Molded body

Abstract

To provide an annular molded body with parallel holes for inserting and frictionally fixing screws or pins, which can be molded only by moving in a direction of mold clamping and mold opening.SOLUTION: An annular molded body 1 with a virtual centerline, which is molded of material by mold clamping and mold opening, is provided with parallel holes 21 for frictionally fixing screws, etc. inserted from an outside. The parallel hole is surrounded by a one-side closing wall 3e which closes the parallel hole side of a one-side lightening wall 4a, and the other-side closing wall 3d which closes the parallel hole side of an other-side lightening wall 4b, respectively. A wall surface 3ea of the one-side closing wall exposed in the one-side lightening wall is a push-off surface, and walls 3eb and 3ec of the one-side closing wall exposed in the other-side lightening wall are bite-off surfaces. Since the parallel holes are formed with the push-off surface and the bite-off surfaces, the parallel holes can be formed only by mold clamping and mold opening without using slide inserts or drills.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The technology disclosed in this specification relates to an annular molded body having parallel holes. [Background technology]

[0002] Conventionally, when a molded body formed by molding a material by clamping and opening a movable mold against a fixed mold has a wall and the wall has a fixed long hole that intersects with the movement direction of the movable mold, the fixed long hole becomes an undercut and cannot be formed by movement only in the clamping and opening directions, and the molding is generally performed by moving a sliding insert (Patent Document 1).

[0003] Another method for forming the fixed slots is to use a drill, in which an annular molded body without a slide insert, i.e., without fixed slots, is clamped and drilled in one direction at a time or in four directions simultaneously toward an imaginary center line. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-261802 Summary of the Invention [Problem to be solved by the invention]

[0005] For this reason, although not limited thereto, when a plurality of fixed long holes are to be formed in the thickness direction of an annular molded body such as a spacer provided between a cylindrical gear case and a motor, the manufacturing cost and labor become a large burden in setting the product price. That is, for example, let us assume that the number of fixed long holes is four, and that these are provided at equal intervals in the circumferential direction of the annular molded body. The positions correspond to the 3 o'clock, 6 o'clock, 9 o'clock, and 12 o'clock directions of a clock. Since these four fixed long holes cannot be formed with one slide insert, a slide insert is required to form each fixed long hole individually. If the number of fixed long holes is increased to five or six, the number of slide inserts must be increased accordingly, which is very uneconomical. Incidentally, the number of slide inserts arranged radially requires a certain exclusive area for each, so the number that can be installed is at most about six, although it depends on the case. In other words, the number of fixed long holes that can be formed cannot be increased to seven, eight, or even more.

[0006] In addition, the diameter of the fixed long hole formed by the slide insert gradually increases from the back to the front direction (radial direction from the imaginary center line of the annular molded body) when viewed from the slide insert. In other words, a draft gradient is unavoidable. Such a draft gradient leads to a gradient in the engagement between the screw or pin that is frictionally fixed and the inner peripheral surface of the fixed long hole, which is not preferable in terms of maintaining strength.

[0007] The inner peripheral surface of the fixed long hole formed by the drill is a parallel hole with no slope (defined later), so the draft problem that occurs with slide inserts does not occur. However, it requires time and drilling equipment, which ultimately has a negative effect on manufacturing costs.

[0008] The problem that the present invention aims to solve is to provide an annular molded body having parallel holes for inserting and frictionally fixing screws or pins, which can be molded simply by moving one mold relative to the other mold in the direction of clamping and opening, without using a slide insert or drill, and without causing problems with hole gradients. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention has the following structural and operational features. (Feature of the invention of claim 1) The annular molded body according to the invention of claim 1 (hereinafter referred to as "the molded body of claim 1") is an annular molded body having an imaginary center line formed by material molding only by the movement of one die relative to the other die in the direction of die clamping and die opening. It has a predetermined height in the length direction of the imaginary center line and a predetermined thickness in the radial direction of the imaginary center line. At least one parallel hole is provided for frictionally fixing a screw or pin inserted in a direction toward the imaginary center line from the outside, and at least one one-side hollowing passage that communicates with the parallel hole and opens toward the one die, and at least two other-side hollowing passages that communicate with the parallel hole and open toward the other die are provided successively from the outside toward the imaginary center line in the order of the other-side hollowing passage, the one-side hollowing passage, and the other-side hollowing passage. The parallel hole is surrounded by a one-side closing wall that closes the parallel hole side of the one-side hollowing passage and an other-side closing wall that closes the parallel hole side of each of the other-side hollowing passages, and a wall surface of the one-side closing wall exposed in the one-side hollowing passage is a push-off surface, and a wall surface of the one-side closing wall exposed in the other-side hollowing passage is a cut-off surface. the law of nature , a burr retainer for retaining burrs generated when inserting a screw or a pin in the other-side hollowing passage between the other-side hollowing passage closer to the imaginary center line and the imaginary center line, It is characterized by:

[0010] (Feature of the invention of claim 2) The annular molded article according to the invention of claim 2 (hereinafter referred to as "the molded article of claim 2") is An annular molded body having an imaginary center line, which is formed by material molding by clamping and opening one die against the other die, has a predetermined height in the length direction of the imaginary center line and a predetermined thickness in the radial direction of the imaginary center line, and is provided with at least one parallel hole for frictionally fixing a screw or pin inserted in a direction toward the imaginary center line from the outside, at least one one-side hollow passage communicating with the parallel hole and opening toward the one die side, and at least two other-side hollow passages communicating with the parallel hole and opening toward the other die side, The other-side cutout passage, the one-side cutout passage, and the other-side cutout passage are provided in this order in succession, and the parallel hole is surrounded by a one-side closing wall that closes the parallel hole side of the one-side cutout passage and a other-side closing wall that closes the parallel hole side of each of the other-side cutout passages, and a wall surface of the one-side closing wall exposed in the one-side cutout passage is a push-off surface, and a wall surface of the one-side closing wall exposed in the other-side cutout passage is a cut-off surface, and a mounting body of a predetermined shape having a through hole through which the screw or pin can pass is frictionally fixed by inserting the screw or pin that has passed through the through hole into the parallel hole. , characterized in that

[0011] (Feature of the invention of claim 3) The annular molded article according to the invention of claim 3 (hereinafter, appropriately referred to as "the molded article of claim 3") is 1 of A preferred form of the molded body is characterized in that an object to be attached has a predetermined shape and has a through hole through which the screw or pin can pass, and the screw or pin passing through the through hole is inserted into the parallel hole and frictionally fixed.

[0012] (Feature of the invention of claim 4) The annular molded article according to the invention of claim 4 (hereinafter, appropriately referred to as "the molded article of claim 4") is 2 or In a preferred embodiment of the molded body of 3, the annular molded body is a spacer provided between a cylindrical gear case constituting the mounting body and a motor, and is fixed to the motor and partially or entirely housed inside the gear case, and is configured so that a screw or pin passing through the through hole of the cylindrical gear case can be inserted and fixed into the parallel hole to prevent the cylindrical gear case from coming off or rotating relative to the motor. Effect of the Invention

[0013] According to the present invention, there is provided an annular molded body having parallel holes for inserting and frictionally fixing screws or pins, which is molded as much as possible by simply moving one mold in the direction of closing and opening the other mold relative to the other mold, without using a slide insert or drill, and without causing any problems with hole gradient. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is an exploded perspective view showing an example of use of the annular molded body (spacer). [Diagram 2] FIG. 2 is a perspective view of the spacer as viewed from one side. [Diagram 3] FIG. 11 is a perspective view of the spacer as viewed from the other side. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 11 is a plan view of the spacer as viewed from the other side. [Figure 7] 7 is a cross-sectional view of the spacer shown in FIG. 6 along the line AA. [Figure 8] FIG. 7 is a cross-sectional view of the spacer shown in FIG. 6 . [Figure 9] 5 is a schematic cross-sectional view of a mold showing a molding process of a spacer. FIG. [Figure 10] 5 is a schematic cross-sectional view of a mold showing a molding process of a spacer. FIG. [Figure 11] 5 is a schematic cross-sectional view of a mold showing a molding process of a spacer. FIG. [Figure 12] 5 is a schematic cross-sectional view of a mold showing a molding process of a spacer. FIG. [Figure 13] FIG. 4 is a partial cross-sectional view showing the relationship between a spacer and a die. [Figure 14] 5 is a schematic cross-sectional view of a mold showing a molding process of a spacer. FIG. [Figure 15] FIG. [Figure 16] FIG. 16 is a partial enlarged view of the spacer shown in FIG. [Figure 17] FIG. 11 is a perspective view of a spacer according to a modified example of the embodiment, as viewed from one side. [Figure 18] FIG. 11 is a perspective view of a spacer according to a modified example of the embodiment, as viewed from the other side. [Figure 19] FIG. 11 is a plan view of a spacer according to a modified example of the embodiment, as viewed from one side. [Figure 20] 20 is a cross-sectional view of the spacer shown in FIG. 19 taken along the line A'-A'. [Figure 21] FIG. 11 is a perspective view of a spacer according to a modified example of the embodiment. [Figure 22] FIG. 22 is a partial enlarged view of the spacer shown in FIG. 21.

[0015] To mold an annular molded body having parallel holes for inserting and frictionally fixing screws or pins, without using a slide insert or drill, and without causing problems with hole gradient, by simply moving one mold relative to the other mold in the direction of clamping and opening. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (definition) The definitions of terms used in this application are as follows: (1) Annular molded body It refers to a molded body that is hollow with a center hole surrounded by an inner peripheral wall and has an outer side defined by an outer peripheral wall. Although a round appearance like a ring is the basic shape, in this application, ovals and square shapes are also included. It also includes a shape in which the shape of the outer peripheral wall is different from the shape of the inner peripheral wall, for example, a circular outer peripheral wall and a square inner peripheral wall. It also includes a shape in which unevenness that does not cause undercuts is provided on one or both of the outer peripheral wall and the inner peripheral wall. In this application, a spacer provided between a cylindrical gear case and a motor is given as an example of an embodiment as an example of an annular molded body. In addition, the cylindrical gear case is designed to be attached to the spacer as an attached body. (2) One of the molds The one of the dies is either a fixed die that does not move during molding or a movable die. In this embodiment, for convenience of explanation, it is referred to as a movable die. (3) The other mold It is a movable mold when one of the molds is a fixed mold, or a fixed mold when one of the molds is a movable mold. In this embodiment, it will be referred to as a fixed mold for convenience of explanation. In molding a molded product that generates an undercut, a slide insert or the like may be used when clamping the mold, which may require movement other than in the mold clamping / single-opening direction, but the mold movement in this application is only in the mold clamping and single-opening directions. For example, when an ejector pin is used to eject a molded product, the movement of this ejector pin accompanies single-opening, and is included in the "single-opening" movement in this application. (4) Parallel holes This refers to a hole whose diameter does not vary depending on the position and whose inner circumferential wall is parallel when viewed in cross section. Holes that have no intentional diameter gradient such as a draft angle are included in the parallel hole of this application, even if there are unavoidable dimensional errors and slight play. (5) Frictional fixation Friction fixing refers to fixing by friction alone against the inner peripheral wall of a parallel hole when an inserting member such as a screw inserted by threading, a press-fitted parallel pin, or a spring pin that elastically pushes in the direction of radial expansion is inserted. Although it is not prohibited to apply adhesive or the like after friction fixing for post-reinforcement, friction fixing must be the main method, and the intent is to exclude cases where fixing to achieve the purpose cannot be achieved without adhesive or the like. (6) Cutting surface The cut-off surface is the surface that comes into contact with the mold in a direction perpendicular or inclined to the direction of clamping and opening between one mold and the other mold. (7) Cutting surface The mating surface refers to the mating surface between one mold and the other mold that runs along the direction of mold clamping and single-opening (not necessarily parallel).

[0017] (Examples of uses for annular molded bodies) As shown in FIG. 1, the annular molded body 1, together with the cylindrical gear case 103 and the motor 105, is one of the components of the geared motor 101, and is a part called a spacer. Hereinafter, the spacer 1 will be referred to as the spacer 1 instead of the annular molded body 1. The spacer 1 is fixed to the motor 105, and a part (or the entire part depending on the shape) is housed inside the gear case 103. In the housed state, a screw 51 penetrating a through hole 104 (FIG. 1) of the cylindrical gear case 103 from the outside is inserted into the spacer 1 by screw action, and the cylindrical gear case 103 is frictionally fixed. Therefore, for the spacer 1, the cylindrical gear case 103 is a mounting object, and is also a reinforcing body that reinforces the mounting of the screw 51 to the parallel hole 21 described later. The parallel hole 21 and the cylindrical gear case 103 (through hole 104) work together to effectively prevent the cylindrical gear case 103 from coming off and rotating relative to the motor 105 within the range of use of the gear motor 101. In this embodiment, a tap screw is used as an example of the screw 51. Instead of the screw, a spring pin having a gap in the length direction, other pins, etc. may be used.

[0018] A group of gears (not visible as they are obstructed by the cylindrical gear case 103) are housed inside the cylindrical gear case 103, and the rotation of the motor 105 is reduced in speed and output from the output shaft 107. The detailed structure and manufacturing method of the spacer 1 will be described later. Note that the spacer 1 is an example of an annular molded body, and the technical idea of ​​the present invention also applies to other annular molded bodies. In addition, various molding materials are available for the annular molded body, and resins such as polyacetal, polybutylene terephthalate, and ABS, metals such as aluminum and zinc, and even ceramics and sintering materials can be used.

[0019] (Outline of spacer structure) The structure of the spacer 1 will be described with reference to Figs. 1 to 8. The spacer 1 is a member for connecting the cylindrical gear case 103 and the motor 105, and in this embodiment, is an annular molded body made of molded polyacetal. If attention is paid to strength, a sintered material or an aluminum zinc die-cast material can also be used. The two-dot chain line CL in Figs. 2 and 8 indicates an imaginary center line passing through the center of the spacer 1 in the length direction. The imaginary center line CL does not actually exist, but is a convenient reference for indicating the length direction (the vertical direction in Figs. 2 and 8) and the radial direction as viewed from the imaginary center line CL. The spacer 1 has a height dimension in the length direction of the imaginary center line CL (the vertical direction in Figs. 2 and 8) and a width dimension in the radial direction.

[0020] (Details of spacer structure) The spacer 1 has a cylindrical spacer body 3 and a flange portion 5 having a length dimension slightly less than half the length dimension (length direction of the imaginary center line CL) of the spacer body 3 at one end side in the length direction of the imaginary center line CL of the spacer body 3 (lower side in Figs. 2 and 8). The flange portion 5 shares the imaginary center line CL with the spacer body 3, and its radial thickness dimension is set to be larger than the thickness dimension of the spacer body 3. Therefore, the flange portion 5 has a shape that protrudes in the radial direction over the entire circumference from the spacer body 3. The outer dimension of the spacer body 3 is slightly smaller than the inner diameter of the cylindrical gear case 103 with a play that does not interfere with insertion. This allows the spacer body 3 to be stored in the cylindrical gear case 103. On the other hand, the outer dimension of the flange portion 5 is larger than the outer dimension of the cylindrical gear case 103 (the reason will be described later), and is approximately the same as the outer dimension of the motor 105 mainly for the sake of appearance.

[0021] (Flange) The flange 5 is formed to make up for the difference in diameter when the motor 105 is larger than the cylindrical gear case 103, making it easier to attach the motor to the motor 105. For this reason, if there is no difference in diameter between the two, it is not necessarily necessary to provide the flange. Conversely, if the cylindrical gear case 103 has a larger diameter than the motor, the positional relationship shown in Fig. 3 can be reversed. The step 5d (Figs. 2, 4, 5) formed between the flange 5 and the spacer body 3 comes into contact with the open end face of the cylindrical gear case 103 in an abutting state, and therefore also has a function of positioning the cylindrical gear case 103 relative to the entire spacer 1.

[0022] (Draft angle of spacer) Reference numeral 3c in Figs. 7 and 8 denotes a spacer body that faces one end face 3b in the longitudinal direction of the imaginary center line CL. 1 shows the other end face of spacer 1. Spacer body 3 and flange 5 cannot be distinguished from each other in the drawing, but a draft of, for example, about 3 degrees is formed, and they taper slightly from one end face side 3b, 5b toward the other end face 3c. This draft is a gradient to make spacer 1 easier to remove from a mold (not shown). Therefore, the direction from one end face side 3b toward the other end face 3c coincides with the mold opening direction in the molding direction of spacer 1, which will be described later, and the opposite direction coincides with the mold closing direction. Note that drafts are provided not only on the entire spacer body 3 and flange 5, but also on the peripheral walls of the lightening passages, which will be described later, as appropriate.

[0023] (Outer surface and central hole) Spacer body 3 has a body outer peripheral surface 3a that defines its outside, and an inner peripheral surface 11a that defines its inside. The outside of flange 5 is defined by flange outer peripheral surface 5a, and the inside is defined by inner peripheral surface 11a. Inner peripheral surface 11a also surrounds center hole 11 that passes through the center of spacer 1. Center hole 11 is a hole that allows motor shaft 106 (FIG. 1) of motor 105 to pass through without interfering with its rotation.

[0024] (Relief holes and fixing holes) Reference numeral 13 denotes an escape hole that penetrates the spacer body 3 in the lengthwise direction and in the radial direction with a part cut out. Furthermore, reference numeral 15 denotes a fixing hole. The fixing hole 15 is configured to be concentric with the inner diameter of the escape hole 13 and to have a diameter smaller than the inner diameter, and is formed to penetrate the spacer body 3 in the lengthwise direction so that a part of it is bitten into the flange portion 5 in the radial direction. The fixing hole 15 is a hole for allowing a bolt (not shown) with a head larger in diameter than the inner diameter of the fixing hole 15 and slightly smaller in diameter than the inner diameter of the escape hole 13 to pass through the fixing hole 15 from the left side to the right side of the paper of FIG. 1 (i.e., toward the motor 105) with a small amount of play, and to be screwed into a female screw hole formed through the corresponding part of the motor 105. The spacer 1 can be fixed to the motor 105 by this screw fixing. The escape hole 13 is a hole for allowing the head of the bolt and a screwdriver for rotating it to pass through.

[0025] In this embodiment, the number of escape holes 13 is a minimum of two, but it is possible to provide three, four, or, if necessary, five or more. The peripheral wall surrounding the escape hole 13 is also provided with a draft angle that tapers in the escape direction. Accordingly, the number of fixing holes 15, which is currently two, becomes three, four, or five or more.

[0026] (parallel hole) The description will be centered on Figs. 4 to 8. The parallel hole 21 is formed penetrating the spacer body 3 in the thickness direction (left and right direction in Fig. 7), leaving a movable side remaining part 3e (particularly the enlarged view in Fig. 8) with a thickness necessary for strength near the other end face 3c. The parallel hole 21 is set to a diameter dimension that allows the screw 51 (enlarged view in Fig. 7) to be inserted from the outside in a direction toward the imaginary center line CL by screw advancement and to be frictionally fixed. At least one parallel hole 21 is provided, but in this embodiment, four parallel holes 21 are provided at equal intervals in the circumferential direction of the spacer 1. This number of four is determined to be necessary and sufficient to prevent the cylindrical case 103 from coming off and rotating relative to the motor 105. Depending on factors such as the material and shape of the spacer 1, two, three, or five or more may be provided. As will be described later, the thread of the screw 51 is not evenly applied to the parallel hole 21 over the entire length direction, but a part of it is exposed. This point will be described in more detail below.

[0027] 7 and 8, the parallel hole 21 in this embodiment is connected to one one-side cutout passage 4a penetrating from a central portion having a length dimension of about half the total length to one die (a movable die 203 described later) and two other-side cutout passages 4b, 4b each having a length dimension of about a quarter of the total length and penetrating both sides sandwiching the central portion to the other die (a fixed die 205 described later). That is, as shown in Figs. 7 and 8, the other-side cutout passage 4b ​​→ one-side cutout passage 4a → other-side cutout passage 4b ​​are provided continuously in this order from the outside toward the imaginary center line CL, and the parallel hole 21 is formed so as to pierce these three cutout passages. When viewed from a different perspective, the parallel hole 21 is surrounded by a one-side closing wall 3e that closes the parallel hole 21 side of the one-side hollowing passage 4a (the upper end in Figures 7 and 8), and other-side closing walls 3d, 3d that close the parallel hole 21 side of each of the other-side hollowing passages 4b (the lower end in Figure 7).

[0028] With the above configuration, as shown in Fig. 1, a part of the screw 51 inserted through the through hole 104 of the cylindrical gear case 103 engages with the other-side closing wall 3d, 3d and the one-side closing wall 3e (enlarged view in Fig. 7) of the spacer body 3, while the other part is partially exposed in each of the one-side cutting path 4a and the other-side cutting path 4b4b, 4b. As described above, in this embodiment, the other-side cutting path 4b → one-side cutting path 4a → other-side cutting path 4b are provided continuously from the outside toward the imaginary center line CL, but additional cutting paths may be generated in the same manner toward the imaginary center line CL, such as another one-side cutting path 4a → other-side cutting path 4b (hereinafter, repeated) continuous with the other-side cutting path 4b closer to the imaginary center line CL.

[0029] Not only in the case of fixing the screw 51 to the spacer 1, but also in the case of the ring-shaped body according to the present application in general, the fixing strength is not completely reduced by partial exposure. However, by appropriately selecting the material hardness of the spacer 1 according to the application and the intended use, appropriately selecting the number of parallel holes to reduce the individual loads below the tolerable limit, and by using the spacer 1 in combination with a fixed body such as the cylindrical gear case 103 according to the present application, it is possible to maintain sufficient strength to achieve the purpose. As described above, the cylindrical gear case 103 according to the present application is made of polyacetal, and the reinforcing effect of the polyacetal functions synergistically to prevent the cylindrical gear case 103 from coming off and rotating relative to the motor 105 (FIG. 1, enlarged view of FIG. 7). The parallel hole 21 shown in FIG. 8 is semicircular, but this is because the figure is a BB cross-sectional view of FIG. 6, and the cutting line forming this cross-section extends horizontally from the left to the imaginary center line CL and in the 4:30 direction from the imaginary center line CL, respectively.

[0030] (Manufacturing method of spacers) 9 to 14, a method for manufacturing the spacer 1 using a mold will be described. The mold 201 is composed of one mold (movable mold) 203 and the other mold (fixed mold) 205 which moves only in the directions of clamping and opening relative to the movable mold 203. To facilitate the explanation, the illustration of the constituent parts and components of the mold 201, including its overall structure, is kept to a minimum, and various parts such as sprues, ejector pins, and coil springs, as well as a mechanism for moving the movable mold 203, are omitted. It goes without saying that the spacer 1 can be manufactured even if a mold with a different design from that of the mold 201 is used.

[0031] (Movable structure) The movable die 203 has one base portion 203a, one annular peripheral wall portion 203b standing from the periphery of the base portion 203a, and one recess 205e surrounded by the peripheral wall portion 203b. The recess 205e further has four movable-side recessed projections 203c standing from the base portion 203a toward the fixed die 205, and a central projection 203d located at the center of the recess 205e. The peripheral wall portion 203b defines the outer peripheral surface of the spacer 1, and molten resin is injected into the recess 205e from a resin injection port (not shown). The movable-side recessed projections 203c are projections for forming one-side recessed passage 4a (FIG. 8) of the spacer 1. The central projection 203d is a projection for forming a central hole 11 of the spacer 1.

[0032] (Fixed structure) The fixed die 201 has a base portion 205a located on the side farther from the movable die 203, a shoulder portion 205b corresponding to the peripheral wall portion 203b of the movable die 203, a step forming projection 205c projecting from the shoulder portion 205b toward the movable die 203, and a pair of fixed-side recessed projections 205d, 205d. There are two pairs of fixed-side recessed projections 205d, 205d shown in Figures 9 to 12, but there is one pair each on the front and back of the page, making a total of four pairs. This corresponds to the fact that the other-side recessed passages 4b, 4b of the spacer 1 are provided in four locations (four pairs) at equal intervals in the circumferential direction.

[0033] (Molding of spacers) At this point, the movable die 203 indicated by the two-dot chain line moves in the direction of the arrow to close the die (Fig. 9), and molten resin R is injected (Fig. 10). Once the resin has solidified by cooling, the movable die 203 is moved to open the die (Fig. 11), and the molded spacer 1 is removed from the metal mold 201 (Fig. 12). This completes the molding of the spacer 1, and the above procedure is repeated as necessary.

[0034] (Pushing surface / cutting surface) Please refer to Figures 7 and 9 to 14. The wall surface 3ea of ​​the one-side closing wall 3e exposed in the one-side recess 4a is a pressed surface, and the wall surface 3eb of the one-side closing wall 3e exposed in the other-side recess 4b is a cut-off surface. That is, the wall surface 3ea is a surface that is formed when the tip surface of the movable-side recess protrusion 203c comes into contact with the wall surface 3ea during mold closing, and thus a trace of the pressed surface remains. On the other hand, the wall surfaces 3eb, 3ec are mating surfaces along the mold closing / opening direction of the fixed-side recess protrusions 205d, 205d (Figures 9 to 12). Therefore, the wall surfaces 3eb, 3ec have a cut-off mark like abrasion as shown in Figures 13 and 14. The enlarged view of Figure 14 (the same as Figure 22 described later) was enlarged by about 20 times using a Nikon microscope (model number: SMZ645). Incidentally, the wall surfaces 3da, 3db are pressed surfaces.

[0035] As described above, according to the molding of the spacer 1 in this embodiment, the parallel holes 21 for inserting and frictionally fixing the screws 51 or pins can be formed without using a slide insert or a drill, and without causing problems with hole gradients, simply by moving one die 205 in the direction of clamping and opening relative to the other die 203. The parallel holes 21 surrounded by the push-cut surface and the undercut surface do not cause problems with draft gradients.

[0036] (Modification of this embodiment) A modified example of this embodiment (this modified example) will be described with reference to Figures 15 to 18. The basic structure of the spacer 1' according to this modified example is the same as that of the spacer 1 of this embodiment, and the difference between the two is the presence or absence of a burr stopper 12, which will be described next. For this reason, the reference numerals shown in Figures 15 to 18 are the same as those shown in Figures 2 to 8 according to this embodiment for common parts, and descriptions of parts with the same reference numerals will be omitted.

[0037] A feature of the spacer 1' compared to the spacer 1 is that it has the burr stopper 12 described above. That is, a burr stopper is provided between the other-side recessed passage 4b ​​(FIG. 18) closer to the imaginary center line CL and the imaginary center line CL, for keeping burrs (examples of which are shown in FIGS. 19 and 20) generated when inserting a screw or pin within this other-side recessed passage 4b. Although there may be cases where the generation of burrs does not cause any inconvenience, the purpose of this is to prevent the generated burrs from falling into the cylindrical gear case 103 (FIG. 1) and interfering with the rotation of the gear group therein.

[0038] As shown in Fig. 18, the burr stopper 12 is for retaining the burr in the other-side hollowing passage 4b ​​by closing the imaginary center line CL direction. Therefore, there is no limitation on the form as long as the purpose of retaining the burr is achieved. The burr stopper 12 of this modified example is formed over the entire area from the one end face 3b to the other end face 3c, but it is sufficient if it can at least close the other-side hollowing passage 4b. The burr stopper 12 is conveniently formed by cutting away, so that a cutting trace is formed on the wall surface 12a of the burr stopper 12 exposed in the other-side hollowing passage 4b. [Explanation of symbols]

[0039] 1,1´ Maza 3 Spacer body 3a Outer periphery of main body 3b One end face 3c Other end face 3d Other side closing wall 3e One side closing wall 3ea Wall 3eb wall 3ec Wall 4a One-side hollowing passage 4b Other side hollowing passage 5. Flange 5a Flange outer circumferential surface 5d stepped part 11 Center hole 11a Inner surface 12 Deburring 12a Wall 13 Relief hole 15 Fixing hole 21 Parallel hole 51 Screw 101 Gear motor 103 Cylindrical gear case 104 Through hole 105 Motor 107 Output shaft 201 Mold 203 One of the molds (movable mold) 205 The other mold (fixed mold) CL Virtual center line

Claims

1. An annular molded body having a virtual center line, which is formed by molding a material by clamping and opening one mold relative to the other mold, a predetermined height in a length direction of the imaginary center line and a predetermined thickness in a radial direction of the imaginary center line, At least one parallel hole is provided for frictionally fixing a screw or pin inserted from the outside in a direction toward the imaginary center line, at least one one-side hollowing passage communicating with the parallel hole and opening to the one die side, and at least two other-side hollowing passages communicating with the parallel hole and opening to the other die side are provided successively from the outside toward the imaginary center line in the order of the other-side hollowing passage, the one-side hollowing passage, and the other-side hollowing passage; The parallel hole is surrounded by a one-side closing wall that closes the parallel hole side of the one-side hollowing passage and an other-side closing wall that closes the parallel hole side of each of the other-side hollowing passages, a wall surface of the one-side closing wall exposed in the one-side hollowing passage is a push-off surface, and a wall surface of the one-side closing wall exposed in the other-side hollowing passage is a cut-off surface, a burr retainer for retaining burrs generated when inserting a screw or a pin in the other-side hollowing passage between the other-side hollowing passage closer to the imaginary center line and the imaginary center line, 1. An annular molded body comprising:

2. An annular molded body having a virtual center line, which is formed by molding a material by clamping and opening one mold relative to the other mold, a predetermined height in a length direction of the imaginary center line and a predetermined thickness in a radial direction of the imaginary center line, At least one parallel hole is provided for frictionally fixing a screw or pin inserted from the outside in a direction toward the imaginary center line, at least one one-side hollowing passage communicating with the parallel hole and opening to the one die side, and at least two other-side hollowing passages communicating with the parallel hole and opening to the other die side are provided successively from the outside toward the imaginary center line in the order of the other-side hollowing passage, the one-side hollowing passage, and the other-side hollowing passage; The parallel hole is surrounded by a one-side closing wall that closes the parallel hole side of the one-side hollowing passage and an other-side closing wall that closes the parallel hole side of each of the other-side hollowing passages, a wall surface of the one-side closing wall exposed in the one-side hollowing passage is a push-off surface, and a wall surface of the one-side closing wall exposed in the other-side hollowing passage is a cut-off surface, a mounting object having a predetermined shape and a through hole through which the screw or pin can pass, the screw or pin passing through the through hole is inserted into the parallel hole and frictionally fixed; 1. An annular molded body comprising:

3. a mounting object having a predetermined shape and a through hole through which the screw or pin can pass, the screw or pin passing through the through hole is inserted into the parallel hole and frictionally fixed; 2. The annular molded article according to claim 1.

4. the annular molded body constitutes a spacer provided between a cylindrical gear case and a motor, The mounting body constitutes the cylindrical gear case, The gear case is fixed to the motor and is partially or entirely housed inside the gear case, and a screw or a pin passing through the through hole of the cylindrical gear case is inserted into the parallel hole and frictionally fixed to the motor, thereby preventing the cylindrical gear case from coming off and rotating.

4. The molded article according to claim 2 or 3.

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