JP3503076B2 - Gear shaft manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a gear shaft used for a rotary drive mechanism of a one-tub type electric washing machine. 2. Description of the Related Art Conventionally, in a single-tub type electric washing machine in which washing and dehydration are continuously performed in a single tub, a rotary drive mechanism is
For example, a structure as shown in FIG. 8 is generally used. That is, the clutch boss 23 is provided at the lower end of the gear shaft 12 for rotating the dewatering tank 10 and the pulsator 11.
A one-way spring clutch 14 is attached via a pulley 20. When a rotational drive is applied through a pulley 20 in a direction in which the one-way spring clutch 14 is tightened, the outer cylinder 13 externally fitted to the gear shaft 12 It is designed to rotate at high speed integrally with the camera. This high-speed rotation is performed by the gear portion 12 formed at the upper end of the gear shaft 12.
a to planetary gear group 17 and outer ring gear 2 meshing therewith
2 is transmitted to the gear case 15 containing the
It is transmitted to the dehydration tub 10 via a guide cylinder 16 extending upward from 5. Thereby, a dehydration operation is performed. In addition,
Reference numeral 18 denotes a holding guide that integrally holds the rotating shafts of the planetary gear group 17 from above and below. And the outer cylinder 13
Is rotatably supported by a lower bearing cover 25 fixed to the main body of the washing machine via a first bearing 26.
In addition, the guide cylinder 16 is provided with an upper bearing cover 27 similarly fixed to the main body of the washing machine via a second bearing 21.
It is rotatably supported by On the other hand, when the one-way spring clutch 14 is rotationally driven through the pulley 20 in a loosening direction, the outer cylinder 13 does not rotate, and only the gear shaft 12 rotates. This rotation is transmitted to the planetary gear group 17 in the gear case 15, and the reduced rotation is transmitted to the pulsator shaft 19. As a result, the pulsator 11 attached to the upper end of the pulsator shaft 19 rotates at a low speed, and the washing / rinsing operation is performed. Reference numeral 2 denotes a one-way bearing for preventing the outer cylinder 13 from rotating together with the gear shaft 12, and reference numeral 3 denotes its bearing. [0003] The gear shaft 12 used for the above-mentioned rotary drive mechanism is usually manufactured as follows. That is, as shown in FIG. 9A, first, as shown in FIG.
35C) is cut into a predetermined length, and then cut as shown in FIG. 3B to form a large-diameter portion 31 at the upper end and a first small-diameter portion 33 below the intermediate portion 32. And the second small diameter portion 3
4 is formed. And center hole 3 in the center of both upper and lower sides
Drill 5,36. Next, as shown in FIG. 4C, gear teeth 37 are formed by engraving gear teeth on the large diameter portion 31 and four peripheral portions of the first small diameter portion 33 are chamfered. Thus, a detent portion 38 for integrally engaging the clutch boss 23 (see FIG. 8) is formed. Also,
A screw portion 39 is formed on the outer peripheral surface of the second small diameter portion 34 by rolling or cutting. Then, after quenching, the intermediate portion 32 is polished and finished, as shown in FIG. Alternatively, the gear shaft shown in FIG. 9B may be continuously formed by a continuous multi-stage forging machine, and the gear shaft 12 may be obtained in the same manner as in the above-described manufacturing method. As shown in FIG. 10, the continuous multistage forging machine takes in the wire 41 wound in a coil shape around the winding core 40 while unwinding the wire 41, cuts the wire 41 into a predetermined length, and successively cuts it. A molded product can be obtained continuously by continuously mounting a plurality of compression moldings in different mold tools and applying plastic deformation in a stepwise manner. Further, the shape shown in FIG.
Detent portion 38 against small diameter portion 33 (see << c >> in the figure)
May be performed by the continuous multistage forging machine. [0004] However, in these production methods, there is a problem that the material cost and the processing cost are high due to the large cutting allowance. Further, in order to form the gear portion 37 in the large-diameter portion 31, it is necessary to perform a tooth cutting process on each of the portions to engrave irregularities of the gear teeth, and there is also a problem that complicated work is required. In addition, the gear teeth formed as described above have a problem that the surface roughness is poor and the mating gears (specifically, the planetary gear group 17, see FIG. 8) are significantly worn and noise is apt to occur. Therefore, it is strongly desired to solve these problems. The present invention has been made in view of such circumstances, and is capable of integrally molding a shape close to the final shape including the formation of gear teeth, and has a small cutting allowance after molding, and is excellent. It is an object of the present invention to provide a method of manufacturing a gear shaft. In order to achieve the above object, a method of manufacturing a gear shaft according to the present invention is characterized in that the upper end of the shaft is formed in a large-diameter gear portion, and the lower end of the shaft is formed in a small-diameter screw portion. A method of manufacturing a gear shaft in which a chamfered portion for preventing rotation is formed on at least a part of an outer peripheral surface above the screw portion, wherein a metal rod having a predetermined length is compressed in a mold. By plastically deforming, the upper end of the rod-shaped body is formed into a large diameter portion, the lower side of the intermediate portion is formed as a paragraph, narrowed down to a first small diameter portion, and the lower lower end thereof is further formed as a paragraph and formed as a second small diameter. A step of preparing a preformed body narrowed to a portion, and having a cylindrical portion, upward from the center of the cylindrical portion, the lower portion has the same diameter as the outer diameter of the large diameter portion of the preformed body, and the upper portion has the gear teeth. A through-hole formed in the shape that can be shaped is formed. In the through hole, a male upper die through which a lifting pin is inserted from above and a concave portion having the same diameter as the outer diameter of the cylindrical portion of the male upper die are formed on the upper surface, and the cylindrical portion stands upright from the center in the concave portion. A through-hole having the same inner diameter as the outer diameter of the intermediate portion of the preformed body is formed downward from the center of the cylindrical portion, and the lower portion of the through-hole is reduced in diameter to a predetermined portion of the inner peripheral surface. Prepare a mold in combination with a lower knife that is formed in a shape capable of shaping the detent portion of the gear shaft, and lower the preformed body in a through hole of the lower knife. Is inserted and the preform is mounted with the upper part protruding upward, and the male upper die is lowered from above while the cylindrical portion is inserted into the recess of the female lower die, and the male upper die lifting pin Press the upper end surface of the preform with the lower end to lower the preform By lowering, the first small diameter portion of the preformed body is plastically deformed in the lower part of the through hole of the female lower die to form a detent portion, and then the male upper die is further lowered, The large-diameter part of the preform is pushed into the upper part of the through-hole of the male upper mold while the central cylindrical part of the female lower mold is inserted into the through-hole of the male upper mold, and the large-diameter part of the preform is formed. The gear teeth are shaped by plastically deforming the upper part of the male lower die through-hole. That is, according to the present invention, when manufacturing a gear shaft, a metal rod is compressed in a mold and plastically deformed to form a large-diameter portion on the upper portion and a first portion on the lower portion. After obtaining a preformed body having a small diameter portion and a second small diameter portion, the gear portion is formed by forming gear teeth on the large diameter portion by compressing and plastically deforming with a special mold. In addition, a detent portion is formed in the first small diameter portion. According to the present manufacturing method, the molding including the formation of the gear portion is performed with high precision by the plastic deformation, so that the surface roughness of the gear tooth forming portion is better than that obtained by the conventional gear cutting process. Thus, there is an advantage that the wear of the mating part that engages with this part is reduced and the durability is improved. Further, since the entire shape is obtained by plastically deforming the rod-shaped body, there is an advantage that the cutting allowance is minimized, the material is not wasted, and the process is simple. Next, the present invention will be described in detail based on embodiments. First, the desired shape of the gear shaft 12 is as shown in FIG. 9 (d). That is, the upper end of the shaft is formed in the large-diameter gear portion 37, and the lower end of the shaft is formed in the small-diameter screw portion 39. In addition, four portions of the outer peripheral surface above the screw portion 39 are chamfered to form a rotation preventing portion 38. The total length L of this gear shaft is 107 mm, the length M of the portion where the gear portion 37 is formed is 19 mm, and the length N of the intermediate portion 32 is 55 mm.
The length P of the screw portion 39 is 10 mm. Also,
The outer diameter D ₁ of the gear portion 37 is 18 mm,
Outer diameter D ₂ is 10 mm, the outer diameter D ₃ of the threaded portion 39 of 8mm
It is. Further, the outer diameter D ₄ of the portion where the rotation stopper 38 is formed is 9 mm. [0010] In order to manufacture the gear shaft 12, a wire made of S35C (diameter 10.3mm) wound in a coil shape is prepared and supplied to a continuous multi-stage forging machine.
In the apparatus, it was cut to a length of 132 mm. Then, this cut product is subjected to a first compression step, whereby FIG.
As shown in (a), the lower end face was plastically deformed into a clean chamfered shape. Next, the lower end was narrowed down to a small diameter as shown in FIG. Next, by performing a third compression step, as shown in FIG.
I narrowed it down to a slightly smaller diameter. This upper small-diameter portion is connected to a first small-diameter portion 4.
3. The small diameter portion at the lower end is referred to as a second small diameter portion 44. Also,
Simultaneously with the above-mentioned molding, the diameter of the portion slightly lowered from the upper end was increased to a substantially truncated cone shape (substantially truncated cone portion 45). Next, by performing a fourth compression step, as shown in FIG. 2A, the length of the first small diameter portion 43 is slightly extended, and the peripheral surface of the substantially truncated conical portion 45 is formed. The diameter of the upper side was enlarged so that the inclination became gentle. Then, by performing a fifth compression step, the upper side of the substantially frustoconical portion 45 is further expanded as shown in FIG. 4B, and this portion is formed into a cylindrical large diameter portion 46. Formed. By repeating this series of steps, the preformed body 50 having the special shape was continuously obtained from the continuous multistage forging machine. On the other hand, a special mold 51 as shown in FIG. 3 was prepared. The male upper mold 52 of the mold 51 has a cylindrical portion 53.
And a through hole 54 extending upward from the center of the lower surface 53a.
Is formed. The lower portion of the through hole 54 is formed to have the same diameter as the outer diameter of the large diameter portion 46 of the preform 50 (see FIG. 2B). Note that the “same diameter” is not limited to the literal “same diameter”, but also includes a diameter having a dimension with a tolerance that can be fitted to each other. It is used for the same purpose. Also, the upper portion of the through hole 54 is smaller in diameter than the lower portion,
The small-diameter portion 54a is formed with irregularities for gear tooth shaping. The periphery of the portion where the through hole 54 is formed is
The male upper mold 52 is formed of a separate member 55 different from the main body. A vertically movable pin 56 is inserted into the through hole 54 from above. The female lower mold 57 of the mold 51 is constituted by combining an outer cylinder 58 and two upper and lower inner cylinders 59 and 60, and the upper surface of the inner cylinder 59 is formed on the upper surface of the outer cylinder 58. The concave portion 61 is formed on the upper surface of the female lower die 57 so as to be lower than the lower portion. The inner diameter of the concave portion 61 (that is, the inner diameter of the outer cylinder 58) is set to the same diameter as the outer diameter of the cylindrical portion 53 in the male upper die 52. A cylindrical portion 62 is erected upward from the center of the concave portion 61, and the preformed body 50 extends downward from the center of the cylindrical portion 62.
Through hole 63 having the same inner diameter as the outer diameter of intermediate portion 32
Are formed through the inner cylinders 59 and 60. However, the through holes 63 are narrowed down to a slightly smaller diameter in the lower inner cylinder 60, and are provided at four locations on the inner peripheral surface of the small diameter portion 64 with the detent portions 38 (see FIG.
<< d >>) are formed to form four flat portions 65. The through-hole 63 is provided in the inner cylinder 6.
The upper end of the guide pin 68 which moves up and down in the center hole 67 of the base 66 provided below the base 0 enters from below. The periphery of the through-hole 63 is formed by another member 69, 70 different from the main body of the inner cylinder 59, 60. Therefore, the female lower mold 57 of the mold 51 is used.
As shown in FIG.
After the lower part of the preform 50 is inserted into the small diameter part 64 at the lower part of the through-hole 63 and the upper part is protruded upward, as shown in FIG. By lowering the male upper mold 52 from above, the male upper mold 5
While pressing the second cylindrical portion 53 into the concave portion 61 of the female lower die 57, the lower end of the elevating pin 56 of the male upper die 52 presses the upper end surface of the preformed body 50, and The entire lower part is pushed into the small diameter part 64 of the through hole 63 of the female lower die 57. At this time, the lower end surface of the large-diameter portion 46 of the preform 50 contacts the upper end surface of the central cylindrical portion 62 of the female lower die 57, and the lower end surface of the guide pin 68 contacts the lower end surface of the preform 50 below. The preform 50 will not be pushed down any further. By this operation, the first small-diameter portion 43 of the preformed body 50 is plastically deformed in the small-diameter portion 64 of the through-hole 63, and four locations on the outer periphery thereof are crushed into a plane, and the intended detent is stopped. The part 38 (see FIG. 9 << d >>) is shaped. Next, as shown in FIG.
Is further lowered to deepen the overlap between the cylindrical portion 53 of the male upper mold 52 and the concave portion 61 of the female lower mold 57, and the preform 5
The large-diameter portion 46 and the cylindrical portion 62 of the female lower die 57 are inserted into the through holes 54 of the male upper die 52. By this operation, the large diameter portion 46 of the preformed body 50 is
Is plastically deformed in the small-diameter portion 54a for gear shaping provided on the upper side of the gear, and the target gear portion 37 is formed. Then, as shown in FIG. 7, the male upper die 52 was raised, and the guide pin 68 was raised from below the female lower die 57, whereby the formed preform 50 was released. The preformed body 50 on which the gear portion 37 and the detent portion 38 are formed as described above is shown in FIG.
As shown in FIG. 9D, thread cutting is performed by rolling or cutting, and further quenching and polishing are performed.
The target gear shaft 12 as shown in FIG. The gear shaft 12 is not heated at all and the rotation preventing portion 38 and the gear portion 37 are plastically deformed.
Are formed, cutting work for gear cutting and chamfering becomes unnecessary, and the process is simplified. In addition, the surface roughness of the obtained gear portion 37 is improved. Incidentally, when the surface roughness of the gear portion 37 by the conventional gear cutting is 5-6S, that of the gear shaft 12 according to the method of the above embodiment is 3S, and the mating part (planetary gear group) that meshes with this portion in use. ) Is reduced and the durability is improved.
Also, since there is little rattling, the noise prevention effect is high. Further, since the shape close to the final shape is formed by plastic deformation, there is an advantage that the cutting allowance is significantly reduced and the cost is reduced as compared with the case where all the shapes are cut out from the bar. In the above embodiment, the gear shaft 12
Although the S35C wire was used as the material for the above, the material is not necessarily limited to this, and various stainless steels are used. Above all, from the viewpoint of rigidity, toughness, etc., the above S
35C and SUS410 are preferred. Further, not only stainless steel but also various kinds of high-strength metals and alloys can be used. Further, in the above embodiment, the wire is wound in a coil shape, and the wire is passed through a continuous multi-stage forging machine so as to obtain the preform 50 continuously. However, the continuous multi-stage forging machine is not necessarily used. It is not necessary to cut the wire or the bar into a predetermined size in advance, and the preformed body 50 may be obtained by successively passing through a forging machine having a different mold shape. According to this method, the number of steps is increased and the cost is slightly higher than in the case of using the continuous multi-stage forging machine, but it is more advantageous in terms of steps and cost than the conventional method. Further, in the above embodiment, the deformation of the cut product obtained by cutting the wire rod is shown in FIGS. 1 (a) to 1 (c) and FIG.
Although the process is performed in the five steps (a) and (b), the process is not necessarily limited to the five steps and can be performed in an appropriate number of steps. In the above embodiment, the gear shaft 12
Is formed by four chamfered shapes, but the shape is not necessarily limited to this, and the shape is not necessarily limited to this, and may be appropriately determined according to the mounting mode of the clutch boss 23 (see FIG. 8) mounted on this portion. A non-rotating shape can be provided. As described above, in the method of manufacturing a gear shaft according to the present invention, a metal rod is compressed in a mold and plastically deformed to form a large-diameter portion on an upper portion and a lower portion on a lower portion. After obtaining a preformed body in which the first small diameter portion and the second small diameter portion are formed, the preformed body is further compressed and plastically deformed by a special mold to form gear teeth on the large diameter portion to form a gear. And a detent portion is formed in the first small diameter portion. According to the present manufacturing method, the molding including the formation of the gear portion is accurately performed by the plastic deformation, so that the surface roughness of the gear tooth forming portion is better than that obtained by the conventional gear cutting process. Therefore, there is an advantage that the wear of the mating part that engages with this portion is reduced and the durability is improved. Further, since the entire shape is obtained by plastically deforming the rod-shaped body, there is an advantage that the cutting allowance is minimized, the material is not wasted, and the process is simple.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a), 1 (b), and 1 (c) are explanatory views of a forming step of a preform in one embodiment of the present invention. FIGS. 2 (a) and 2 (b) are explanatory views of a forming step of a preform in the above embodiment. FIG. 3 is an explanatory diagram of a mold used in the embodiment. FIG. 4 is an operation explanatory view of a mold used in the above embodiment. FIG. 5 is an operation explanatory view of a mold used in the above embodiment. FIG. 6 is an explanatory diagram of an operation of a mold used in the embodiment. FIG. 7 is an operation explanatory view of a mold used in the embodiment. FIG. 8 is a general explanatory view of a rotation drive mechanism of the electric washing machine. 9 (a), (b), (c) and (d) are explanatory views of a conventional method for manufacturing a gear shaft. FIG. 10 is an explanatory diagram of a wire used for manufacturing a gear shaft. [Explanation of Symbols] 12 Gear shaft 32 Intermediate part 37 Gear part 38 Detent part 39 Screw part 50 Preform 51 Mold 52 Male upper mold 53 Cylindrical part 54 Through hole 54a Small diameter part 56 Elevating pin 57 Female lower mold 61 Recess 62 cylindrical part 63 through hole 64 small diameter part

Claims (1)

(57) [Claim 1] An upper end of a shaft is formed in a large-diameter gear portion, and a lower end of the shaft is formed in a small-diameter screw portion, and at least a part of an outer peripheral surface above the screw portion. A method of manufacturing a gear shaft in which a chamfer for rotation prevention is formed on
By compressing and plastically deforming a predetermined length of a metal rod in a mold, the upper end of the rod is formed into a large-diameter portion, the lower side of the middle portion is formed as a paragraph, and is squeezed to a first small-diameter portion. A step of preparing a preform formed by lowering the lower end portion into a further paragraph and narrowing it to the second small diameter portion; and having a column portion, wherein the preform is upward from the center of the column portion, and the lower portion is the preform body. A male upper die in which a through-hole is formed with the same diameter as the outer diameter of the large-diameter portion and the upper part is formed in irregularities capable of shaping gear teeth, and a lifting pin is inserted from above in the through-hole, A concave portion having the same diameter as the outer diameter of the cylindrical portion of the male upper die is formed on the upper surface, a cylindrical portion is erected upward from the center of the concave portion, and an intermediate portion of the preformed body is formed downward from the center of the cylindrical portion. A through-hole having the same inner diameter as the outer diameter is formed. A mold is prepared by combining a lower part of the scalpel with a predetermined portion of which is formed in a shape capable of shaping the detent portion of the gear shaft of interest, and the preforming is performed in a through hole of the lower part of the scalpel. Insert the preform with the lower part of the body inserted and the upper part protruding upward, lower the male upper die from above while lowering its cylindrical part into the recess of the female lower die, By pressing the upper end surface of the preform with the lower end of the lifting pin and pushing the preform downward, the first small diameter portion of the preform is plastically deformed in the lower part of the through hole of the female lower die. To form a detent, then lower the male upper die further,
The large-diameter part of the preform is pushed into the upper part of the through-hole of the male upper mold while the central cylindrical part of the female lower mold is inserted into the through-hole of the male upper mold, and the large-diameter part of the preform is formed. A method of manufacturing a gear shaft, wherein gear teeth are shaped by plastically deforming the upper portion of a male lower die through-hole.