JPS6127137A - Forging method of gear - Google Patents

Abstract

PURPOSE:To improve the accuracy of a product, and to improve the production efficiency by forming preliminarily a forging billet being in a cavity by an upsetting compression, raising a back pressure of one punch, also lowering a back pressure of the other punch, and punching and forming said billet. CONSTITUTION:An upper die and a lower die 1a, 1b are diesunk on a mating face in accordance with a cavity 2 which is coincided with an external form of a gear. A forging billet 5a is placed between the upper die 1a and the lower die 1b, the upper die 1a is moved by pressure toward the lower die 1b, and an upsetting compression forming is executed. In this case, a low pressure is operated suitably on a punch 3a, and a part of the billet 5a is formed preliminarily so as to generate a recess in a punch hole 4a. Subsequently, the punch 3a is made to descend by raising a back pressure of the punch 3a and also lowering a back pressure of the punch 3b, punching and forming are executed, and a product gear 5d is obtained. According to this method, a product having a good accuracy can be mass-produced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for forging gears such as bevel gears used in differential devices of automobiles, trucks, etc. or power transmission parts of various mechanisms. .

[Conventional technology]

To explain the conventional forging manufacturing method for bevel gears (binion gears are Lugya), first the material (α) is
The first preform (h) is made by forging, and the first preform (b) is subjected to intermediate annealing 1) and lubrication treatment (
b), and then in the second step, a second preform (b) which approximates the t-finish forged product is applied.
After being forged to the rough shape (C), it is again subjected to intermediate annealing and lubrication treatment (gating), and then in the third step it is forged to the second preform (C)' and finished. The forged product (d) is made into a forged product, and in the next fourth step, the forged material (g) is punched out to obtain a finished product (e)'fc as a forged material. It is manufactured into a finished product, a bevel gear (!I).

[Problems with conventional technology]

In the conventional forging manufacturing method for gears, as mentioned above, the number of forging steps is large, and in addition, annealing, lubrication, etc. are required between each forging process, and a large amount of equipment is required. becomes complicated, resulting in poor economic efficiency and productivity.

Furthermore, because of the limitations of the forging deformation process, an intermediate forging material with a shape significantly different from that of the final finished product is produced, resulting in poor material yield and an increase in the number of machining steps required to obtain the final finished product.

The forging process requires a great deal of forging force, resulting in a short die life. There are drawbacks such as.

[Purpose of invention, means for solving problems]

The present invention was developed in order to eliminate the above-mentioned drawbacks in the conventional gear forging method. Upper and lower punches are accommodated in punch holes formed in a closed cavity and connected to the upper and lower cavities, and the back pressure of one of the punches is reduced by using upper and lower molds arranged oppositely. After the forged materials in the upper and lower cavities are upset and compressed by the upper and lower dies to form the closed cavities, the back pressure of one of the punches is increased to form the forged materials on the same side. The relief material in the punch hole is extruded to fill the closed cavity with the preformed forged material to form it into a gear shape, and the back pressure of the other punch is lowered to further extrude one of the punches to form the hole. The second invention is characterized in that the back pressure of one of the punches is lowered and the back pressure is adjusted when upsetting and compressing and preforming in the first invention. The feature is that the amount of material released into the side punch hole is adjusted. The forging material is upset and compressed between the upper and lower cavities of the upper and lower molds to form a closed cavity by preforming, and the back pressure of one of the punches is lowered during the preforming. A part of the forging material escapes into the punch hole on the same side, preventing flash from occurring on the mating surfaces of the upper and lower dies, and inserting the preformed forging material into the closed cavities of the upper and lower dies. In addition, by increasing the back pressure of one of the punches, the relief material in the punch hole on the same side is extruded, and the preformed forging material expands and fills the closed cavity to form a gear shape. (li) By forming the punch in one continuous step by extruding one punch with a low back pressure of the punch, (li), furthermore, during the preforming, the back pressure of one of the punches is low By adjusting the amount of material released into the punch hole on the same side to a desired value according to the condition of the forged material, the shape of the preformed forged material in the closed cavity is controlled, and the preformed material in the closed cavity is controlled. By increasing the expansion and filling accuracy of the forged material, it is possible to forge from the forged material to the gear mold and punch the hole in a single forging process, which saves resources, saves energy, and improves work efficiency. The object of the present invention is to provide a gear forging method that eliminates the above-mentioned conventional drawbacks by allowing high-precision gears to be mass-produced with high efficiency without requiring a large number of steps.

[Embodiments of the invention]

1(A) to 1(A) show the forming process of the gear forging method according to the present invention9. This embodiment is a specific example of forging a pinion pail gear for a differential gear device. (A) and (B) in Figure 1.

(C) and (D) show the entire process of forming a bevel gear by the forging method of the present invention.

The upper and lower dies used in the forging method of the present invention consist of an upper die (1α) and a lower die (1h), and an upper die and a lower die (1α) as shown in FIG. Upper and lower cavities (depressions) are formed on the mating surface side of (1h) by die engraving.
When the upper and lower molds (1cc) and (1b) are matched, the upper and lower cavities form a closed cavity (2) that matches the shape (outer shape) of the bevel gear to be forged. Further, an upper punch hole (4α) is continuously provided by drilling in the center of the upper cavity in the upper mold (1α), and the upper punch hole (4α) is inserted into the vertically arranged punch hole (4α).
3α) is inserted and housed so as to be movable up and down, and
A lower punch hole (4h) is continuously drilled in the center of the lower cavity in the lower mold (1b), and the lower punch (3b) is inserted vertically into the vertically arranged punch hole (4b). It is movably inserted and housed, and is connected to the punch hole (4α) and (
4b) is a vertical-straight arrangement, and the upper and lower punches (3
The axes of αX3b) are arranged oppositely on the same straight line.

Furthermore, back pressure is applied to the punches (3α) and (3b) individually by a device not shown, and the back pressure can be adjusted in level, and the punches (3α) and (3b) (3b) A configuration in which the back pressure is controlled by appropriate means so as to be maintained at predetermined high and low adjustment values even when the punch is moved up and down due to the pressure applied by the forged material in the cavity. It has become.

The forging method of the present invention is carried out using upper and lower molds having the above-described configuration, and first, as shown in FIG. 1(A), the upper mold (1α) is and the punch hole (4α x 4A) diameter between the upper and lower cavities of the lower mold (1h).

Install a larger forged material (5α) and use a stopper die (1α).
) is pressurized and moved toward the lower die (1b) as indicated by the arrow, and the forged material (5α) is upset compression molded (compression plastic deformation). At that time, punch holes (
A back pressure corresponding to the pressure applied from the forging material (5α) side during the upsetting compression forming was applied to the punch (3h) in 4h), and the same punch (3b) was removed in Figure 81 (A). As shown in , the forging material (5cL) is maintained in a state aligned with the lower cavity surface to prevent part of the forging material (5cL) from being pushed into the punch hole (4b), and the punch hole (4α) in the upper mold (1α) is ) is applied with an appropriately lower back pressure than the pressure applied from the inside of the cavity, so that a part of the forged material (5α) is inserted into the punch hole (4α) during the upsetting compression forming. The mating surfaces of the upper and lower molds (1α) and (1b) (one of them is as shown in FIG. 1(B) The top is molded to perfectly match the
The lower cavity is closed to form a closed cavity (2).

In the above preforming, the back pressure to one punch (3α) was set low to a predetermined value, so that a part of the forged material (5α) could be extruded into the punch hole (4α) on the same side and escape. , the mating surface (1) of the upper and lower molds (1α) and (1h)
Part of the forging material (5α) can be prevented from entering between the gaps, and the mating surfaces (1) of the upper and lower molds (1α) (IA) can be brought into perfect contact, preventing the occurrence of flash. This can be prevented and the closed cavity (2) can be completely sealed.

By lowering the back pressure on the punch (3α) side and setting it to a predetermined value in advance, the initial purpose can be achieved. The preformed product (5b) has a shape close to that of a complete product, but two voids remain in the closed cavity (2).

The gap (2 is the set value of the low back pressure of the punch (3α) and the amount of material released into the punch hole (4α) (5
'A) is formed in relation to the void (2).
The degree to which the molded product is formed greatly affects the molding of the preformed product (5h) and also affects the accuracy of the final product. Therefore, during the preforming, the low back pressure of the punch (3α) can be controlled and adjusted to an appropriate value in accordance with the material, quantity, temperature, etc. of the forging material (5α). By controlling and adjusting the low back pressure of the punch (3α), the amount of material released into the punch hole (3a) (5/h)
becomes an appropriate value, the voids (two) are minimized, and the shape of the preform (5b) is brought closer to the final finished product.

Next, from the state of the first part), the back pressure of the punch (3α) on the upper mold (1α) side is increased to lower the pressure, and the hole in the punch hole (4a) is inside the closed cavity (2). Release material (5'
h), and if necessary, use the same punch C3CL')
By pushing the preformed forged material (5A)' (e) into the cavity (2), the closed cavity (2) is completely filled and the closed cavity (5A) is expanded as shown in FIG. Form the bevel gear (5C) K following the shape of 2).At this time, since the preformed product (5b) has a shape similar to the finished product, the pressure drop required on the punch (3α) side is reduced. The back pressure, that is, the forging force, is small, and the life of the mold is extended without applying excessive pressure to the upper and lower molds, and the accuracy of the bevel gear (5C) can be sufficiently ensured by using a teaspoon of forging force.

Furthermore, from the state shown in Fig. 1(C), the lower mold (1b
), the punch (3α) is further lowered due to the high back pressure and penetrates the center of the bevel gear (5C), causing the excess material to flow into the punch hole (41). ) and punched into the final bevel gear (5d) with a through hole in the center.At this time, the closed cavity (2) is completely closed as described above. Since the upsetting and expanding molding is performed by pushing in the reed and the punch (3α), the closed cavity (2) is further filled and molded without generating excessive pressure or force.

Finally, while lowering the back pressure of the punch (3b) moderately, the upper mold (1a) is raised and the bevel gear (5d) is taken out.

[Action and effect of the invention]

The gear forging method of the present invention uses upper and lower molds having the above-described construction, upper and lower cavities, punch holes, and punches. The forged parts are made into preformed parts in the cavity of the forging machine, and then the preformed parts are expanded and filled into the closed cavity using a punch to form a bevel gear shape. Gear products can be mass-produced with high efficiency.

Furthermore, in detail, according to the forging method, a final product with no flash or the like and punched holes can be obtained, and the precision of the tooth profile is significantly improved and the shape of the spherical part is good. , almost no cutting process is required, preventing a decrease in hardness, reliability) 5Li is high, the metal yield is improved, forging force can be saved, the mold life is longer, and the equipment is significantly simplified. This has the effect of significantly reducing equipment costs.

In the above embodiments, the explanation was focused on forging bevel gears, but the present invention can be applied to a wide range of forging methods for various gears.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited to such embodiments, and may be modified in various designs without departing from the spirit of the present invention. be.

[Brief explanation of the drawing]

Figures 1) to 2) are process diagrams of a gear forging method according to the method of the present invention, and Figure 2 is a process diagram of manufacturing a bevel gear by conventional forging. 1α: Stopper mold 1b: Lower mold 2: Closed cavity (upper and lower cavities) 3α, 3b:
Punch 4α, 4b: Punch hole agent Patent attorney Oka
Honju, 3 people outside the text Figure 2

Claims (2)

[Claims] (1) A gear-shaped closed cavity is formed by the upper and lower cavities provided in the upper and lower molds, and the upper and lower punches are accommodated in the punch holes connected to the upper and lower cavities. Using the upper and lower molds which are provided, the forging material in the upper and lower cavities is upset and compressed by the upper and lower molds by lowering the back pressure of one of the punches to preform the forging material. After forming a closed cavity, the back pressure of one of the punches is increased to extrude the relief material in the punch hole on the same side, filling the closed cavity with the preformed forging material and forming it into a gear shape, and forming the preformed forging material into a gear shape. A method for forging a gear, characterized in that the back pressure of the punch is lowered, and one of the punches is further extruded to form a hole. (2) A gear-shaped closed cavity is formed by the upper and lower cavities provided in the upper and lower molds, and the upper and lower punches are accommodated in the punch holes connected to the upper and lower cavities. Using upper and lower molds, the back pressure of one of the punches is lowered and the back pressure is adjusted to adjust the amount of material released into the punch hole on the same side to a predetermined amount. After upsetting and compressing the forged materials in the upper and lower cavities using the upper and lower molds and preforming them to form the closed cavities,
The back pressure of one of the punches is increased to extrude the relief material in the punch hole on the same side, filling the closed cavity with the preformed forging material and forming it into a gear shape, and the back pressure of the other punch is lowered. A method for forging a gear, characterized in that one of the punches is further extruded to form a hole.