JPH0155062B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to a method for manufacturing a gear material having a dog hole and an apparatus used to carry out the method.

(2) Prior Art First, an example of a conventional gear material with dog holes will be described with reference to FIG. Gear material 1 is
an annular tooth surface portion 2 in which a tooth surface is formed on the outer peripheral surface;
It has a hub part 3 having a shaft hole 4, and an annular recessed part 5 between the tooth surface part 2 and the hub part 3, and this recessed part 5 has a plurality of holes spaced apart from each other in the circumferential direction. dog holes 6 are formed, and ribs 7 are formed between each dog hole 6 by these dog holes 6.

Now, in manufacturing the gear material 1 having the dog hole 6 as shown in FIG. 1, it has conventionally been common to go through the steps shown in FIGS. 2a to 2g.
That is, as shown in FIG. 2a, first, a metal bar is cut out to a certain length in the axial direction and heated, and then the raw material 8 is roughly formed by forging in the axial direction. Then, as shown in Figure 2b,
By forging, the raw material 8 is roughly formed so that a concave portion 9 is formed on the upper surface side of the raw material 8, and a central protrusion 10 is formed at the center portion of the lower surface side.

The raw material 8 after rough molding is transferred to the next mold and positioned using the central protrusion 10, and as shown in FIG. 2c, the dog hole 6 is extruded forward and the shaft is Holes 4 are extruded backwards. Next, as shown in FIG. 2d, the shaft hole 4 is punched out using a punch for punching the shaft hole, and then, as shown in FIG. 11 is removed, and the gear material 1 is completed.

Thereafter, as shown in FIG. 2 f, each surface portion 12 to 17 of the gear material 1 is machined, and as shown in FIG. 2 g, both upper and lower edges of the dog hole 6 are chamfered. After that, gear cutting is performed on the outer circumferential surface of the tooth flank portion 2 to form a tooth flank.

(3) Problems to be Solved by the Invention In the conventional forging process as shown in FIG. 2, the dog hole 6 is formed by forward extrusion.
When forming this dog hole 6, it is essential to form a relief part 11 in order to make the material flow smoothly. If there is no flesh relief part 11, the material will not flow smoothly and an excessive load will be applied to the lower forging die and punch, reducing the durability of the lower die and punch. This makes forging impossible. Therefore, the forging die was made larger and the relief part 1
As a result, the axial cutting length of the metal bar necessary for the raw material 8 must be increased, and as shown in Fig. 2 e, after forging, the gear material Meat relief part 11 that is unnecessary for 1
must be removed. In addition, the meat relief part 11
As a result of the cutting process, burrs are likely to occur on the lower edge of each dog hole 6, resulting in a poor material yield and an increase in the time required for machining.

The present invention has been proposed in view of the above-mentioned circumstances, and instead of forward extrusion molding of the dog hole as in the conventional method, the dog hole is punched and molded by press shearing, thereby extruding the dog hole. It is an object of the present invention to provide a method for forging a gear material having a dog hole, which can eliminate various inconveniences caused by the forging, and an apparatus used for carrying out the method.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the method of the present invention involves cutting out a metal bar by a certain length in the axial direction, heating it, and then pressing it by forging. A step of roughly forming a raw material for a gear material; A step of roughly forming the raw material by forging; A press shearing process is performed on the raw material after the rough forming using a punch for punching a dog hole to remove the punched portion; A step of punching and forming the dog hole until it is slightly connected to the main body side of the raw material without being completely separated; and a lower mold that is different from the lower mold used in the punching and molding process. and punching out the punching removal part with a dog hole penetrating punch to completely separate it from the main body side of the raw material. A gear material used in the process of punching and forming dog holes is subjected to press shearing processing until the punched removed part is slightly connected to the main body side of the raw material to the extent that it is not completely separated. The manufacturing apparatus includes: a lower mold for placing and fixing the raw material on the upper surface; A blind hole-like recess is formed in the upper surface of the lower mold to correspond to the dog hole punch, and the recess is configured to move up and down with respect to the dog hole. It is characterized by having a cross-sectional size and shape that are sufficient to create a shear gap with respect to the teeth of the hole-punching punch, and a depth dimension that is larger than the thickness of the punch-removed portion.

(2) Effects According to the method of the present invention, the dog holes are punched out from the raw material by press shearing, which eliminates the large amount of undercut that is required when the dog holes are conventionally extruded forward. It is no longer necessary to specially provide the raw material, and when cutting out the raw material, only a small amount of material needs to be cut out. Furthermore, since the forging force required for press shearing is smaller than that for extrusion molding, the forging pressure for the entire process of forming the gear material is averaged.

In particular, in the punching and forming step using the press shearing process, the punching removed portion of the dog hole is slightly connected to the main body side of the raw material to the extent that it is not completely separated. In the next step, a lower mold different from the lower mold used in the previous step is used, and the punched-out portion is punched out with a dog hole penetrating punch to completely separate it from the main body side of the raw material. As a result, the work of separating and taking out the punched-out portion, that is, the scrap portion, can be efficiently performed using the punch and lower mold that are most suitable for the work.

Furthermore, in the apparatus of the present invention, the concave portion formed on the upper surface of the lower mold used in the punching process by the press shearing process is such that the punching removal portion is forced to be removed when the raw material is press sheared by the dog hole punch. Since it can be accepted without any problems, the press shearing process can be performed smoothly without any problems.
Furthermore, since the recess is formed in the shape of a blind hole and does not penetrate through the lower mold, a decrease in the strength of the lower mold due to the formation of the recess can be minimized. Further, during the punching and forming process by the press shearing process, the punched removed portion is not separated from the raw material, so the punched removed portion does not fall into the blind hole-like recess.

(3) Examples Examples of the present invention will be described below with reference to the drawings. First, as shown in FIG. 3a, a metal bar is cut out in the axial direction to a certain length calculated in advance, heated, and then the raw material 18 is forged in the axial direction to make it rough. Then, as shown in FIG. 3b, the raw material 18 is forged to form a concave portion 19 on the upper surface side and a central protrusion 20 at the center of the lower surface side. The material 18 is roughly formed. Up to this step, there is no difference from the conventional process, but since the raw material 18 does not contain the material necessary to form the fillet relief part as in the conventional method, the material yield is improved.

The raw material 18 after rough molding is transferred to the mold 21 shown in FIG. 4, and positioned on the lower mold 22 using the central protrusion 20. As the upper mold is lowered, the outer peripheral surface of the raw material 18 is regulated by the inner peripheral surface of the annular upper outer mold 23, and the raw material 18 is regulated by the inner peripheral surface of the annular upper outer mold 23.
The upper surface of the outer periphery of 8 is regulated by the lower end surface of the annular interpolation mold 24 . In this state, the dog hole 6 is formed by press shearing using the dog hole punch 25 disposed on the inner circumferential side of the intervening mold 24, and the shaft hole 4 is pushed out backward by the shaft hole forming punch 26. Shape. At this time, the punching removal portion 29 created by forming the dog hole 6 is removed from the raw material 20.
The device remains slightly connected to the main body of the device without being completely separated from the main body.

As shown in FIG. 5, the tooth portion 27 of the dog hole punch 25 has a flat lower end surface, and this lower end surface is sharply orthogonal to the side peripheral surface of the tooth portion 27. Further, the lower mold 22 has a blind hole-shaped recess 28 corresponding to each dog hole punch 25, and this recess 28 is formed by the teeth 27 of the dog hole punch 25.
It has a cross-sectional size and shape that are sufficient to generate a shear gap, and a depth dimension that is larger than the thickness of the punched-out portion 29. The side peripheral surface of the recess 28 is sharply orthogonal to the upper surface of the lower mold 22.

As described above, the shaft hole 4, the recessed part 5, and the dog hole 6 are formed in the raw material 18, as shown in FIG. 3c.

In order to clarify the structural features of the teeth 27 of the dog hole punch 25 and the recess 28 of the lower mold 22 shown in FIG. 5, FIG. Dog hole extrusion punch 30
An example of the relationship between the protrusion 31 and the recess 33 of the lower mold 32 is shown. The intersection between the lower end surface of the protrusion 31 and the side peripheral surface, the side peripheral surface of the recess 33 and the lower mold 32
In order to facilitate the flow of the material of the raw material 8 during extrusion molding, at the intersection with the upper surface of the
A smooth roundness is formed by chamfering, and between the protrusion 31 and the side peripheral surface of the recess 33, in order to facilitate the flow of the material of the raw material 8 into the recess 33 during extrusion molding, A sufficient gap is formed.

Now, after being molded by the mold 21 shown in FIG. 4, the raw material 1 is taken out from the mold 21.
8 is transferred to the mold 34 shown in FIG. 7 and positioned on the lower mold 35. Here, the mold 34
As the upper mold is lowered, the outer peripheral surface and the upper surface of the outer peripheral surface of the raw material 18 are regulated by the annular upper outer mold 36, and the punching removal part 29 is completely removed from the raw material 18 by the dog hole penetrating punch 37. is separated from the main body side. Then, the dog hole penetrating punch 37 is removed from the dog hole 6 while the ejector pin 38 presses the bottom surface of the shaft hole 4, and after the entire upper mold of the mold 34 has been raised, the extrusion action of the ejector pin 39 causes , the raw material 18 is separated from the lower mold 35, and the third
The state shown in Figure d is reached.

Next, the raw material 18 is transferred to a mold 40 shown in FIG. 8 and FIG. The tip of the ironing punch 41 is brought into contact with the corresponding dog hole 6, and the central protrusion 20 of the raw material 18 is brought into contact with the central hole 42 of the lower mold, so that the raw material 18 is It is positioned on the lower mold of the mold 40. As the upper die of the die 40 descends, the circumferential side surface of each dog hole 6 that is the engagement surface with the dog is moved by the ironing surface 43 formed on the outer circumferential surface of the tip of the ironing punch 41. While being ironed, the shaft hole 4 is punched out by the shaft hole punch on the upper mold side, and the central protrusion 20 is separated from the main body side of the raw material 18 and falls into the central hole 42.

At the base of the ironing punch 41, the ironing punch 4
A tapered chamfered portion 4 whose tip end side is tapered
4 is formed, and as the upper die of the die 40 descends, this chamfer 44 eliminates the fracture surface generated at the lower edge of each dog hole 6, which is a punched hole, by forging, as shown in FIG. A gear blank 1 having a dog hole 6 as shown in f is formed. When the upper mold is raised, the push-out pin 45 releases the gear blank 1 from the lower mold. Thereafter, for example, each surface portion 46, 47, 48, 49, etc. is machined in the same manner as in the conventional case.

C. Effects of the Invention As described above, according to the method of the present invention, in manufacturing a gear material having a dog hole, the dog hole is stamped into the raw material by press shearing, so that the dog hole can be formed by stamping the raw material by press shearing. There is no need to specially provide a large amount of fillet relief in the raw material, which is required when forward extruding holes, and only a small amount of material is cut out when cutting out the raw material, resulting in a lower material yield. is significantly improved. Furthermore, since the forging force required for press shearing is smaller than that for extrusion molding, the forging pressure for the entire process of forming the gear material can be averaged, and for example, the supply operating pressure to the transfer press can be made uniform. Furthermore, since the life of a punch for press shearing is generally longer than that of a punch for extrusion molding, the frequency of tool replacement can be reduced. Furthermore, unlike the conventional method, the troublesome process of cutting out the relief portion by machining after forging is not necessary, so the machining time can be shortened accordingly.

In addition, in the punching forming process using the press shearing process, the punching removal part of the dog hole is slightly connected to the main body side of the raw material to the extent that it is not completely separated, and in the next process, the punching removal part is Using a lower mold different from the lower mold used in the molding process, the punching removal section was punched out using a dog hole penetrating punch to completely separate it from the main body side of the raw material, so that the punching removal section could be completely separated from the main body side of the raw material. The work of separating and taking out the parts, that is, the scrap parts, can be carried out efficiently and easily in subsequent processes by using the punch and lower mold that are most suitable for these works. Moreover, during the punching process using the press shearing process, there is no risk that the scrap part will fall into the recess of the lower mold, which should receive the scrap part. It becomes possible to use a lower mold with high rigidity, which can contribute to making the lower mold lighter and thinner.

Furthermore, the apparatus of the present invention is a gear material manufacturing apparatus used in the step of punching and forming dog holes by the press shearing process, which comprises a lower mold for placing and fixing the raw material on the upper surface, and a lower mold for placing and fixing the raw material on the upper surface. includes at least a dog hole punch that is movable up and down with respect to the lower mold, the punch being disposed corresponding to the position where each of the dog holes is to be punched, and the upper surface of the lower mold is provided with the dog hole punch. A blind hole-like recess is formed corresponding to the hole punch, and the recess has a cross-sectional size and shape that is sufficient to create a shear gap with respect to the teeth of the dog hole punch. In addition, since the recess has a depth dimension larger than the thickness of the punched-out portion, the recess can easily receive the punched-out portion when press-shearing the raw material with the dog hole punch. The press shearing process is performed smoothly without any problems. Moreover, since the recess is formed in the shape of a blind hole and does not penetrate through the lower mold, the decrease in strength of the lower mold due to the formation of the recess can be minimized, and the lower mold can be Even if it is made thin to reduce weight, it can sufficiently withstand the powerful press shearing load applied through the raw material. In addition, during the punching and forming process using the press shearing process, there is no fear that the punched removed portion will fall into the recess, so even if the recess is formed into a blind hole, the punched removed portion will not remain at the bottom of the recess. .

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a gear material, Figs. 2 a to g are explanatory diagrams showing the conventional forging process of gear material, and Figs. 3 a to f are forging of gear material when the present invention is adopted. An explanatory diagram showing the process, FIG. 4 is a vertical cross-sectional view of the main part showing the process of punching out dog holes, FIG. 5 is an enlarged view of the main part of FIG. 4, and FIG. Enlarged view of main parts for comparative explanation, No. 7
The figure is a vertical cross-sectional view of the main part showing the cutting process of the punching and removal part of the dog hole, FIG. FIG. 2 is a vertical cross-sectional view of a main part taken along the - line in the figure. 1... Gear material, 6... Dog hole, 18... Raw material, 22... Lower mold, 25... Punch for punching dog hole, 27... Teeth, 28... Recess, 29... Punching removal Part, 35...Lower mold.

Claims (1)

[Scope of Claims] 1. A step of cutting a metal bar material to a certain length in the axial direction and heating it, and then roughly forming a raw material 18 for gear material by forging; A step of forming; applying press shearing to the rough-formed raw material 18 using a punch 25 for punching out dog holes to such an extent that the punching removal part 29 is not completely separated from the main body side of the raw material 18; until the dog hole 6 is slightly connected.
a step of punching and forming; using a lower mold 35 different from the lower mold 22 used in the punching and molding step, the punching removal portion 29 is formed with a dog hole penetrating punch 3;
7 to completely separate the raw material 18 from the main body side; 2 Perform press shearing on the raw material 18,
This gear material manufacturing device is used in a step of punching and forming a dog hole 6 until the punching removal part 29 is slightly connected to the main body side of the raw material 18 to the extent that it is not completely separated. a lower mold 22 for mounting and fixing the raw material 18 on the upper surface; and a lower mold 22 disposed corresponding to the positions of the raw material 18 where each of the dog holes 6 is to be punched and formed. A blind hole-shaped recess 28 is formed on the upper surface of the lower mold 22 in correspondence with the dog hole punch 25. 28 is
It has a cross-sectional size and shape sufficient to create a shear gap with respect to the tooth portion 27 of the dog hole punch 25, and has a depth dimension larger than the thickness of the punch removal portion 29. , gear material manufacturing equipment.