JP5246588B2 - Gear manufacturing apparatus and method - Google Patents

Description

The present invention relates to a gear manufacturing apparatus and a gear manufacturing method, and more particularly, to a gear manufacturing apparatus for forming a helical gear on an inner peripheral surface of an annular gear material and a method for manufacturing the gear.

Conventionally, as a method of manufacturing a helical gear, there has been known a method of forming a tooth profile by extruding a gear material in cold forging (Patent Documents 1 and 2). This method has a disadvantage that the tooth profile accuracy of the obtained product is poor because the gear material is strongly twisted during extrusion. Still, when the twist angle of the gear is as small as 20 degrees or less, the shape of the introduction part at the initial stage of extrusion was devised, so that twisting of the material was suppressed and the tooth profile accuracy could be maintained to some extent. However, in manufacturing a gear with a high helix angle, the tooth profile accuracy cannot be sufficiently maintained. Therefore, conventionally, it has been impossible to form a high helix angle gear by cold forging.

In order to form a helical gear with a high helix angle by cold forging, a gear shaping method based on the flesh approach method has been developed. For example, a ring-shaped material is inserted into a ring-shaped gap between a die and a mandrel arranged coaxially in the cylindrical hole of the die, and the material and the mandrel are both put together by the pressing means such as a punch. The material is pressed along the axial direction of the mandrel, and the material is plastically moved from its center by the reduced diameter portion provided on the inner peripheral surface of the cylindrical hole of the die, and the inner peripheral surface side of the material is moved to the outer peripheral surface of the mandrel. Press on the helical gear molding tooth mold provided to mold the helical gear on the inner peripheral surface, and then press the outer peripheral surface side of the material against the straight gear molding tooth mold provided on the inner peripheral surface of the cylindrical hole of the die Thus, there is known a method for simultaneously forming inner and outer gears in which a straight gear is formed on the outer peripheral surface independently or in parallel with the helical gear (Patent Document 3). As a result, it has become possible to form a gear with a high helix angle by cold forging, but there is a drawback in that sufficient tooth profile accuracy is not yet obtained at the forming tip. Therefore, in order to make a product, it is necessary to cut a portion having a low tooth profile accuracy at the initial stage of molding, resulting in poor yield of the gear material and high cost.

A method of manufacturing a gear having a spur gear on the outer periphery and a helical spline on the inner periphery, comprising a material forming an annular body, an external tooth forming member having a spur gear forming tooth on the inner periphery, and a helical on the outer periphery. An internal tooth forming member having spline forming teeth is prepared, the internal tooth forming member is inserted into the inner periphery of the external tooth forming member, and the material is disposed in the outer peripheral space of the helical spline forming tooth, and the material By pressing the material from both end surfaces in a state where the outer peripheral surface of the material is regulated, a helical spline is formed on the inner periphery of the material, and the material is continuously pushed out to the inner peripheral space of the spur gear forming tooth. A gear manufacturing method in which a spur gear is formed on the outer periphery of the material is known (Patent Document 4). According to this method, since the helical spline is formed by upsetting the material from both ends, the gears are formed at once. Therefore, the resistance increases and the material cannot be sufficiently pushed into the helical spline forming tooth mold, and sufficient tooth profile accuracy cannot be obtained. Further, in the molding of a product with a high helix angle, there is a problem that the resistance is further increased, and the helical spline molded teeth are subjected to a large load and are inclined more than the original inclination, and the tooth trace accuracy is deteriorated. In addition, when forming spur gears on the outer periphery, there are parts where the material is moved inward by spur gear forming teeth and parts that cannot be moved inward, so that the helical splines that are internal teeth are finished uniformly in the circumferential direction. There was also a problem that it could not be molded and the tooth profile accuracy deteriorated.

JP 2005-342779 A Japanese Patent Laid-Open No. 10-99937 JP 11-147158 A JP 10-2111539 A

The present invention relates to a gear manufacturing apparatus capable of forming a helical gear having a remarkably good tooth profile accuracy over the entire inner peripheral surface of an annular gear material regardless of the torsion angle of the formed helical gear, and the manufacturing of the gear. A method is provided.

The inventors of the present invention have studied various reasons why the method of Patent Document 3 cannot obtain sufficient tooth profile accuracy at the forming tip. As a result, the material is plastically moved from its center by the reduced diameter portion provided on the die, and the helical gear is formed by pressing the inner peripheral surface side of the material against the helical gear forming tooth die provided on the outer peripheral surface of the mandrel. At this time, it was found that the material does not sufficiently penetrate into the helical gear molding tooth mold, and a phenomenon that the material flows downward at the end opposite to the pressing end, so-called “sag” occurs. However, in order to prevent this “sag”, as described in Patent Document 4, when the material is evenly pressurized from both end surfaces and the internal teeth are formed by upsetting, the method is similar to the method described in Patent Document 4. Therefore, the tooth profile accuracy cannot be increased. Thus, as a result of further studies, the inventors can unexpectedly prevent “sag” if the helical gear is formed by plastically moving the material by the reduced diameter portion while pressing the material from both end faces. It has been found that the material can be plastically deformed satisfactorily and the material can be sufficiently penetrated into the helical gear forming tooth mold, and the present invention has been completed.

That is, the present invention
(1) A die (A) having a cylindrical hole (1) extending in the axial direction, wherein the hole (1) is a cylindrical part (2) extending from the opening (O), followed by a reduced diameter. Part (3), followed by a cylindrical part (4) having a smaller diameter,
A cylindrical mandrel (B) having an outer diameter smaller than the diameter of the cylindrical part (4) and having a helical gear forming tooth mold (5) on the outer peripheral surface, wherein the mandrel is a die (A) In a cylindrical cavity (1) of
An annular gap (C) formed between the die (A) and the mandrel (B), where an annular gear blank (W) is disposed in the gap, and the annular gap (C) Means (D) for pressing the gear material (W) to be arranged along the axial direction from the opening toward the inside.
A cylindrical part (4) having a smaller diameter of the die (A) and a helical part of the mandrel (B) through the reduced diameter part (3) through the annular gear material (W) by the pressing means (D) In the gear manufacturing apparatus that forms a helical gear on the inner peripheral surface of the gear blank (W) by being pushed into a gap formed by the portion provided with the gear forming tooth mold (5), an annular gear is formed by the pressing means (D). When the material (W) is pushed into the gap, the gear material (W) can be pressed from the other end of the gear material (W) toward the opening in the direction opposite to the pressing direction by the pressing means (D). Further comprising means (E) and pressing the annular gear material (W) by the pressing means (D) and (E), the gear material (W), the pressing means (D) and (E), and the mandrel ( B) together, the cylindrical part of the die (A) (4) It is a device which is characterized in that can be moved in the pressing direction by the pressing means (D) along an inner circumferential surface.

As a preferred embodiment,
(2) The ratio of the pressure applied to the gear blank (W) by the pressing means (E) to the pressure applied to the gear blank (W) by the pressing means (D) is 0.1 or more and less than 1.00 ( 1) a device according to
(3) The ratio of the pressure applied to the gear material (W) by the pressing means (E) to the pressure applied to the gear material (W) by the pressing means (D) is 0.13 or more and less than 1.00 ( 1) a device according to
(4) The above (1), wherein the ratio of the pressure applied to the gear material (W) by the pressing means (E) to the pressure applied to the gear material (W) by the pressing means (D) is 0.2 to 0.3. ) The device described,
(5) The device according to any one of (1) to (4), wherein the helical gear formed has a twist angle of 15 to 40 degrees,
(6) The device according to any one of (1) to (4) above, wherein the helical angle of the formed helical gear is 20 to 40 degrees,
(7) The device according to any one of (1) to (4) above, wherein the helical gear formed has a twist angle of 20 to 30 degrees.
(8) The apparatus as described in any one of (1) to (7) above, wherein the inclination angle (θ) of the reduced diameter portion (3) is 20 to 30 degrees.

The present invention also provides
(9) A die (A) having a cylindrical hole (1) extending in the axial direction, where the hole (1) is a cylindrical part (2) extending from the opening (O), followed by a reduced diameter. A cylindrical portion (4) having a smaller diameter after the portion (3), and having an outer diameter smaller than the diameter of the cylindrical portion (4), and a helical gear molding tooth mold on the outer peripheral surface A cylindrical mandrel (B) having (5) is prepared, the mandrel (B) is coaxially disposed in the cylindrical hole (1) of the die (A), and the die (A) and the mandrel are arranged. (B), an annular gap (C) is formed, and an annular gear blank (W) is arranged in the annular gap (C), and then the gear blank (W) is directed from the opening to the inside. And press along the axial direction to move the gear blank (W) through the reduced diameter portion (3) and the smaller diameter of the die (A). The helical gear is formed on the inner peripheral surface of the gear blank (W) by being pushed into a gap formed by the cylindrical portion (4) having a portion and the portion of the mandrel (B) having the helical gear forming tooth mold (5). In the gear manufacturing method, when the annular gear material (W) is pushed into the gap, the gear material (W) is moved in the direction opposite to the pressing direction from the other end of the gear material (W) toward the opening. The gear blank (W) is moved inward along the inner circumferential surface of the cylindrical portion (4) of the die (A) while pressing the helical gear, and the helical gear is applied to the inner circumferential surface of the gear blank (W). It is a method characterized by forming.

As a preferred embodiment,
(10) While pressing the gear blank (W) from the other end toward the opening, the gear blank (W) is directed inward along the inner peripheral surface of the cylindrical portion (4) of the die (A). The above (9), wherein the movement is carried out by moving together the gear blank (W), the pressing means (D) and (E) pressing it from both ends, and the mandrel (B). Described method,
(11) Pressure for pressing the gear blank (W) from the other end of the gear blank (W) toward the opening in the opposite direction to the pressure for pressing the gear blank (W) in the axial direction from the opening toward the inside. The method according to (9) or (10) above, wherein the ratio is from 0.1 to less than 1.00,
(12) Pressure for pressing the gear blank (W) from the other end of the gear blank (W) toward the opening in a direction opposite to the pressing direction with respect to the pressure pressing the gear blank (W) inward along the axial direction from the opening. The ratio according to (9) or (10), wherein the ratio is 0.13 or more and less than 1.00,
(13) Pressure for pressing the gear blank (W) from the other end of the gear blank (W) toward the opening in a direction opposite to the pressing direction with respect to the pressure pressing the gear blank (W) from the opening toward the inside along the axial direction. The method according to (9) or (10) above, wherein the ratio is from 0.2 to 0.3,
(14) The method according to any one of (9) to (13), wherein the helical gear formed has a twist angle of 15 to 40 degrees.
(15) The method according to any one of (9) to (13) above, wherein the helical angle of the formed helical gear is 20 to 40 degrees.
(16) The method as described in any one of (9) to (13) above, wherein the helical gear formed has a twist angle of 20 to 30 degrees.

According to the apparatus and method of the present invention, a helical gear having remarkably good tooth profile accuracy can be formed over the entire inner peripheral surface of the annular gear material. In particular, even if the helical gear to be formed has a large torsion angle, extremely good tooth profile accuracy can be obtained. Therefore, when manufacturing a gear, the material yield can be remarkably increased, and a helical gear product having remarkably good tooth profile accuracy can be manufactured at a very low cost. On the other hand, according to the apparatus and method of the present invention, for example, to produce an internal / external gear having a helical gear as an internal tooth and a flat tooth as an external tooth, the external tooth is formed by machining or the like after the internal tooth is formed. There is a need to. However, in the present invention, the internal helical gear has a remarkably good tooth profile accuracy and can be manufactured with a remarkably high yield. Therefore, for example, the internal and external gears described in Patent Documents 3 and 4 are simultaneously used. Compared to the internal and external gears manufactured by the forming apparatus and method, the internal and external gears manufactured by the present invention are significantly superior and inexpensive.

A preferred embodiment of the gear manufacturing apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a vertical sectional view of a gear manufacturing apparatus according to the present invention. In FIG. 1, the die (A) is installed on the lower plate (11), and has a cylindrical hole (1) extending in the axial direction (vertical direction in FIG. 1) in the center of the die (A). Yes. The cylindrical hole (1) has a cylindrical portion (2) extending from its opening (O) and then has a reduced diameter portion (3) continuing from the cylindrical portion (2); Next, a cylindrical portion (4) having a diameter smaller than the diameter of the cylindrical portion (2) continues from the reduced diameter portion (3). The cylindrical hole (1) has a reduced diameter, that is, an inner diameter, at a connecting portion between the cylindrical portion (2) and the cylindrical portion (4), that is, a reduced diameter portion (3). The reduced diameter portion (3) presses an annular gear blank (W) (shown by a dotted line in FIG. 1) from the opening (O) toward the inside (vertically downward in FIG. 1). 2 can be pushed into the gap formed by the cylindrical part (4) having a smaller diameter of the die (A) and the part of the mandrel (B) with the helical gear forming tooth mold (5). The inclination angle (θ) shown in FIG. The inclination angle (θ) is preferably 20 to 30 degrees. The die (A) is fixed to the lower plate (11) by a die holding plate (12) and a die housing (13).

The mandrel (B) is cylindrical and has an outer diameter that is smaller than the diameter of the cylindrical portion (4) of the die (A). In FIG. 1, the mandrel (B) is provided with a helical gear forming tooth mold (5) composed of a plurality of helical tooth molds at the lower part of the outer peripheral surface thereof. The helical gear shaping tooth mold (5) can be variously changed according to the desired helical gear specifications (for example, helix angle). The mandrel (B) can move up and down in the axial direction independently of the dice (A). In FIG. 1, the mandrel (B) is positioned above the die (A) so that it can be arranged coaxially with the cylindrical hole (1) in the cylindrical hole (1) of the die (A). Has been. The mandrel (B) is connected to the upper plate (16) via the mandrel holder (14) and the upper housing (15).

In FIG. 1, an annular pressing means (molding punch) (D) for pressing an annular gear material (W) along the axial direction from the opening (O) toward the inside (vertical downward direction in FIG. 1). The upper peripheral surface of the helical gear forming tooth mold (5) provided in the mandrel (B) is provided. The inner diameter of the pressing means (D) is substantially the same as the outer diameter of the mandrel (B), and the outer diameter is substantially the same as the inner diameter of the cylindrical portion (2) extending from the opening (O) of the die (A). is there. The pressing means (D) is connected to the second upper knockout pin (P2) via the first upper knockout pin (P1). Press means (D), first upper knockout pin (P1) and second upper knockout pin (P2) associated therewith, mandrel (B), associated mandrel holder (14), upper housing (15) and upper plate (16) is formed independently. There is an upper spacer (18) between the pressing means (D) and its associated part and the mandrel (B) and its associated part. The pressure applied to the annular gear blank (W) by the pressing means (D) includes the dimensions of the gear blank (W), the specifications of the helical gear to be manufactured, the scale and shape of the device, and the following pressing means (E However, the speed of movement of the gear blank (W) in the axial downward direction (vertically downward in FIG. 1) during gear formation is usually about 1 to 5 mm / second. Is set as follows. Thus, although it is difficult to specify uniquely the pressure applied by a press means (D), it is about 200-500 tons. If the pressure is too small, the gear blank (W) is formed by the cylindrical portion (4) having a smaller diameter of the die (A) and the portion including the helical gear forming tooth die (5) of the mandrel (B). If the pressure cannot be sufficiently pushed into the gap and the pressure is too large, a remarkable effect cannot be obtained, and the device specification becomes excessive due to excessive pressure, resulting in high costs.

In the state of FIG. 1, the upper plate (16) and the second upper knockout pin (P2) are moved up and down in the axial direction (vertical direction in FIG. 1) to leave the mandrel (B) and the pressing means (D) as they are. Can be moved up and down together in the axial direction. Also, the upper plate (16) is moved upward in the axial direction, and at the same time, the first upper knockout pin (P1) and the second upper knockout pin (P2) are moved downward to push the mandrel (B) upward. The means (D) can be moved independently downward.

In FIG. 1, a pressing means that can press an annular gear material (W) from the other end of the gear material (W) in a direction opposite to the pressing direction by the pressing means (D) (vertically upward direction in FIG. 1). A back pressure ring (E) is annularly provided along the inner peripheral surface of the cylindrical part (4) having a smaller diameter of the die (A). The outer diameter of the pressing means (E) is substantially the same as the inner diameter of the cylindrical portion (4) of the die (A), and the inner diameter is substantially the same as the outer diameter of the mandrel (B). The pressure applied to the gear blank (W) by the pressing means (E) is smaller than the pressure applied by the pressing means (D). The lower limit of the ratio of the pressure applied to the gear blank (W) by the pressing means (E) to the pressure applied to the gear blank (W) by the pressing means (D) is preferably 0.1, more preferably 0.13, and even more preferably. Is 0.14, particularly preferably 0.2. The upper limit is not particularly limited as long as it is less than 1.00, but is preferably 0.8, more preferably 0.3. If it is less than the lower limit, the phenomenon that the material flows downward at the lower end of the gear material (W), that is, so-called “sag” cannot be sufficiently prevented. When the pressure ratio is too large, the required molding pressure increases, and the capacity of the press device increases, resulting in high costs.

The pressing means (E) is connected to the hydraulic circuit (F) shown in FIG. 12 via the lower knockout pin (17). The hydraulic circuit (F) can control the pressure applied to the annular gear blank (W) by the pressing means (E) to be less than the pressure applied by the pressing means (D), and the pressure applied by both pressing means. While maintaining the difference substantially constant, the moving speed of the annular gear blank (W) in the axial downward direction (vertical downward direction in FIG. 1) can be controlled to be substantially constant. That is, the annular gear material (W) is pressed by the pressing means (D), the reduced diameter portion (3), and the cylindrical portion (4) having a smaller diameter of the die (A) and the helical gear of the mandrel (B). When the helical gear is formed on the inner peripheral surface of the gear blank (W) by being pushed into the gap formed by the portion having the molded tooth mold (5), the annular gear blank (W), the gear blank (W ) Pressing means (D) and (E) pressing from above and below, and the mandrel (B) are moved axially downward along the inner peripheral surface of the cylindrical portion (4) of the die (A). And its movement speed can be controlled. The dimensions of the dice (A), mandrel (B) and pressing means (D) and (E) depend on the dimensions of the gear to be manufactured, that is, the dimensions of the annular gear blank (W). It can be changed as appropriate.

Next, a gear manufacturing method using the gear manufacturing apparatus shown in FIG. 1 will be described. When the mandrel (B) is coaxially disposed in the cylindrical hole (1) of the die (A), the inner peripheral surface of the cylindrical hole (1) of the die (A) and the outer peripheral surface of the mandrel (B) An annular gap (C) is formed between the two. An annular gear material (W) is disposed in the annular gap (C). Preferably, the inner diameter of the annular gear blank (W) is slightly larger than the outer diameter of the mandrel (B), and the outer diameter is slightly smaller than the inner diameter of the cylindrical portion (2) of the die (A). As shown in FIG. 1, in the state where the mandrel (B) is positioned above the die (A), the annular gear blank (W) is installed in the annular gap (C). As shown in FIG. 2, the lower end of the disposed gear blank (W) is supported by the reduced diameter portion (3) of the die (A). Next, the mandrel (B) and the pressing means (D) are moved together axially downward (vertically downward in FIG. 1). The movement is applied to the upper plate (16) by pressing the upper plate (16) and the second upper knockout pin (P2) together axially downward using a pressing means (not shown). The mandrel (B) fixed via the upper housing (15) and the mandrel holder (14) moves downward in the axial direction, and at the same time, pressing means (abutting on the lower surface of the mandrel holder (14)) D) is achieved by being pressed against the mandrel holder (14) and moving axially downward together with the mandrel (B). As shown in FIG. 3 (at the start of molding), the pressing means (D) is in contact with the upper surface of the gear material (W), and the inner surface of the gear material (W) is the outer peripheral surface of the mandrel (B). It arrange | positions so that it may oppose with the helical gear shaping | molding tooth type | mold (5) which exists in (3). In this state, when the mandrel (B) and the pressing means (D) are further moved downward in the axial direction, the lower part of the gear blank (W) supported by the reduced diameter portion (3) of the die (A) The downward movement is prevented and plastic deformation starts in the mandrel (B) direction. Further, when the mandrel (B) and the pressing means (D) are moved downward in the axial direction, the lower surface of the gear blank (W) contacts the pressing means (E) as shown in FIG. In contact with the pressing means (D), the helical gear is formed so as to start receiving axially upward pressure with a pressure less than the axially downward pressure, and the lower part of the gear material (W) is present on the outer peripheral surface of the mandrel (B). It begins to enter the tooth mold (5). Further, when the upper plate is pressed and the mandrel (B) and the pressing means (D) continue to move downward in the axial direction, the gear blank (W) is moved by the pressing means (E) to the shaft by the pressing means (D). As shown in FIG. 5 (on completion of molding), the gear blank is moved along with the mandrel (B) while receiving an axial upward pressure less than the downward pressure in the axial direction. All of the inner surface side of (W) enters the helical gear forming tooth mold (5) existing on the outer peripheral surface of the mandrel (B), and a helical gear is formed on the inner peripheral surface of the gear blank (W). After the helical gear is formed on the inner peripheral surface of the gear blank (W), the downward pressing in the axial direction by the upper plate (16) is stopped.

Next, the formed annular gear blank (W) is removed from the apparatus. When the formation of the gear blank (W) is completed, first, the mandrel (B), the pressing means (D), and the gear blank (W) are left as they are to remove the gear blank (W) from the mandrel (B). It is pulled up to a predetermined position. Next, as shown in FIG. 6, the pressing means (E) is moved upward in the axial direction, and abuts against the lower surface of the gear material (W) to support the gear material (W). In this state, when the pressing means (D) is fixed and only the mandrel (B) is pulled upward, the annular gear material (W) becomes a helical tooth shape formed on the outer peripheral surface of the mandrel (B). As shown in FIG. 7, the gear blank (W) is removed from the mandrel (B) to complete one cycle.

FIG. 12 is a schematic diagram of a basic hydraulic circuit used in the present invention. Hereinafter, based on this, the relationship between the apparatus of the present invention shown in FIG. 1 and the hydraulic circuit will be described. The piston rod (21) in contact with the lower knockout pin (17) is controlled by the main pump (24) and the switching valve (26) so that it can be raised and lowered. Before starting the gear shaping, the switching valve (26) on the main pump (24) side at a predetermined position of the piston rod (21) (a position corresponding to the gear material (W) set position before the gear shaping start). Is set to the neutral position (the state shown in FIG. 12). On the other hand, the spool of the switching valve (27) on the auxiliary pump (30) side is in the communication position (the state shown in FIG. 12). The spring pressure of the pressure control valve (28) is adjusted in advance so as to be a predetermined back pressure. In addition, the throttle amount of the flow control valve (29) is set in advance so that a predetermined flow rate is obtained. In this state, when pressing of the gear material (W) from above by the pressing means (D) starts, the piston rod (21) descends while the back pressure is held constant by the pressure control valve (28), and the gear material Molding of (W) is completed. When the formation of the gear blank (W) is completed, the mandrel (B), the pressing means (D), and the gear blank (W) remain as they are until they are removed from the mandrel (B). Be raised. When the gear material (W) is pulled up to the removal position, the spool of the switching valve (26) on the main pump side is switched from the neutral position to the rising position, and the spool position of the switching valve (27) on the auxiliary pump side is changed to the communication position. The piston rod (21) is raised to a predetermined position (a position corresponding to the removal position of the gear blank (W)), and the spool of the switching valve (26) on the main pump side is moved from the raised position to the neutral position. And the ascent of the piston rod (21) stops. Thus, the pressing means (E) contacts the lower surface of the gear material (W) to support the gear material (W). In this state, as described in the paragraph [0020] above, the gear blank (W) is removed from the mandrel (B) by pulling only the mandrel (B) upward. Thereafter, the spool of the main pump side switching valve (26) is switched from the neutral position to the lowered position, and the piston rod (21) is lowered. When the piston rod (21) is lowered to a predetermined position (a position corresponding to the gear material (W) set position before the gear forming start), the spool of the main pump side switching valve (26) is switched from the lowered position to the neutral position, The piston rod (21) stops. Then, the spool of the auxiliary pump side switching valve (27) is switched from the shut-off position to the communication position, and the setting of the gear material (W) and the preparation for molding are completed.

As described above, the helical gear can be formed on the inner surface of the annular gear material (W). The annular gear blank (W) having the helical gear on the inner surface thus obtained is cut into a predetermined dimension as necessary. For example, in order to manufacture an internal / external gear having a straight gear on the outer peripheral surface, the straight gear can be formed on the outer peripheral surface by machining. There is no restriction | limiting in particular in the helix angle of the helical gear manufactured by this invention, The angle is not ask | required from a small thing to a big thing. Preferably it is 15-40 degrees, More preferably, it is 20-40 degrees, More preferably, it is 20-30 degrees.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by this Example.

The gear manufacturing apparatus and the annular gear material used in the examples and comparative examples are as follows.

<Device>
The gear manufacturing apparatus used is the one shown in FIG. The dimensions of the main part are as follows.
Diameter of the cylindrical part (2) of the die (A): 149.2mm
Diameter of cylindrical part (4) of die (A): 138.0 mm
Outer diameter of mandrel (B): 125.0mm
Width of annular gap (C): 24.2 mm
Angle of inclination (θ) of reduced diameter portion (3): 25 degrees

<Annular gear material (W)>
Shape: outer diameter: 149.0 mm, inner diameter: 125.0 mm, length: 36.0 mm
Material: As a surface treatment for lubricating chromium alloy steel SCr420H-SA material, soap treatment was performed in addition to bond treatment.

Example 1
The annular gear blank (W) was placed in the annular gap (C) of the apparatus shown in FIG. 1, and cold forging was performed to produce an internal helical gear having the specifications shown in Table 1. This operation was repeated for 10 annular gear blanks (W). In all the above operations, the pressure (back pressure) applied by the pressing means (E) was 50 tons, and the pressure applied by the pressing means (D) was 358 tons (applied by the pressing means (E)). Pressure / pressure applied by pressing means (D) = 0.14). Further, the moving speed of the annular gear material (W) in the axial downward direction was 3 mm / second.

For the 10 internal helical gears manufactured as described above, according to JIS B1702, single pitch error (left, right), cumulative pitch error (left, right), tooth gap runout error, maximum The tooth profile error (left, right) and the maximum tooth trace error (left, right) were measured to determine the JIS gear accuracy grade. The results are shown in FIG. Each grade is obtained from an average value of 10 internal helical gears.

(Example 2)
The pressure applied by the pressing means (E) (back pressure) was 100 tons, and the pressure applied by the pressing means (D) was 421 tons (pressure applied by the pressing means (E) / pressing means (D This was carried out in the same manner as in Example 1 except that the pressure applied by 0.2) was 0.23). The results are shown in FIG.

(Comparative Example 1)
Comparative Example 1 uses the apparatus and method described in Patent Document 3, which is a conventional method. That is, in the apparatus of FIG. 1, pressure (back pressure) is not applied by the pressing means (E), but 302 ton pressure is applied only by the pressing means (D) (pressure / pressing means applied by the pressing means (E) ( D) the same as in Example 1 except that the pressure applied by D) is 0.00) and the moving speed of the annular gear blank (W) is 3 mm / sec, which is the same as in Example 1. In practice, an internal helical gear was manufactured, and each JIS gear accuracy grade was determined. The results are shown in FIG.

(Comparative Example 2)
The pressure (back pressure) applied by the pressing means (E) was 20 tons, and the pressure applied by the pressing means (D) was 323 tons (pressure applied by the pressing means (E) / pressing means (D This was carried out in the same manner as in Example 1, except that the pressure applied by 0.0) was 0.06). The results are shown in FIG.

The internal helical gears of Examples 1 and 2 manufactured using the gear manufacturing apparatus and the gear manufacturing method of the present invention are the same as the internal helical gear of Comparative Example 1 manufactured using the conventional apparatus and method. In comparison, single pitch error (left, right), cumulative pitch error (left, right), tooth gap runout error, maximum tooth profile error (left, right), and maximum tooth trace error (left, right) Also had high accuracy. In particular, the effect was remarkable for the maximum tooth trace error (left, right). Further, from the results of Examples 1 and 2, it was found that when the ratio of the pressure applied by the pressing means (E) to the pressure applied by the pressing means (D) is increased, the gear accuracy is further increased. On the other hand, as can be seen from Comparative Example 2, if the pressure ratio is small, the gear accuracy does not increase.

According to the apparatus and method of the present invention, a helical gear having remarkably good tooth profile accuracy can be formed over the entire inner peripheral surface of the annular gear material. In particular, even if the helical gear to be formed has a large torsion angle, extremely good tooth profile accuracy can be obtained. Therefore, the internal / external gear having the helical gear on the inner peripheral surface obtained by the apparatus and method of the present invention is extremely useful for, for example, a ring gear of an automatic transmission of an automobile.

It is a vertical sectional view of one embodiment of the gear manufacturing apparatus of the present invention. FIG. 2 is a vertical sectional view of a die portion of the gear manufacturing apparatus shown in FIG. 1. FIG. 2 is a vertical sectional view at the start of molding in the gear manufacturing apparatus shown in FIG. 1. It is a vertical sectional view in the middle of molding in the gear manufacturing apparatus shown in FIG. FIG. 2 is a vertical sectional view at the time of completion of molding in the gear manufacturing apparatus shown in FIG. 1. FIG. 2 is a vertical sectional view in the middle of taking out a gear material after molding in the gear manufacturing apparatus shown in FIG. FIG. 2 is a vertical sectional view when a gear material after molding is taken out in the gear manufacturing apparatus shown in FIG. 1. It is the graph which showed the JIS gear precision grade of the helical gear manufactured with the apparatus of this invention (Example 1). It is the graph which showed the JIS gear precision grade of the helical gear manufactured with the apparatus of this invention (Example 2). It is the graph which showed the JIS gear precision grade of the helical gear manufactured with the apparatus of the conventional method (comparative example 1). It is the graph which showed the JIS gear precision grade of the helical gear manufactured using the small back pressure by the apparatus of this invention (comparative example 2). It is the schematic of the basic hydraulic circuit used by this invention.

Explanation of symbols

A Die B Mandrel C Annular gap D Pressing means E for pressing the gear blank (W) from the opening toward the inside along the axial direction What is the pressing direction of the gear blank (W) by the pressing means (D)? Pressing means F for pressing from the other end of the gear blank (W) in the opposite direction Back pressure / speed control device O Opening P1 of the die (A) First upper knockout pin P2 Second upper knockout pin W Annular gear blank 1 Die (A) Cylindrical hole 2 Cylindrical portion 3 extending from the opening (O) of the die (A) 3 Reduced diameter portion 4 of the die (A) Cylindrical portion 5 having a smaller diameter of the die (A) Helical gear Molded tooth mold 11 Lower plate 12 Die holding plate 13 Die housing 14 Mandrel holder 15 Upper housing 16 Upper plate 17 Lower knockout pin 18 Upper spacer 21 Pisto Rod 22 Cylinder tube 24 main pump 26 main pumping side switching valve 27 auxiliary pump side switching valve 28 pressure control valve 29 the flow control valve 30 auxiliary pump 31 hydraulic tank

Claims (3)

A die (A) having a cylindrical hole (1) extending in the axial direction, wherein the hole (1) has a cylindrical part (2) extending from the opening (O), followed by a reduced diameter part (3 ), And subsequent cylindrical portion (4) having a smaller diameter,
A cylindrical mandrel (B) having an outer diameter smaller than the diameter of the cylindrical part (4) and having a helical gear forming tooth mold (5) on the outer peripheral surface, wherein the mandrel is a die (A) In a cylindrical cavity (1) of
An annular gap (C) formed between the die (A) and the mandrel (B), where an annular gear blank (W) is disposed in the gap, and the annular gap (C) Means (D) for pressing the gear material (W) to be arranged along the axial direction from the opening toward the inside.
A cylindrical part (4) having a smaller diameter of the die (A) and a helical part of the mandrel (B) through the reduced diameter part (3) through the annular gear material (W) by the pressing means (D) In the gear manufacturing apparatus that forms a helical gear on the inner peripheral surface of the gear blank (W) by being pushed into a gap formed by the portion provided with the gear forming tooth mold (5), an annular gear is formed by the pressing means (D). When the material (W) is pushed into the gap, the gear material (W) can be pressed from the other end of the gear material (W) toward the opening in the direction opposite to the pressing direction by the pressing means (D). means (E), die further comprises in the vicinity of the inner peripheral surface of the cylindrical portion (4) having a smaller diameter following the reduced diameter portion (3) of (a), and pressing means (D) and pressed may means While pressing the annular gear material (W) by (E), the gear material ( ), Pressing means (D) and means capable of pressing (E), and a mandrel (B) together, the die (pressing means along the inner circumferential surface of the cylindrical portion (4) of A) (D) The ratio of the pressure applied to the gear material (W) by the means (E) that can be moved in the pressing direction by the pressing means (D) to the pressure applied to the gear material (W) by the pressing means (D) is 0.1-0. .3 der Rukoto apparatus according to claim. The ratio of the pressure applied to the gear blank (W) by the pressing means (E) to the pressure applied to the gear blank (W) by the pressing means (D) is 0.2 to 0.3. Equipment. The device according to claim 1 or 2, wherein the helical gear formed has a twist angle of 15 to 40 degrees.

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