JP2006198662A - Method for forming hollow stepped shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a hollow stepped shaft with which a blank cost can be reduced by using a solid blank as the blank and a through-hole having the larger inner diameter at the intermediate part in the axial direction than that of the other portion can be easily be formed. <P>SOLUTION: Both sides of the solid rod-like blank 6 are held with upper and lower metallic molds 8, 9 having stepped large diameter parts on the faced parts. Successively, punches 10, 11 having smaller diameter than the blank, are pushed from at least one side end in the axial direction of the blank, and the large diameter part along the above stepped large diameter parts on the outer peripheral part with the push-out formation of the punches and the through-hole 5 having the same diameter over the whole length at the axial center part with the punches, are formed, respectively. Then, the respective end parts of the shaft part at both sides in the large diameter part, are formed into the shrunk diameter with the other upper and lower dies 13, 14 so as to shrink the diameter of both end parts of the through-hole into the smaller diameter than that of the intermediate part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a hollow stepped shaft having a stepped portion having a diameter larger than that of a shaft portion at an axially intermediate portion and having a through hole over the entire axial length of the shaft center portion.

  As a conventional method of forming a hollow stepped shaft of this type, a hollow tube is used as a raw material from the beginning, and a filler with a low touch point is filled into the hollow raw material, which is then opened or sealed. Both sides in the axial direction are pressed together with the filler in the mold, and the intermediate portion thereof is expanded and deformed into an annular recess provided in the mold (see, for example, Patent Document 1).

JP 2001-334317 A

  The unit price of the tubular body as a raw material is 3 to 5 times the weight unit price with respect to the solid material (bar material), and thus there is a problem that the material cost is high in the above-described conventional molding method using the tubular body. .

  Further, in the case of this type of hollow stepped shaft, a gear may be formed on the large diameter portion thereof, and an oil hole communicating with a through hole provided in the shaft center portion is provided on the tooth bottom of the gear, There is one that supplies the lubricating oil supplied to the through hole to the gear portion through the oil hole.

  At this time, if the inner diameter of the portion provided with the oil hole of the through hole is larger than the diameter on both sides in the axial direction, the difference from the centrifugal force with the other portion causes the oil hole to the gear portion. Lubricating oil can be easily supplied without using a pressurizing device, but in the case of a hollow stepped shaft formed by plastic deformation, the axial intermediate portion of the through hole of this hollow stepped shaft In order to make the diameter larger than the part, it is necessary to use machining, and there is a problem that it is costly to form.

  The present invention has been made in view of the above, and it is possible to reduce the cost of a material by using a solid, for example, round bar as a material, and the inner diameter of the axial intermediate portion is larger than the inner diameter of other portions. It is an object of the present invention to provide a method for forming a hollow stepped shaft that can be easily formed.

  In order to achieve the above object, a hollow stepped shaft forming method according to the present invention holds both sides in the axial direction of a solid rod-shaped material with upper and lower molds having stepped large diameter portions at opposing portions. Next, a punch having a diameter smaller than that of the material is pressed from at least one axial end of the material, and a large diameter portion along the stepped large diameter portion is formed on the outer peripheral portion by extrusion molding with this punch, and the punch is formed on the axial center portion over the entire length. Each through hole with the same diameter is molded, and each end of the shaft part on both sides of the large diameter part is reduced in diameter by other upper and lower molds, and both ends of the through hole are reduced in diameter to a smaller diameter than the intermediate part. I tried to do it.

  Further, another hollow stepped shaft forming method according to the present invention is to hold both sides in the axial direction of a solid rod-shaped material with upper and lower molds having stepped large-diameter portions at opposing portions, and then At least one end in the axial direction is pressed with a punch having a diameter smaller than that of the material, and by extrusion molding with this punch, a large-diameter portion along the stepped large-diameter portion is formed on the outer peripheral portion, and a punch in the axial center portion. Each through hole with a small diameter on the tip side is molded, and the outer diameter part on the large diameter side of the through hole is reduced in diameter with another mold to reduce the large diameter side end of the through hole. I tried to diameter.

  According to the molding method of the present invention, by using a solid, for example, round bar, as a material, the material cost can be significantly reduced as compared with the conventional case where a tube is used as the material. In addition, since the solid material is expanded by deforming the stepped portion of the intermediate portion together with the through-hole by extrusion molding with a punch, the forging line of the portion thickened and deformed to a large diameter may be wound in the axial direction and buckled. The forged streamline of the stepped portion is not cut and becomes fluidized, and defects such as cracks do not occur in this portion.

  And the through-hole which made the internal diameter of the axial direction intermediate part larger diameter than another part can be easily shape | molded by the shaping | molding process by a series of plastic deformation, without machining.

  By pressing a solid material in the mold in the axial direction, the outer peripheral shape is molded into a shape having a stepped portion in the middle in the axial direction which is a shape along the mold, and together with this, the shaft center portion Is punched out with a punch, and is formed using a solid material that is cheaper than the tube, and a solid stepped shaft that does not cause cracks in the stepped diameter-expanded portion is formed.

  FIG. 5 shows an example of a hollow stepped shaft to be molded in the first embodiment. The hollow stepped shaft 1 has a stepped portion 2 having a larger diameter than other portions in an axially intermediate portion, The stepped portion 2 has shaft portions 3 and 4 on both sides in the axial direction, and has a through hole 5 having a larger diameter in the axial center portion than the other portions in the shaft center portion and is hollow. .

  FIGS. 1 to 3 show the first, second, and third steps of the first step for forming the hollow stepped shaft 1. In the figure, 6 is a material using a solid round bar. 7 is a first mold apparatus, 8 is an upper mold thereof, 9 is a lower mold, and 10 and 11 are upper and lower punches, respectively. The upper mold 8 and the lower mold 9 are provided with concentric holes 8a and 9a into which the material 6 is inserted, and stepped large diameter parts 8b having diameters larger than the respective holes 8a and 9a at the opposing parts. 9b is provided. The upper and lower punches 10 and 11 are smaller in diameter than the material 6 and are inserted into the holes 8 a and 9 a of the upper and lower molds 8 and 9.

  FIG. 4 shows the second step, in which 12 is a second mold apparatus, 13 is an upper mold, and 14 is a lower mold. The upper mold 13 and the lower mold 14 have stepped portions for forming the stepped portion 2 of the hollow stepped shaft 1 with the intermediate portion of the stepped portion 2 of the hollow stepped shaft 1 to be formed as a split surface. 13a, 14a and shaft forming portions 13b, 14b for forming one shaft portion 3 and the other shaft portion 4. At the axial ends of the shaft forming portions 13b and 114b, throttle portions 13c and 14c having a smaller diameter than the shaft forming portions 13b and 14b are provided.

  Next, a molding method using the first and second mold apparatuses 7 and 12 will be described with reference to FIGS.

  First, in the first step (FIG. 1) of the first process shown in FIGS. 1 to 3, the material 6 is set in the holes 8a and 9a of the first mold apparatus 7 in the mold-clamping state. At this time, the material 6 is supported by the sleeve-like knockout 16 or both the punch 11 and the knockout 16 and positioned in the vertical direction. The position in the vertical direction (axial direction) of the material 6 is set according to the installation position in the axial direction of the stepped portion 2 of the hollow stepped shaft (molded product) 1 shown in FIG. See left side).

  Next, in the second step (FIG. 2), the upper and lower punches 10 and 11 are operated in the opposing direction to extrude from the axial direction side of the material 6. As a result, both end portions of the material 6 are extruded to the open sides of the upper and lower molds 8 and 9 by front and rear extrusion, respectively, and the intermediate portions are stepped large diameter portions 8b of the upper and lower molds 8 and 9, respectively. The diameter is expanded and deformed in 9b. At this time, the knockout 16 supporting the material 6 is moved downward according to the lower rear extrusion.

  In the second step shown in FIG. 2, the extrusion of the punches 10, 11 is completed in a state where the tips of both punches 10, 11 have reached the position facing the stepped large diameter portions 8 b, 9 b. Cylindrical portions 18a and 18b are formed on both sides in the axial direction with a plug-like portion 17 positioned between the opposed punches 10 and 11 at the axially intermediate portion. At the same time, a step-shaped enlarged diameter portion 18c is formed at a position facing the step-shaped large diameter portions 8b, 9b at the intermediate portion. Since the step-shaped enlarged diameter portion 18c at this time is expanded and deformed in a step shape from the solid state, the portion is deformed by a continuous forging line without causing buckling.

  Next, in the third step shown in FIG. 3, for example, the lower punch 11 is extracted, and the upper punch 10 is further extruded. As a result, the plug-like portion 17 is sheared in the axial direction and extruded as a drawn residue, and the first step is completed, and a hollow stepped intermediate formed body 19 having a through hole is formed.

  The intermediate molded body 19 is finish-molded in the second step shown in FIG. The lower cylindrical portion 18b of the intermediate molded body 19 is inserted into the large diameter portion of the shaft molding portion 14b of the lower mold 14 of the second mold apparatus 12, and the intermediate molded body 19 is set in the second mold 12. . In this embodiment, the mandrel 15 is not inserted into the hollow portion of the intermediate molded body 19.

  Next, the upper mold 13 is moved downward. As a result, the intermediate molded body 19 is reduced in diameter by the narrowed portions 13c and 14c in which the end portions of the cylindrical portions 18a and 18b are smaller in diameter than the shaft forming portions 13b and 14b of the upper die 13 and the lower die 14. The hole diameter of the lever portion is reduced. Further, the stepped large diameter portion 18c is pushed in the axial direction by the step forming portions 13a, 14a of the upper die 13 and the lower die 14 to be expanded in diameter, and is formed into the inner shape of the step forming portions 13a, 14a. . As a result, as shown in FIG. 5, the outer shape is finish-molded into a shape that conforms to the shape of the second mold apparatus 12 shown in FIG. 4, and the intermediate portion of the through hole 5 has a larger diameter than both side portions thereof. A hollow stepped shaft 1 having a stepped portion 2 is obtained.

  In the second step, a mandrel that defines the hole diameter may be partially inserted into the reduced diameter portion.

  FIG. 11 shows another example of the hollow stepped shaft to be molded in the second embodiment. The hollow stepped shaft 21 has a gear forming portion 22 having a larger diameter than the other portions in the intermediate portion in the axial direction. And a shaft portion 23, 24 on both sides in the axial direction of the gear forming portion 22, and a hollow having a through-hole 25 having a larger diameter in the axial center than the other portion in the axial center portion. It has become.

  6 and 7 show the first and second steps of the first step for forming the hollow stepped shaft 21, FIG. 8 shows the second step, FIG. 9 shows the third step, and FIG. 10 shows a 4th process.

  26 is a first mold apparatus, 27 is an upper mold thereof, 28 is a lower mold, 29 is a punch, and 30 is a knockout punch. The upper mold 27 and the lower mold 28 are provided with concentric holes 27a and 28a into which the material 6 is fitted, and stepped large diameter parts 27b having diameters larger than the hole parts 27a and 28a at the opposing parts. 28b is provided. The punch 29 has a smaller diameter than the material 6.

  In FIG. 8 showing the second step, reference numeral 31 denotes a punch for punching, and this punching punch 31 is provided with a small-diameter punching die 31 a at the tip of the body having the same diameter as the punch 29.

  In FIG. 9 showing the third step, 32 is a second mold apparatus, 33 is an upper mold thereof, 34 is a lower mold, and a stepped large diameter is formed by forming a gear forming portion at the opposing portion of both molds 33, 34. Portions 33a and 34a are provided.

  In FIG. 10 showing the fourth step, 35 is a third mold apparatus, 36 is an upper mold, 37 is a lower mold, and an aperture part having a smaller diameter than the other part (shaft part) on the opening side of the upper mold 36. 36a.

  Next, a molding method using the first to third mold apparatuses 26 and 35 will be described with reference to FIGS.

  First, in the first step shown in FIGS. 6 and 7, the material 6 set in the holes 27 a and 28 a is pressed by the punch 29 that operates downward while being supported by the knockout punch 30. A stepped portion is formed while a bottomed hole is formed in the material 6 by the punch 29.

  Next, in the second step shown in FIG. 8, the punching punch 31 is inserted into the hole instead of the punch 29 and moved downward. As a result, the bottom of the hole is pulled out in a plug shape by the punching die 31a to form a through hole. At this time, the tip of the through hole has a smaller diameter than other portions.

  In the third step shown in FIG. 9, stepped gear forming portions are formed by the stepped large diameter portions 33 a, 34 a of the upper and lower molds 33, 34.

  In the fourth step shown in FIG. 10, the upper shaft 36 is lowered by the lower portion of the upper die 36 by the restricting portion 36 a of the upper die 36, and the diameter of the through hole in this portion is reduced. As a result, as shown in FIG. 11, a large-diameter portion serving as a gear material is formed in the middle in the axial direction, and a through-hole 25 having a larger inner diameter in the axial middle portion than both ends is formed in the shaft center portion.

  The large diameter portion in the hollow stepped shaft 21 shown in FIG. 11 is a gear forming portion as described above, and the large diameter portion is subjected to gear processing by plastic working such as rolling or machining by a hob. 38 is processed, and further, an oil hole 39 that communicates the root of the tooth and the large diameter portion of the through hole is provided.

  In Example 2, instead of the punch 31 in the second step shown in FIG. 8, the punch 29 in the first step shown in FIG. 8 is used as it is, and at the end of the first step, the punch 29 is used. May be further pushed to penetrate the hole provided in the first step. Since the through hole in this case has the same diameter over the entire length, the both end support portions are reduced in diameter at both ends of the through hole with upper and lower molds as shown in FIG.

  In both of the above embodiments, the finish molding of the stepped portion 2 and the gear molding portion 22 may be performed in a separate process by inserting a mandrel into the hollow portion before the diameter reduction molding of the shaft portion. Thereby, at the time of finish molding of the stepped portion 2 and the gear forming portion 22, it is possible to prevent the inner diameter side of this portion from expanding into the hollow portion by the mandrel. Thereafter, the shaft portion is reduced in diameter so that the hollow hole having a larger diameter than the other portion formed in the intermediate portion in the axial direction can be formed into a smooth cylindrical shape.

  Moreover, in both the above-described embodiments, an example in which each forming process is performed in the vertical direction is shown. However, this may be formed in the horizontal direction, and the description of the present invention will be made. The upper and lower words in the book are substantially synonymous with the horizontal direction (left and right).

  The molding in both of the above-described embodiments is carried out by heating a part or the whole of the material 6 at room temperature or in a heating range without an oxidation coating at 200 to 700 ° C. In addition, even if it shape | molds at normal temperature, a raw material is heated up to 200-700 degreeC by a deformation | transformation.

3 is a cross-sectional view showing a first step of a first step in Example 1. FIG. 6 is a cross-sectional view showing a second step of the first step in Example 1. FIG. FIG. 6 is a cross-sectional view showing a third step of the first step in Example 1. 6 is a cross-sectional view showing a second step of Example 1. FIG. 1 is a cross-sectional view showing a hollow stepped shaft that is molded in Example 1. FIG. 10 is a cross-sectional view showing a first step of a first step in Example 2. FIG. 12 is a cross-sectional view showing a second step of the first step in Example 2. FIG. 10 is a cross-sectional view showing a second step of Example 2. FIG. 10 is a cross-sectional view showing a third step of Example 2. FIG. 6 is a cross-sectional view showing a fourth step in Example 2. FIG. It is sectional drawing which shows the hollow stepped axis | shaft shape | molded in Example 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 21 ... Hollow stepped shaft, 2 ... Stepped part, 3, 4 ... Shaft part, 5 ... Through-hole, 6 ... Material, 7 ... 1st mold apparatus, 8 ... Upper mold | type, 9 ... Lower mold | type, 8a , 9a ... hole, 8b, 9b ... stepped large diameter part, 10, 11 ... punch, 12 ... second mold device, 13 ... upper mold, 14 ... lower mold, 13a, 14a ... step forming part, 13b, 14b ... Shaft forming part, 13c, 14c ... Restriction part, 15a, 15b ... Mandrel, 16 ... Knockout, 17 ... Plug-like part, 18a, 18b ... Cylindrical part, 18c ... Step-shaped enlarged diameter part, 19 ... Intermediate molding , 21 ... hollow stepped shaft, 22 ... gear forming part, 23, 24 ... shaft part, 25 ... through hole, 26 ... first mold device, 27 ... upper mold, 28 ... lower mold, 27a, 28a ... hole part , 27b, 28b ... stepped large diameter part, 29 ... punch, 30 ... knockout punch, 31 ... punch for punching, 31a ... punching die, 32 ... second mold 33 ... Upper die, 34 ... Lower die, 33a, 34a ... Stepped large diameter portion, 35 ... Third mold device, 36 ... Upper die, 37 ... Lower die, 36a ... Throttle portion, 38 ... Gear, 39 ... oil holes.

Claims (2)

Hold both sides in the axial direction of the solid rod-shaped material with upper and lower molds that have stepped large diameter parts at the opposing part,
Next, a punch having a diameter smaller than that of the material is pressed from at least one end in the axial direction of the material, and the large diameter portion along the stepped large diameter portion is formed on the outer peripheral portion by extrusion molding using the punch, and the punch is formed on the axial center portion over the entire length. Each through hole with a diameter,
A hollow characterized in that each end of the shaft portion on both sides of the large-diameter portion is reduced in diameter by other upper and lower molds, and both end portions of the through hole are reduced in diameter from the intermediate portion. A method of forming a stepped shaft. Hold both sides in the axial direction of the solid rod-shaped material with upper and lower molds that have stepped large diameter parts at the opposing part,
Next, a punch having a diameter smaller than that of the material is pressed from at least one end in the axial direction of the material, and a large diameter portion along the stepped large diameter portion is formed on the outer peripheral portion by extrusion molding using the punch, and a punch is formed on the shaft center portion by the punch. Forming each through-hole with a small diameter on the tip side in the pressing direction,
Hollow stepping, characterized in that one end of the axial direction and the outer diameter of the large diameter side of the through hole are reduced in diameter by another mold to reduce the diameter of the large diameter side end of the through hole Shaft forming method.

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