JP2008230053A - Molding device for resin-made helical gear and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means to directly fabricate a mold matrix without requiring tooth profile transfer from an electrode master model for electrical discharge machining, with regard to an inverse helical form part of a molding die, and in this case, enable fabricating of the inverse helical form part only by milling operation using a low-priced general-purpose machine e.g. a machining center or an NC milling machine instead of a high-priced machining unit such as a CNC gear grinding machine or an NC eletrical discharge machining unit of C-axis control specifications, in a molding device for a resin-made helical gear and also, a manufacturing method of the resin-made helical gear. <P>SOLUTION: The tooth profile formation peripheral surface part of a cavity C of an injection molding die for the resin-made helical gear G, is structured of inserts 1... for the tooth profile part divided in many segments in the peripheral direction. Further, each insert 1 for the tooth profile part is equipped with the inverse helical form part 11 equivalent to a pitch of the tooth profile. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a molding apparatus for producing a resin helical gear by injection molding, and a method of manufacturing the helical gear.

In general, in the injection molding of an external toothed plastic helical gear, a molding die comprising a stationary mold and a movable mold forming opposing walls of the cavity and an annular gear piece forming the helical tooth profile of the cavity is used. The molding apparatus provided is used. Therefore, when the mold is opened after the resin material such as polyacetal filled in the cavity in a molten state is opened and the molded product is taken out, the molded product is prevented from rotating by uneven engagement between one of the fixed mold and the movable mold, In the process of ejecting the molded product with the ejector pin and releasing the mold, the gear piece is rotated by the helical guide of the helical tooth profile (Patent Document 1). Conversely, the molded product is rotated in the axial direction without rotating the gear piece. A method of moving (Patent Document 2) is known.
JP-A-5-104587 JP 2002-205322 A

  By the way, the helical gear is a cylindrical gear in which tooth traces form a winding line, and its tooth profile is an involute curve that is twisted in the gear axis direction and has a shape that extrudes the tooth profile curve three-dimensionally. Therefore, in the manufacture of the gear piece in the forming die for the helical gear, the reverse helical shape portion having the twisted surface cannot be easily processed by the wire electric discharge machine like the tooth profile portion in the forming die for the spur gear. First, an electrode master model for electrical discharge machining of a helical gear made of a copper alloy or the like is manufactured by a CNC gear grinding machine, and then the tooth profile of the master model is set to a C-axis control specification (in the three-dimensional direction of the XYZ axis, for example, the Z-axis In general, a machining method is adopted in which the workpiece is transferred to the base material of the gear piece by an NC electric discharge machine that rotates in the center and can be fed in the axial direction and controlled in the other two directions). ing.

  However, the above machining methods are complicated and inefficient due to the complicated machining process from the production of the electrode master model for electric discharge machining to the tooth profile transfer by electric discharge machining, and the CNC gear grinding machine and the NC discharge of the C axis control specification. Equipment cost is very high due to the need for an expensive processing machine, and the electrode master model for electric discharge machining is dimensioned with consideration given to the discharge gap clearance and molding shrinkage for the next electric discharge machining. In addition, in a structure in which the helical gear protrudes from the wall surface as a part of the resin part, it is necessary to divide the master model itself into a gear part and another part for tooth profile cutting. It takes a lot of time and effort even at the design stage, and the production cost of the gear piece and the product cost of the Hasuba gear are high. I did not get very choice but to high cost.

  In addition, since resin-made helical gears inevitably undergo curing shrinkage after molding, at the prototype mold stage, the accuracy of the tooth profile of the molded product is inspected to meet quality standards. Modification of the reverse husba shape part corresponding to the gear piece in the mold and remodeling of the mold itself, and inspection of the molded product with the modified molding mold will be conducted again. There are many cases where remodeling is repeated many times. However, in the conventional machining method, since the electric discharge machining electrode master model is inevitably modified or reworked, a great amount of labor, time and cost are required for the work.

  In view of the above-described circumstances, the present invention does not require a tooth profile transfer from an electrode master model for electric discharge machining as in the past with respect to a reverse helical shape portion in a molding die as a molding apparatus and a manufacturing method for a resin helical gear. In addition, it can be directly machined and formed on the die base material, and it can be used with inexpensive general-purpose machines such as machining centers and NC milling machines without using expensive processing machines such as CNC gear grinding machines and NC electric discharge machines with C-axis control specifications. It aims at providing the means which can be formed only by milling.

  If the means for achieving the above object is shown with reference numerals in the drawings, the resin helical gear forming apparatus according to claim 1 of the present invention is a cavity C in an injection mold of the resin helical gear G. The tooth profile forming peripheral surface portion is composed of tooth profile portion inserts 1... Divided into a large number in the circumferential direction, and each tooth profile portion insert 1 includes at least one inverted Hasba shape portion 11 corresponding to one tooth profile pitch.

  According to a second aspect of the present invention, in the resin helical gear forming apparatus according to the first aspect, the adjacent tooth profile portion inserts 1 and 1 are divided at the position of the inverted helical bar bottom 11b.

  According to a third aspect of the present invention, in the molding apparatus for the resin helical gear according to the first or second aspect, the molding die is for the external helical gear G.

  According to a fourth aspect of the present invention, in the resin helical gear forming apparatus according to any one of the first to third aspects, all of the tooth profile nestings 1 are screwed to the mounting base (base member 2, fixed mold 5). It is assumed that

  According to a fifth aspect of the present invention, there is provided the plastic helical gear forming apparatus according to any one of the first to third aspects, wherein all the tooth profile nestings 1 are between the mounting base and the pressing member 3 screwed to the mounting base. It is set as the structure pinched by.

  According to a sixth aspect of the present invention, in the resin helical gear forming apparatus according to the fourth or fifth aspect, the leg portion 12 is integrally formed with each tooth profile portion insert 1, and the leg portion 12 of the insert 1 is inserted into the mounting base. The positioning hole 21 to be fitted is provided.

  According to a seventh aspect of the present invention, in the resin helical gear forming apparatus according to the sixth aspect of the invention, the tooth profile portion insert 1 is provided with a leg portion 12 on the rear side with the inverted helical shape portion 11 in front, and at least one The leg portion 12 of the insert 1A is formed to be tapered by a notch 13 on the rear surface side.

  According to an eighth aspect of the present invention, in the resin helical gear forming apparatus according to any one of the fourth to seventh aspects, the mounting base is the base member 2 of the gear pieces K1 to K4, and the movable wall constituting the opposing wall surface of the cavity C is provided. One of the mold 4 and the fixed mold 5 is provided with a fitting holding portion 50 for the gear pieces K1 to K4.

  The invention according to claim 9 is the resin helical gear molding apparatus according to any one of claims 4 to 7, wherein the movable mold 4 or the fixed mold 5 constituting the opposed wall surface of the cavity C is used as the mounting base. It is assumed that all tooth profile inserts 1 are attached directly to the base.

  According to a tenth aspect of the present invention, in the resin-made helical gear forming apparatus according to any one of the fourth to sixth, eighth, and ninth aspects, at least one of the mounting bases in front of the reverse helical shape 11 of the tooth profile insert 1 is provided. A surplus space portion 22 is formed behind the arrangement portion 2b of each nest 1, and when the nest 1 is attached to the mounting base, the nest 1 is advanced from the rear position to the cavity C setting position using the surplus space portion 22. In addition, the spacer 6 for preventing the insert 1 from retreating is fitted into the surplus space 22 after the advance.

  On the other hand, in the method for manufacturing a resin helical gear according to the invention of claim 11, the resin material R is filled in the cavity C of the molding die S <b> 1 having the gear pieces K <b> 1 to K <b> 4 of claim 8. The hardened Hasuba gear molded product M is taken out from the molding die S1 integrally with the gear pieces K1 to K4, and the release jig 7 is pressed against the molded product M while the gear pieces K1 to K4 are fixed. The gear molded product M is separated from the gear pieces K1 to K4.

  If the effect of the invention based on the above configuration is shown with reference numerals in the drawings, according to the resin helical gear molding apparatus according to the invention of claim 1, the tooth profile forming peripheral surface portion of the cavity C in the injection mold is provided. , Each of which is divided into a plurality of tooth profile portion inserts 1 each having a reverse helical bar shape portion 11 corresponding to one pitch of the tooth profile, so that when the reverse helical bar shape portions 11 of the individual inserts 1 are formed by machining, The degree of freedom of operation of the insert 1 is small. For example, the corresponding helical shaft center position is used as a base point of a cutting tool such as a small-diameter ball end mill, and the cutting blade side is fed toward the insert 1 side to perform reverse helical motion. Can be formed. In addition, since the plurality of divided tooth profile inserts 1 may have the same shape, a plurality of or all of the raw materials are arranged at a small pitch in the machining center, and the reverse helical bar is simultaneously processed by batch processing by a milling processing pass. It is also possible to process and form the shape portions 11.

  Therefore, in the production of the tooth profile forming peripheral surface portion of the cavity C in this injection mold, the machining process is greatly simplified and the labor required for machining is compared with the electric discharge machining by the tooth profile transfer from the conventional electrode master model for electric discharge machining. In addition to significantly reducing time, it does not require expensive processing machines such as CNC gear grinding machines or NC electric discharge machines with C-axis control specifications, and inexpensive general-purpose machines such as machining centers and NC milling machines can be used. Cost can be greatly reduced.

  In addition, if the accuracy of the tooth profile part of the molded product does not meet the quality standards at the prototype stage of the plastic helical gear and thus the molding die, only the tooth profile part insert 1 corresponding to the non-conforming part is corrected or manufactured. Compared with the case where the entire tooth profile forming peripheral surface of the mold is modified or remodeled, or further modified or remodeled from the electrode master model for electric discharge machining, labor, time and cost are reduced. It is possible to achieve a final molding die configuration that can be remarkably reduced and can form a helical gear having high tooth profile accuracy. Further, in this molding die, only the tooth profile forming portion of the cavity C can be easily changed by exchanging the tooth profile inserts 1..., So that a plurality of types of helical gears G having different dislocation coefficients of the Hasuba shaped portion are required. The plurality of types of helical gears G can be manufactured at a minimum cost by simply preparing the tooth profile portion inserts 1 corresponding to each dislocation coefficient and sharing the other mold components.

  According to the invention of claim 2, since the adjacent tooth profile portion inserts 1, 1 in the molding die are divided at the position of the bottom portion 11 b of the reverse Hasuba shape, the reverse Hasuba shape portion 11 of each insert 1 is The side surfaces of the tooth traces face both sides, and in the machining formation of the reverse helical bar-shaped portion 11, a wide movable space for the cutting tool on both sides can be secured, and the machining formation is facilitated accordingly.

  According to the invention of claim 3, the molding die has a high utility value for the externally toothed helical gear G which is in great demand, and the tooth profile nestings 1 are annularly arranged so as to surround the cavity C. Therefore, the outside can be set wide with respect to each inwardly-facing inverted helical bar-shaped portion 11, and it is easy to stabilize the mounting state on the mounting base using the wide outside portion.

  According to the invention of claim 4, all the tooth profile nests 1 are screwed to the mounting base, so that their mounting strength can be increased to ensure accuracy as a molding die, and the nests 1. Easy to attach and detach.

  According to the invention of claim 5, since all the tooth profile nests 1 are sandwiched between the mounting base and the pressing member 3 screwed to the mounting base, the fixing operation of these nests 1 to the mounting base is performed. The inserts 1... Themselves can be made easily and in a short time, and the screw holes and the like for individual mounting are no longer necessary, which simplifies the structure and facilitates manufacture.

  According to the sixth aspect of the present invention, each tooth profile portion insert 1 is automatically positioned by inserting its leg portion 12 into the positioning hole 21 of the mounting base. Well done efficiently.

  According to the seventh aspect of the present invention, the side surfaces 10e and 10f to be in close contact with each other between the adjacent tooth profile nests 1 and 1 are inclined in a division along the tooth trace of the Hasuba, so that these nests 1. Are inserted into the positioning holes 21 of the mounting base and the leg portions 12 are sequentially inserted and sequentially attached, and the insert 1 remaining between the inserts 1 and 1 attached in advance can be similarly inserted. Although it becomes extremely difficult, a nesting 1A in which a leg portion 12 is tapered by a notch 13 on the rear surface side is used as the remaining nesting 1, and the rear surface side of the leg portion 12 is positioned on the rear inner surface of the mounting base 21. The insert 1A is held obliquely so as to be in contact with the insert, and the reverse helical bar-shaped portion 11 side is inserted between the inserts 1 and 1 that have been attached first, and then the entire leg portion 12 is placed in the positioning hole 21. Insert into And by, easily mounting of the nest 1A.

  According to the eighth aspect of the present invention, the mounting base is the base member 2 of the gear piece K, and the gear pieces K1 to K4 are attached to one of the movable mold 4 and the fixed mold 5 constituting the opposing wall surface of the cavity C. Since the fitting holding portion 50 is provided, a plurality of types of helical gears can be formed by using the movable die 4 and the fixed die 5 in common by exchanging and using a plurality of types as the gear pieces K1 to K4.

  According to the ninth aspect of the present invention, since the movable mold 4 or the fixed mold 5 constituting the opposing wall surface of the cavity C is used as the mounting base, all the tooth profile nests 1 are attached directly to the mounting base. As a whole, the molding die has a small number of parts and is structurally simple.

  According to the invention of claim 10, in the final stage when the tooth profile portion inserts 1 are sequentially attached to the attachment base as described above, the insert 1 remaining between the inserts 1 and 1 attached previously. However, since the surplus space portion 22 is formed behind the disposition portion of the at least one insert 1 in the mounting base, the surplus space portion 22 is disposed in the final stage. For the nesting 1, the nesting 1 is disposed on the rear side of the surplus space portion 22, and the nesting 1, to which the nesting 1 is first attached, is advanced from the rear side to the cavity C setting position. The fitting 1 can be appropriately fitted between the two, and the spacer 1 can be fitted into the surplus space 22 after the advancement to prevent the insert 1 from moving backward.

  According to the method for manufacturing a resin helical gear according to the invention of claim 11, a helical gear molding in which the resin material R is filled in the cavity C of the molding die S1 including the gear pieces K1 to K4 and the resin material R is cured. The product M is taken out from the molding die integrally with the gear pieces K1 to K4, and the release gear 7 is pressed against the molded product M while the gear pieces K1 to K4 are fixed. Since it is made to detach | leave from the pieces K1-K4, it is not necessary to incorporate the bearing which rotates the gear pieces K1-K4 in the molding die S1, and the molding die S1 becomes structurally simple and the molding die accordingly. Since the molded product M is released from the gear pieces K1 to K4 in a state in which the molded product M is sufficiently cooled or reaction-cured outside the mold S1, the dimensional change of the molded product M due to stress at the time of mold release can be prevented.

  Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 10 are the first embodiment, FIGS. 11 to 13 are the second embodiment, FIG. 14 is the third embodiment, FIGS. 15 and 16 are the fourth embodiment, and FIGS. FIG. 21 shows the fifth embodiment, and FIG. 22 shows the sixth embodiment, respectively, of the molding operation of the resin helical gear by the molding apparatus of the fourth embodiment.

  FIG.1 and FIG.2 shows the gear piece K1 used for the shaping | molding apparatus of 1st embodiment. As shown in the figure, this gear piece K1 is provided inside a short cylindrical base member 2 for a large number (26 in the figure) of tooth profile portions corresponding to the number of teeth of the helical gear (26 in the figure) to be formed. The inserts 1 are arranged in an annular shape in close contact with each other at the inner side, and the tooth profile forming peripheral surface portion of the helical gear forming cavity C is formed on the inner peripheral side thereof.

  As shown in FIGS. 3 and 4, the base member 2 of the gear piece K1 has an annular nesting portion 2b stepped down from the peripheral wall portion 2a on the inner peripheral side, and the nesting portion 2b includes A rectangular positioning hole 21 corresponding to each of the tooth profile inserts 1 is opened, and a circular bolt head arrangement hole 23 is formed on the lower surface so as to face each positioning hole 21. The bottom portions of the bolt head arrangement holes 23 communicate with each other through a small diameter bolt insertion hole 24. In addition, the inner periphery of the peripheral wall 2a is formed into a polygon in plan view (26-gon in the figure) as a whole by the flat portion 25 corresponding to one side of the rectangle of each positioning hole 21. Further, the central hole 20 is a tapered hole that is slightly expanded in diameter downward for fitting with a core convex portion 51 (see FIGS. 17 and 18) of the fixed mold 5 described later.

  As shown in FIG. 5 and FIG. 6, each tooth profile portion nest 1 hangs down from a horizontally long main body portion 10 having an inverted helical shape portion 11 corresponding to one pitch of a tooth shape at a front end, and a rear end portion of the main body portion 10. The prism 12 has a substantially inverted L-shape when viewed from the side. A screw hole 14 is formed in the leg 12 so as to open on the lower surface. The rear end face 1a is the main body with the main body 10 facing upward. A continuous vertical surface is formed from 10 to the leg 12. And the reverse helical bar shape part 11 of the front end is a shape in which a slanted tooth crest 11a is in the center, and ½ width tooth bottom parts 11b are arranged on both sides thereof. Since it follows the winding (spiral), the apparent inclination from the front is larger at the root portion 11b than at the tooth crest 11a.

  Further, the body portion 10 of the tooth profile portion insert 1 has a longitudinal section corresponding to the inclination of the tooth trace of the inverted Hasuba-shaped portion 11 while the front half portion becomes narrower forward with respect to the rear half portion of the same width. Is inclined to one side (right side as viewed from the inverted Hasba-shaped portion 11 side) so that the upper and lower surfaces 10a, 10b and the bottom surface 12a of the leg portion 12 are parallel and perpendicular to each other. It is orthogonal to the rear end face 1a, and both side faces 10c, 10d on the rear side are also parallel. On the other hand, both side surfaces 10e and 10f on the front side of the main body 10 have a form in which the main body 10 is narrowed toward the front, and both side edges of the inverted Hasba-shaped portion 11 are the bottom of the tooth bottom portion 11b. Since it is along the spiral direction (the direction of the vine) as the center line, it forms a twisted three-dimensional curved surface.

  As shown in FIG. 4, each tooth profile part insert 1 is inserted into the positioning hole 21 of the base member 2 so that the main body part 10 has the reverse helical part 11 at the front end. In this state, the cap bolt 15 is screwed from the lower surface side of the base member 2 into the screw hole 14 of the leg portion 12 through the bolt insertion hole 24. The base member 2 is fixed by tightening and tightening. And in this fixed state, the nests 1... And the base member 2 are such that the upper surface 10a of the nest 1 is flush with the top surface of the peripheral wall portion 2a of the base member 2, and the rear end surface 1a is of the peripheral wall portion 2a. The size is set so that the reverse helical shape 11 at the front end protrudes inward from the peripheral edge of the central hole 20 of the base member 2 in close contact with the flat portion 25 on the inner surface side. The bolt head 15a of the cap bolt 15 is larger in diameter than the bolt insertion hole 24, whereby the inner bottom of the bolt head arrangement hole 23 constitutes a bolt seat surface.

  In the gear piece K1, all the tooth profile portion inserts 1 fixed to the base member 2 are twisted on the front side of the main body 10 between the adjacent inserts 1 and 1, as shown in FIGS. Both side surfaces 10e and 10f are in close contact with each other, and the tooth profile forming peripheral surface portion of the helical gear forming cavity C is divided into a large number in the circumferential direction using the side surfaces 10e and 10f as split surfaces. That is, as shown in FIGS. 2 and 7, in each insert 1, the upper surface center line P <b> 1 connecting the center O of the gear piece K <b> 1 and the upper center of the inverted Hasba-shaped portion 11 coincides with the lower edge direction of the side surface 10 f, An upper surface center line P2 connecting the same center O and the center of the lower end of the inverted Hasba-shaped portion 11 coincides with the upper edge direction of the side surface 10e, and the side surfaces 10e and 10f are twisted three-dimensionally moving from the center line P1 to the center line P2. In the plane.

  In assembling the gear piece K1, the body portion 10 of each tooth profile portion insert 1 is inclined in a parallelogram shape in the longitudinal section. Therefore, when the inserts 1 are assembled to the base member 2, the leg portion 12 is moved upward. When inserting into the positioning hole 21 of the base member 2 from above, as shown in FIG. 8, the base member 2 is sequentially stacked along the circumferential direction (counterclockwise direction). However, the last one in the assembling order of these nestings 1... Interferes with one of the nestings 1 and 1 on both sides (the first nesting 1 in the assembling order) that is mounted first in the form of being lowered from the upper position. Therefore, the leg portion 12 cannot be inserted into the positioning hole 21 and cannot be assembled.

  Therefore, in the first embodiment, as shown in FIG. 9, the nesting 1A which is the last in the above assembling order is different from the other nesting 1... The shape is tapered. In other words, at the end of the assembly order, the insert 1A has a rear end surface that is inclined along the flat surface portion 25 on the inner surface side of the peripheral wall portion 2a of the base member 2 as shown by an imaginary line in FIG. By tilting the front end side down, the front end side is inserted between the nestings 1 and 1 on both sides, and the whole body is pushed down by sucking diagonally forward as indicated by the arrow from this state. The entire portion 10 is inserted between the inserts 1 and 1 on both sides, and at the same time, the leg portion 12 is inserted into the positioning hole 21 and positioned in the same manner as the other inserts 1. It sticks to.

  In the gear piece K2 used in the molding apparatus of the second embodiment shown in FIGS. 11 to 13, the thickness of the peripheral wall 2a of the base member 2 is set large, and at one place in the circumferential direction of the peripheral wall 2a, The base member 2 is provided with a surplus space portion 22 formed of a rectangular hole that communicates with the one positioning hole 21, and a circular bolt head arrangement hole facing the surplus space portion 22 on the lower surface side of the base member 2. 26 is formed, and a circular bolt head arrangement hole 23 is formed on the lower surface side so as to face each positioning hole 21, and a bolt insertion hole 27 having a small diameter between the excess space portion 22 and the bottom portion of the bolt head arrangement hole 26 is formed. It communicates through. Further, inside the base member 2, tooth profile forming inserts 1, all of which are the same as those used in the first embodiment, are annularly arranged in close contact with each other at the inner portion thereof, The tooth profile forming peripheral surface portion of the helical gear forming cavity C is formed on the peripheral side.

  In the assembly of the gear piece K2 in the second embodiment, as in the first embodiment, the leg portions 12 of the respective tooth profile forming inserts 1 are inserted into the positioning holes 21 of the base member 2 from above, All the nestings 1 are sequentially stacked on the nesting arrangement part 2b of the base member 2 along one circumferential direction (counterclockwise direction), but the main body part 10 of each tooth profile part nesting 1 is also longitudinally cross-sectional. Since it is the form inclined in the parallelogram shape, the last one in the assembling order of these inserts 1... Cannot be assembled by simply lowering from the upper position. However, in the second embodiment, since the surplus space portion 22 is provided at one place in the circumferential direction of the peripheral wall portion 2a of the base member 2, instead of using a different insert 1A as in the first embodiment, the insert arrangement portion 2b As the assembly part of the nesting 1 with the position facing the surplus space part 22 as the last, the nesting 1 having the same configuration as the rest is first applied to the surplus space part 22 as indicated by the phantom line in FIG. Is placed on the side, and advanced from this rear side to the cavity C setting position as shown by the solid line in FIG. it can.

  Thus, after the insert 1 which has been last in the assembly order as described above is advanced to the cavity C setting position, the angular shaft spacer 6 is fitted into the empty space portion 22 which is again empty. The nest 1 is positioned so as not to be retractable. Further, by using the spacer 6 having a screw hole 6a that opens on the lower surface side, by screwing and tightening the cap bolt 16 from the lower surface side of the base member 2 to the screw hole 6a through the bolt insertion hole 27, As shown in FIG. 13, the spacer 6 can be fixed to the base member 2 together with the last insert 1. The top surface of the spacer 6 is dimensioned so as to be flush with the top surface of the peripheral wall portion 2a of the base member 2 in the above-mentioned fixed state.

  The gear piece K3 used in the molding apparatus of the third embodiment shown in FIG. 14 is formed by replacing the tooth profile forming inserts 1 ... with the base member 2 as in the first and second embodiments. The tooth form nestings 1 are sandwiched between the pressing member 3 made of an annular thick plate that is screwed thereto with cap bolts 17. The inserts 1 ... and the base member 2 have the same outer shape as that used in the first and second embodiments, and the leg portions 12 of the inserts 1 are inserted into the positioning holes 21 of the base member 2. The positioning is performed, but naturally a structure without screw holes or bolt insertion holes may be used. Further, the nesting 1 that is the last in the assembly order with respect to the base member 2 is rearward using the surplus space portion 22 provided in one circumferential direction of the peripheral wall portion 2a of the base member 2 as in the second embodiment. Although it is a structure which advances and assembles from the side to the cavity C setting position, the spacer 6 fitted into the surplus space portion 22 which has been vacated by the advancement of the insert 1 is naturally used without a screw hole. The

  In such a gear piece K3 of the third embodiment, it is not necessary to individually screw the tooth form forming inserts 1 ... and the spacer 6 to the base member 2, so that the assembling operation of the gear piece K3 can be easily performed. It can be done in a short time. Also, since the inserts 1..., The spacer 6 and the base member 2 do not require screw holes or bolt insertion holes, they are simplified in structure and easy to manufacture.

  In the first to third embodiments described above, the tooth profile forming nests 1 are illustrated as having the reverse Hasba shaped portion 11 corresponding to one pitch of the tooth profile at the front end. However, the tooth profile nest used in the present invention is, for example, FIG. And like the insert 1 of the gear piece K4 used for the shaping | molding apparatus of 4th embodiment shown in FIG. 16, the reverse Hasba shape part 11 may be provided with the part for the same pitch of multiple pitches.

  The gear piece K4 in the fourth embodiment includes a rectangular base member 2 having a circular center hole 20 and 13 pieces arranged in an annular shape facing the center hole 20 (FIG. 15 shows a state in which one is removed). And the tooth profile forming peripheral surface of the helical gear forming cavity C is formed on the inner peripheral side of the inserts 1. Each nesting 1 includes a reverse helical bar-shaped portion 11 corresponding to 3 pitches of the tooth profile at the front end of the main body portion 10, and a substantially prismatic leg portion 12 with each corner being rounded on the rear end side of the main body portion 10. Are integrally formed. Further, the base member 2 is formed with an annular nesting arrangement portion 2b stepped down from the periphery facing the central hole 20, and a rectangular positioning hole 21 into which the leg portion 12 of each nesting 1 is inserted into the arrangement portion 2b. In addition, the outer periphery of the placement portion 2b is formed in a 13-sided shape by the flat portion 25 corresponding to one side of the rectangle of each positioning hole 21.

  Further, even in this gear piece K4, as in the first to third embodiments, the adjacent nestings 1 and 1 are in close contact with each other by the twisted side surfaces 10e and 10f on the front side of the main body 10. In addition, the rear end surface 1a of each insert 1 is in close contact with the flat portion 25 on the base member 2 side, and the upper surface 10a of each insert 1 is flush with the upper surface of the base member 2.

  Although not shown, for fixing each insert 1 in the gear piece K4, the same screwing means as in the first and second embodiments or the base member 2 similar to that in the third embodiment are used. The clamping means by the pressing member 3 can be adopted. Further, as the means for assembling the insert 1 which is the last in the assembling order with respect to the base member 2, the leg 12 side is deformed as in the first embodiment, or the surplus space portion as in the second and third embodiments. 22 and spacer 6 can be used.

  In the gear pieces K1 to K4 used in the molding devices of the first to fourth embodiments described above, the tooth profile forming peripheral surface portion of the cavity C is divided into a large number of tooth profile inserts 1. What is necessary is just to process and form the reverse helical shape part 11 for every nesting 1 when forming the tooth profile of reverse helical. And since the reverse Hasuba-shaped portion 11 in each nesting 1 has a narrow width of about 1 to several pitches of the tooth profile, almost the entire tooth profile surface including both side surfaces of the tooth trace can be formed by cutting from the opposing direction, Less freedom of movement on the cutting tool side. Therefore, for example, the tooth profile of the reverse Hasba can be formed by milling processing in which the corresponding gear shaft center position of the insert 1 is used as a base point of a cutting tool such as a small-diameter ball end mill and the cutting blade side is sent toward the insert 1 side. In addition, in the case of a tooth profile that causes an undercut in the feed direction of the cutting blade, a ball end mill having a spherical tooth tip larger than the shank diameter may be used, or further, milling by 5-axis control may be used. Further, since the plurality of divided tooth profile inserts 1 may have the same shape, a plurality of or all of the raw materials are arranged at a small pitch in the machining center, and simultaneously reversed by batch processing by a milling processing pass. It is also possible to process and form the helical shape 11.

  Therefore, in the manufacture of the tooth profile forming peripheral surface of the cavity C, the machining process is greatly simplified and the labor and time required for machining are significantly reduced compared with the conventional EDM by tooth profile transfer from the electrode master model for EDM. In addition, an expensive general-purpose machine such as a machining center or NC milling machine can be used without the need for expensive processing machines such as CNC gear grinding machines or NC electric discharge machines with C-axis control specifications, greatly reducing equipment costs. it can.

  In addition, if the accuracy of the tooth profile part of the molded product does not meet the quality standards at the prototype stage of the plastic helical gear and thus the molding die, only the tooth profile part insert 1 corresponding to the non-conforming part is corrected or manufactured. Compared with the case where the entire tooth profile forming peripheral surface of the mold is modified or remodeled, or further modified or remodeled from the electrode master model for electric discharge machining, labor, time and cost are reduced. It is possible to achieve a final molding die configuration that can be remarkably reduced and can form a helical gear having high tooth profile accuracy. Furthermore, in this molding die, only the tooth profile forming portion of the cavity C can be easily changed by exchanging the tooth profile inserts 1... If you need to insert a tooth profile part insert 1 corresponding to each type, you can make the multiple types of helical gears at a minimum cost by sharing the other mold components. Is possible.

  In addition, when the tooth profile forming peripheral surface portion of the cavity C is divided into a large number of tooth profile forming inserts 1 in the circumferential direction, it is possible to set the split position to the position of the helical tooth crest (tooth tip) 11a in the inverted helical shape. However, if it is configured to be divided at the position of the tooth bottom portion 11b as in the tooth profile forming insert 1 used in the first to fourth embodiments, the reverse Hasuba shaped portion 11 of each insert 1 faces the tooth trace side surfaces on both sides. In the machining formation of the inverted helical bar-shaped portion 11, a wide movable space for the cutting tool on both sides can be secured, and the machining formation is facilitated accordingly.

  Next, a method for manufacturing a resin helical gear using an injection mold using the gear pieces K1 to K4 will be described in detail with reference to FIGS. In the figure, the gear piece K1 used in the first embodiment is shown as a representative of the gear piece. Further, as shown in FIG. 20, the cavity C of the injection mold G1 is formed by integrating a cylindrical rim 101 having a helical tooth profile 100 on the outer periphery and a central cylindrical boss 102 at a disk portion 103. The helical gear G is a target for molding.

  The injection mold S1 shown in FIG. 17 is provided on the upper surface side of the core 5a of the movable mold 4, which is disposed at the upper position and moves up and down, the fixed mold 5 which is disposed at the lower position, and the fixed mold 5. It is comprised with the gear piece K1 fitted by the fitting holding | maintenance part 50 which consists of an annular recessed part. The core 4 a of the movable mold 4 is provided with an annular convex portion 41 at the center of the lower surface thereof, and a spool gate 42 that opens at a position close to the annular convex portion 41. On the other hand, the core portion 5 a of the fixed mold 5 is formed with a truncated cone-shaped core convex portion 51 protruding upward inside the fitting holding portion 50, and a movable mold is formed on the top surface of the core convex portion 51. An annular convex portion 52 that faces the annular convex portion 41 on the four side, and a boss hole projecting shaft portion 53 that projects from the center position inside the annular convex portion 52 to the upper end position of the fixed mold 5. Is provided. The fixed die 5 has a molded product ejector pin 8a, whose top end faces the annular convex portion 52, and a gear piece ejector pin 8b, whose top end faces the lower surface of the base portion 2 of the gear piece K1. Inserted in the direction.

  When the gear piece K1 is fitted in the fitting holding portion 50 of the fixed mold 5, as shown in FIG. 18A, the core on the fixed mold 5 side is inserted into the central hole 20 on the gear piece K1 side. The convex part 51 fits appropriately, the upper surface of the gear piece K1 and the upper end surface of the fixed die 5 are flush with each other, and the space for the cavity C surrounded by the tooth shape forming inserts 1 of the gear piece K1 An annular convex portion 52 on the top surface of the core convex portion 51 and a protruding shaft portion 53 for the boss hole enter to constitute the lower end surface of the cavity C. When the movable mold 4 is lowered and joined to the fixed mold 5, the annular convex portion 41 on the movable mold 4 side also enters the cavity C space and constitutes the upper end surface of the cavity C. That is, the inside of the tooth profile forming insert 1... In which the gear piece K1 is annularly arranged is a cylindrical rim 101 having a helical tooth profile 100 of the helical gear G, the boss hole protruding shaft 53 is surrounded by the boss 102, both molds 4, Between the five annular convex portions 41 and 52, the disk portion 103 is formed.

  As shown in FIG. 18A, the helical gear G is formed in a state in which the movable mold 4 is joined to the fixed mold 5 and the molten resin material R such as polyacetal is passed through the spool gate 42 into the cavity C. The resin material R may be hardened by injection filling. When the resin material R in the cavity C is cured, the molds 4 and 5 are separated from each other by the ascent of the movable mold 4, and then a molded product as shown in FIG. The ejector pins 8a... For the gear pieces and the ejector pins 8b for the gear pieces are simultaneously projected upward to lift the helical gear molded product M integrally with the gear piece K1 and take it out of the fixed mold 5.

  Next, as shown in FIG. 19, a gear piece K1 holding a molded product M is positioned and placed on an annular release frame 71, and a piece with a through hole 72a is placed on the gear piece K1, and the pressing plate With the through hole 72a of 72 facing the molded product M, a round shaft-shaped release tool 7 is inserted into the through hole 72a from above and protruded downward. As a result, the molded product M held inside the gear piece K1 is detached from the gear piece K1 with rotation by the induction of the helical tooth of the helical tooth shape, and falls into the inner space 71a of the release frame 71. become. In addition, on the upper surface side of the release frame 71 and the lower surface side of the pressing plate 72, concave surface portions 71b and 72b are provided for facilitating the positioning of the gear piece K1. Further, a flange-like stopper 7a is provided at the upper end of the releasing jig 7, and as shown by an imaginary line in the drawing, the stopper 7a is engaged with the periphery of the through hole 72a of the holding plate 72, The release jig 7 is prevented from dropping more than that.

  Thus, the helical gear molded product M in which the resin material R is cured in this way is taken out from the molding die S1 integrally with the gear piece K1, and the molded product M is released by pressing the release jig 7 outside. In the system, it is not necessary to incorporate a bearing for rotating the gear piece K1 in the molding die G, and the molding die G1 is structurally simplified, and the molded product M is sufficiently cooled and reaction-cured. Since the mold is released from the gear piece K1, the dimensional change of the molded product M due to the stress at the time of mold release is also prevented.

  In the molding apparatus of the first to fourth embodiments, the mounting base of the tooth profile nestings 1... Forming the tooth profile forming peripheral surface portion of the cavity C is set to the base member 2 of the gear pieces K1 to K4. However, in a mold configuration that does not use a gear piece, for example, a movable mold that constitutes the opposing wall surface of the cavity C as in the injection molds S2 and S3 of the fifth and sixth embodiments shown in FIGS. The tooth profile part inserts 1... May be directly attached using the mold 4 or the fixed mold 5 as an attachment base.

  An injection mold S2 used in the molding apparatus of the fifth embodiment shown in FIG. 21 is composed of an upper movable mold 4 and a lower fixed mold 5, and a bus bar between the central portions of both molds 4,5. A cavity C for the gear G is formed, and the cavity C is filled with a resin material through the spool gate 42 of the core portion 4a on the movable mold 4 side. And the tooth profile forming peripheral surface portion of the cavity C is composed of a large number of tooth profile portion inserts 1 in the circumferential direction similar to those in the first and second embodiments, and these inserts 1 are fixed. It is fitted and arranged in a nested arrangement part 52 that is recessed in the upper surface of the core part 5a of the mold 5, and is screwed and fixed to the fixed mold 5 by a cap bolt 18 inserted from the lower surface side of the core part 5a. Yes. Further, the ejector pins 8a for moldings whose top ends face the cavities C are inserted in the core portion 5a of the fixed mold 5 in the vertical direction. Reference numeral 6 denotes a spacer, which is inserted into the surplus space 22 in the same manner as in the last nesting method in the second embodiment and is screwed to the fixed mold 5 via the cap bolt 19.

  According to this injection mold S2, after the resin material filled in the cavity C is cured, the movable mold 4 is raised and opened to project the ejector pins 8a for molding, thereby forming a helical gear. The object M is detached from the fixed mold 5 with the rotation by the induction of the twisted tooth muscle having the helical tooth shape.

  The injection mold S3 used in the molding apparatus of the sixth embodiment shown in FIG. 22 is a helical gear between the central portions of the movable mold 4 and the fixed mold 5 in the same manner as the molding mold S2 in the fifth embodiment. A cavity C for G is formed, and a large number of circumferential inserts 1 in the circumferential direction constituting the tooth profile forming peripheral surface portion of the cavity C are fitted and arranged in the insert arrangement part 52 on the fixed mold 5 side. However, these inserts 1 are not screwed to the fixed mold 5 as in the fifth embodiment, and instead, the fixed mold 5 is inserted with insert ejector pins 8c corresponding to the respective inserts 1. Yes. Similarly, the spacer 6 is also provided with a spacer ejector pin 8d instead of screwing.

  According to this injection mold S3, after the resin material filled in the cavity C is cured, the movable mold 4 is raised to open the mold, and the ejector pins 8a for moldings, the ejector pins 8c for nesting,. By simultaneously ejecting the spacer ejector pins 8d, the spacer 6 is separated, but the helical gear molded product M is taken out with the tooth profile inserts 1 attached to the periphery. Pull 1 away in the radial direction. Then, the separated inserts 1... And the spacer 6 are mounted on the fixed mold 5 again to prepare for the next molding.

  In each of the illustrated embodiments, the leg portion 12 is tapered or the surplus space portion 22 is formed in order to enable the assembly of the tooth shape forming inserts 1 to the last one in the assembling order to the mounting base. However, in the present invention, the same assembling means may be provided not only for the last one in the assembling order but also for a plurality of nestings 1. Moreover, in the system which provides the surplus space part 22, after providing the surplus space part 22 over the perimeter of the nest | insert arrangement | positioning part 2b and making all the nest | inserts 1 ... advance from a rear position, it makes the remaining cyclic | annular surplus space part 22 A ring-shaped spacer may be fitted into the.

  Furthermore, instead of sequentially assembling the tooth profile forming inserts 1 along the circumferential direction with respect to the mounting base, all the inserts 1 are assembled in an annular shape in advance using an appropriate jig. It is also possible to attach to the mounting base all at once in the arrangement form.

  In addition, the helical gear to be molded by the molding apparatus field nominal molding method of the present invention is not limited to the gear form as a single unit as illustrated in FIG. 20, but various resins in which the helical gear is integrated with various functional parts. In addition to including parts, it is desirable that the number of teeth is 14 or more in terms of practical use. Accordingly, in the present invention, the number of tooth profile nestings (the number of divisions) that divide and configure the tooth profile forming peripheral surface portion of the cavity C is preferably 14 or more, and the tooth profile forming peripheral surface portion is 360 degrees in one round. It is desirable that the angular width of one piece is 26 degrees (≈360 degrees / 14) or less.

It is a perspective view of the gear piece used for the shaping | molding apparatus which concerns on 1st embodiment of this invention. It is a top view of the gear piece. It is a top view of the half part of the base member of the gear piece. It is a vertical side view which shows attachment operation of the tooth-form formation nest with respect to the base member of the gear piece. It is a perspective view of the nest for tooth profile formation used for the gear piece. The nest | insert for the same tooth profile formation is shown, (A) is a front view, (B) is a rear view. It is a top view of the principal part which shows the attachment state of the nest | insert for tooth profile formation with respect to the base member of the gear piece. It is a perspective view which shows the assembly | attachment state of the nest | insert for the same tooth profile formation. It is a side view of the insert for tooth profile formation which becomes the last of an assembly order. It is a vertical side view which shows the attachment state with respect to the base member of the tooth shape formation nest | insert which becomes the last. It is a top view of the principal part of the gear piece used for the shaping | molding apparatus which concerns on 2nd embodiment of this invention. The tooth profile forming nest is attached to the base member of the gear piece according to the second embodiment in the order of attachment, (A) is a vertical side view of the nest fitting stage, and (B) is the nest fitting. It is a vertical side view of the spacer fitting stage after wearing. It is a vertical side view of the gear piece after the spacer fitting. It is a vertical side view of the gear piece used for the shaping | molding apparatus which concerns on 3rd embodiment of this invention. It is a top view which shows the gear piece used for the shaping | molding apparatus which concerns on 4th embodiment of this invention in the state which removed one insert for tooth shape formation. It is a perspective view from the bottom face side of the tooth profile formation nest used for the gear piece in the fourth embodiment. It is a longitudinal cross-sectional view which shows the injection mold used for one manufacturing method of the resin helical gears which concerns on this invention in an exploded state. The molding operation by the injection mold is shown, (A) is a longitudinal sectional view of the molding stage, and (B) is a longitudinal sectional view of the removal stage after molding. It is a longitudinal cross-sectional view which shows mold release operation of the molded product from the taken out gear piece. It is a perspective view of the helical gear used as a molding object of the injection mold. It is a longitudinal cross-sectional view of the injection mold used for the shaping | molding apparatus which concerns on 5th embodiment of this invention. It is a longitudinal cross-sectional view of the injection mold used for the shaping | molding apparatus which concerns on 6th embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tooth profile insertion insert 1A Tooth profile formation insert which becomes the last of assembly | attachment order 10 Main body part 11 Reverse helical shape part 11a Tooth crest 11b Tooth bottom part 12 Leg part 13 Notch 2 Base member 2a Nest arrangement part 21 Positioning hole 22 Excess space part 3 Holding member 4 Movable mold 5 Fixed mold 50 Fitting holding part 6 Spacer 7 Mold release jig C Cavity G Hasba gear K1 to K4 Gear piece M Hasuba gear molding R Resin material S1 to S3 Injection mold

Claims (11)

  The tooth profile forming peripheral surface portion of the cavity in the injection mold of the resin helical gear is composed of a plurality of tooth profile nests divided in the circumferential direction, and each tooth profile nest has at least one inverted tooth shape of the tooth profile. A resin helical gear forming apparatus comprising:   The apparatus for molding a resin helical gear according to claim 1, wherein adjacent nests for tooth profile portions are divided at a tooth bottom position of an inverted helical shape.   3. The resin helical gear molding apparatus according to claim 1, wherein the molding die is for external toothed helical gears.   4. The resin helical gear molding apparatus according to claim 1, wherein all the tooth profile nests are screwed to the mounting base.   The resin helical gear molding apparatus according to any one of claims 1 to 3, wherein all the tooth profile nests are sandwiched between the mounting base and a pressing member screwed to the mounting base.   The resin helical gear forming apparatus according to claim 4 or 5, wherein a leg portion is integrally formed with each tooth shape portion nest, and a positioning hole for inserting the leg portion of the nest is inserted into the mounting base.   7. The resin-made article according to claim 6, wherein the nest for the tooth profile portion includes the leg portion on the rear side with the inverted Hasuba shaped portion in front, and at least one leg portion of the nest portion is tapered by a notch on the rear surface side. Hasuba gear forming device.   The mounting base is a base member of a gear piece, and a fitting holding portion for the gear piece is provided on one of a movable die and a fixed die constituting the opposing wall surface of the cavity. The resin-made helical gear forming apparatus described in 1.   The resin-made product according to any one of claims 4 to 7, wherein a movable mold or a fixed mold constituting an opposing wall surface of the cavity is used as an attachment base, and all the tooth profile inserts are directly attached to the attachment base. Hasuba gear forming device.   A surplus space portion is formed behind the arrangement portion of at least one nesting in the mounting base, with the inverted Hasuba shape portion of the tooth shape portion nesting in front, and when the nesting is attached to the mounting base, the nesting is inserted into the surplus space portion. And a spacer for preventing the nesting from retracting into the surplus space after the advancing operation. An apparatus for molding a plastic helical gear according to any one of the above.   Filling a cavity of a molding die having the gear piece according to claim 8 with a resin material, taking out a Hasuba gear molding in which the resin material is cured from the molding die integrally with the gear piece, and molding the mold while the gear piece is fixed. A method for producing a plastic helical gear, wherein a helical gear molded product is detached from a gear piece by pressing a release jig against an article.

Images