Multi-stage helical gear manufacturing device and multi-stage helical gear manufacturing method

Abstract

To enable manufacturing of a multistage helical gear.SOLUTION: A large gear rotary core 24 and a sleeve pin 27 are supported by a first mold 22. A small gear rotary insert 29 and an insert pin 31 are supported by a second mold 23. The insert pin 31 prohibits rotation of the small gear rotary insert 29 when mold clamping, and retreats from the small gear rotary insert 29 when mold opening, to permit the rotation of the small gear rotary insert 29. The second mold 23 retracts the insert pin 31 from the small gear rotary insert 29 when mold opening, and thereafter moves the insert pin 31 and the small gear rotary insert 29 in a direction away from the first mold 22. The first mold 22 prohibits rotation of the large gear rotary core 24 when mold clamping, and permits the rotation of the large gear rotary core 24 when mold opening, and when the insert pin 31 and the small gear rotary insert 29 of the second mold 23 move in a direction away from the first mold 22. After the moving of the insert pin 31 and the small gear rotary insert 29, the first mold 22 advances the sleeve pin 27 in a direction approaching the second mold 23.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a manufacturing apparatus for a multi-stage helical gear and a manufacturing method for a multi-stage helical gear. [Background technology]

[0002] As shown in Patent Document 1, when a resin product is manufactured by injection molding, resin is injected into a cavity between a first mold and a second mold that are clamped together. Then, when the first mold and the second mold are opened, the product formed from the resin is removed.

[0003] It is desirable to manufacture the following multi-stage helical gear by the above-mentioned injection molding. The multi-stage helical gear has a large gear and a small gear arranged on the same axis. First helical teeth are formed on the outer peripheral surface of the large gear. Second helical teeth, which have an inclination different from that of the first helical teeth of the large gear, are formed on the outer peripheral surface of the small gear. The multi-stage helical gear also has a center hole extending along the center line between the large gear and the small gear. Linear splines extending along the center line are formed on the inner peripheral surface of the center hole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-34311 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the injection molding technique described in Patent Document 1 is intended to produce a product with a relatively simple shape, such as a worm wheel, the first and second molds used to produce the product also have a relatively simple structure. Therefore, the technique described in Patent Document 1 is difficult to use to produce a multi-stage helical gear with a complex shape, such as first helical teeth, second helical teeth, a center hole, and splines. [Means for solving the problem]

[0006] The means for solving the above problems and their effects will be described below. The multi-stage helical gear manufacturing device that solves the above problem is for manufacturing a multi-stage helical gear having a large gear and a small gear arranged on the same axis. The multi-stage helical gear has a center hole extending along the center line between the large gear and the small gear. The center hole has a linear spline extending along the center line on the inner peripheral surface. The large gear has a first helical tooth on the outer peripheral surface. The small gear has a second helical tooth on the outer peripheral surface, the second helical tooth having a different inclination than the first helical tooth on the large gear. Then, when the first and second molds are clamped together, resin is injected into the cavity between the first and second molds, and the multi-stage helical gear formed with the resin is removed when the first and second molds are opened. The first mold rotatably supports a large gear rotating core for forming the large gear and the first helical tooth, and supports a sleeve pin for forming the center hole and the spline so that it can move toward and away from the second mold. The second mold rotatably supports a small gear rotating insert for forming the small gear and the second helical teeth, and supports an insert pin inserted inside the small gear rotating insert so that it can move toward and away from the small gear rotating insert relative to the first mold. The cavity is formed between the first mold and the second mold by the large gear rotating core, sleeve pin, small gear rotating insert, and insert pin when the molds are closed. The insert pin prohibits the small gear rotating insert from rotating relative to the second mold when it advances relative to the small gear rotating insert during mold closing, and allows the small gear rotating insert to rotate relative to the second mold when it retreats relative to the small gear rotating insert during mold opening. The second mold is configured to retract the insert pin relative to the small gear rotating insert during mold opening, and then move the insert pin and the small gear rotating insert in a direction away from the first mold. The first mold prohibits rotation of the large gear rotating core when the molds are closed, and allows rotation of the large gear rotating core when the insert pin and small gear rotating insert of the second mold move in a direction away from the first mold when the molds are opened. Furthermore, the first mold is configured to advance the sleeve pin relative to the resin in a direction approaching the second mold after the insert pin and small gear rotating insert move away from the resin.

[0007] According to the above configuration, resin is injected into the cavity when the first mold and the second mold are clamped. At this time, rotation of the large gear rotating core relative to the first mold is prohibited, and relative rotation of the small gear rotating insert relative to the second mold is prohibited by the insert pin. When the first mold and the second mold are opened, the insert pin is first retracted relative to the small gear rotating insert, allowing relative rotation of the small gear rotating insert relative to the second mold. Thereafter, the insert pin and the small gear rotating insert move in a direction away from the first mold, causing the small gear rotating insert to be extracted from the resin in the cavity while rotating relative to the first mold. When the insert pin and the small gear rotating insert move in a direction away from the first mold, rotation of the large gear rotating core relative to the first mold is allowed. Then, after the small gear rotating insert is extracted from the resin in the cavity, the sleeve pin is advanced relative to the resin in a direction approaching the second mold, and the multi-stage helical gear formed from the resin is extracted while rotating the large gear rotating core relative to the first mold. In this way, the multi-stage helical gear is manufactured.

[0008] A method for manufacturing a multi-stage helical gear that solves the above-mentioned problems is for manufacturing a multi-stage helical gear having a large gear and a small gear arranged on the same axis. The multi-stage helical gear has a center hole extending along the center line between the large gear and the small gear. The center hole has a linear spline extending along the center line on the inner peripheral surface. The large gear has a first helical tooth on the outer peripheral surface. The small gear has a second helical tooth on the outer peripheral surface, the second helical tooth having a different inclination from the first helical tooth on the large gear. Then, when a first mold and a second mold are clamped together, resin is injected into a cavity between the first and second molds, and when the first and second molds are opened, the multi-stage helical gear formed with the resin is removed. A large gear rotating core for forming the large gear and the first helical tooth is rotatably supported in the first mold, and a sleeve pin for forming the center hole and the spline is supported so as to be movable toward and away from the second mold. The second mold rotatably supports a small gear rotating insert for forming the small gear and the second helical teeth, and a pin inserted into the small gear rotating insert is supported so as to be movable toward and away from the small gear rotating insert relative to the first mold. The cavity is formed between the first mold and the second mold by the large gear rotating core, sleeve pin, small gear rotating insert, and insert pin when the molds are closed. The insert pin prohibits the small gear rotating insert from rotating relative to the second mold when it advances relative to the small gear rotating insert during mold closing, and allows the small gear rotating insert to rotate relative to the second mold when it retreats relative to the small gear rotating insert during mold opening. When the first mold and the second mold are opened, a first step is performed in which the insert pin is retreated relative to the small gear rotating insert to allow relative rotation of the small gear rotating insert relative to the second mold. After the first step is performed, a second step is performed in which the insert pin and small gear rotating insert are moved in a direction away from the first mold. After the second step is performed, the rotation of the large gear rotating core relative to the first mold, which was prohibited when the mold was closed, is permitted, and after the insert pin and small gear rotating insert are moved away from the resin, the sleeve pin is advanced relative to the resin in a direction approaching the second mold.

[0009] According to the above method, resin is injected into the cavity when the first mold and the second mold are clamped. At this time, rotation of the large gear rotating core relative to the first mold is prohibited, and relative rotation of the small gear rotating insert relative to the second mold is prohibited by the insert pin. When the first mold and the second mold are opened, the insert pin is first retracted relative to the small gear rotating insert, thereby allowing relative rotation of the small gear rotating insert relative to the second mold. Thereafter, the insert pin and the small gear rotating insert move in a direction away from the first mold, thereby extracting the small gear rotating insert from the resin in the cavity while rotating relative to the first mold. When the insert pin and the small gear rotating insert move in a direction away from the first mold, rotation of the large gear rotating core relative to the first mold is allowed. Then, after the small gear rotating insert is extracted from the resin in the cavity, the sleeve pin is advanced relative to the resin in a direction approaching the second mold, and the multi-stage helical gear formed from the resin is extracted while rotating the large gear rotating core relative to the first mold. In this way, the multi-stage helical gear is manufactured. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a multi-stage helical gear. [Figure 2] FIG. 2 is a cross-sectional view showing the multi-stage helical gear of FIG. 1. [Figure 3] 2 is a schematic diagram showing a manufacturing apparatus for manufacturing the multi-stage helical gear. [Figure 4] 4 is a schematic diagram showing the mold opening process of the manufacturing apparatus. [Figure 5] 4 is a schematic diagram showing the mold opening process of the manufacturing apparatus. [Figure 6] 4 is a schematic diagram showing the mold opening process of the manufacturing apparatus. [Figure 7] 4 is a schematic diagram showing the mold opening process of the manufacturing apparatus. [Figure 8] FIG. 2 is a cross-sectional view showing the internal structure of the manufacturing apparatus. [Figure 9] FIG. 2 is a perspective view showing an insert pin of the manufacturing apparatus. [Figure 10]FIG. 2 is a cutaway perspective view showing a small gear rotating insert of the manufacturing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a manufacturing apparatus and a manufacturing method for a multi-stage helical gear will be described with reference to FIGS. <Structure of multi-stage helical gear> As shown in Figures 1 and 2, the multi-stage helical gear 11 is made of resin. The multi-stage helical gear 11 has a large gear 12 and a small gear 13 arranged on the same center line. A large number of first helical teeth 12a are formed on the outer peripheral surface of the large gear 12 at intervals in the circumferential direction. A large number of second helical teeth 13a, which have an inclination different from that of the first helical teeth 12a of the large gear 12, are formed on the outer peripheral surface of the small gear 13 at intervals in the circumferential direction.

[0012] The multi-stage helical gear 11 has a center hole 14 that extends along the center line between the large gear 12 and the small gear 13. A number of linear splines 15, 16 that extend along the center line are formed at intervals in the circumferential direction on the inner peripheral surface of the center hole 14. The spline 15 is formed on one side of the center hole 14 in the direction in which the center line extends. The spline 16 is formed on the side of the center hole 14 opposite the side on which the spline 15 is formed in the direction in which the center line extends.

[0013] <Manufacturing equipment for multi-stage helical gears> 3 to 7 schematically show a manufacturing apparatus 21 for manufacturing a multi-stage helical gear by injection molding. The manufacturing apparatus 21 shown in Fig. 3 includes a first mold 22 and a second mold 23 separated by a parting line (PL).

[0014] 3 shows the manufacturing device 21 when the first mold 22 and the second mold 23 are clamped together. When the first mold 22 and the second mold 23 are opened, the manufacturing device 21 operates in the order of FIG. 3 → FIG. 4 → FIG. 5 → FIG. 6 → FIG. 7. When the opened first mold 22 and the second mold 23 are clamped together, the manufacturing device 21 operates in the order of FIG. 7 → FIG. 6 → FIG. 5 → FIG. 4 → FIG. 3.

[0015] When the resin multi-stage helical gear 11 is manufactured by the manufacturing device 21, molten resin is injected into the cavity between the clamped first mold 22 and second mold 23. Then, when the first mold 22 and the second mold 23 are opened, the multi-stage helical gear 11 formed from the hardened resin is removed.

[0016] Plates P1 and P2 are provided in this order in the first mold 22 in a direction away from the second mold 23. Plates P3, P4, and P5 are provided in this order in the second mold 23 in a direction away from the first mold 22. Plates P1, P2, P3, P4, and P5 come into contact with each other when the first mold 22 and the second mold 23 are clamped together.

[0017] The manufacturing device 21 is configured so that a spring load N1 acts between the plates P3 and P4 of the first mold 22 in a direction separating them. The manufacturing device 21 is also configured so that a spring load N2 acts between the plates P4 and P5 of the first mold 22 in a direction separating them.

[0018] The first mold 22 and the second mold 23 are provided with a locking mechanism R1 that can fix and release the fixation of the plate P1 and the plate P2. The locking mechanism R1 is biased by a spring so as to fix the plate P1 and the plate P2 when the first mold 22 and the second mold 23 are clamped together. When the first mold 22 and the second mold 23 are opened, the locking mechanism R1 releases the fixation of the plate P1 and the plate P2 against the biasing force of the spring when the plate P3 moves away from the plate P1 as shown in FIG.

[0019] The first mold 22 and the second mold 23 are provided with a locking mechanism R2 that can fix and release the fixation of the plate P1 and the plate P3. The locking mechanism R2 is biased by a spring so as to fix the plate P1 and the plate P3 when the first mold 22 and the second mold 23 are clamped together. When the first mold 22 and the second mold 23 are opened from each other, the locking mechanism R2 releases the fixation of the plate P1 and the plate P3 against the biasing force of the spring when the force pressing the plate P3 against the plate P1 in FIG. 5 weakens.

[0020] The locking mechanism R1, locking mechanism R2, spring load N1, and spring load N2 of the manufacturing device 21 are set so that the following operations (A) to (D) are performed in order when the clamped first mold 22 and second mold 23 are opened.

[0021] (A) As shown in Figures 3 and 4, plates P4 and P5 are spaced apart from plate P3. (B) As shown in Figures 4 and 5, plate P5 is spaced apart from plate P4. (C) As shown in Figures 5 and 6, plates P3, P4, and P5 are spaced apart from plate P1. (D) As shown in Figures 6 and 7, plate P2 is spaced apart from plate P1.

[0022] As a result, when the clamped first mold 22 and second mold 23 are opened, plates P1, P2, P3, P4, and P5 of the manufacturing device 21 move in the order of Figure 3 → Figure 4 → Figure 5 → Figure 6 → Figure 7.

[0023] Next, the internal structure of the manufacturing apparatus 21 will be described in detail. A large gear rotating core 24 is rotatably supported by bearings 25 and 26 on plate P1 (FIGS. 3 to 7) of the first mold 22 shown in FIG. 8. The large gear rotating core 24 is used to form the large gear 12 and first helical teeth 12a of the multi-stage helical gear 11 shown in FIGS. 1 and 2.

[0024] A sleeve pin 27 and an ejector pin 28 are supported on the first mold 22. The sleeve pin 27 is used to form the center hole 14 and splines 15 of the multi-stage helical gear 11, and is supported so as to be movable back and forth in directions toward and away from the second mold 23. The ejector pin 28 is used to remove the multi-stage helical gear 11 formed from the resin when the first mold 22 and the second mold 23 are opened, and is supported so as to be movable back and forth in directions toward and away from the second mold 23.

[0025] Plate P2 (Figures 3 to 7) of the first mold 22 prohibits rotation of the large gear rotating core 24 when it contacts plate P1 during mold closing, and allows rotation of the large gear rotating core 24 when it moves away from plate P1 as the mold opens.

[0026] A small gear rotating insert 29 is rotatably supported by a bearing 30 on a plate P3 (FIGS. 3 to 7) of the second mold 23 shown in FIG. 8. The small gear rotating insert 29 is used to form the small gear 13 and the second helical teeth 13a of the multi-stage helical gear 11.

[0027] A nesting pin 31 is supported on plate P4 (Figs. 3 to 7) of the second mold 23. The nesting pin 31 is inserted inside the small gear rotation nest 29. The nesting pin 31 can move forward and backward relative to the small gear rotation nest 29 in a direction approaching or separating from the first mold 22 as plate P2 approaches or separates from plate P1. The nesting pin 31 comes into contact with the sleeve pin 27 when the first mold 22 and the second mold 23 are clamped together. The nesting pin 31 is used to form the center hole 14 and splines 16 of the multi-stage helical gear 11.

[0028] The insert pin 31 prohibits or allows relative rotation of the small gear rotation insert 29 with respect to the plate P3 of the second mold 23. More specifically, when the insert pin 31 advances relative to the small gear rotation insert 29 during mold closing, the insert pin 31 prohibits the small gear rotation insert 29 from rotating relative to the plate P3 of the second mold 23. In addition, when the insert pin 31 retreats relative to the small gear rotation insert 29 during mold opening, the insert pin 31 allows the small gear rotation insert 29 to rotate relative to the second mold 23.

[0029] A cavity 32 is formed between the clamped first mold 22 and second mold 23 by the large gear rotating core 24, sleeve pin 27, small gear rotating insert 29, and insert pin 31. At this time, the sleeve pin 27 and insert pin 31 protrude into the cavity 32 and are in contact with each other. A runner 33 and a gate 34 for injecting the resin into the cavity 32 are formed on plate P5 (FIGS. 3 to 7) of the second mold 23. Then, when the molds are clamped, molten resin is injected into the cavity 32 from the runner 33 and gate 34, and the resin is then hardened to form the multi-stage helical gear 11.

[0030] <Insertion pin 31, small gear rotation insert 29> As shown in Fig. 9, a projection 35 projecting radially is formed on the outer peripheral surface of the insert pin 31. As shown in Fig. 10, an accommodation groove 36 for accommodating the projection 35 when the insert pin 31 is inserted is formed on the inner peripheral surface of the small gear rotating insert 29, into which the insert pin 31 is inserted. The accommodation groove 36 has a helical wall 37 and a vertical wall 38, and is wider than the projection 35 of the insert pin 31. The helical wall 37 extends helically along the inner peripheral surface of the small gear rotating insert 29. When the insert pin 31 is inserted into the small gear rotating insert 29, the projection 35 of the insert pin 31 comes into contact with the helical wall 37. The vertical wall 38 extends parallel to the center line of the small gear rotating insert 29. When the insert pin 31 is inserted deep inside the small gear rotating insert 29, the vertical wall 38 contacts the protrusion 35 together with the spiral wall 37, thereby preventing the small gear rotating insert 29 from rotating relative to the plate P3 of the second mold 23.

[0031] When the first mold 22 and the second mold 23 are clamped together and the plate P4 is in contact with the plate P3, the insert pin 31 is inserted deep into the small gear rotation insert 29. As a result, the protrusion 35 of the insert pin 31 contacts both the spiral wall 37 and the vertical wall 38 of the accommodation groove 36 of the small gear rotation insert 29. As a result, rotation of the small gear rotation insert 29 relative to the plate P3 of the second mold 23 is prohibited. When the first mold 22 and the second mold 23 are opened, the plate P4 moves away from the plate P3, causing the insert pin 31 to retract relative to the small gear rotation insert 29. As a result, the protrusion 35 of the insert pin 31 moves to a wider portion of the accommodation groove 36 of the small gear rotation insert 29. As a result, relative rotation of the small gear rotation insert 29 relative to the plate P3 of the second mold 23 is permitted.

[0032] When the first mold 22 and the second mold 23 are closed together after the molds are opened, the plate P4 approaches the plate P3, causing the insert pin 31 to advance relative to the small gear rotation insert 29. This causes the protrusion 35 of the insert pin 31 to be pressed against the helical wall 37 of the accommodation groove 36 of the small gear rotation insert 29. As a result, the small gear rotation insert 29 rotates relative to the plate P3 of the second mold 23. When the insert pin 31 is inserted deep into the small gear rotation insert 29, the protrusion 35 of the insert pin 31 comes into contact with both the helical wall 37 and the vertical wall 38, thereby preventing the small gear rotation insert 29 from rotating relative to the plate P3 of the second mold 23. The relative rotation position of the small gear rotation insert 29 with respect to the plate P3 at this time is always constant every time the molds are closed due to the helical wall 37 and the vertical wall 38 of the accommodation groove 36.

[0033] <Manufacturing method for multi-stage helical gears> Next, a method for manufacturing the multi-stage helical gear 11 using the manufacturing apparatus 21 will be described. In this manufacturing method, the first mold 22 and the second mold 23 are repeatedly clamped and opened. When the first mold 22 and the second mold 23 are clamped, molten resin is injected into a cavity 32 shown in Fig. 8 between the first mold 22 and the second mold 23 via a runner 33 and a gate 34. When the clamped first mold 22 and the second mold 23 are opened, the following first, second, and third steps are performed.

[0034] In the first step, the operation (A) described above in the manufacturing apparatus 21 shown in FIGS. 3 and 4 causes plates P4 and P5 to move away from plate P3 of the second mold 23. As a result, the insert pin 31 is retracted relative to the small gear rotating insert 29 (FIG. 8). This allows the small gear rotating insert 29 to rotate relative to plate P3 of the second mold 23. Furthermore, the operation (B) described above in the manufacturing apparatus 21 shown in FIGS. 4 and 5 causes plate P5 to move away from plate P4 of the second mold 23. As a result, the runner 33 and the gate 34 (FIG. 8) are separated from the cavity 32 between the first mold 22 and the second mold 23.

[0035] After the first step is performed, the second step is performed. In the second step, the operation (C) described above in the manufacturing apparatus 21 shown in Figures 5 and 6 causes plates P3, P4, and P5 of the second mold 23 to move away from plate P1 of the first mold 22. As a result, the insert pin 31 and the small gear rotating insert 29 shown in Figure 8 move in a direction away from the first mold 22. At this time, the small gear rotating insert 29 is extracted from the resin in the cavity 32 while rotating relative to plate P3 of the second mold 23.

[0036] By the above-mentioned operations (A) and (B) of the manufacturing device 21 in the first step and the second step, the insert pin 31 retracts relative to the small gear rotating insert 29 when the mold is opened, and then the insert pin 31 and the small gear rotating insert 29 move in a direction away from the first mold 22. In other words, the first mold 22 is configured to realize such movement of the insert pin 31 and the small gear rotating insert 29.

[0037] After the second step is performed, the third step is performed. In the third step, the operation (D) described above in the manufacturing apparatus 21 shown in Figures 6 and 7 causes the plate P2 to move away from the plate P1 of the first mold 22. As a result, the rotation of the large gear rotating core 24 relative to the plate P1 of the first mold 22, which was prohibited during mold clamping, is permitted. In other words, the first mold 22 is configured to prohibit the rotation of the large gear rotating core 24 during mold clamping, and to permit the rotation of the large gear rotating core 24 when the insert pin 31 and the small gear rotating insert 29 of the second mold 23 move in a direction away from the first mold 22 during mold opening.

[0038] In the third step, after the insert pin 31 and the small gear rotating insert 29 have been separated from the resin in the cavity 32 by the movement described above in the second step, the sleeve pin 27 (FIG. 8) is advanced relative to the resin in a direction approaching the second mold 23. That is, the first mold 22 is configured so that after the insert pin 31 and the small gear rotating insert 29 have been separated from the resin in the cavity 32 by the movement described above, the sleeve pin 27 is advanced relative to the resin in a direction approaching the second mold 23. In this way, the multi-stage helical gear 11 formed from the resin is taken out while the large gear rotating core 24 is rotated relative to the plate P1 of the first mold 22.

[0039] Furthermore, the ejector pin 28 advances in a direction closer to the second mold 23 than the sleeve pin 27 (FIG. 8). As a result, the multi-stage helical gear 11 is removed from the sleeve pin 27.

[0040] According to the present embodiment described above in detail, the following advantageous effects can be obtained. (1) When the first mold 22 and the second mold 23 are clamped together, molten resin is injected into the cavity 32 between the first mold 22 and the second mold 23. At this time, rotation of the large gear rotation core 24 relative to the plate P1 of the first mold 22 is prohibited, and relative rotation of the small gear rotation insert 29 relative to the plate P3 of the second mold 23 is prohibited by the insert pin 31. When the first mold 22 and the second mold 23 are opened, the insert pin 31 first retracts relative to the small gear rotation insert 29, thereby allowing relative rotation of the small gear rotation insert 29 relative to the plate P3 of the second mold 23. Thereafter, the insert pin 31 and the small gear rotation insert 29 move in a direction away from the first mold 22, and the small gear rotation insert 29 is extracted from the resin in the cavity 32 while rotating relative to the plate P3 of the first mold 22. When the insert pin 31 and the small gear rotating insert 29 move in a direction away from the first mold 22, the large gear rotating core 24 is allowed to rotate relative to the plate P1 of the first mold 22. Then, after the small gear rotating insert 29 is extracted from the resin in the cavity 32, the sleeve pin 27 advances relative to the resin in a direction approaching the second mold 23. As a result, the multi-stage helical gear 11 formed from the resin is extracted while the large gear rotating core 24 is rotated relative to the plate P1 of the first mold 22. In this manner, the multi-stage helical gear 11 is manufactured.

[0041] (2) When the first mold 22 and the second mold 23 are clamped together, the sleeve pin 27 and the insert pin 31 protrude into the cavity 32 between the first mold 22 and the second mold 23. At this time, the insert pin 31 is in contact with the sleeve pin 27. Then, in the central hole 14 of the multi-stage helical gear 11 formed by injecting resin into the cavity 32, the spline 15 is formed by the sleeve pin 27, and the spline 16 is formed by the insert pin 31. Therefore, the splines 15, 16 formed in the central hole 14 of the multi-stage helical gear 11 can be of two types: those formed by the sleeve pin 27 and those formed by the insert pin 31.

[0042] (3) When the first mold 22 and the second mold 23 are clamped together, if the insert pin 31 is inserted deep inside the small gear rotation insert 29, the protrusion 35 of the insert pin 31 comes into contact with both the spiral wall 37 and the vertical wall 38 of the accommodation groove 36 of the small gear rotation insert 29. This prohibits rotation of the small gear rotation insert 29 relative to the plate P3 of the second mold 23. When the first mold 22 and the second mold 23 are opened, the insert pin 31 retracts relative to the small gear rotation insert 29, so that the protrusion 35 of the insert pin 31 moves to a location wider than the deepest part of the accommodation groove 36 of the small gear rotation insert 29. This allows relative rotation of the small gear rotation insert 29 relative to the plate P3 of the second mold 23. When the first mold 22 and the second mold 23 are closed after the molds are opened, the insert pin 31 advances relative to the small gear rotation insert 29, and the protrusion 35 of the insert pin 31 is pressed against the helical wall 37 of the accommodation groove 36 of the small gear rotation insert 29. This causes the small gear rotation insert 29 to rotate relative to the plate P3 of the second mold 23. When the insert pin 31 is inserted deep into the small gear rotation insert 29, the protrusion 35 of the insert pin 31 comes into contact with the helical wall 37 of the accommodation groove 36 and also with the vertical wall 38, thereby preventing the small gear rotation insert 29 from rotating relative to the plate P3 of the second mold 23. The relative rotation position of the small gear rotation insert 29 with respect to the plate P3 of the second mold 23 at this time can be kept constant every time the molds are closed due to the helical wall 37 and the vertical wall 38 of the accommodation groove 36. Therefore, the manufacturing precision of the multi-stage helical gear 11 can be improved.

[0043] The above embodiment can be modified as follows, for example. The multi-stage helical gear 11 may have only the spline 15 formed in its center hole 14. In this case, when the first mold 22 and the second mold 23 of the manufacturing device 21 are clamped together, the insert pin 31 is prevented from protruding into the cavity 32, and the sleeve pin 27 is brought into contact with the insert pin 31 within the cavity 32.

[0044] Next, the technical concept that can be understood from the above embodiment will be described. (A) The present invention is for manufacturing a multi-stage helical gear having a large gear and a small gear arranged on the same axis, The multi-stage helical gear has a center hole formed therein that extends along a center line between the large gear and the small gear, and linear splines extending along the center line are formed on the inner peripheral surface of the center hole, first helical teeth are formed on the outer peripheral surface of the large gear, and second helical teeth that are inclined differently from the first helical teeth of the large gear are formed on the outer peripheral surface of the small gear, 1. A manufacturing apparatus for a multi-stage helical gear, comprising: a first mold and a second mold; a cavity between the first mold and the second mold is opened; a mold opening mechanism for opening the first mold and the second mold; and a multi-stage helical gear formed by the resin; a large gear rotary core for forming the large gear and the first helical teeth is rotatably supported by the first die, and a sleeve pin for forming the center hole and the spline is supported so as to be movable toward and away from the second die; a small gear rotatable insert for forming the small gear and the second helical teeth is rotatably supported by the second die, and an insert pin inserted into the small gear rotatable insert is supported so as to be movable toward and away from the small gear rotatable insert relative to the first die, the cavity is formed between the first mold and the second mold by the large gear rotation core, the sleeve pin, the small gear rotation insert, and the insert pin when the molds are clamped, the insert pin prohibits the small gear rotating insert from rotating relative to the second mold when it advances relative to the small gear rotating insert during mold closing, and allows the small gear rotating insert to rotate relative to the second mold when it retreats relative to the small gear rotating insert during mold opening, the second mold is configured to retract the insert pin relative to the small gear rotating insert when the mold is opened, and then move the insert pin and the small gear rotating insert in a direction away from the first mold, The first mold prohibits rotation of the large gear rotating core when the mold is closed, allows rotation of the large gear rotating core when the insert pin and the small gear rotating insert of the second mold move in a direction away from the first mold when the mold is opened, and advances the sleeve pin relative to the resin in a direction approaching the second mold after the insert pin and the small gear rotating insert have moved away from the resin.

[0045] (B) In the manufacturing apparatus for a multi-stage helical gear described in (A) above, The first mold is provided with a plate P1 and a plate P2 in this order in a direction away from the second mold, The large gear rotary core is rotatably supported on the plate P1, The plate P2 prohibits the rotation of the large gear rotary core when it contacts the plate P1, and allows the rotation of the large gear rotary core when it separates from the plate P1, The second mold is provided with a plate P3, a plate P4, and a plate P5 in this order in a direction away from the first mold, The small gear rotating insert is rotatably supported on the plate P3, The plate P4 supports the insert pin, The plate P5 is formed with a runner and a gate for injecting the resin into the cavity, a spring load N1 acts between the plate P3 and the plate P4 in the second mold, and a spring load N2 acts between the plate P4 and the plate P5, the plate P1, the plate P2, the plate P3, the plate P4, and the plate P5 come into contact with each other when the first mold and the second mold are clamped together, The first mold and the second mold are provided with a locking mechanism R1 capable of fixing and releasing the plate P1 and the plate P2, and a locking mechanism R2 capable of fixing and releasing the plate P1 and the plate P3, The apparatus for manufacturing a multi-stage helical gear has the locking mechanism R1, the locking mechanism R2, the spring load N1, and the spring load N2 set so that, when the first mold and the second mold are opened, the plates P1, P2, P3, P4, and P5 move in the following order: the plates P4 and P5 move away from the plate P3, the plate P5 moves away from the plate P4, the plates P3, P4, and P5 move away from the plate P1, and the plate P2 moves away from the plate P1.

[0046] (C) In the manufacturing apparatus for a multi-stage helical gear according to (B) or (C), The insert pin protrudes into the cavity and contacts the sleeve pin when the first mold and the second mold are clamped together, and forms the center hole and the splines of the multi-stage helical gear at the point where it protrudes into the cavity.

[0047] (D) In the manufacturing apparatus for a multi-stage helical gear according to any one of (A) to (C), A protrusion that protrudes in the radial direction is formed on the outer peripheral surface of the insert pin, an accommodation groove for accommodating the protrusion when the insert pin is inserted is formed on an inner peripheral surface of the small gear rotating insert into which the insert pin is inserted; The receiving groove has a spiral wall and a vertical wall, and is wider than the protrusion of the insert pin, the helical wall extends helically along the inner peripheral surface of the small gear rotating insert, and the protrusion of the insert pin comes into contact with the helical wall when the insert pin is inserted into the small gear rotating insert, When the insert pin is inserted deep inside the small gear rotating insert, the vertical wall comes into contact with the protrusion together with the helical wall, thereby preventing the small gear rotating insert from rotating relative to the second mold.

[0048] (F) The present invention is for manufacturing a multi-stage helical gear having a large gear and a small gear arranged on the same axis, The multi-stage helical gear has a center hole formed therein that extends along a center line between the large gear and the small gear, and linear splines extending along the center line are formed on the inner peripheral surface of the center hole, first helical teeth are formed on the outer peripheral surface of the large gear, and second helical teeth that are inclined differently from the first helical teeth of the large gear are formed on the outer peripheral surface of the small gear, A method for manufacturing a multi-stage helical gear, comprising: injecting a resin into a cavity between a first mold and a second mold when the first mold and the second mold are clamped together; and then removing the multi-stage helical gear formed from the resin when the first mold and the second mold are opened; a large gear rotary core for forming the large gear and the first helical teeth is rotatably supported by the first die, and a sleeve pin for forming the center hole and the spline is supported so as to be movable toward and away from the second die; a small gear rotatable insert for forming the small gear and the second helical teeth is rotatably supported by the second die, and an insert pin inserted into the small gear rotatable insert is supported so as to be movable toward and away from the small gear rotatable insert relative to the first die, the cavity is formed between the first mold and the second mold by the large gear rotating core, the sleeve pin, the small gear rotating insert, and the insert pin when the molds are clamped, the insert pin prohibits the small gear rotating insert from rotating relative to the second mold when it advances relative to the small gear rotating insert during mold closing, and allows the small gear rotating insert to rotate relative to the second mold when it retreats relative to the small gear rotating insert during mold opening, a first step of allowing the small gear rotation insert to rotate relative to the second mold by retracting the insert pin relative to the small gear rotation insert when the first mold and the second mold are opened, After the first step is performed, a second step is performed in which the insert pin and the small gear rotating insert are moved in a direction away from the first die, After the second step is performed, the method for manufacturing a multi-stage helical gear performs a third step in which the rotation of the large gear rotating core relative to the first mold, which was prohibited when the mold was closed, is permitted, and after the insert pin and the small gear rotating insert are separated from the resin by the movement, the sleeve pin is advanced relative to the resin in a direction approaching the second mold. [Explanation of symbols]

[0049] 11...Multi-stage helical gear 12...Large gear 12a…1st oblique tooth 13...Small gear 13a...Second inclined tooth 14...Center hole 15,16...Spline 21...Manufacturing equipment 22...First mold 23...Second mold 24...Large gear rotating core 25,26...Bearings 27...Sleeve pin 28...Ejector pin 29...Small gear rotating insert 30...Bearing 31...Inserted pin 32...cavity 33... Runner 34...Gate 35...Protrusion 36...Storage groove 37...Spiral wall 38…Vertical wall P1~P5...Plates

Claims

1. The present invention is for manufacturing a multi-stage helical gear having a large gear and a small gear arranged on the same axis, The multi-stage helical gear has a center hole formed therein that extends along a center line between the large gear and the small gear, and linear splines extending along the center line are formed on the inner peripheral surface of the center hole, first helical teeth are formed on the outer peripheral surface of the large gear, and second helical teeth that are inclined differently from the first helical teeth of the large gear are formed on the outer peripheral surface of the small gear, 1. An apparatus for manufacturing a multi-stage helical gear, comprising: a first mold and a second mold; a cavity between the first mold and the second mold being clamped; a mold opening step for opening the first mold and the second mold; and a multi-stage helical gear formed from the resin being removed; a large gear rotary core for forming the large gear and the first helical teeth is rotatably supported by the first die, and a sleeve pin for forming the center hole and the spline is supported so as to be movable toward and away from the second die; a small gear rotatable insert for forming the small gear and the second helical teeth is rotatably supported by the second die, and an insert pin inserted into the small gear rotatable insert is supported so as to be movable forward and backward relative to the small gear rotatable insert in a direction toward and away from the first die, the cavity is formed between the first mold and the second mold by the large gear rotation core, the sleeve pin, the small gear rotation insert, and the insert pin when the molds are clamped, the insert pin prohibits the small gear rotating insert from rotating relative to the second mold when it advances relative to the small gear rotating insert during mold closing, and allows the small gear rotating insert to rotate relative to the second mold when it retreats relative to the small gear rotating insert during mold opening, the second mold is configured to retract the insert pin relative to the small gear rotating insert when the mold is opened, and then move the insert pin and the small gear rotating insert in a direction away from the first mold, The first mold prohibits rotation of the large gear rotating core when the mold is closed, and allows rotation of the large gear rotating core when the insert pin and the small gear rotating insert of the second mold move in a direction away from the first mold when the mold is opened, and after the insert pin and the small gear rotating insert move away from the resin due to their movement, the sleeve pin advances relative to the resin in a direction approaching the second mold.

2. The first mold is provided with a plate P1 and a plate P2 in this order in a direction away from the second mold, The large gear rotary core is rotatably supported on the plate P1, The plate P2 prohibits the rotation of the large gear rotary core when it contacts the plate P1, and allows the rotation of the large gear rotary core when it separates from the plate P1, The second mold is provided with a plate P3, a plate P4, and a plate P5 in this order in a direction away from the first mold, The small gear rotating insert is rotatably supported on the plate P3, The plate P4 supports the insert pin, The plate P5 is formed with a runner and a gate for injecting the resin into the cavity, A spring load N1 acts between the plate P3 and the plate P4 in the second mold, and a spring load N2 acts between the plate P4 and the plate P5, the plate P1, the plate P2, the plate P3, the plate P4, and the plate P5 come into contact with each other when the first mold and the second mold are clamped together, The first mold and the second mold are provided with a locking mechanism R1 capable of fixing and releasing the plate P1 and the plate P2, and a locking mechanism R2 capable of fixing and releasing the plate P1 and the plate P3, 2. The manufacturing apparatus for a multi-stage helical gear according to claim 1, wherein the locking mechanism R1, the locking mechanism R2, the spring load N1, and the spring load N2 are set so that, when the first mold and the second mold are opened, the plates P1, P2, P3, P4, and P5 move in the following order: the plates P4 and P5 move away from the plate P3, the plate P5 moves away from the plate P4, the plates P3, P4, and P5 move away from the plate P1, and the plate P2 moves away from the plate P1.

3. 2. The manufacturing apparatus for a multi-stage helical gear according to claim 1, wherein the insert pin protrudes into the cavity and contacts the sleeve pin when the first mold and the second mold are clamped together, and the portion protruding into the cavity forms the center hole and the splines of the multi-stage helical gear.

4. A protrusion that protrudes in the radial direction is formed on the outer peripheral surface of the insert pin, an accommodation groove for accommodating the protrusion when the insert pin is inserted is formed on an inner peripheral surface of the small gear rotating insert into which the insert pin is inserted; The receiving groove has a spiral wall and a vertical wall, and is wider than the protrusion of the insert pin, the helical wall extends helically along the inner peripheral surface of the small gear rotating insert, and the protrusion of the insert pin comes into contact with the helical wall when the insert pin is inserted into the small gear rotating insert, 4. The manufacturing device for a multi-stage helical gear according to claim 1, wherein when the insert pin is inserted deep inside the small gear rotating insert, the vertical wall comes into contact with the protrusion together with the helical wall, thereby prohibiting rotation of the small gear rotating insert relative to the second mold.

5. The present invention is for manufacturing a multi-stage helical gear having a large gear and a small gear arranged on the same axis, The multi-stage helical gear has a center hole formed therein that extends along a center line between the large gear and the small gear, and linear splines extending along the center line are formed on the inner peripheral surface of the center hole, first helical teeth are formed on the outer peripheral surface of the large gear, and second helical teeth that are inclined differently from the first helical teeth of the large gear are formed on the outer peripheral surface of the small gear, A method for manufacturing a multi-stage helical gear, comprising: injecting a resin into a cavity between a first mold and a second mold when the first mold and the second mold are clamped together; and then removing the multi-stage helical gear formed from the resin when the first mold and the second mold are opened, a large gear rotary core for forming the large gear and the first helical teeth is rotatably supported by the first die, and a sleeve pin for forming the center hole and the spline is supported so as to be movable toward and away from the second die; a small gear rotatable insert for forming the small gear and the second helical teeth is rotatably supported by the second die, and an insert pin inserted into the small gear rotatable insert is supported so as to be movable forward and backward relative to the small gear rotatable insert in a direction toward and away from the first die, the cavity is formed between the first mold and the second mold by the large gear rotation core, the sleeve pin, the small gear rotation insert, and the insert pin when the molds are clamped, the insert pin prohibits the small gear rotating insert from rotating relative to the second mold when it advances relative to the small gear rotating insert during mold closing, and allows the small gear rotating insert to rotate relative to the second mold when it retreats relative to the small gear rotating insert during mold opening, a first step of retracting the insert pin relative to the small gear rotating insert when the first mold and the second mold are opened, thereby enabling the small gear rotating insert to rotate relative to the second mold; After the first step is performed, a second step is performed in which the insert pin and the small gear rotating insert are moved in a direction away from the first die; After the second step is performed, the method for manufacturing a multi-stage helical gear performs a third step in which the rotation of the large gear rotating core relative to the first mold, which was prohibited when the mold was closed, is allowed, and after the insert pin and the small gear rotating insert move away from the resin, the sleeve pin is advanced relative to the resin in a direction approaching the second mold.

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