plate 53, and the die 55 is fixed to the die plate 53 by a die press 54.

  The die plate 53 and the die presser 54 are fixed to the upper surface of the backing plate 52 with high accuracy at desired positions by bolts 541 and knock pins 542.

  As shown in FIG. 4 (1), on the left side of the backing plates 42 and 52, a plate 48 is fixed to the lower surface of the upper mold holder 41 with a bolt (not shown), and a plate 58 is illustrated on the upper surface of the lower mold holder 51. Not fixed by bolts. Guide bolts 481 and 581 are screwed into the plate 48 and the plate 58, respectively, and the upper stripper 482 and the lower stripper 582 are movable in the vertical direction by being guided by the guide bolts 481 and 581, respectively.

  A spring 483 is inserted between the upper stripper 482 and the plate 48, and the upper stripper 482 is always biased downward by the spring 483. A spring 583 is inserted between the lower stripper 582 and the plate 58, and the lower stripper 582 is always urged upward by the spring 583.

  As shown in FIG. 4 (1), a positioning block 59 is fixed to the upper surface of the backing plate 52 on the right side of the die plate 53. When the rack material 1 is carried into the intermediate molding process mold shown in FIG. 4, the right end surface 14 of the rack material 1 comes into contact with the positioning block 59 and the position of the rack material 1 in the axial direction is positioned.

  Accordingly, when the rack material 1 is carried into the intermediate forming mold shown in FIG. 4 and the ram of the press machine is lowered, the upper stripper 482 sandwiches the outer periphery 11 of the rack material 1 with the lower stripper 582. Therefore, the position of the rack material 1 in the intermediate molding process mold shown in FIG. 4 is fixed. At the same time, the flat surfaces 13 and 13 formed on both sides of the outer periphery of the rack material 1 on the side orthogonal to the rack tooth forming side are sandwiched by the constraining surfaces 551 formed on the die 55. The width of the constraining surface 551 of the die 55 is substantially the same as the width W1 between the flat surfaces 13 and 13 of the rack material 1.

  A knockout 56 is fitted into the restraining surface 551 of the die 55 so as to be slidable in the vertical direction, and an upward biasing force is always applied by a spring (not shown). The knockout 56 supports the rack material 1 from below by urging force upward when pressing the punch 45 against the rack material 1 to form an approximate rack tooth on the rack material 1. Further, when the intermediate forming process is completed and the ram of the press machine is raised, the knockout 56 pushes the rack material 1 upward by the biasing force of a spring (not shown), and the rack tooth forming portion of the rack material 1 is forced from the die 55. Apart

  When the ram of the press machine is lowered, a rough rack tooth profile (roughly processed rack tooth profile) 451 formed on the lower surface of the punch 45 presses the rack tooth forming portion on the outer periphery of the rack material 1 to rack the approximate rack teeth. Molded into material 1. At the time of the approximate rack tooth forming mold in the intermediate forming step, the flat surfaces 13 and 13 formed on both outer peripheral sides of the rack material 1 on the side orthogonal to the rack tooth forming side are constrained by the constraining surfaces 551 of the die 55. Since the material material of the material 1 does not flow to the outer peripheral side of the rack material 1, the material material flows to the rack teeth effectively.

  At the time of the rough rack-forming mold of the intermediate molding process, since the material material excluded at the time of rack-tooth molding flows into the inner diameter hole 12 of the rack material 1 and a void remains in the inner diameter hole 12, the mold However, since the molding load is small, the mold life is extended. Further, since the molding load is small, it is possible to perform the molding in the cold, and the molding accuracy of the rack teeth is improved.

  Further, since the material material excluded at the time of forming the rack teeth is accommodated in the inner diameter hole 12 of the rack material 1, no burrs are formed on the formed rack teeth, and the number of processing steps for removing the burrs is reduced. Moreover, since a tubular rack material is used, parts other than the rack tooth molding part are also reduced in weight.

  When the intermediate forming process is completed, the punch 45 rises as the ram of the press machine rises, and the approximate rack tooth profile 451 on the lower surface of the punch 45 is separated from the rack tooth forming portion of the rack material 1. At this time, the lower stripper 582 forcibly separates the left side of the rack material 1 from the die 55 by the biasing force of the spring 583. At the same time, the knockout 56 forcibly separates the rack tooth forming portion of the rack material 1 from the die 55 by the biasing force of a spring (not shown).

* Sizing molding process In the sizing molding process of (4A) and (4B) in FIG. 2, a die having a desired rack tooth profile and a desired outer peripheral shape on the side facing the rack tooth molding side (the rack shaft in this embodiment) The rack blank 1 after the intermediate forming step is sandwiched and pressed between dies having a semicircular cross section perpendicular to the center. As a result, desired rack teeth (finished rack teeth) are formed while increasing the width W1 between the outer peripheries 13 and 13 on the side perpendicular to the rack tooth forming side of the rack material 1. FIG. 5 shows the structure of the mold in this sizing molding process.

  The sizing mold shown in FIG. 5 includes a flat plate-shaped upper mold holder 61 attached to the lower surface of a ram (not shown) that can be raised and lowered in a press machine, and a flat plate attached to the upper surface of a bed of press equipment. It is comprised from the lower mold | type holder 71 of a shape.

  On the lower surface of the upper mold holder 61, an upper die 65 is stacked and fixed in this order from the top to the bottom via an upper die plate 63. The upper die plate 63 is positioned on the upper mold holder 61 by knock pins 631 and 631. The upper die 65 is positioned on the upper die plate 63 by knock pins 651 and 651.

  Further, the left and right sides (FIG. 5B) of the upper die 65 are pressed against the upper die plate 63 by pressing plates 67 and 67 fixed to the lower surface of the upper die holder 61 with bolts 671. Thus, the upper die 65 is fixed to the upper die plate 63 in the vertical direction. On the lower surface of the upper die 65, a desired outer peripheral shape on the side facing the rack tooth forming side (in this embodiment, a cross section perpendicular to the rack axis is a semicircle) is formed.

  Further, on the upper surface of the lower mold holder 71, a lower die 75 is stacked and fixed in this order from the bottom to the top via a lower die plate 73. The lower die plate 73 is positioned on the lower mold holder 71 by knock pins 731 and 731. The lower die 75 is positioned on the lower die plate 73 by knock pins 751 and 751.

  Further, the left and right sides (FIG. 5B) of the lower die 75 are pressed against the lower die plate 73 by pressing plates 77 and 77 fixed to the upper surface of the lower die holder 71 with bolts 771. Thus, the lower die 75 is fixed to the lower die plate 73 in the vertical direction. A desired rack tooth profile (a rack tooth profile for finishing) is formed on the upper surface of the lower die 75.

  As shown in FIG. 5 (1), on the left side of the upper die plate 63 and the lower die plate 73, a plate 68 is fixed to the lower surface of the upper die holder 61 by bolts (not shown), and the upper surface of the lower die holder 71 is The plate 78 is fixed with bolts (not shown). Guide bolts 681 and 781 are screwed into the plate 68 and the plate 78, respectively, and are guided by the guide bolts 681 and 781, respectively, so that the upper stripper 682 and the lower stripper 782 can move in the vertical direction.

  A spring 683 is inserted between the upper stripper 682 and the plate 68, and the upper stripper 682 is always biased downward by the spring 683. Further, a spring 783 is inserted between the lower stripper 782 and the plate 78, and the lower stripper 782 is always urged upward by the spring 783.

  As shown in FIG. 5 (1), a positioning block 79 is fixed to the upper surface of the lower die holder 71 on the right side of the lower die plate 73. When the rack material 1 is carried into the sizing molding process mold shown in FIG. 5, the right end surface 14 of the rack material 1 comes into contact with the positioning block 79 and the position of the rack material 1 in the axial direction is positioned.

  Therefore, when the rack material 1 is carried into the sizing molding process mold shown in FIG. 5 and the ram of the press machine is lowered, the upper stripper 682 sandwiches the outer periphery 11 of the rack material 1 with the lower stripper 782. Accordingly, the position of the rack material 1 in the sizing molding process mold shown in FIG. 5 is fixed.

  Subsequently, the outer periphery of the rack material 1 is pressed between a semicircular pressing surface 652 formed on the lower surface of the upper die 65 and a pressing surface 752 having a desired rack tooth shape formed on the upper surface of the lower die 75. . As a result, desired rack teeth (finished rack teeth) are formed while the width W1 between the outer peripheries 13 and 13 on the side perpendicular to the rack tooth forming side of the rack material 1 is increased.

  By the upsetting process, the width W1 between the flat surfaces 13 and 13 formed on both sides of the outer periphery on the side orthogonal to the rack tooth forming side is made narrower than the width between both sides of the desired rack tooth profile. Therefore, it is easy to put the rack material 1 into the sizing molding process, and even if the upper die 65 and the lower die 75 used in the sizing molding process are a pair of upper and lower simple dies, Since burrs do not protrude to the outer periphery, the number of processing steps for removing burrs is reduced.

  When the sizing process is completed, the upper die 65 is separated from the lower die 75 as the ram of the press machine rises. At this time, the lower stripper 782 forcibly separates the rack material 1 from the lower die 75 by the biasing force of the spring 783.

  Next, a second embodiment of the present invention will be described. FIG. 6 is a process diagram showing a method of manufacturing a rack according to a second embodiment of the present invention, (1A) and (1B) are explanatory views showing rack materials, and (1A) is a left side view of (1B). is there. (2A), (2B) is explanatory drawing which shows the intermediate | middle shaping | molding process which shape | molds a rough rack tooth, (2A) is GG sectional drawing of (2B).

  FIG. 7 is a process diagram showing a post-process of the process of FIG. 6, (3A) and (3B) are explanatory diagrams showing a sizing molding process for molding a desired rack tooth, and (3A) is a diagram of (3B). It is HH sectional drawing. FIG. 8 shows the structure of a mold for performing the intermediate molding process of Example 2, wherein (1) is a longitudinal sectional view cut along a vertical plane passing through the axis of the rack, and (2) is J- of (1). It is J sectional drawing. In the following description, only structural parts different from the above-described embodiment will be described, and redundant description will be omitted.

  The second embodiment is an example in which the upsetting process of the first embodiment is omitted, thereby shortening the processing time and reducing the die cost. That is, as shown in FIGS. 6 (1A) and (1B), the rack material 1 of the second embodiment is formed in a hollow cylindrical shape in which the outer periphery 11 and the inner diameter hole 12 have a circular cross section, as in the first embodiment. Yes.

* Intermediate forming process As shown in the process diagram of FIG. 6, the manufacturing method of the rack of Example 2 prepares a hollow cylindrical rack material 1 having a circular cross section as shown in (1A) and (1B), As shown in the intermediate forming step of (2A) and (2B) in FIG. 6, the outer periphery 11 of the rack material 1 is constrained by a die 55, and the punch 45 having an approximate rack tooth shape is attached to the rack teeth on the outer periphery of the rack material 1. A rough rack tooth (roughly processed rack tooth) is formed by pressing against the forming part. FIG. 8 shows the structure of the mold in this intermediate molding step.

  The intermediate molding process mold shown in FIG. 8 includes a flat plate-shaped upper mold holder 41 attached to the lower surface of a ram (not shown) that can be raised and lowered in a press machine, and a flat plate attached to the upper surface of a bed of press equipment. It is comprised from the lower mold | type holder 51 of a shape.

  On the lower surface of the upper mold holder 41, a backing plate 42 and a punch plate 43 are stacked and fixed in this order from the top to the bottom. The backing plate 42 and the punch plate 43 are accurately positioned at desired positions on the lower surface of the upper holder 41 by knock pins 431, and the punch plate 43 is fixed to the lower surface of the backing plate 42 by bolts 432.

  A punch 45 is fitted in the long groove 433 formed in the punch plate 43. A spacer 46 is fixed to the upper surface of the punch 45 by bolts 461, and the spacer 46 abuts on the lower surface of the backing plate 42, thereby restricting the vertical position of the punch 45. A rough rack tooth profile (roughly processed rack tooth profile) 451 is formed on the lower surface of the punch 45.

  On the upper surface of the lower mold holder 51, a backing plate 52, a die plate 53, and a die presser 54 are stacked and fixed in this order from the bottom to the top. The backing plate 52 is fixed to the upper surface of the lower mold holder 51 at a desired position with a bolt 521 and a knock pin 522 with high accuracy. A die 55 is fitted in the long groove 531 formed in the die plate 53, and the die 55 is fixed to the die plate 53 by a die press 54.

  The die plate 53 and the die presser 54 are fixed to the upper surface of the backing plate 52 with high accuracy at desired positions by bolts 541 and knock pins 542.

  As shown in FIG. 8 (1), on the left side of the backing plates 42 and 52, a plate 48 is fixed to the lower surface of the upper mold holder 41 with a bolt (not shown), and a plate 58 is shown on the upper surface of the lower mold holder 51. Not fixed by bolts. Guide bolts 481 and 581 are screwed into the plate 48 and the plate 58, respectively, and the upper stripper 482 and the lower stripper 582 are movable in the vertical direction by being guided by the guide bolts 481 and 581, respectively.

  A spring 483 is inserted between the upper stripper 482 and the plate 48, and the upper stripper 482 is always biased downward by the spring 483. A spring 583 is inserted between the lower stripper 582 and the plate 58, and the lower stripper 582 is always urged upward by the spring 583.

  Further, as shown in FIG. 8 (1), a positioning block 59 is fixed to the upper surface of the backing plate 52 on the right side of the die plate 53. When the rack material 1 is carried into the intermediate molding process mold shown in FIG. 8, the right end surface 14 of the rack material 1 comes into contact with the positioning block 59 and the position of the rack material 1 in the axial direction is positioned.

  Therefore, when the rack material 1 is carried into the intermediate forming mold shown in FIG. 8 and the ram of the press machine is lowered, the upper stripper 482 sandwiches the outer periphery 11 of the rack material 1 with the lower stripper 582. Therefore, the position of the rack material 1 in the intermediate molding process mold shown in FIG. 8 is fixed.

  The die 55 has an inclined restraint surface 552 formed on the upper side, and a parallel restraint surface 553 is continuously formed so as to be connected to the lower side of the tilt restraint surface 552. The width W3 (see FIG. 6 (2A)) of the upper opening end of the inclined restraining surface 552 is formed to be substantially the same as or slightly larger than the outer diameter D of the outer periphery 11 of the rack material 1. 6 (2A) and FIG. 8 (the direction in which the punch is pressed) has a width that decreases linearly, is parallel to the axis of the rack material 1, and It is formed in a tapered shape having an angle θ with respect to a vertical plane passing through the axis. The width W4 of the parallel restraint surface 553 is set to be the same as the width W1 between the flat surfaces 13 and 13 of the first embodiment.

  Therefore, when the punch 45 comes into contact with the rack tooth forming side of the rack material 1 and presses the rack material 1 downward, both outer peripheral sides on the side orthogonal to the rack tooth forming side of the rack material 1 are inclined restraining surfaces 552 of the die 55. As the rack material 1 descends, the width between the outer peripheral sides on the side perpendicular to the rack tooth forming side of the rack material 1 is gradually reduced.

  A knockout 56 is fitted in the parallel restraint surface 553 of the die 55 so as to be slidable in the vertical direction, and an upward biasing force is always applied by a spring (not shown). The knockout 56 supports the rack material 1 from below by urging force upward when pressing the punch 45 against the rack material 1 to form an approximate rack tooth on the rack material 1. When the intermediate forming process is completed and the ram of the press machine is raised, the rack tooth forming portion of the rack material 1 is forcibly separated from the die 55 by the biasing force of a spring (not shown).

  When the ram of the press machine descends and the punch 45 reaches the descending end, a rough rack tooth profile (roughly processed rack tooth profile) 451 formed on the lower surface of the punch 45 is a rack tooth molding portion on the outer periphery of the rack material 1. To form a rough rack tooth on the rack material 1. At the time of the rough rack forming mold of the intermediate forming step, both the outer peripheral sides of the rack material 1 on the side orthogonal to the rack tooth forming side are constrained by the inclined constraining surface 552 and the parallel constraining surface 553 and the width is reduced. . Accordingly, since the material of the rack material 1 does not flow to the outer peripheral side of the rack material 1, the material material flows to the rack teeth effectively.

  In the intermediate forming process of the second embodiment, the width of the outer periphery on the side orthogonal to the rack tooth forming side of the rack material 1 and the rough rack tooth forming are simultaneously performed, so that the forming time is shortened. Since the mold for the upsetting process is not required, the mold cost can be reduced.

  When the intermediate forming process is completed, the punch 45 rises as the ram of the press machine rises, and the approximate rack tooth profile 451 on the lower surface of the punch 45 is separated from the rack tooth forming portion of the rack material 1. At this time, the lower stripper 582 forcibly separates the left side of the rack material 1 from the die 55 by the biasing force of the spring 583. At the same time, the knockout 56 forcibly separates the rack tooth forming portion of the rack material 1 from the die 55 by the biasing force of a spring (not shown).

* Sizing Molding Process Next, in the sizing molding process of (4A) and (4B) in FIG. 7, as in the first embodiment, the die 75 having a desired rack tooth profile and the desired on the side facing the rack tooth molding side The rack material 1 having been subjected to the intermediate forming step is sandwiched and pressed between the die 65 having a peripheral shape (in this embodiment, the cross section orthogonal to the rack axis is semicircular). Thus, desired rack teeth (finished rack teeth) are formed while increasing the width between the outer circumferences of the rack material 1 on the side orthogonal to the rack tooth forming side. Since the structure of the mold in the sizing molding process of the second embodiment is the same as that of the first embodiment, the drawings and detailed description are omitted.

  In Example 2, the width between the outer peripheral sides on the side orthogonal to the rack tooth forming side is made narrower than the width between the outer peripheral sides of the desired rack tooth profile by the intermediate forming step. Therefore, it is easy to put the rack material 1 into the sizing molding process, and even if the upper die 65 and the lower die 75 used in the sizing molding process are a pair of upper and lower simple dies, Since burrs do not protrude to the outer periphery, the number of processing steps for removing burrs is reduced.

  Next, a third embodiment of the present invention will be described. FIG. 9 is a process diagram showing a method of manufacturing a rack according to a third embodiment of the present invention, (1A) and (1B) are explanatory views showing rack materials, and (1A) is a left side view of (1B). is there. (2A), (2B) is explanatory drawing which shows the process of the first half of the intermediate forming process which shape | molds a rough rack tooth, (2A) is KK sectional drawing of (2B).

  FIG. 10 is a process diagram showing the subsequent process of FIG. 9, wherein (3A) and (3B) are explanatory views showing the latter half of the intermediate molding process for molding the approximate rack teeth, and (3A) is It is LL sectional drawing of (3B). (4A), (4B) is explanatory drawing which shows the sizing shaping | molding process which shape | molds a desired rack tooth, (4A) is MM sectional drawing of (4B).

  FIG. 11 (1) is an enlarged cross-sectional view of the main part showing the rack teeth 15 formed in the first half of the intermediate forming step of FIGS. 9 (2A) and (2B), FIG. 11 (2) is FIG. 10 (3A), It is an expanded sectional view of the principal part which shows the rack tooth | gear 16 shape | molded by the latter half process of the intermediate | middle shaping | molding process of (3B). In the following description, only structural parts different from the above-described embodiment will be described, and redundant description will be omitted.

  In the third embodiment, the intermediate forming process of the second embodiment is divided into the first half and the second half. In the first half, the rack teeth are formed every other tooth, and the remaining rack teeth are formed in the second half. Thus, the surface pressure at the time of forming the rack teeth is increased, and the flow of the material material to the rack teeth is effectively performed. That is, as shown in FIGS. 9 (1A) and (1B), the rack material 1 of the third embodiment has a hollow cylindrical shape in which the outer periphery 11 and the inner diameter hole 12 have a circular cross section, as in the first and second embodiments. Is formed.

* The first half of the intermediate forming process As shown in the process diagram of FIG. 9, the rack manufacturing method of Example 3 is a hollow cylindrical rack material 1 having a circular cross section as shown in (1A) and (1B). As shown in the first half of the intermediate forming step (2A) and (2B) in FIG. 9, the outer periphery 11 of the rack material 1 is constrained by a die 55, and an approximate rack tooth profile is set every other tooth. The punch 45 is pressed against the rack tooth forming portion on the outer periphery of the rack material 1 to form a rough rack tooth (roughly processed rack tooth) 15. Since the structure of the mold in this intermediate molding step is the same as that of FIG. 8 of the second embodiment, detailed drawings and description of the mold structure will be omitted, and differences from the second embodiment will be mainly described.

  That is, on the lower surface of the punch 45, an approximate rack tooth profile (an alternate rack tooth profile for every other tooth) 452 is formed. As in the second embodiment, the die 55 has an inclined restraint surface 552 formed on the upper side, and a parallel restraint surface 553 is continuously formed so as to connect to the lower side of the tilt restraint surface 552. The width W3 of the upper opening end of the inclined restraining surface 552 is formed to be substantially the same as or slightly larger than the outer diameter D of the outer periphery 11 of the rack material 1.

  The inclined constraining surface 552 has a width that decreases linearly downward (in the direction in which the punch is pressed) in FIG. 9 (2 A), is parallel to the axis of the rack material 1, and is aligned with the axis of the rack material 1. It is formed in a taper shape with an angle θ with respect to the vertical plane passing through. The width W4 of the parallel restraint surface 553 is set to be the same as the width W1 between the flat surfaces 13 and 13 of the first embodiment.

  Therefore, when the punch 45 comes into contact with the rack tooth forming side of the rack material 1 and presses the rack material 1 downward, both outer peripheral sides on the side orthogonal to the rack tooth forming side of the rack material 1 are inclined restraining surfaces 552 of the die 55. As the rack material 1 descends, the width between the outer peripheral sides on the side perpendicular to the rack tooth forming side of the rack material 1 is gradually reduced.

  A knockout 56 is fitted in the parallel restraint surface 553 of the die 55 so as to be slidable in the vertical direction, and an upward biasing force is always applied by a spring (not shown). The knockout 56 supports the rack material 1 from below by urging force upward when pressing the punch 45 against the rack material 1 to form an approximate rack tooth on the rack material 1. When the intermediate forming process is completed and the ram of the press machine is raised, the rack tooth forming portion of the rack material 1 is forcibly separated from the die 55 by the biasing force of a spring (not shown).

  When the punch 45 reaches the descending end, an approximate rack tooth profile (roughly processed rack tooth profile) 452 formed on the lower surface of the punch 45 presses the rack tooth forming portion on the outer periphery of the rack material 1 to form one. The approximate rack teeth 15 of the teeth are formed on the rack material 1. At the time of forming an approximate rack tooth 15 for every other tooth in the intermediate forming step, both outer peripheral sides of the rack material 1 on the side orthogonal to the rack tooth forming side are restrained by the inclined restraining surface 552 and the parallel restraining surface 553 of the die 55. The width is shrinking. Therefore, since the material of the rack material 1 does not flow to the outer peripheral side of the rack material 1, the material material flows to the rack teeth 15 effectively.

  When the intermediate forming process is completed, as the ram of the press machine rises, the punch 45 rises, and the approximate rack tooth profile 452 of every other tooth on the lower surface of the punch 45 is separated from the rack tooth forming portion of the rack material 1. At this time, the lower stripper 582 forcibly separates the left side of the rack material 1 from the die 55 by the biasing force of the spring 583. At the same time, the knockout 56 forcibly separates the rack tooth forming portion of the rack material 1 from the die 55 by the biasing force of a spring (not shown).

* Process in the latter half of the intermediate molding process For the rack material 1 in which the first half of the intermediate molding process in (2A) and (2B) in FIG. 9 is completed, the process in the intermediate molding process in FIGS. 10 (3A) and (3B) The second half of the process is performed. That is, the outer periphery 11 of the rack material 1 is constrained by the die 55, and the punch 45 having the approximate rack tooth shape of the desired number of teeth is pressed against the rack tooth forming portion on the outer periphery of the rack material 1 to obtain the desired number of teeth. A rough rack tooth 16 (roughly processed rack tooth) is formed. Since the structure of the mold in this intermediate molding process is the same as that in FIG. 8 of the second embodiment, detailed drawings and description of the mold structure are omitted.

  That is, a rough rack tooth profile (roughly processed rack tooth profile) 453 having a desired number of teeth is formed on the lower surface of the punch 45. As in the second embodiment, the die 55 has an inclined restraint surface 552 formed on the upper side, and a parallel restraint surface 553 is continuously formed so as to connect to the lower side of the tilt restraint surface 552. The width W3 of the upper opening end of the inclined restraining surface 552 is formed to be substantially the same as or slightly larger than the outer diameter D of the outer periphery 11 of the rack material 1. The inclined restraining surface 552 has a width that decreases linearly downward (in the direction in which the punch is pressed) in FIG. 10 (3A), is parallel to the axis of the rack material 1, and is aligned with the axis of the rack material 1. It is formed in a taper shape with an angle θ with respect to the vertical plane passing through. The width W4 of the parallel restraint surface 553 is set to be the same as the width W1 between the flat surfaces 13 and 13 of the first embodiment.

  Therefore, when the punch 45 comes into contact with the rack tooth forming side of the rack material 1 and presses the rack material 1 downward, both outer peripheral sides on the side orthogonal to the rack tooth forming side of the rack material 1 are inclined restraining surfaces 552 of the die 55. And enters the parallel restraint surface 553.

  A knockout 56 is fitted in the parallel restraint surface 553 of the die 55 so as to be slidable in the vertical direction, and an upward biasing force is always applied by a spring (not shown). The knockout 56 supports the rack material 1 from below by pressing the punch 45 against the rack material 1 to form an approximate rack tooth 16 having a desired number of teeth on the rack material 1 by an upward biasing force. When the intermediate forming process is completed and the ram of the press machine is raised, the rack tooth forming portion of the rack material 1 is forcibly separated from the die 55 by the biasing force of a spring (not shown).

  When the punch 45 reaches the descending end, a rough rack tooth profile (roughly processed rack tooth profile) 453 formed on the lower surface of the punch 45 presses the rack tooth forming portion on the outer periphery of the rack material 1. The remaining rack teeth that were not formed in the first half of the intermediate forming step are formed, and as a result, the approximate rack teeth 16 having a desired number of teeth are formed on the rack material 1.

  At the time of the approximate rack tooth forming die having the desired number of teeth in the latter half of the intermediate forming step, both the outer peripheral sides of the rack material 1 on the side orthogonal to the rack tooth forming side are inclined by the inclined restraint surfaces 552 and parallel restraint surfaces 553 of the die 55. Since the material material of the rack material 1 is restrained and does not flow to the outer peripheral side of the rack material 1, the material material flows to the rack teeth 16 effectively.

  When the intermediate forming process is completed, the punch 45 rises as the ram of the press machine rises, and the approximate rack tooth profile 453 of the desired number of teeth on the lower surface of the punch 45 moves away from the rack tooth forming portion of the rack material 1. . At this time, the lower stripper 582 forcibly separates the left side of the rack material 1 from the die 55 by the biasing force of the spring 583. At the same time, the knockout 56 forcibly separates the rack tooth forming portion of the rack material 1 from the die 55 by the biasing force of a spring (not shown).

* Sizing molding process Next, in the sizing molding process of (4A) and (4B) in FIG. 10, as in the first and second embodiments, the die 75 having a desired rack tooth profile is opposed to the rack tooth molding side. The rack material 1 after the latter half of the intermediate forming step is sandwiched between a die 65 having a desired outer peripheral shape (in this embodiment, the cross section perpendicular to the axis of the rack is semicircular). And press. Thus, desired rack teeth (finished rack teeth) are formed while increasing the width between the outer circumferences of the rack material 1 on the side orthogonal to the rack tooth forming side. Since the structure of the mold in the sizing molding process of the third embodiment is the same as that of the first embodiment, the drawings and detailed description are omitted.

  In Example 3, the intermediate forming step is divided into the first half and the second half, and the number of teeth to be formed at one time is reduced. Therefore, the surface pressure when forming the rack teeth is increased, and as a result, the rack teeth It is possible to cause the material material to flow effectively.

  Further, as shown in FIG. 11 (1), the rack teeth 16 molded in the latter half of the intermediate molding step shown in FIG. 11 (2) are used for the pressure angle α of the rack teeth 15 molded in the first half of the intermediate molding step. Is set to be larger than the pressure angle β. Accordingly, since the material material in the latter half of the intermediate molding process flows along the tooth surfaces of the rack teeth 15 formed in the first half of the intermediate molding process, the stress required for molding is reduced, and the material The material can flow smoothly.

  In Example 3, molding is performed with the rack tooth profile of every other tooth in the first half of the intermediate molding process, and the remaining half of the rack tooth profile is molded in the second half, but the number of teeth to be molded in the first half and the number of teeth to be molded in the second half are formed. The ratio may be an arbitrary ratio.

  Next, a fourth embodiment of the present invention will be described. FIG. 12 shows rack teeth formed by the method of manufacturing a rack according to the fourth embodiment of the present invention, and (1) is an enlarged cross-sectional view of the main part showing the rack teeth 17 formed in the latter half of the intermediate forming process. 2) is an enlarged cross-sectional view of the main part showing the rack teeth 18 formed in the sizing molding process. FIG. 13 is an explanatory view showing the flow state of the rack material during the sizing molding process of the fourth embodiment of the present invention. In the following description, only structural parts different from the above-described embodiment will be described, and redundant description will be omitted.

  In Example 4, in the latter half of the intermediate forming process, the approximate pressure angle β of the rack teeth 17 is smaller than the pressure angle γ of the desired rack teeth 18, and the tooth depth H 2 is greater than the tooth rack H 3 of the desired rack teeth. In the sizing molding process, it is enlarged and molded so as to obtain a desired rack tooth pressure angle and tooth depth.

  That is, FIG. 12 (1) shows the rack teeth 17 that have finished the latter half of the intermediate forming process of FIGS. 10 (3A) and (3B). FIG. 12 (2) shows the rack teeth 18 after the sizing molding process of FIGS. 10 (4A) and 10 (4B). As shown in FIGS. 12 (1) and 12 (2), the pressure angle β of the rack tooth 17 that has finished the latter half of the intermediate forming process is smaller than the pressure angle γ of the rack tooth 18 that has finished the sizing forming process. Further, the tooth gap H2 of the rack tooth 17 that has finished the latter half of the intermediate molding process is smaller than the tooth gap H3 of the rack tooth 18 that has finished the sizing molding process. Therefore, since the molding pressure during the intermediate molding process can be small, rack teeth can be easily molded during the intermediate molding process.

  Further, in the sizing molding process of FIG. 13, the lower die having a pressing surface 752 having a desired rack tooth profile on the rack teeth 17 (pressure angle β, toothpick H2) that has finished the latter half of the intermediate molding process. 75 is pressed to form a desired rack tooth. 13 (1) shows a state immediately before the lower die 75 contacts the rack teeth 17, FIG. 13 (2) shows a state in the middle of forming the lower die 75 in contact with the rack teeth 17, FIG. 3) shows a state in which a desired rack tooth (pressure angle is γ, toothpaste H3) is formed after the sizing molding process is completed.

  By performing a molding process in which the pressure angle is increased from β to γ and the tooth depth is increased from H2 to H3, the material material 171 on the tooth surface shown in black in FIG. It is possible to form the desired tooth profile accurately by moving the material smoothly and sufficiently filling the tooth tip with the material.

  The mold structure of the intermediate molding process of Example 4 is the same as FIG. 8 of Example 2, and the mold structure of the sizing molding process is the same as that of Example 1. The drawings and detailed description are omitted.

It is process drawing which shows the manufacturing method of the rack of Example 1 of this invention, (1A), (1B) is explanatory drawing which shows a rack raw material, (2A), (2B) shows the rack raw material after upsetting processing It is explanatory drawing. It is process drawing which shows the post process of the process of FIG. 1, (3A), (3B) is explanatory drawing which shows the intermediate | middle shaping | molding process which shape | molds a rough rack tooth, (4A), (4B) shows a desired rack tooth. It is explanatory drawing which shows the sizing shaping | molding process to shape | mold. The structure of the metal mold | die which performs upsetting of Example 1 is shown, (1) is the longitudinal cross-sectional view cut | disconnected along the vertical plane which passes along the axial center of a rack, (2) is DD sectional drawing of (1). It is. The structure of the metal mold | die which performs the intermediate molding process of Example 1 is shown, (1) is the longitudinal cross-sectional view cut | disconnected along the vertical plane which passes along the axial center of a rack, (2) is EE sectional drawing of (1). It is. The structure of the metal mold | die which performs the sizing shaping | molding process of Example 1 is shown, (1) is the longitudinal cross-sectional view cut | disconnected along the vertical plane which passes along the axial center of a rack, (2) is FF sectional drawing of (1). It is. It is process drawing which shows the manufacturing method of the rack of Example 2 of this invention, (1A), (1B) is explanatory drawing which shows a rack raw material, (2A), (2B) is intermediate molding which shape | molds a rough rack tooth | gear It is explanatory drawing which shows a process. FIG. 7 is a process diagram showing a subsequent process of the process of FIG. 6, and (3A) and (3B) are explanatory diagrams showing a sizing molding process for molding a desired rack tooth. The structure of the metal mold | die which performs the intermediate molding process of Example 2 is shown, (1) is the longitudinal cross-sectional view cut | disconnected along the vertical plane which passes along the axial center of a rack, (2) is JJ sectional drawing of (1). It is. It is process drawing which shows the manufacturing method of the rack of Example 3 of this invention, (1A), (1B) is explanatory drawing which shows a rack raw material, (2A), (2B) is intermediate molding which shape | molds an approximate rack tooth | gear It is explanatory drawing which shows the process of the first half of a process. FIG. 10 is a process diagram showing a subsequent process of FIG. 9, wherein (3A) and (3B) are explanatory diagrams showing the latter half of the intermediate forming process for forming an approximate rack tooth, and (4A) and (4B) are desired It is explanatory drawing which shows the sizing shaping | molding process which shape | molds the rack teeth. (1) is an enlarged cross-sectional view of the main part showing the rack teeth formed in the first half of the intermediate forming step of FIG. 9, and (2) is a main part showing the rack teeth formed in the second half of the intermediate forming step of FIG. It is an expanded sectional view of a part. The rack tooth shape | molded with the manufacturing method of the rack of Example 4 of this invention is shown, (1) is an expanded sectional view of the principal part which shows the rack tooth shape | molded by the latter half process of the intermediate forming process, (2) is sizing. It is an expanded sectional view of the principal part which shows the rack tooth shape | molded by the formation process. It is explanatory drawing which shows the flow condition of the material of the rack raw material at the time of the sizing shaping | molding process of Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rack material 11 Outer periphery 12 Inner diameter hole 13 Flat surface 14 Right end surface 15 Approximate rack tooth of every other tooth 16 Approximate rack teeth of desired number of teeth 17, 18 Rack teeth 171 Material material 172 Tooth tip 21 Upper mold holder 22 Backing Plate 221 Bolt 222 Knock pin 23 Punch plate 231 Long groove 24 Punch press 241 Long groove 242 Bolt 243 Knock pin 25 Upper punch 251 Press surface 26 Spacer 27 Press plate 271 Bolt 28 Plate 281 Guide bolt 282 Upper stripper 283 Spring 31 Lower plate holder 32 Bolt 322 Knock pin 33 Punch plate 331 Long groove 34 Punch press 341 Long groove 342 Bolt 343 Knock pin 35 Lower punch 351 Press surface 36 Spacer 37 Press plate 71 Bolt 38 Plate 381 Guide bolt 382 Lower stripper 383 Spring 39 Positioning block 41 Upper mold holder 42 Backing plate 43 Punch plate 431 Knock pin 432 Bolt 433 Long groove 45 Punch 451 General rack tooth profile 452 General rack tooth profile 453 desired Rack teeth with approximate number of teeth 46 Spacer 461 Bolt 48 Plate 481 Guide bolt 482 Upper stripper 483 Spring 51 Lower mold holder 52 Backing plate 521 Bolt 522 Knock pin 53 Die plate 531 Long groove 54 Die retainer 541 Bolt 542 Knock pin 55 Die 551 551 Inclination restraint surface 553 Parallel restraint surface 56 Knockout 58 Plate 581 Guide bolt 582 Lower stripper 583 Spring 59 Positioning block 61 Upper die holder 63 Upper die plate 631 Knock pin 65 Upper die 651 Knock pin 652 Pressing surface 67 Holding plate 671 Bolt 68 Plate 681 Guide bolt 682 Upper stripper 683 Spring 71 Lower die holder 73 Lower die plate 731 Knock pin 75 Lower die 751 Dowel pin 752 Pressing surface 77 Pressing plate 771 Bolt 78 Plate 781 Guide bolt 782 Lower stripper 783 Spring 79 Positioning block

Claims (9)

Using a tubular rack material with an inner diameter hole,
Restrain the outer peripheral sides on the side perpendicular to the rack tooth molding side of the rack material with a die,
An intermediate forming step of forming a rough rack tooth by pressing a punch having a rough rack tooth shape against a rack tooth forming portion on the outer periphery of the rack material;
By sandwiching and pressing the rack material after the intermediate forming step between a die having a desired rack tooth shape and a die having a desired outer peripheral shape on the side facing the rack tooth forming side, the rack A sizing molding process that molds a desired rack tooth while expanding the width between the outer peripheral sides on the side orthogonal to the rack tooth molding side of the material,
A method for manufacturing a rack for a steering apparatus, comprising: forming a rack tooth by accommodating a material material excluded at the time of forming the rack tooth in an inner diameter hole of the rack material. In the manufacturing method of the steering device rack according to claim 1,
A method for manufacturing a rack for a steering device, wherein the rack material is a hollow cylinder. In the manufacturing method of the steering device rack according to claim 1,
As a pre-process of the intermediate molding process,
A method for manufacturing a rack for a steering device, comprising: an upsetting process of forming both sides of the outer periphery of the rack material perpendicular to the rack tooth forming side into a flat shape over a rack tooth forming length. In the manufacturing method of the steering device rack according to claim 1,
The constraining surface of the die that constrains both outer peripheral sides on the side perpendicular to the rack tooth forming side of the rack material is as follows:
A method of manufacturing a rack for a steering apparatus, wherein the rack is formed in a taper shape that continuously reduces the width between outer peripheral sides in the pressing direction of the punch. In the manufacturing method of the steering device rack according to claim 1,
The intermediate molding step is
The first half of the process of forming the approximate rack teeth on the rack material with a punch having an approximate rack tooth shape having a smaller number of teeth than the desired number of teeth, and then forming the remaining rack teeth to form the desired rack material A method of manufacturing a rack for a steering device, characterized in that the method is divided into a second half step of forming approximately the same number of rack teeth as the number of teeth. In the manufacturing method of the steering device rack according to claim 5,
A manufacturing method of a rack for a steering apparatus, characterized in that the punch having a rough rack tooth shape having a smaller number of teeth than the desired number of teeth has a rack tooth shape formed every other tooth of the desired number of teeth. In the manufacturing method of the steering device rack according to claim 5,
A method for manufacturing a rack for a steering device, wherein a pressure angle of a rough rack tooth having a smaller number of teeth than the desired number of teeth is larger than a pressure angle of a rough rack tooth having the same number as a desired number of teeth. In the manufacturing method of the steering device rack according to claim 1,
In the intermediate forming step, the pressure angle of the approximate rack tooth is smaller than the pressure angle of the desired rack tooth, the tooth depth of the approximate rack tooth is formed smaller than the tooth rack of the desired rack tooth,
A method of manufacturing a rack for a steering device, wherein, in the sizing molding step, an expansion molding is performed so that a desired rack tooth pressure angle and tooth depth are obtained.   A steering device rack manufactured by the method for manufacturing a steering device rack according to any one of claims 1 to 8.

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