JP4040963B2 - Injection mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical member whose inner and outer peripheral surfaces are injection-molded, and an injection mold for molding the cylindrical member.
[0002]
[Prior art]
According to a conventional injection mold using an inner slide core (open core), it is easy to form a complex shaped member with a cam or helicoid formed on the inner peripheral surface, such as a camera frame member. can do. As an injection mold using the above inner slide core, the injection mold described in Patent Document 1 or Patent Document 2 has a first slide core divided into six and a second slide core as a center core. The center core is retracted in the axial direction when the mold is opened, and the first and second slide cores are squeezed toward the center core and the molded member is taken out. ing. Such an injection mold has a feature that an article having a complicated shape can be easily molded, but there is a problem in that burrs are likely to occur on the divided surface of the mold.
[0003]
As a conventional method for preventing burrs, a method of increasing the clamping force and bringing the die-splitting surface into close contact with a larger force is common. As another means, there is a method disclosed in Patent Document 3. In this method, as shown in the partial sectional view of the mold of FIG. 20, the divided surface 102 a on one side contacting the divided surface 101 a of the cavity portion 103 of the molds 101 and 102 to be clamped is provided with a convex contact surface. Thus, high surface pressure is applied to prevent the generation of burrs. If the molded product still has burrs, the burrs must be removed manually.
[0004]
[Patent Document 1]
The above-mentioned Patent Document 1 is Japanese Patent Publication No. 1-46296.
[0005]
[Patent Document 2]
The above Patent Document 2 is Japanese Patent Publication No. Hei 4-42971.
[0006]
[Patent Document 3]
The said patent document 3 is patent publication 2001-232639.
[0007]
[Problems to be solved by the invention]
According to the inner slide type (open core type) described in Patent Document 1 or 2, there is a possibility that burrs may occur between the first slide core and the second slide core. Even if the strength is increased, the adhesive force between the first slide core and the second slide core does not increase so much due to its mold structure. That is, increasing the clamping force is not effective in preventing burrs.
[0008]
Therefore, even if an attempt is made to apply the burr generation prevention structure according to Patent Document 3 to the inner slide mold, the shape of the first slide core and the second slide core is complicated, so that the convex shape shown in FIG. In order to provide the contact surface on the slide core, a highly accurate processing technique is required, and application is extremely difficult. And it is difficult to remove the burrs generated in the inner periphery of the molded product, and it can be said that it is an unavoidable requirement to suppress the generation of these burrs.
[0009]
The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a cylindrical member with few burrs in the parting line (parting line part) of the inner periphery. Another object is to provide an injection mold for injection molding of a cylindrical member with few burrs.
[0010]
[Means for Solving the Problems]
  Claim 1 of the present inventionThe injection mold is an injection mold for molding a cylindrical member by injection molding, and is provided apart from each other around the center core in order to form the center core and the inner peripheral surface of the cylindrical member. A plurality of first slide cores that can move relative to the center core, and an inner peripheral surface of the cylindrical member, and is disposed between the plurality of first slide cores around the center core. And having a mating surface portion with the first slide core, and configured so that the mating surface portion is covered with the first slide core when the mold is closed, and a plurality of movable relative to the center core when the mold is opened and closed. The second slide core and a plurality of slide cores in the circumferential direction of the outer peripheral surface of the cylindrical member, and a first gate is provided so as to face the first slide core. A second gate having a gate opening smaller than an area of the gate opening of the first gate and facing the second slide core to form an outer shape of the cylindrical member. It is characterized by that.
[0011]
  Claim 2 of the present inventionThe injection mold according to claim 1, further comprising: a first outer mold configured to face the second slide core in the circumferential direction of the outer peripheral surface of the cylindrical member. 2 is provided, and the right-angle cross-sectional area perpendicular to the injection molding material flow direction of the sprue leading to the second gate is smaller than that of the sprue leading to the first gate. Features.
[0012]
  Claim 3 of the present inventionThe injection mold according to claim 1, wherein the outer mold further includes a first outer mold configured to face the second slide core in the circumferential direction of the outer peripheral surface of the cylindrical member. 2, and the injection molding material flow path length of the second gate is longer than the injection molding material flow path length of the first gate facing the first slide core.
[0013]
  Claim 4 of the present inventionThe injection mold according to claim 1, further comprising: a first outer mold configured to face the second slide core in the circumferential direction of the outer peripheral surface of the cylindrical member. 2 is provided, and the injection molding material flow path length of the sprue that leads to the second gate is longer than the injection molding material flow path length of the sprue that leads to the first gate.
[0014]
  An injection mold according to claim 5 of the present invention isIn the injection mold for molding the cylindrical member by injection molding, in order to form the center core and the inner peripheral surface of the cylindrical member, the center core is provided apart from each other around the center core, A plurality of first slide cores that can be moved relative to each other and an inner peripheral surface of the cylindrical member are arranged between the plurality of first slide cores around the center core, and the mold is closed when the mold is closed. A plurality of second slide cores having a mating surface portion with the first slide core, the mating surface portion being configured to be covered by the first slide core, and movable relative to the center core when the mold is opened and closed; The cylindrical member includes a plurality of slide cores in the circumferential direction of the outer peripheral surface of the cylindrical member, and is separated from a parting line between the first slide core and the second slide core. A gate is provided to face the ride core, and the injection direction of the molding material from the gate is the first direction with respect to a straight line passing through the center core center and the parting line in a plane orthogonal to the mold opening / closing direction. And an outer shape mold for forming the outer shape of the cylindrical member having a predetermined angle so that the gate faces the outer peripheral surface of the slide core.
[0015]
  An injection mold according to claim 6 of the present invention is6. The injection mold according to claim 5, wherein the gate is separated from the parting line by a predetermined distance in the circumferential direction of the outer peripheral surface of the cylindrical member, and the outer periphery of the first slide core. It is characterized by facing on the surface.
[0016]
  An injection mold according to claim 7 of the present invention isIn the injection mold according to claim 6, when the predetermined angle is α and the predetermined distance is d,
  α ≧ 10 ° and d ≧ 0.5 mm
  It is characterized by being.
[0017]
  An injection mold according to claim 8 of the present invention isIn the injection mold according to claim 6, when the predetermined angle is α and the predetermined distance is d,
  α ≧ 15 ° and d ≧ 1.0 mm
  It is characterized by being.
[0018]
  An injection mold according to claim 9 of the present invention is7. The injection mold according to claim 6, wherein the outer shape mold includes a plurality of outer slides, and a sprue and the gate are provided on a parting surface in contact with each other.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a cam frame of a cylindrical member according to the first embodiment of the present invention.
[0030]
The cam frame 10 of this embodiment is a cylindrical frame member applicable to a lens barrel of a camera, for example, and has a plurality of cam grooves 10a, 10b, 10c on the inner peripheral surface as shown in FIG. Is provided. This cam frame 1 is a synthetic resin member that can be molded by injection molding dies 9, 11, 21, 31, 41, 51, etc. of each embodiment described later. The injection molds 9 to 51 include a split inner slide core having a plurality of mating surfaces (parting lines) and a plurality of secondary gates / sprues (including a secondary gate part and a secondary spur part). It is a metal mold | die which has the division | segmentation outer side slide core which is an external form to have.
[0031]
The inner peripheral surface of the cam frame 10 is formed by the inner slide core, but a plurality of parting line traces 10d due to the mating surfaces at the time of molding the inner slide core remain on the inner peripheral surface. The cam groove 10a and the like are formed across the parting line mark 10d.
[0032]
The outer peripheral surface of the cam frame 10 is formed by the outer slide core. On the outer peripheral surface of the outer peripheral surface, a gate mark by a gate opening of a secondary gate / sprue provided on the outer slide core is a parting line mark. On the other hand, it remains at a position separated by a predetermined distance in the circumferential direction. However, in the case of the cam frame 1 molded by the injection molding die 41, the gate mark remains on the end surface of the cylindrical portion, not on the outer peripheral surface.
[0033]
As will be described later, the cam frame 10 according to the present embodiment applies a suitable shape to the gate portion of the injection mold 9 and the like, so that there is little burring in the parting line portion and the parting line trace is not noticeable. It can be molded in a state. In addition, if the burr | flash which generate | occur | produced in the said parting line part comes out large, a deburring operation will become difficult. Further, if the parting line mark is large, the cam follower that slides on the cam groove 10a or the like malfunctions, which is not preferable, but these problems are improved in the cam frame 10 of the present embodiment.
[0034]
Next, an injection mold according to a second embodiment of the present invention will be described with reference to FIGS.
FIG. 2 is a transverse cross-sectional view showing a cross section (BB cross section in FIG. 3) perpendicular to the axis of the injection mold according to the present embodiment. 3 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 4 is an exploded perspective view of the secondary gate / sprue of the outer slide core in the injection mold. FIG. 5 is a view taken in the direction of arrow E in FIG. 3 and shows the secondary gate / sprue as viewed from the upper sprue side. FIG. 6 is a part of the BB cross section of FIG. 3 and shows the gate portion of the secondary gate / sprue.
[0035]
The injection mold 9 of the present embodiment is a mold that can mold the cam frame 10 that is the cylindrical member of the first embodiment, and includes a fixed mold and a movable mold. As shown in FIGS. 2 and 3, the fixed mold has a fixed core 5, and the movable mold is a movable insert 6, a six-divided inner slide mold described later, and an outer mold, which will be described later. And an outer slide mold.
[0036]
The six-part inner slide mold is arranged around one center core 1 that can move in the direction of the axis C0 of the mold, and can be moved relative to the axis C0 by sliding in the radial direction. It has a plurality of first slide cores 2A, 2B, 2C which are inner slide cores and a plurality of second slide cores 3A, 3B, 3C. These first slide core and second slide core are slidable relative to the center core 1 in the direction of the axis C0. These relative movements occur when the mold is opened and closed.
[0037]
The center core 1 has three dovetail grooves 1a and 1b that are inclined at a predetermined angle with respect to the axis C0.
[0038]
Each of the first slide cores 2A,... Has an arcuate cross-sectional shape, a divided outer peripheral surface 2a for forming the cam frame inner peripheral surface, and a mating surface 2c on both width sides of the divided outer peripheral surface 2a. The dovetail portion 2b is slidably fitted in the dovetail portion of the center core 1.
[0039]
Each of the second slide cores 3A,... Has a substantially trapezoidal cross-sectional shape, and a divided outer peripheral surface 3a for forming the cam frame inner peripheral surface, and the mating surface 2c from the both ends of the divided outer peripheral surface 3a to the inside. And the dovetail part 3b slidably fitted in the dovetail part of the center core 1.
[0040]
The first slide core 2A,... And the second slide core 3A,... Are in a state where the mating surfaces 2c and 3c are combined, that is, the mating surface 3c is covered by the mating surface 2c. It is alternately arranged around. When the mold is closed, as shown in FIG. 2, the first slide core 2A,... And the second slide core 3A,. In this state, the mating surface 2c is held in close contact with the mating surface 3c. In the mold closed state, the outer peripheral surface of the inner slide core is formed by the divided outer peripheral surfaces 2 a and 3 a, and the outer peripheral surface is the inner peripheral surface of the cavity 7 for forming the inner peripheral surface of the cam frame 10. Moreover, the peripheral surface edge part of the said mating surfaces 2c and 3c becomes a parting line at the time of shaping | molding. A parting line mark 10d on the outer peripheral surface of the cam frame 10 which is a molded product is formed at the parting line portion.
[0041]
On the other hand, at the time of mold opening, since the center core 1 moves in the mold opening direction (downward in FIG. 3) along the axis C0, the dovetail groove portions 1a and 1b slide on the dovetail portions 2b and 3b. The first slide cores 2A,... And the second slide cores 3A,... Slide so as to squeeze in the radial direction toward the axis C0. During this movement, the movement amount of the second slide cores 3A,... Is larger than the movement amount of the first slide cores 2A,... And the mating surfaces 2c, 3c do not interfere with each other. The cam frame 10 molded in this mold open state can be taken out from the mold.
[0042]
The outer slide type includes outer slide cores 4A, 4B, 4C, 4D, 4E, and 4F divided into six parts, each of which is in the radial direction of the axis C0 outside the first and second slide cores. It is possible to slide in the outward direction.
[0043]
Each of the outer slide cores 4A,..., 4F has a divided inner peripheral surface that forms an inner peripheral surface 4a of the outer slide core, and the outer side adjacent to each side surface of each divided inner peripheral surface. A die-matching surface 4f is provided on which the slide cores are in close contact. In the case of the adjacent outer slide cores, for example, the outer slide cores 4A and 4B, the die-matching surface 4f is a divided surface along a bisecting angle of an angle between the sliding directions D1 and D2, and has an axis C0. , Or the first slide core 2A,... Or the second slide core 3A,.
[0044]
In the closed state of the outer slides 4A,..., 4F, the mold matching surfaces 4f are held in close contact with each other, and the inner peripheral surface 4a becomes the outer diameter surface of the cavity 7. The outer peripheral surface of the cam frame 10 can be formed by this outer diameter surface.
[0045]
Pin gates 5a (six locations) serving as primary gates of the fixed core 5 are disposed on the end surface on the upper surface side in FIG. 3 of the die-matching surface 4f of the outer slide cores 4A,. A secondary gate / sprue is arranged at each position on the mold matching surface 4f facing the pin gate 5a.
[0046]
The secondary gate / spr is composed of two types of secondary gates, a first secondary gate / sprue and a second secondary gate / sprue. The first secondary gate / spr is composed of a secondary sprue part 4b and a secondary gate part 4c that are relatively long with respect to the second secondary gate / sprue. The second secondary gate / sprue includes a secondary sprue portion 4d and a secondary gate portion 4e which are relatively short with respect to the first secondary gate / sprue (FIG. 3). Each of these gates / sprues is provided in a symmetrical state in which the gates / sprels are divided into two parts across the mold matching surfaces 4f of the outer slide cores 4A,. Then, the first secondary gate / spr and the second secondary gate / spr are alternately arranged with respect to the mold matching surface 4f (FIG. 2).
[0047]
The secondary sprue portion 4b of the first secondary gate / spr is opened at a position facing the pin gate 5a in a mold-closed state, is provided along a direction parallel to the axis C0, and has a length L1. The secondary sprue portion 4b has parallel wall surfaces 4bb along the sliding directions D1 and D2 so that the outer slide core can slide outward (FIGS. 3, 4, and 5). However, the parallel wall surface 4bb is not limited to the parallel surface, but may be any inclined surface that can be punched.
[0048]
The secondary gate portion 4c of the first secondary gate / spr is in communication with the tip end portion of the secondary sprue portion 4b and is open to the inner peripheral surface 4a of the outer slide core. That is, it has a gate opening 4cc opening on the cavity 7 side. The circumferential position of the gate opening 4cc is desirably a position passing through the vicinity of the center line of the width of the second slide core 3A,..., But not necessarily a position passing through the vicinity of the center line of the width. It is sufficient that a predetermined distance d1 (described later) from 3c is secured. Further, the position of the gate opening 4cc in the direction of the axis C0 is a position below the fixed core 5 side by a distance L1 in FIG.
[0049]
On the other hand, the secondary sprue portion 4d of the second secondary gate / sprue has a length L2 shorter than the length L1 (FIG. 3), and the other portions have the same shape as the secondary sprue portion 4b. And
[0050]
The secondary gate part 4e of the second secondary gate / sprue similarly communicates with the tip of the secondary sprue part 4d, is provided to open to the inner peripheral surface 4a, and has a gate opening 4ee. Yes. The circumferential position of the gate opening 4ee is preferably a position passing through the center line of the width of the first slide core 2A,..., But is not necessarily a position passing through the vicinity of the center line of the width. It is sufficient that a predetermined distance d2 (described later) from 3c is secured. Further, the position of the gate opening 4ee in the direction of the axis C0 is a position below the fixed core 5 side by a distance L2 in FIG.
[0051]
In the injection mold 9 of the present embodiment, the positions of the gate openings 4cc and 4ee of the secondary gate / sprue secondary gate portions 4c and 4e are set to the first slide core 2A,. One important point is that the predetermined spacing distances d1 and d2 are separated from the parting line positions at the ends of the mating surfaces 2c and 3c.
[0052]
That is, as the distances d1 and d2 along the circumferential direction between the gate openings 4cc and 4ee and the parting line portion in the mold 9 of this embodiment (FIG. 6), the high-pressure molten resin is directly applied to the parting line portion. In order to avoid hitting, the minimum distance should be 1.5 mm or more, and more preferably 3.0 mm or more. The separation distance data is data obtained by experimentally molding a cylindrical member with an injection mold. In the case of this embodiment, as described above, the gate openings 4cc and 4ee are arranged on the center line extension of the width of the second slide core 3A,... Or the first slide core 2A,. The separation distance d is satisfied. However, the position of the gate opening is not limited to the extension of the center line of the width as described above, and the separation distances d1 and d2 may be ensured in some cases.
[0053]
It should be noted that gate marks are formed at the positions of the gate openings 4cc, 4ee such as the outer slide cores 4A,... On the outer peripheral surface of the cam frame 10 which is a molded product.
[0054]
In other words, the injection mold of the present invention is provided around the center core 1 so as to be separated from each other in order to form the center core 1 and the inner peripheral surface of the cylindrical member. The plurality of first slide cores 2A, 2B, 2C and the plurality of first slide cores 2A, 2B, 2C around the center core 1 to form the inner peripheral surface of the cylindrical member. The mating surface portions 2c and 3c are arranged between the first slide cores 2A, 2B, and 2C, and the mating surface portions are covered with the first slide cores 2A, 2B, and 2C when the mold is closed. A plurality of second slide cores 3A, 3B, 3C that can move relative to the center core 1 when the mold is opened and closed, and a gate 4e that faces at least the first slide cores 2A, 2B, 2C are provided. It may always be as having a a contour mold for forming the outer shape.
[0055]
Next, the operation when the cam frame 10 is molded by the injection mold 9 of the present embodiment having the above-described configuration will be described.
First, the injection mold 9 is closed. That is, when the outer slide cores 4A,..., 4F are slid and moved so that the die-matching surfaces 4f are in contact with each other as shown in the figure, the inner slide core 4A is formed with the inner slide core. The outer peripheral surface of the cavity 7 (the outer peripheral surface of the cam frame 10) is formed by the peripheral surface 4a. On the other hand, by moving the center core 1 upward, the first slide cores 2A, 2B, 2C and the second slide cores 3A, 3B, 3C are slid to a predetermined outward position. In the sliding state, the mating surfaces 2c and 3c of the first and second slide cores are held in contact. The inner peripheral surface of the cavity 7 (the inner peripheral surface of the cam frame 10) is formed by the divided inner peripheral surfaces 2a and 3a of the first and second slide cores. Note that the upper end surface of the cavity 7 in the drawing is formed by the fixed core 5, and the lower end surface in the drawing is formed by the movable side insert 6 and the step portions of the first and second slide cores.
[0056]
Under the mold closing state, high-pressure molten resin is injected from the pin gate 5a into the secondary sprue portions 4b and 4d of the first and second secondary gates / sprue. The molten resin is injected into the cavity 7 from the secondary gate portions 4c and 4e.
[0057]
After the molten resin is cooled and solidified, the mold 9 is opened. That is, the outer slide cores 4A,..., 4F are slid in the directions D1, D2, etc. to be opened. At the same time, by moving the center core 1 downward in the direction of the axis C0, the first slide core 2A,... And the second slide core 3A,. The molded product of the frame 10 can be taken out from the mold 9.
[0058]
As described above, in the injection mold 9 of the present embodiment, the gate openings 4cc and 4ee are disposed by being separated from the parting line positions at the ends of the mating surfaces 2c and 3c by the separation distances d1 and d2. The molten resin injected into the cavity 7 at a high pressure and high speed from the gate opening does not reach the parting line portion directly from the gate. Therefore, burrs are hardly generated in the parting line portions (ends of the mating surfaces 2c and 3c).
[0059]
Further, in the injection mold 9 of the present embodiment, the secondary sprue parts 4b and 4d and the secondary gate parts 4c and 4e of the secondary gate / sprue are formed on the die mating surfaces 4f of both the outer slide cores 4A,. Since it is provided in a state of being divided into symmetrical shapes, it is easy to mold the secondary gate portion.
[0060]
Further, in the injection mold 9 of the present embodiment, as the secondary gate / sprue, two types of secondary gates / sprues having different sprue lengths are alternately arranged around the cavity 7, The molten resin is injected into the cavity 7 in a more uniform state, and the moldability is improved.
[0061]
In addition, although the injection mold 9 of the present embodiment has been described for forming the cam frame 10 as a cylindrical member, the present invention is not limited to this, and other shapes of cylindrical shapes are formed by applying a split inner slide core. A similar configuration can be applied to a member molding die.
[0062]
Next, an injection mold according to a third embodiment of the present invention will be described with reference to the cross-sectional view of the mold shown in FIG.
As shown in FIG. 7, the injection mold 11 of the present embodiment is characterized in that secondary gates / sprues are provided at three locations of a six-split outer slide core. In addition, the fixed-side core 5 in which the pin gate 5a is arranged and the 6-divided inner slide type to which the first, second slide cores 2A,... And 3A,. The same reference numerals are used, and different parts will be described below. Moreover, let the cylindrical member shape | molded be the cam frame 10 of the said 1st Embodiment, for example.
[0063]
In the injection mold 11 of the present embodiment, three sets of secondary gates / sprules having the same shape are arranged across both mold joining surfaces 14f of the outer slide cores 14A and 14F, 14B and 14C, and 14D and 14E. .
[0064]
The three sets of secondary gates / sprels each include a secondary sprue portion 14b having an opening facing the pin gate 5a, and a gate opening 14cc communicating with the secondary sprue portion and opening on the inner peripheral surface 14a of the outer slide core. Secondary gate part 14c having
[0065]
The secondary sprue portion 14b and the secondary gate portion 14c have the same shape as the secondary sprue portion 4b and the secondary gate portion 4c of the secondary gate / sprue in the first embodiment. The mold-matching surface 14f of the outer slide core on which the secondary sprue portion 14b and the secondary gate portion 14c are arranged is located on a radial line connecting the axis C0 and the width center of the first slide cores 2A, 2B, 2C. is doing. Therefore, the gate opening 14cc of the secondary gate portion 14c is located in the middle in the width direction of the mating surfaces 2c, 3c of the first and second slide cores outside the first slide cores 2A,. However, the gate opening may be arranged at a position where the circumferential separation distance from the ends of the mating surfaces 2c and 3c is, for example, 1.5 mm or more, more preferably 3 mm or more. It is not limited to the middle position in the width direction,
When the cam frame 10 is molded by the injection mold 11 having the above-described configuration, the mold is closed in the same manner as the injection mold 9 of the second embodiment. Under the mold closing state, high-pressure molten resin is injected from the pin gate 5a into the secondary sprue portion 14b of the secondary gate / sprue. The molten resin is injected into the cavity 17 from the secondary gate portion 14c.
[0066]
After the molten resin is cooled and solidified, the mold 11 is opened. That is, the outer slide cores 14A,..., 14F are slid in the directions D1, D2, etc. to be opened. At the same time, by moving the center core 1 downward in the drawing in the direction of the axis C0, the first slide core 2A,... And the second slide core 3A,. The formed product of the cam frame 10 can be taken out from the mold 11.
[0067]
In the case of the injection mold 11 of this embodiment, when the molten resin is injected, the first slide core 2A on the side of the mating surface 2c that comes into contact with the outside of the mating surface 3c of the second slide core 3A,. ,... Are pressed by the high pressure and high radiation output of the molten resin acting on the gate opening. On the other hand, since there is no gate opening outside the second slide cores 3A,..., The high pressure of the molten resin does not act directly. Therefore, a state in which the mating surface 2c is in close contact with the mating surface 3c is obtained. Furthermore, since the gate opening is located at a predetermined distance from the end of the mating surface 2c and the mating surface 3c, the molten resin does not flow directly from the gate into the mating surface 2c and the end of the mating surface 3c. . Therefore, the occurrence of burrs at the parting line portions at the ends of the mating surface 2c and the mating surface 3c is suppressed.
[0068]
Next, an injection mold according to a fourth embodiment of the present invention will be described with reference to FIGS.
FIG. 8 shows a cross-sectional view (NN cross section of FIG. 9) of the injection mold according to the present embodiment. 9 is a cross-sectional view taken along line MM in FIG.
[0069]
In the injection molding die 9 of the second embodiment, two types of secondary gates / sprues having different sprue lengths are arranged at each position of the die mating surface 4f of the outer slide core. (FIG. 3). On the other hand, in the injection mold 21 of the present embodiment, two types of secondary gate / sprue are provided, but the cross-sectional area of the flow path through which the molten resin of the secondary sprue flows and the flow path of the secondary sprue part Two types of secondary gates / sprels having different lengths, secondary gate lengths, and gate opening areas are provided. Other mold structures, that is, the same as the injection mold of the second embodiment, such as application of a 6-part inner slide mold and an outer slide mold, are used. Therefore, the same components are denoted by the same reference numerals, and the description thereof will not be made. Differences will be described below.
[0070]
The injection mold 21 of the present embodiment is a mold that can mold the cam frame 10 that is the cylindrical member of the first embodiment, and includes a fixed mold and a movable mold. As shown in FIGS. 8 and 9, the fixed mold has a fixed core 5, and the movable mold includes a movable insert 6, a center core 1 constituting a six-part inner slide mold, and a first core. The slide cores 2A,..., 2C and the second slide cores 3A,..., 3C, and outer slide cores 24A,.
[0071]
As shown in FIGS. 8 and 9, pin gates 5a (six locations) serving as primary gates of the fixed-side core 5 are arranged on the upper surface side in the drawing of the mold-matching surfaces 24f of the outer slide cores 24A,. Yes. A secondary gate / sprue is disposed at each position on the mold matching surface 24f facing the pin gate 5a.
[0072]
The secondary gate / spr has two types of gates, a first secondary gate / sprue and a second secondary gate / sprue. The first secondary gate / spr has a channel cross-sectional area which is wider than the second spur length L3 as compared with the second secondary gate / spr later described as the shape relating to the flow path for the molten resin. It has a secondary sprue portion 24b and a secondary gate portion 24c having a relatively short flow path length and a relatively large opening area gate opening 24cc.
[0073]
On the other hand, the second secondary gate / sprue has a shape related to the flow path for the molten resin, the sprue length L3 in the first secondary gate / sprue, and a longer sprue length relative to the cross-sectional area perpendicular to the flow path. A secondary sprue 24d having a narrower cross-sectional area perpendicular to L4 and a gate opening 24ee having an area longer than the gate flow path length of the first secondary gate / spr and smaller than the gate opening area. Secondary gate part 24e.
[0074]
Each of the first and second secondary gates / sprules is provided in a symmetrical shape divided into two mold matching surfaces 24f of the outer slide cores 24A,..., 24F. On the other hand, the first secondary gate / spr and the second secondary gate / spr are alternately arranged (FIG. 8). Note that the opening area of the pin gate 5a facing the first and second secondary gates / spools is also the first secondary gate / spool side of the second secondary gate / sprue on the secondary sprue portion 24d side. It is smaller than that on the secondary sprue portion 24b side of the sprue.
[0075]
The secondary sprue parts 24b and 24d of the first and second secondary gates / spres open at positions facing the pin gate 5a in the mold closed state, and are provided along a direction parallel to the axis C0. The secondary sprues 24b and 24d have wall surfaces along the sliding directions D1 and D2 so that the outer slide core can slide outward.
[0076]
The secondary gate portions 24c and 24e of the first and second secondary gates / sprue are communicated with the distal end portion of the secondary sprue portion 24b or 24d, and open to the inner peripheral surface 24a of the outer slide core. Yes. More specifically, the circumferential position of the gate opening 24cc of the first secondary gate / sprue-side secondary gate portion 24c opening in the cavity 27 is an outer position passing through the width center line of the first slide core 2A,. Alternatively, although it is in the vicinity thereof (FIG. 8), as the separation distance along the circumferential direction between the gate opening 24cc and the parting line portion, even in the shortest distance as in the case of the second embodiment, 1. 5 mm or more, more preferably, 3.0 mm or more is secured. Further, the position of the gate opening 24cc in the direction of the axis C0 is located below the fixed core 5 side by a distance L3 in the drawing.
[0077]
On the other hand, the circumferential position of the gate opening 24ee of the second gate part 24e of the second secondary gate / sprue that opens into the cavity 27 is the outer position passing through the center line of the second slide core 3A,. Although it is in the vicinity thereof (FIG. 8), as the separation distance along the circumferential direction between the gate opening 24ee and the parting line portion, as in the case of the second embodiment, the shortest distance is 1.5 mm or more, Further, preferably, 3.0 mm or more is secured. Further, the position of the gate opening 24ee in the direction of the axis C0 is located below the fixed core 5 side by a distance L4 in the drawing.
[0078]
Next, the operation at the time of molding the cam frame 10 by the injection molding die 21 of the present embodiment having the above-described configuration is the same as that of the injection molding die 9 of the second embodiment, and the mold is in a closed state. Originally, the high-pressure molten resin is injected into the cavity 27 from the secondary gate portions 24c and 24e through the secondary sprue portions 24b and 24d from the pin gate 5a.
[0079]
After the molten resin is cooled and solidified, the mold 21 is opened. That is, the outer slide cores 24A,..., 24F are slid in the directions of D1, D2, etc. to be opened. At the same time, when the center core 1 is moved downward in the direction of the axis C0, the first slide core 2A,... And the second slide core 3A,. The molded product of the cam frame 10 can be taken out from the mold 21.
[0080]
As described above, the gate openings 24cc and 24ee are spaced apart from each other by a predetermined distance along the circumferential direction of the parting line portion on the mold so that high pressure and high speed can be obtained from the gate opening into the cavity 27. The injected molten resin does not reach the parting line portion directly from the gate. Therefore, burrs are hardly generated in the parting line portions (ends of the mating surfaces 2c and 3c).
[0081]
In particular, in the injection mold 21 of the present embodiment, as described above, the first secondary gate / spr and the second secondary gate / spr are the cross-sectional area of the flow path of the secondary spur part. Since the length and the gate opening area are different, the flow resistance (including the influence of the gate opening) of the molten resin passing through the gate / sprue is small on the first secondary gate / spr side, and the second secondary The gate / sprue side is large. Therefore, the first secondary core 2A,... In which the first secondary gate / sprue side gate opening 24cc is located outward of the cavity is located on the second secondary gate / sprue side gate opening 24ee. Will be pressed more strongly by the high pressure and high radiation output by the molten resin than the second slide cores 3A,. In this way, the first slide cores 2A,... Are pressed more strongly, so that the mating surfaces 2c, 3c of the first and second slide cores are strongly adhered at the time of molten resin injection, and the ends of the mating surfaces 2c, 3c Occurrence of burrs in the parting line part of the part is suppressed.
[0082]
In the injection molding die 21 of the present embodiment, a secondary is used to make a difference in flow path resistance (including the influence of the gate opening) between the first secondary gate / sprue and the second secondary gate / sprue. The cross-sectional area of the sprue, the length of the secondary sprue, the length of the secondary gate, and the secondary gate opening are all different, but not limited to this, select at least one of the above items to make the difference Even if the first and second secondary gates / sprue are formed as described above, the same effect can be obtained.
[0083]
Next, an injection mold according to a fifth embodiment of the present invention will be described with reference to FIGS.
FIG. 10 is a cross-sectional view (GG cross-sectional view of FIG. 11) of the injection mold according to the present embodiment. 11 is a cross-sectional view taken along line FF in FIG. FIG. 12 is an exploded perspective view of the secondary gate / sprue of the injection mold. FIG. 13 is a part of the GG cross section of FIG. 11 and shows a cross section of the secondary gate portion of the secondary gate / sprue.
[0084]
The injection mold 31 of the fifth embodiment has a first slide core 2A,..., And a second shape like the injection mold 9 of the second embodiment because of the shape of the cylindrical member to be molded. A mold that is applied when the die mating surface of the outer slide core cannot be disposed at a place other than the mating surface of the slide core 3A,..., And the first slide core 2A,. This is a mold in which the die mating surface of the outer slide core is located in the vicinity of the mating surface of the slide cores 3A,. Therefore, the shape of the secondary gate / sprue is different from that in the second embodiment. The other mold structures, that is, the same as the injection mold of the second embodiment, such as applying a 6-split inner slide mold and an outer slide mold. Therefore, the same components are denoted by the same reference numerals, and different points will be described below.
[0085]
The injection mold 31 of the present embodiment is a mold that can mold the cam frame 10 that is the tubular member of the first embodiment, and includes a fixed mold and a movable mold. As shown in FIGS. 10 and 11, the fixed mold has a fixed core 5, and the movable mold includes a movable insert 6 and a center core 1 and a first core constituting a six-part inner slide mold. The slide cores 2A,..., 2C and the second slide cores 3A,..., 3C, and outer slide molds 34A,. 34F of the outer slide molds 34A,..., 34F are located in the vicinity of the end portions of the mating surfaces 2c, 3c of the first slide cores 2A,.
[0086]
As shown in FIGS. 10 and 11, pin gates 5a (six locations) serving as primary gates of the fixed core 5 are arranged on the upper surface side of the die-matching surfaces 34f of the outer slide cores 34A,. Yes. A secondary gate / sprue is disposed at each position on the mold matching surface 34f facing the pin gate 5a.
[0087]
The secondary gate / sprue includes a secondary sprue part 34b and a secondary gate part 34c, and is arranged in a state straddling the die-matching surface 34f of each outer slide core 34A,..., 34F, and the outer slide cores 34A, 34C. , 34E is provided with the secondary gate part 34c symmetrical in the circumferential direction, and the secondary sprue part 34b is provided on the outer slide cores 34B, 34D, 34F side (FIG. 10).
[0088]
The shapes of the secondary sprue part 34b and the secondary gate part 34c will be described with reference to an example provided on the mold matching surfaces 34f of the outer slide cores 34A and 34B. In addition, the shapes of the secondary sprue portion 34b and the secondary gate portion 34c provided on the mold matching surfaces 34f of the outer slide cores 34B and 34C, 34C and 34D, 34D and 34E, 34E and 34F, 34F and 34A are the same. It has the shape of However, they are either the secondary gate part 34c symmetrical with respect to each outer slide core or the secondary sprue part 34b.
[0089]
As shown in FIG. 12, the secondary sprue 34b has a flow path parallel to the axial center C0 from the upper surface of the outer slide core 34B, and a surface 34bb parallel to the sliding direction D2 of the outer slide core 34B is formed. Yes. However, the parallel surface 34bb is not limited to a parallel surface and may be any surface that can be punched.
[0090]
The secondary gate portion 34c is formed by an inclined surface 34ca inclined at a predetermined angle at a position facing the bottom portion of the secondary sprue portion 34b on the mold fitting surface of the outer slide core 34A. A gate opening 34cc is formed on the inner peripheral surface (the outer surface of the cavity 27). The injection direction of the molten resin is determined by the inclined surface 34ca of the secondary gate portion 34c.
[0091]
The secondary sprue part 34b and the secondary gate part 34c have a predetermined positional relationship with respect to the first and second inner slide cores 2A and 3A when the outer slide cores 34A and 34B are clamped. That is, as shown in FIG. 13, the circumferential position of the gate opening 34cc is the width of the first slide core 2A from the end faces (parting line portions) of the mating surfaces 2c and 3c of the first and second slide cores 2A and 3A. A position where a predetermined distance d3 is secured toward the center. Further, the inclination of the inclined surface 34ca giving the resin injection direction is such that the first slide core in the resin injection direction with respect to the center line connecting the axis C0 and the end faces of the first and second slide cores 2A and 3A. A predetermined inclination angle α3 inclined so as to fall down on the outer peripheral side of 2A is secured.
[0092]
In the injection mold 31 of the present embodiment, the distance d3 of the gate opening 34cc of the secondary gate / sprue secondary gate portion 34c is at least d3≥0.5 mm, and the inclined surface 34ca of the gate opening 34c The inclination angle α3, which is the inclination, is set to α3 ≧ 10 °. Furthermore, it is desirable to adopt d3 ≧ 1.0 mm and α3 ≧ 15 °. Note that these values are values obtained through experimental examination.
[0093]
Next, the operation at the time of molding the cam frame 10 by the injection mold 31 of the present embodiment having the above-described configuration is performed in the mold closed state as in the case of the injection mold 9 of the second embodiment. Then, a high-pressure molten resin is injected from the pin gate 5a into the secondary sprue 34b of the secondary gate / sprue. The molten resin is injected into the cavity 37 from the secondary gate portion 34c. At that time, the molten resin is inclined with respect to the mold matching surface 34f from the gate opening 34cc, which is separated from the mating surfaces 2c, 3c of the first, second slide cores 2A,. Injected toward the center of the width of the slide core 2A. Therefore, the high-speed and high-pressure molten resin does not directly hit the mating surfaces 2c, 3c of the first slide core 2A,... And the second slide core 3A,.
[0094]
After the molten resin is cooled and solidified, the mold 31 is brought into the mold open state. That is, the outer slide cores 34A,..., 34F are slid in the directions of D1, D2, etc. and released. At the same time, by moving the center core 1 in the direction of the axis C0 and away from the fixed mold (downward in the figure), the first slide core 2A,... And the second slide core 3A,. Then, the molded product of the cam frame 10 formed in the cavity 27 can be taken out from the mold 31.
[0095]
According to the injection mold 31 of the present embodiment, by adopting the shape and dimensions as described above, the outer slide core is provided in the vicinity of the mating surface of the first slide core 2A,... And the second slide core 3A,. Even in a mold in which the mold-matching surface is located, a high-speed and high-pressure molten resin is gated at the ends of the mating surfaces 2c, 3c of the first slide core 2A,. The barrier generated in the parting line portion can be suppressed.
[0096]
Further, since the position of the opening 34cc of the secondary gate portion 34c is limited to the first slide core 2A,..., The high-pressure radiant power of the molten resin acts only on the first slide core 2A,. Therefore, the adhesion of the mating surfaces 2c, 3c with the second slide cores 3A,... Is increased, and from this point, the barrier generated in the parting line portion is suppressed.
[0097]
Next, an injection mold according to a sixth embodiment of the present invention will be described with reference to FIGS.
FIG. 14 is a cross-sectional view (II cross-sectional view of FIG. 15) of the injection mold according to the present embodiment. 15 is a cross-sectional view taken along line HH in FIG. FIG. 16 is a part of a cross-sectional view taken along the line II of FIG. 15 and shows the arrangement of the pin gate of the injection mold.
[0098]
The injection mold 41 according to the present embodiment has a pin gate at a predetermined position near the end surface of the first slide core without providing a secondary gate / sprue unlike the injection mold 9 according to the second embodiment. The generation of burrs in the cylindrical member formed by arranging the slab is suppressed. The other mold structures, that is, the application of the six-divided inner slide mold and the outer slide mold, and the like are the same as those of the injection mold 9 of the second embodiment. Therefore, the same components are denoted by the same reference numerals, and the description thereof will not be made. Differences will be described below.
[0099]
The injection mold 41 of the present embodiment is a mold that can mold the cam frame 10 that is the cylindrical member of the first embodiment, and includes a fixed mold and a movable mold. As shown in FIGS. 14 and 15, the fixed mold has a fixed core 45. The movable type includes a movable side insert 6, a center core 1, a first slide core 2A,..., 2C and a second slide core 3A,. There are some outer slide cores 44A,..., 44F.
[0100]
The fixed core 45 is located near the upper end surface of the first slide cores 2A, 2B, 2C and at the upper end position in FIG. 15 of the cavity 47 facing the first slide cores 2A, 2B, 2C. Three pairs of pin gates 45a and 45b each having an opening are arranged. The cavity 47 is divided into an inner peripheral surface 44a of the outer slide cores 44A,..., 44F, a divided outer peripheral surface 2a of the first slide cores 2A, 2B, 2C, and a second slide core 3A, 3B, 3C. It is formed with the outer peripheral surface 3a.
[0101]
As the circumferential positions of the pin gates 45a and 45b, as shown in FIG. 16, from the mating surfaces 2c and 3c of the first slide cores 2A and 2A to the pin gates 45a and 45b. The distances d4 and d5 that are separated in the circumferential direction toward the center of the width of the first slide cores 2A,... Are 1.5 mm or more, preferably 3.0 mm or more. Note that these values are values obtained through experimental examination.
[0102]
Next, the operation at the time of molding the cam frame 10 by the injection mold 41 of the present embodiment having the above-described configuration is performed in the closed state as in the case of the injection mold 9 of the second embodiment. Thus, high-pressure molten resin is injected from the pin gate 45a into the cavity 47. At that time, since the molten resin is injected from the pin gates 45a and 45b which are separated from the mating surfaces 2c and 3c of the first and second slide cores 2A, ... and 3A, ..., the first slide core 2A, .. And the second slide cores 3A,... Are not directly hit by the high-speed and high-pressure molten resin.
[0103]
After the molten resin is cooled and solidified, the mold 41 is brought into the mold open state. That is, the outer slide cores 44A,..., 44F are slid in the directions D1, D2, etc. to be opened. At the same time, by moving the center core 1 in the direction of the axis C0, downward in the figure, the first slide core 2A,... And the second slide core 3A,. The formed product of the cam frame 10 can be taken out from the mold 41.
[0104]
According to the injection mold 41 of the present embodiment, by arranging the pin gate on the fixed side core 45 as described above, the mating surface 2c of the first slide core 2A,... And the second slide core 3A,. , 3c can be prevented from generating burr at the parting line portion. The pin gates 45a, 45b can be freely arranged without being limited by the position and size of the outer slide cores 44A,. Further, the pin gate structure of the mold 41 of the present embodiment can be adopted even for a mold in which the outer slide cores 44A,. Furthermore, if a large number of the pin gates are arranged on the first slide cores 2A,... Side, a force that presses the first slide cores 2A,. The adhesion of the mating surfaces 2c, 3c between the first slide cores 2A,... And the second slide cores 3A,.
[0105]
Next, an injection mold according to a seventh embodiment of the present invention will be described with reference to FIGS.
FIG. 17 shows a cross-sectional view of the injection mold according to this embodiment (cross-section KK in FIG. 18). 18 is a cross-sectional view taken along line JJ in FIG. FIG. 19 is a cross-sectional view taken along the line QQ in FIG. 18 and shows the gate opening of the submarine gate of the injection mold.
[0106]
The injection mold 51 of the present embodiment is such that a submarine gate is provided on the outer slide core with respect to the secondary gate / spr provided on the outer slide core of the injection mold 9 or the like of the second embodiment. . Other mold structures, that is, the same as the injection mold 9 of the second embodiment, such as applying a 6-split inner slide mold and an outer slide mold. Therefore, the same components are denoted by the same reference numerals, and the description thereof will not be made. Differences will be described below.
[0107]
The injection mold 51 of the present embodiment is a mold that can mold the cam frame 10 that is the cylindrical member of the first embodiment, and includes a fixed mold and a movable mold. As shown in FIG. 18, the fixed mold has a fixed core 55. The movable type includes a movable side insert 6, a center core 1, a first slide core 2A,..., 2C and a second slide core 3A,. A certain outer slide core 54A,..., 54F is provided.
[0108]
The outer slide cores 54A,..., 54F each have a divided inner peripheral surface that forms an outer slide core inner peripheral surface 54a, and the outer slide cores adjacent to both side surfaces of each divided inner peripheral surface are adjacent to each other. Is provided with a mold matching surface 54f. The mold-matching surface 54f is formed by the divided surfaces of adjacent outer slide cores (FIG. 19). The mold matching surface 54f is located on a radial line connecting the axis C0 and the center of each width of the first slide core 2A,... Or the second slide core 3A,.
[0109]
In the mold closed state of the outer slides 54A,..., 54F, the mold matching surfaces 54f are held in close contact with each other, the inner peripheral surface 54a is formed by the divided inner peripheral surface, and the inner peripheral surface 54a is a cavity. 57 is the outer peripheral surface. The outer peripheral surface of the cam frame 10 can be formed by this outer peripheral surface.
[0110]
On the upper surface side in the figure of the die-matching surface 54f of the outer slide cores 54A,..., 54F, straight-shaped secondary spurs 55a (six locations) of the fixed-side core 55 are arranged. A submarine gate 54b is arranged in a state straddling each position of the mold matching surface 54f facing the sprue 55a (FIGS. 17 and 18).
[0111]
The submarine gate 54b has a flow channel that is inclined from the opening of the upper surface portion of the mold matching surface 54f in the drawing toward the cavity 57 below the axial center C0, and the flow channel cross-sectional area is gradually reduced. A gate opening 54bb that opens to the inner peripheral surface 54a is formed at the tip.
[0112]
The circumferential position of the gate opening 54bb is preferably a position passing through the vicinity of the width center line of the first and second slide cores 2A,..., 3A,. The distance d6 from the mating surfaces 2c, 3c to the first slide core 2A,..., The side gate opening 54bb, and the distance from the mating surfaces 2c, 3c to the second slide core 3A,. It is sufficient that a predetermined distance described later is secured as the distance d7. Further, the position of the gate opening 54bb in the direction of the axis C0 is substantially the center position below the fixed side core 55 side by a distance L5.
[0113]
The distances d6 and d7 along the circumferential direction between the gate opening 54bb and the mating surfaces 2c and 3c (parting line portions) in the mold 51 of the present embodiment (FIG. 19), at least 1.5 mm or more, Further, preferably, 3.0 mm or more is secured.
[0114]
When the cam frame 10 is molded by the injection mold 51 of this embodiment, high-pressure molten resin is injected into the cavity 57 from the gate opening 54bb of the submarine gate 54b at a high speed. However, as described above, the gate opening 54bb of the submarine gate 54b is arranged at a position separated from the mating surfaces 2c, 3c of the first slide core 2A,... And the second slide core 3A,. Therefore, the high-speed and high-pressure molten resin does not directly hit the mating surfaces 2c and 3c from the gate. Therefore, burrs are hardly generated on the parting lines at the ends of the mating surfaces 2c and 3c.
[0115]
According to the injection mold 51 of the present embodiment, the same effects as those of the injection mold 41 of the sixth embodiment can be obtained. Further, since the gate opening 54bb at the tip of the submarine gate 54b can be arranged in the middle part of the cavity 57, the flow balance when the molten resin is injected into the cavity 57 is improved, and the cam frame molded product to be molded is improved. Deformation due to molding can be kept small.
[0116]
In each of the above-described embodiments, the 6-split inner slide type is applied, and the first slide core 2A,... And the second slide core 3A,. It is not limited to the mold, and may be an 8-divided type, a 10-divided type, a more or less divided type.
[0117]
Further, in each of the above-described embodiments, the number of divisions of the outer-type outer slide core is a division obtained by adding the number of the first slide cores and the number of the second slide cores for easy understanding. Although the number is adopted, the present invention is not limited to the number of outer slide cores. Furthermore, the shape of each outer slide core need not be the same.
[0118]
Furthermore, in each of the above-described embodiments, the description has been given as an example applied to a synthetic resin injection mold, but the molding material is not necessarily limited to a synthetic resin, for example, metal injection molding, The gist of the present invention is applicable.
[0119]
In addition, the member molded by the injection mold of each of the above embodiments is not limited to a cylindrical member like the cam frame 10, and is a cylindrical shape composed of a rectangular cylinder or a cylindrical portion and a rectangular cylindrical portion. The present invention can be applied to cylindrical members having various shapes such as members.
[0120]
【The invention's effect】
According to the present invention, it is possible to provide a cylindrical member that can suppress a burr generated on the inner peripheral surface by arranging the gate position on the outer peripheral surface at an appropriate position in the cylindrical member, and the cylindrical member. A mold capable of injection-molding a member can be provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a cam frame of a cylindrical member according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a cross section orthogonal to the axis of an injection mold according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view taken along the line AA in FIG.
4 is an exploded perspective view of the secondary gate / sprue of the outer slide core in the injection mold shown in FIG. 2; FIG.
FIG. 5 is a view as seen from the direction of arrow E in FIG. 3 and shows the secondary gate / spr as viewed from the upper entrance side.
6 is a part of the BB cross-sectional view of FIG. 3 and shows a cross-section of the secondary gate portion of the secondary gate / sprue. FIG.
FIG. 7 is a cross-sectional view of an injection mold according to a third embodiment of the present invention.
FIG. 8 is a cross-sectional view of an injection mold according to a fourth embodiment of the present invention.
9 is a cross-sectional view taken along line MM in FIG.
FIG. 10 is a cross-sectional view of an injection mold according to a fifth embodiment of the present invention.
11 is a cross-sectional view taken along line FF in FIG.
12 is an exploded perspective view of a secondary gate / sprue of the injection mold shown in FIG. 10; FIG.
13 is a part of the GG cross section of FIG. 11 and shows a cross section of the secondary gate portion of the secondary gate / sprue. FIG.
FIG. 14 is a cross-sectional view of an injection mold according to a sixth embodiment of the present invention.
15 is a cross-sectional view taken along the line HH in FIG.
16 is a part of the II cross-sectional view of FIG. 15 and shows the arrangement of pin gates of the injection mold.
FIG. 17 is a cross-sectional view of an injection mold according to the present embodiment.
18 is a cross-sectional view taken along the line JJ of FIG.
FIG. 19 is a cross-sectional view taken along the line QQ in FIG. 18 and shows a gate opening of a submarine gate of the injection mold.
FIG. 20 is a cross-sectional view around a cavity of a conventional injection mold.
[Explanation of symbols]
1 ... Center core
2A, 2B, 2C
... First slide core (inner slide core)
2c, 3c
... Mating surface (Mating surface)
3A, 3B, 3C
... Second slide core (inner slide core)
4A-4F, 14A-14F, 24A-24F,
34A-34F, 44A-44F,
54A-54F
... Outer slide core (outer shape)
4b, 4d, 14b, 34b
... Secondary sprue (sprue)
4c, 4e, 14c, 34c,
... Secondary gate (gate)
4cc, 4ee, 14cc, 34cc, 54bb
... Gate opening
4f, 14f, 24f, 34f, 44f, 54f
... Molding surface
(Mating surface between outer slide cores)
9, 11, 21, 31, 41, 51
... Injection mold
10: Cam frame (tubular member)
10d ... Parting line trace
(Parting line)
24b ... Secondary sprue
(Sprue leading to the first gate)
24c ... Secondary gate part (first gate)
24cc ... gate opening
(Gate opening of the first gate)
24d ... Secondary sprue
(Sprue leading to the second gate)
24e ... Secondary gate part (second gate)
24ee ... gate opening
(Gate opening of the second gate)
45a, 45b ... Pin gate (gate)
54b ... Submarine gate (gate)
d1, d2, d3, d4, d5, d6, d7
... Separation distance (predetermined distance)
α3… Inclination angle (predetermined angle)

Claims (9)

In an injection mold for molding a cylindrical member by injection molding,
With the center core,
A plurality of first slide cores that are spaced apart from each other around the center core and are movable relative to the center core to form an inner peripheral surface of the cylindrical member;
In order to form the inner peripheral surface of the cylindrical member, the cylindrical member is disposed between the plurality of first slide cores around the center core, and has a mating surface portion with the first slide core. A plurality of second slide cores that are configured to be covered with the first slide core, and are movable relative to the center core when the mold is opened and closed;
In the circumferential direction of the outer peripheral surface of the cylindrical member, the cylindrical member includes a plurality of slide cores, and a first gate is provided so as to face the first slide core. An outer shape for providing a second gate having a gate opening smaller than the area of the gate opening of the first gate to form the outer shape of the cylindrical member;
An injection mold characterized by comprising: Further, the outer shape mold is provided with a second gate so as to face the second slide core in the circumferential direction of the outer peripheral surface of the cylindrical member, and an injection molding material for the sprue that leads to the second gate. 2. The injection mold according to claim 1, wherein a right-angle cross-sectional area perpendicular to the flow path traveling direction is smaller than the right-angle cross-sectional area of the sprue communicating with the first gate. Further, the outer shape die is provided with a second gate so as to face the second slide core in the circumferential direction of the outer peripheral surface of the cylindrical member, and the injection molding material flow path length of the second gate. 2. The injection mold according to claim 1, wherein is longer than a flow path length of an injection molding material of the first gate facing the first slide core. Further, the outer shape mold is provided with a second gate so as to face the second slide core in the circumferential direction of the outer peripheral surface of the cylindrical member, and an injection molding material for the sprue that leads to the second gate. 2. The injection mold according to claim 1, wherein the flow path length is longer than the flow path length of the injection molding material of the sprue that communicates with the first gate. In an injection mold for molding a cylindrical member by injection molding,
With the center core,
A plurality of first slide cores that are spaced apart from each other around the center core and are movable relative to the center core to form an inner peripheral surface of the cylindrical member;
In order to form the inner peripheral surface of the cylindrical member, it is disposed between the plurality of first slide cores around the center core, and has a mating surface portion with the first slide core at the time of mold closing, The mating surface portion is configured to be covered by the first slide core, and a plurality of second slide cores movable relative to the center core when the mold is opened and closed,
It consists of a plurality of slide cores in the circumferential direction of the outer peripheral surface of the cylindrical member, and is separated from the parting line between the first slide core and the second slide core so as to face the first slide core. And a molding material injection direction from the gate with respect to a straight line passing through the center core center and the parting line in a plane orthogonal to the mold opening and closing direction is the outer peripheral surface of the first slide core. An outer shape for forming the outer shape of the cylindrical member with the gate having a predetermined angle so as to face upward;
An injection mold characterized by comprising: The gate is separated from the parting line by a predetermined distance in the circumferential direction of the outer peripheral surface of the cylindrical member, and faces the outer peripheral surface of the first slide core. Item 6. An injection mold according to Item 5. If the predetermined angle is α and the predetermined distance is d,
  α ≧ 10 ° and d ≧ 0.5 mm
The injection mold according to claim 6, wherein: If the predetermined angle is α and the predetermined distance is d,
  α ≧ 15 ° and d ≧ 1.0 mm
The injection mold according to claim 6, wherein: The injection mold according to claim 6, wherein the outer shape mold includes a plurality of outer slides, and the sprue and the gate are provided on a parting surface in contact with each other.

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