JP4987305B2 - Injection mold - Google Patents

Description

The present invention relates to an injection molding die for molding a molded article having an undercut portion in a plurality of directions.

  Conventionally, as an injection mold for obtaining a molded product having an undercut portion (a concavo-convex shape that cannot be released as it is when the molded product is taken out from the mold), for example, a technique disclosed in Patent Document 1 Is known.

  According to this molding die, as shown in FIGS. 29 and 30, a cavity mold 361 and a core 362 for molding a cylindrical outer cylinder 357 are provided. A unit 365 for undercut molding is provided on the tip side (the upper region in the figure) of the cavity mold 361 and the core 362. The unit 365 has a plurality of first and second slide cores 363 and 364 each having an undercut forming collar 367 formed on the outer periphery.

  The first slide core 363 and the second slide core 364 are alternately arranged in the circumferential direction on the outer periphery of the upper core 366 disposed above the core 362, and the first slide core 363 is formed by the spring 368. It is configured to be biased in the direction (center axis side).

  Then, after injecting a resin material from the sprue 369 to form the outer cylinder 357, the cavity mold 361 is moved together with the unit 365 in the direction of the arrow D shown in the figure, and is moved upward from the center of the first and second slide cores 363, 364. By pulling out the core 366, the first and second slide cores 363 and 364 are moved inward by the biasing force of the spring 368. Thereafter, the first and second slide cores 363 and 364 are removed from the outer cylinder 357 to form the outer cylinder 357 in which an undercut is formed.

As another conventional technique, for example, Patent Document 2 discloses a method for forming a molded product having an undercut separately from the above.
According to this prior art, as shown in FIG. 31, after the molded product 315 is placed concentrically on a molding die 320 having a smaller diameter, the molding die 320 is rotated with respect to the rotating shaft 314. Then, the pressure roller 311 is moved by feeding it in the radial direction and is pressed onto the molding die 320. At this time, the side wall of the molded product 315 is molded. After molding, the pressure roller 311 is returned radially by a prescribed operation, and at that time, the molded product 315 is retracted to the initial concentric position in cooperation with the alignment device 322.

In this initial position, the molded product 315 can be removed from the molding die 320 without fear of being caught.
JP-A-6-190874 (5th page, FIG. 2) Japanese Patent Laid-Open No. 9-285824 (page 5, FIG. 1)

  However, in the technique described in Patent Document 1, since a plurality of mold constituent members are sequentially separated from the mold main body at the time of mold release, the mold product is finally taken out. It was necessary to perform difficult mold release work. Moreover, since the mold configuration is complicated, there is a problem that the mold manufacturing cost increases.

  Furthermore, in the technique described in Patent Document 2, the molding method is complicated, and much effort is required to adjust the constituent members for molding. In addition, this molding method has a problem that the molding object is limited to a rotationally symmetric molded product.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an injection mold in which a molded product having undercut portions in a plurality of directions can be easily obtained. .

In order to achieve the object, the invention according to claim 1
In the injection mold that can take out the cassette mold to mold the molded product from the mold body,
The cassette mold is formed with a cavity for molding a molded product having an undercut forming surface on the outer peripheral surface, and a plurality of the molds disposed opposite to each other on the upper and lower sides, the left and right sides, and the front and rear sides around the molded product in the cavity. An assembly of blocks,
A gate formed in at least one of the plurality of block assemblies and in communication with the cavity;
The mold main body includes a recess having substantially the same size as the assembly of the plurality of blocks.
Prior to molding, the cassette mold is housed in the recess of the mold body and fixed in position,
Resin is injected into the cavity through the gate at the time of molding,
After the molding, the cassette mold is taken out from the recess, and a block corresponding to the undercut forming surface of the molded product in the cavity is released in a direction substantially orthogonal to the undercut forming surface.

The invention according to claim 2 is the injection mold according to claim 1,
The cassette mold is housed in the recess in a state assembled outside the mold body, and can be taken out from the recess in a state in which the cassette mold is filled with resin after molding.

The invention according to claim 3 is the injection mold according to claim 1 or 2 ,
When a molded article has a hollow part, it has a mandrel as a block arranged in the hollow part.

The invention according to claim 4 is the injection mold according to claim 1,
The gate is formed in a block arranged along a longitudinal direction of a molded product in the cavity.

The invention according to claim 5 is the injection mold according to claim 4 ,
The gate is formed at a position deviating in a longitudinal direction of the molded product from a region having an undercut portion of the molded product in the cavity.

  According to the present invention, when molding a molded product having an undercut portion, the cassette mold for molding the molded product is accommodated in the concave portion of the mold body before molding, and after molding, the cassette mold is taken out from the concave portion and molded product. By releasing the block corresponding to the undercut forming surface in a direction substantially orthogonal to the undercut forming surface, a molded product having undercut portions in a plurality of directions can be easily obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a partial cross-sectional view showing the structure of an injection mold 1. The injection mold 1 includes a fixed mold 10 and a movable mold 20. The fixed side mold 10 has a fixed side mold plate 11 provided with a sprue 12 at the center thereof, and a fixed side mounting plate 13 to which the fixed side mold plate 11 is attached. The central locating ring 14 serves to center the nozzle (not shown) of the molding machine and the sprue bushing 15 of the mold 10.

  The movable side mold 20 includes a movable side mold plate 21, a receiving plate 27, and a movable side mounting plate 22 attached to the receiving plate 27 via a spacer block 23. In addition, a projecting mechanism for projecting the molded product from the movable side mold plate 21 is provided inside the spacer block 23 and in a space between the movable side mounting plate 22 and the receiving plate 27. The protruding mechanism includes an ejector plate (upper) 24, an ejector plate (lower) 25, and an ejector pin 26.

  In the present embodiment, a cassette mold 33 (an assembly of a plurality of blocks) that molds a molded product inside the fixed-side mold plate 11 and the movable-side mold plate 21 (specifically, inside contacting each parting surface). The recessed part 30 (30a, 30b) which accommodates is formed. The recesses 30 (30a, 30b) have substantially the same size as the cassette mold 33 and the runner block 42 arranged in contact with the cassette mold 33.

  As shown in FIGS. 1 to 3, the cassette mold 33 includes a plurality of first blocks 36 to 36 so that a cavity 34 (space) for molding a molded product 70 (see FIG. 8) having an undercut portion is formed. The assembly is constituted by the sixth block 41. The material of each block is made of steel, for example. In the present embodiment, since the molded product has a hollow cylindrical shape (see FIG. 8), a mandrel 35 as a block constituting the assembly is disposed at the center of the cavity 34.

  The first and second blocks 36 and 37 are arranged to face each other so as to sandwich the above-described mandrel 35 from above and below along the axial direction. The first and second blocks 36 and 37 have inner peripheral walls 46a and 46b which are divided on the side facing the mandrel 35 and have a larger diameter than the mandrel 35 and have a circular arc cross section so as to surround the mandrel 35. Is formed. In addition, three protrusions 47a and 47b corresponding to the undercut portions 71 (see FIG. 8) of the molded product 70 are formed on the inner peripheral walls 46a and 46b, respectively. Each of the protrusions 47 a and 47 b is columnar, and its axis is perpendicular to the central axis of the mandrel 35.

  Furthermore, a gate 48 is formed on the first block 36 on the side facing the third block 38 that contacts the first block 36. The resin injected from the sprue 12 is filled into the cavity 34 through the gate 48. That is, the gate 48 is formed in the first block 36 arranged along the longitudinal direction of the molded product in the cavity 34. In the present embodiment, the case where the gate 48 is formed in the first block 36 has been described. However, the present invention is not limited to this. May be formed.

  The third and fourth blocks 38 and 39 are arranged to face each other so as to sandwich the above-described mandrel 35 from the left and right sides in the longitudinal direction. The third and fourth blocks 38 and 39 have inner peripheral walls 49a and 49b which are divided on the side facing the mandrel 35 and have a larger diameter than the mandrel 35 and have a circular arc cross section so as to surround the mandrel 35. Is formed. These inner peripheral walls 49a and 49b form the outer peripheral surface (circular cross section) of the cavity 34 together with the above-described inner peripheral walls 46a and 46b. In addition, three protrusions 50a and 50b corresponding to the undercut portions 71 (see FIG. 8) of the molded product 70 are formed on the inner peripheral walls 49a and 49b, respectively. Each protrusion 50a, 50b is columnar, and its axis is perpendicular to the central axis of the mandrel 35.

  The fifth and sixth blocks 40 and 41 are arranged to face each other in a pair so as to sandwich the mandrel 35 from both front and rear end sides in the axial direction. These fifth and sixth blocks 40 and 41 are formed with bottomed holes 51a and 51b for fitting and supporting both ends of the mandrel 35.

  That is, as shown in FIG. 2, the cassette mold 33 has six molded parts 70 (formed on the outer peripheral side of the mandrel 35) as the center, and is arranged to be opposed to the upper and lower sides, the left and right sides, and the front and rear sides. It has blocks (36-41).

  A runner block 42 is disposed on the side of the first block 36. The runner block 42 is formed with a runner 44 that communicates with the sprue 12 provided on the fixed-side template 11 and a gate 45 that communicates with the gate 48 of the first block 36.

  The runner block 42 is fixed to a pocket-shaped recess 30b formed in the movable side mold plate 21 using screws (not shown). In the recess 30b, an excessive space is formed even after the runner block 42 is fixed. Then, the cassette mold 33 (the first block 36 to the sixth block 41, the mandrel 35) is fitted into the surplus space with an appropriate fit. Therefore, the recess formed by the excess space and the recess 30a is substantially the same size as the cassette mold 33, and the cassette mold 33 can be accommodated in the recess.

  In the present embodiment, the cassette mold 33 is accommodated so that a gap of approximately 0.05 mm is formed between this excess space and the cassette mold 33. And after this cassette type | mold 33 is assembled outside the injection mold 1, it is accommodated in this recessed part 30b.

  In the present embodiment, the injection mold 1 (fixed side mold 10 + movable side mold 20) is fixed to an injection molding machine (not shown) with proper clamping force and injection resin capacity. Further, the fixed side mold plate 11 and the movable side mold plate 21 are provided with through holes (not shown) for circulating the temperature control medium.

  In this through hole, a temperature controller (not shown) is set through a temperature control medium hose, and the entire temperature of the injection mold 1 is set particularly at the time of molding a part that needs to manage the dimensional accuracy and the surface condition. Be controlled.

Next, the shaping | molding method of this embodiment is demonstrated.
A plasticized resin is prepared for injection by an injection molding machine (not shown), and a mold clamping operation is performed therewith. Next, the injection cylinder of the injection molding machine advances toward the injection mold 1, and an appropriate amount of resin is injected from the sprue 12 into the injection mold 1 from the injection nozzle at the tip of the injection cylinder. After this molding process, the process proceeds to the cooling process, but the processes up to the above are the same as those in the normal injection molding process.

  After the cooling process, the mold opening operation of the injection molding machine is performed. Then, the movable mold 20 is pulled away from the fixed mold 10, and the ejector plates (upper) (lower) 24, 25 are moved toward the movable mold 21 as shown in FIG. As a result, the ejector pin 26 also moves, and the entire cassette mold 33 protrudes from the concave portion 30 b of the movable side mold plate 21.

  Then, as shown in FIG. 5, an operator takes out the protruding cassette mold 33 from the recess 30 b of the movable side mold plate 21 to the outside. In this state, the sprue 12, the runner 44, and the sprue portion 12 ′, the runner portion 44 ′, and the gate portion 45 ′ made of the resin filled in the gate 45 are taken out integrally with the cassette mold 33. At this stage, the molded product cannot be visually observed from the appearance, but the molded product 70 is molded in the cavity 34 in the cassette mold 33.

  When the fifth and sixth blocks 40 and 41 are released in the axial direction of the mandrel 35 and removed from the state of FIG. 5, the state of FIG. 6 is obtained. In the state of FIG. 6, both end portions of the mandrel 35 in the axial direction are exposed. Next, the mandrel 35 is moved in the axial direction of the molded product 70 and pulled out. At this time, one end of the mandrel 35 is grasped with a tool such as pliers (not shown) and pulled out from the molded product 70.

  Next, when the first block 36 to the fourth block 39 are removed from the molded product 70, the state shown in FIG. This is a state in which the sprue portion 12 ′, the runner portion 44 ′, and the gate portion 45 ′ are integrally connected to the molded product 70. In this case, each block is released in a direction substantially orthogonal to the undercut forming surface 72 of the molded product 70. Further, when removing the third block 38, the sprue portion 12 ', the runner portion 44', and the gate portion 45 'made of resin become obstacles.

  Therefore, since this portion is different from the molded product 70, the sprue portion 12 ′ and the runner portion 44 ′ may be cut from the gate portion 45 ′, or they may be easily deformed and released. You may do it.

  Next, when the gate portion 45 ′ is separated from the molded product 70, a cylindrical molded product 70 can be obtained as shown in FIGS. This molded product 70 has a hollow cylindrical shape and has an undercut forming surface 72 in which an undercut portion (small hole) 71 is formed on the outer peripheral surface.

  Thus, after obtaining the molded product 70, the process proceeds to a molding process for obtaining the next molded product. In this process, the first block 36 to the sixth block 41 and the mandrel 35 are removed from the cassette mold 33. Follow the reverse procedure. That is, the next process is started by assembling the cassette mold 33 outside the injection mold 1 and setting it in the recess 30 (30a, 30b) of the injection mold 1. In this way, a desired number of molded products 70 can be obtained by repeatedly performing the molding process.

Conventionally, when the molded product 70 having the undercut portion 71 is molded, an injection mold having a complicated structure such as a slide structure is required. However, according to the present embodiment, the cassette mold 33 is independent from the mold body formed from the injection mold 1, that is, the fixed mold plate 11 and the movable mold plate 21 of the injection mold 1. After removing the cassette mold 33, the cassette mold 33 is easily disassembled. Specifically, among the blocks constituting the cassette mold 33, the axial direction of the undercut portion of the block forming the undercut portion The molded product 70 having the undercut portions 71 in a plurality of directions can be obtained by a simple operation of disassembling the cassette mold 33 by moving to.
(First modification)
FIG. 9 is a diagram showing a cassette mold 33 according to a modification of the present embodiment. In this modification, the same or corresponding members as those in the above-described embodiment will be described with the same reference numerals, and only different points will be described.

  In the present modification, each component block of the cassette mold 33 is restrained by knock pins 60 and 61. That is, the knock pin 60 protruding in parallel with the axial direction of the molded product 70 is fitted with the fifth and sixth blocks 40 and 41 by “fitting fit” at the base end side as one end of the knock pin 60. The first and second blocks 36 and 37 that are in contact with the inner end faces of the fifth and sixth blocks 40 and 41 are provided with knock pin holes 62 (the second block 37 side is not shown). The knock pin hole 62 is processed so as to be “clearance fit” with the tip end side which is the other end of the knock pin 60.

  Since the knock pin hole 62 coincides with the axial direction of the molded product 70, if the knock pin hole 62 is a through hole, the depth of the hole becomes large, which is disadvantageous in processing. Therefore, in this modification, processing is performed with a bottomed hole from the end face side of the first and second blocks 36 and 37.

  The knock pin 61 protruding in the direction perpendicular to the axial direction of the molded product 70 passes through the first block 36, the third and fourth blocks 38 and 39, and the second block 37. Further, the knock pin 61 is processed so as to have a “clearance fit” with the knock pin hole formed in the first block 36 to the fourth block 39.

  In the above, in order to disassemble the cassette mold 33, first, the fifth and sixth blocks 40 and 41 are moved in the axial direction of the molded product 70, respectively, and the first and second blocks 36 and 37 are moved. After removal, the mandrel 35 is removed from the molded product 70. Thereafter, the knock pin 61 protruding in the direction perpendicular to the axial direction of the molded product 70 is extracted from the first and second blocks 36 and 37. The subsequent steps are the same as those in the first embodiment.

According to this modification, each block constituting the cassette mold 33 is accurately positioned by being restrained by the knock pins 60 and 61, respectively, and is more excellent in shape accuracy and dimensional accuracy than in the first embodiment. A molded product can be obtained.
(Second modification)
FIG. 10 is a view showing a cassette mold 33 according to another modification of the present embodiment. In this modification, the same or corresponding members as those in the above-described embodiment will be described with the same reference numerals, and only different points will be described.

  In this modified example, the knock pins 60 and 61 of the modified example described above are replaced with bolts. That is, as shown in FIG. 10, the first block 36 to the sixth block 41 are fastened and fixed by the hexagon socket bolts 63 and 64. The first block 36 and the second block 37 are formed with bolt fixing tap holes (not shown) to be inserted from the upper side and the left and right sides of the drawing, respectively.

  In this modification, the case where all the mounting positions of the knock pins 60 and 61 described above are replaced with hexagon socket head bolts 63 and 64 is described. However, the present invention is not limited to this. Thus, the knock pins 60 and 61 and the hexagon socket head cap bolts 63 and 64 can be used in combination.

According to the present modification, the above-described knock pins 60, 61 are replaced with hexagon socket head bolts 63, 64. Therefore, it is easier to remove the hexagon socket head bolts 63, 64 than to remove the knock pins 60, 61. Yes, assembly and disassembly of the cassette mold 33 is further simplified.
(Second Embodiment)
11 to 13 show a cassette mold 133 according to the second embodiment.

  The cassette type 133 has a first block 134 to a third block 136, and fourth and fifth blocks (mandrel) 137 and 138. Then, on the axial center side of the first block 134 to the third block 136, the inside of the cross-sectional substantially kamaboko shape (hereinafter referred to as “substantially cylindrical”) in which the cross-section is partially cut off at the axial end portion side. Peripheral walls 134a, 135a, 136a are formed on the central side in the axial direction, and inner peripheral walls 134b, 135b, 136b having the same cross section are formed by dividing the peripheral wall into three in the circumferential direction (see FIG. 13).

  In this case, in a state where the first to third blocks 134 and 136 are assembled, the diameter of the cross section on the end side in the axial direction is formed smaller than the diameter of the cross section on the central side in the axial direction. Then, a fourth block (mandrel) 137 is inserted from one end side of these substantially cylindrical portions, and a fifth block (mandrel) 138 is inserted from the other end side.

  In the inserted state, the fifth block (mandrel) 138 is disposed on the end face of the fourth block (mandrel) 137 with a slight gap therebetween. Thus, a predetermined gap (cavity) is formed between the fifth block (mandrel) 138 and the axially central portion of the cylindrical portion. And this space | gap is a cavity space formed in the cassette type | mold 133, and becomes a bottomed cylindrical space similar to the molded article 170 mentioned later.

  The second block 135 has a gate 145 that communicates with the inner peripheral wall 135b. Further, the third block 136 is formed with surfaces 147 and 148 that are parallel to the axial direction of the molded product 170 and parallel to each other for the convenience of processing.

  Further, as shown in FIG. 13, a projection 139 corresponding to an undercut portion (small hole) 171 of a molded product 170 described later is formed on the inner peripheral wall 135 b of the second block 135. A projecting portion 140 corresponding to an undercut portion (oval hole) 172 of a molded product 170 described later is formed on the inner peripheral wall 136b of the third block 136.

Further, a convex portion 146 corresponding to an undercut portion (concave portion) 173 of a molded product 170 described later is formed on the bottom portion of the fourth block (mandrel) 137.
FIG. 14 shows a state where the molded product 170 is taken out together with the fifth block (mandrel) 138. And the molded product 170 is obtained by extracting the 5th block (mandrel) 138 from this state.

That is, FIGS. 15 and 16 show the appearance of the molded product 170.
The molded product 170 has a bottomed cylindrical shape with a cross-section partially cut out in an approximately kamaboko shape, and has an undercut portion (small hole) 171 and another undercut portion (oval hole) 172 on the side surface. Further, another undercut portion (concave portion) 173 is formed at the bottom.

Next, the shaping | molding method of this embodiment is demonstrated.
The steps from when the resin is injected into the injection mold 1 by the injection molding machine until the cassette mold 133 is taken out from the injection mold 1 after molding are the same as those in the first embodiment.

  FIG. 17 shows the appearance of the cassette mold 133 taken out from the injection mold 1 after molding. Further, a sprue portion 112 ′, a runner portion 144 ′, and a gate portion 145 ′ made of a filling resin are integrally connected to the gate 145 formed in the second block 135.

  FIG. 18 shows a state in which the first block 134 is released from the state of FIG. 17, and the molded product 170 can be visually observed at this stage. Thereafter, the gate portion 145 ′ and the like are cut and separated from the molded product 170. In this case, the gate portion 145 ′ and the like may be cut off with a nipper (not shown), but depending on the required external quality, the gate portion 145 ′ and the like may be finished with a cutter or a file (not shown).

  In FIG. 14 described above, the second block 135 to the fourth block 137 are released from the state of FIG. 18 by moving the projections in the axial direction corresponding to the undercut portions formed in each block. In FIG. 14, only the fifth block 138 is in contact with the molded product 170.

  The fifth block 138 is a block that molds the inside of the cross section of the molded product 170, and is engaged with the molded product 170 with a relatively strong force due to the shrinkage of the resin. Therefore, a tool for mold release is used. . Through such steps, the molded product 170 shown in FIGS. 15 and 16 can be obtained.

  Further, the third block 136 can be easily manufactured using the surfaces 147 and 148 parallel to each other. That is, FIG. 19 shows the third block 136 fixed to the vice 141 of the machining center. Since the projecting portion 140 applied to the third block 136 is installed in a direction substantially perpendicular to the rotation axis of the cutting tool 142 of the machining center, it is easy to perform processing.

  If this is to be installed in a direction other than vertical, after processing once, the third block 136 is once detached from the vice 141, and the processing is performed after changing the fixing direction. Is required.

According to the present embodiment, it is possible to easily obtain a molded product 170 having a complicated shape having various undercut portions 171, 172, 173 in a plurality of directions. Also in the manufacture of the mold part, for example, as in the case of the third block 136, parallel surfaces 147 and 148 are provided to facilitate the processing setup.
(Third embodiment)
FIG. 20 shows a cassette mold 233 of the third embodiment.

  In this embodiment, the cassette mold 233 includes a mandrel 239 that passes through the cassette mold 233 in the axial direction, and two first blocks 234, four second blocks 235 that are respectively disposed opposite to the mandrel 239, There are two third blocks 236, four fourth blocks 237, and eight fifth blocks 238.

  The first block 234 to the third block 236 have substantially the same sectional fan shape. A groove 247 having two parallel surfaces is formed in the first block 234, and the two parallel surfaces are processed by being fixed to a vice as described above. The grooves having two parallel surfaces are also formed as grooves 248 and 249 in the second block 235 and the third block 236, respectively.

  As shown in FIGS. 20 and 21, inner peripheral walls 234a, 235a, and 236a having a substantially cylindrical cross section are provided on the axial ends of the first block 234 to the third block 236 on the axial end side. The inner peripheral walls 234b, 235b, and 236b having a substantially cylindrical cross section are formed on the central side in the axial direction by being divided into four in the circumferential direction. A mandrel 239 is inserted into a cylindrical portion formed by these inner peripheral walls.

  In this case, the diameter of the cylinder on the end side in the axial direction is formed smaller than the diameter of the cylinder on the center side in the axial direction. For this reason, a predetermined space (cavity) is formed between the mandrel 239 inserted into the cylindrical portion and the axially central cylindrical portion. In the first block 234, a gate 240 of a pin gate type that communicates with the inner peripheral wall 234b is formed. Gates are not formed in the second block 235 and the third block 236.

  Further, as shown in FIG. 21, the inner peripheral walls 234b, 235b, 236b on the center side in the axial direction of the first block 234 to the third block 236 and the inner peripheral walls of the fourth block 237 are formed on the molded product 270 ( Projections 241 and 242 corresponding to the undercut portions 271 and 272 of FIG. 24) are formed.

  Further, as shown in FIG. 22, a protrusion 243 is also formed on the inner peripheral wall of the fifth block 238. These protrusions 241, 242, and 243 correspond to the undercut portions 271 and 272 formed on the molded product 270. Further, in consideration of ease of processing, the fifth block 238 is formed with two protrusion-like parallel surfaces 238a and 238b.

  Further, as shown in FIGS. 20 to 22, the protrusions 241 and 242 formed on the inner peripheral walls 234 b, 235 b and 236 b of the first block 234 to the third block 236 and the inner peripheral wall of the fourth block 237 are When the cassette mold 233 is assembled, it is formed at an angle of approximately 90 ° in the circumferential direction. The protrusions 241 and 242 and the protrusion 243 formed on the fifth block 238 are formed at an angle of approximately 45 ° in the circumferential direction when assembled as the cassette mold 233.

Next, the molding method of the present embodiment will be described.
The steps from when the resin is injected into the injection mold 1 by the injection molding machine until the cassette mold 233 is taken out from the injection mold 1 are substantially the same as in the above-described embodiment. In this embodiment, a pin gate system is employed, and at this stage, the injected resin from the sprue bush 15 to the sprue 12 is already released.

  Next, the mandrel 239 is pulled out in the axial direction with respect to the cassette type 233 taken out. After that, when the blocks constituting the cassette mold 233 are sequentially released from the molded product 270 by the movement of the projections corresponding to the undercut portions to be molded in each block in the axial direction, the state shown in FIG. Become. Also in this case, each block is released in a direction substantially orthogonal to the undercut forming surface 273 of the molded product 270.

  Furthermore, when the eight fifth blocks 238 are released from the state shown in FIG. 23, a molded product 270 shown in FIG. 24 can be obtained. The molded product 270 has a hollow cylindrical shape, and a plurality of undercut portions (small holes) 271 and 272 are formed on the undercut molding surface 273.

According to the present embodiment, by increasing the number of divisions of each block constituting the cassette mold 233, it is possible to cope with undercuts in six directions (directions of the protrusions 241, 242, and 243), and forming a complicated shape. The product can be easily obtained.
(Modification)
FIG. 25 shows a cassette type 333 of this modification.

In this modification, only points different from the third embodiment described above will be described, and the same or corresponding members will be denoted by the same reference numerals, and description thereof will be omitted.
FIG. 25 shows a state where the assembly of the cassette mold 333 is completed.

  In this modification, the cassette mold 333 has a configuration similar to that of the third embodiment. That is, although not shown, as in FIG. 21, the inner peripheral wall on the center side in the axial direction of the first block 234 to the third block 236, the inner peripheral wall of the fourth block 237, and the inner surface of the fifth block 238 A protrusion corresponding to the undercut portion of the molded product 270 is formed on the peripheral wall.

  The first block 234 and the mandrel 239 are formed with through holes (not shown). The third block 236 has a tapped hole (not shown). Then, a hexagon socket head cap bolt 250 is inserted through the first block 234 and the mandrel 239 to reach the third block 236, and the cassette mold 333 is fastened as an assembly.

  As shown in FIG. 26, the mandrel 239 has a flat plate member 251 that is inscribed in a circle having a common cross section, and two crescent-shaped half-moon members 252 that are arranged so as to sandwich the plate member 251. ing. The plate member 251 is slidable with respect to the half moon member 252.

  The mandrel 239 is formed with through holes 253 at both ends in the longitudinal direction, and a protrusion 254 is formed at the central portion substantially parallel to the through hole 253. Although not shown, the protrusion 254 corresponds to an undercut portion formed on the inner peripheral wall of the molded product 270.

Next, a molding method according to this modification will be described.
The steps from when the resin is injected into the injection mold 1 by the injection molding machine until the cassette mold 333 is taken out from the injection mold 1 are the same as in the third embodiment.

  Next, the hexagon socket head cap screw 243 fastening the cassette mold 333 is removed with a tool, and the first block 234 to the fifth block 238 are released from the molded product 270. Further, only the central plate member 251 of the mandrel 239 is pulled out in the axial direction. Then, the state shown in FIG. 27 is obtained. An undercut portion 274 (small hole) is formed on the surface of the molded product 270.

  Thereafter, the two meniscus members 252 divided into the upper and lower parts are moved in the axial direction of the protrusions 254 in the axial direction until the protrusions 254 come off from the inner wall of the molded product 270. Next, the moved two meniscus members 252 are moved in the axial direction to release the mold. Then, a molded product 270 as shown in FIG. 28 is obtained. Although not shown, the molded product 270 has an undercut portion (concave portion) formed on the inner peripheral wall.

  According to the present modification, a plurality of mold parts (mandrel 239) constituting the inside of the molded product 270 are divided into a plurality of parts, so that even in a shape having an undercut on the inner peripheral side of the molded product 270, it is easy. Can be molded.

  In each of the above embodiments, the mold main body has been described as being formed by the fixed-side mold plate 11 and the movable-side mold plate 21, but the mold main body can be formed by only one of the mold plates. .

It is a fragmentary sectional view of the injection mold used for this Embodiment. It is an external appearance perspective view of a cassette type and a runner block of a 1st embodiment. It is an expanded sectional view of the principal part of FIG. It is an external appearance perspective view of a movable side metal mold | die. It is an external appearance perspective view of the cassette type taken out from the metal mold body. It is an external appearance perspective view of a cassette type same as the above. It is an external appearance perspective view of the state which released all the blocks from the cassette type same as the above. (A) is the external appearance perspective view of a molded article, (b) is sectional drawing which follows the II line | wire. It is an external appearance perspective view of the modification of the cassette type of 1st Embodiment. It is an external appearance perspective view of another modification of a cassette type same as the above. It is an external appearance perspective view of the cassette type of 2nd Embodiment. It is an external appearance perspective view of a cassette type same as the above. It is an external appearance perspective view of a section of a cassette type same as the above. It is an external appearance perspective view in the state where a part of block was released from the cassette type same as the above. It is an external appearance perspective view of a molded article same as the above. It is an external appearance perspective view of a molded article same as the above. It is an external appearance perspective view of the cassette type taken out from the metal mold | die main body same as the above. It is an external appearance perspective view of the cassette type taken out from the metal mold | die main body same as the above. It is a figure which shows the processing state of the block which comprises a cassette type | mold same as the above. It is an external appearance perspective view of the cassette type of 3rd Embodiment. It is an external appearance perspective view of a part of cassette type same as the above. It is an external appearance perspective view of a part of cassette type same as the above. It is an external appearance perspective view of a part of cassette type same as the above. It is an external appearance perspective view of a molded article same as the above. It is an external appearance perspective view of the modification of the cassette type of 3rd Embodiment. It is an external appearance perspective view of the block which comprises a cassette type same as the above. It is an external appearance perspective view in the state where a part of block was released from the cassette type same as the above. It is an external appearance perspective view of a molded article same as the above. It is a cross-sectional plan view of a conventional injection mold It is sectional drawing which follows the XX line same as the above. It is a figure which shows the conventional shaping | molding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection mold 10 Fixed side mold 11 Fixed side mold plate 12 Spru 12 'Sprue part 13 Fixed side mounting plate 20 Movable side mold 21 Movable side mold plate 22 Movable side mounting plate 23 Spacer block 24 Ejector plate (upper)
25 Ejector plate (bottom)
26 Ejector pin 27 Receiving plate 30a Recess 30b Recess 33 Cassette mold 34 Cavity 35 Mandrel 36 First block 37 Second block 38 Third block 39 Fourth block 40 Fifth block 41 Sixth block 42 Runner block 44 runner 44 'runner part 45 gate 45' gate part 46a inner peripheral wall 46b inner peripheral wall 47a protrusion 47b protrusion 48 gate 49a peripheral wall 49b peripheral wall 50a protrusion 50b protrusion 51a bottomed hole 51b bottomed hole 60 knock pin 61 knock pin 62 knock pin hole 63 hexagon Hexagon socket head cap screw 70 Molded product 71 Undercut portion 72 Undercut forming surface 112 ′ Sprue portion 133 Cassette mold 134 First block 135 Second block 136 Third block 137 Fourth block 138 Block 139 protrusions 140 protruded portion 144 'runner 145 gate 145' gate portion 146 protrusion 170 molded article 171 undercut portion (small hole)
172 Undercut (Oval hole)
173 Undercut (recess)
174 Undercut forming surface 233 Cassette mold 234 1st block 235 2nd block 236 3rd block 237 4th block 238 5th block 239 Mandrel 240 Gate 241 Projection 242 Projection 243 Projection 244 Gate 270 Molded product 271 Under Cut part (small hole)
272 Undercut part (small hole)
273 Undercut forming surface 274 Undercut part (convex part)

Claims (5)

In the injection mold that can take out the cassette mold to mold the molded product from the mold body,
The cassette mold is formed with a cavity for molding a molded product having an undercut forming surface on the outer peripheral surface, and a plurality of the molds disposed opposite to each other on the upper and lower sides, the left and right sides, and the front and rear sides around the molded product in the cavity. An assembly of blocks,
A gate formed in at least one of the plurality of block assemblies and in communication with the cavity;
The mold main body includes a recess having substantially the same size as the assembly of the plurality of blocks.
Prior to molding, the cassette mold is housed in the recess of the mold body and fixed in position,
Resin is injected into the cavity through the gate at the time of molding,
After the molding, the cassette mold is removed from the recess, and the block corresponding to the undercut forming surface of the molded product in the cavity is released in a direction substantially orthogonal to the undercut forming surface.
An injection mold characterized by that. The cassette mold is housed in the recess in a state assembled outside the mold body, and can be removed from the recess in a state in which the cassette mold is filled with resin after molding.
The injection mold according to claim 1. When the molded product has a hollow part, it has a mandrel as a block arranged in the hollow part,
The injection mold according to claim 1 or 2 , characterized in that. The gate is formed in a block arranged along the longitudinal direction of the molded product in the cavity.
The injection mold according to claim 1. The gate is formed at a position deviated in the longitudinal direction of the molded product from a region having an undercut portion of the molded product in the cavity.
An injection mold according to claim 4 .