JP2019107849A - Injection molding die and method of manufacturing the same - Google Patents

Abstract

To provide an injection molding die which allows a gate to be cut with a small force while having a simple structure, and to provide a manufacturing method using the same.SOLUTION: An injection molding die 10 is provided with a fixed die 20 and a movable die 30. When a resin is allowed to flow into the clamped injection molding die 10, a tip portion 34a of an undercut pin 34 is embedded in a product 40. When the resin hardens, the injection molding die 10 is opened, and a gate part 53 of a molded article 50 is cut with a gate cut pin 33. At this time, the product 40 is fixed to the movable die 30 with an undercut pin 34. Finally, the product 40 is pushed with eject pins 36 37, the undercut pin 34 is removed from the product 40, and the product 40 is removed from the movable die 30.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an injection mold capable of performing in-mold gate cutting and a manufacturing method using the same.

  In molded articles obtained by injection molding, the resin remaining in the gate, runner and spool is connected to the product (hereinafter, the resin remaining in the gate, runner and spool is referred to as "spool portion", "runner portion", " "The gate part." For this reason, it is necessary to cut off the gate part and remove the gate part, the runner part and the spool part from the product.

  In order to obtain the product, the molded product may be taken out of the injection molding die and then the gate may be cut, but when the resin flows into the injection molding die, the gate is cut while the injection molding die is tightened. You may. In particular, the latter is called in-mold gate cut and has merits such as process simplification, low pressure molding, low residual strain, good cut surface, and prevention of sink marks.

  For example, Patent Document 1 describes an injection mold having a gate block having a gate cut portion at its tip. The gate block has a slope at the lower end, and the slope is in contact with the slope of the hydraulic slide block. That is, in accordance with the horizontal movement of the slide block, the gate block moves up and down, and the gate cut portion crosses the gate portion. In the gate cut by the injection molding die, the gate width and the gate pressure are reduced during pressure holding, and all resin in the gate is cut after completion of pressure holding.

Unexamined-Japanese-Patent No. 2001-9878 (FIG. 1)

  However, in the injection molding die described in Patent Document 1, the gate block is moved in a situation where there is no escape place for the resin at the gate cut. For this reason, compressive deformation of the resin by the gate block is required, and as a result, cutting is performed with a large force.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an injection mold having a simple structure and capable of gate cutting with a small force and a manufacturing method using the same.

  In order to solve the above object, the injection mold of the present invention is an injection mold having a fixed mold and a movable mold, wherein the movable mold includes a gate cut pin for cutting a product and a gate portion, and a cavity. The apparatus is characterized by comprising an undercut pin which protrudes and whose upper end becomes wide, and an eject pin which pushes a product to remove the product from the movable mold.

In the injection mold of the present invention, the resin is allowed to flow into the space formed in a clamped state. At this time, the tip of the undercut pin is embedded in the product. When the holding pressure is completed and the resin is cured, the movable mold is moved to open the injection molding die, and the gate portion of the resin is cut with a gate cut pin. At the time of cutting the gate portion, the product is fixed to the movable mold by the undercut pin. Finally, push the product with the eject pin, remove the product from the undercut pin and remove it from the moveable mold.

  The fixed mold may have a protrusion facing the gate cut pin.

  In the manufacturing method using the injection molding die of the present invention, the resin flows into the injection molding die in which the fixed die and the movable die are clamped, so that the product embeds the tip of the undercut pin, and the resin is Holding, cooling and curing, moving the movable mold to open the injection mold, and exposing the upper part of a molded article including the product from the movable mold, and raising a gate cut pin Cutting the gate part of the molded product and removing the part other than the product of the molded product from the movable mold with an eject pin, and from the tip of the undercut pin and the movable mold with another eject pin And removing the product.

  As described above, in the injection molding die of the present invention and the manufacturing method using the same, the injection molding die is opened, the gate is cut while the product is fixed by the undercut pin, and the product is finally removed from the movable die . That is, at the time of gate cutting, since the escape place of the resin is secured in the fixed mold direction, the force for compressive deformation of the resin is hardly applied to the gate cut pin. Therefore, the injection mold of the present invention and the manufacturing method using the same can be gate-cut with a small force while the structure of the injection mold is simple.

It is sectional drawing of the open state of the injection mold shown as 1st Embodiment of this invention. It is sectional drawing of the state which tightened the injection mold shown in FIG. It is a top view of the product manufactured with the injection mold shown in FIG. It is a top view of the molded article manufactured with the injection mold shown in FIG. It is sectional drawing of the state which made resin flow in into the injection molding metal mold | die shown in FIG. It is sectional drawing of the state which opened the injection mold shown in FIG. FIG. 7 is a cross-sectional view of the injection molding die shown in FIG. 6 with the spool removed. It is sectional drawing of the state which removed the product from the injection mold shown in FIG. It is sectional drawing of the injection mold shown as 2nd Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals and redundant description will be omitted.

First Embodiment
FIG. 1 is a cross-sectional view of an injection molding mold 10 shown as a first embodiment of the present invention in an open state. The injection mold 10 includes a fixed mold 20 and a movable mold 30. The spool bush 21 is fitted in the fixed mold 20. At the center of the spool bush 21 is a resin passage (hereinafter referred to as "spool 22"). The spool 22 is a truncated cone-like cavity which is wide at the bottom of the figure. A part of the spool 22 is also present on the movable mold 30 side.

  The movable mold 30 includes a movable cavity mold 31, a movable receiving plate 32, a gate cut pin 33, an undercut pin 34, and eject pins 35, 36, 37. The movable cavity mold 31 is provided with a cavity 38 in which a portion of the spool 22, runners, gates and products are formed. The movable side receiving plate 32 is disposed below the movable side cavity mold 31.

  The gate cut pin 33 has a blade portion 33 a and a flat portion 33 b at the upper end, and penetrates the movable side cavity mold 31. The tip of the blade portion 33 a reaches the middle portion of the cavity 38, and the flat portion 33 b is at the same height as the bottom surface of the cavity 38. Below the movable side receiving plate 32 (not shown), there is a driving device which enables the vertical movement of the gate cut pin 33.

  The undercut pin 34 has a portion (hereinafter referred to as a “tip portion 34 a”) processed at the upper end so as to have a wider upper end and is embedded in the movable cavity mold 31. The tip 34 a is disposed in the cavity 38, and the shoulder portion (bottom of the inverted truncated cone) is flush with the bottom of the cavity 38.

  The eject pins 35, 36, 37 have flat top ends and penetrate the movable cavity mold 31. The upper end surface of the eject pin 35 is equal in height to the bottom surface of the portion of the cavity 38 which is to be a part of the spool 22. The upper end surfaces of the eject pins 36, 37 have the same height as the bottom of the product forming portion of the cavity 38. Below the movable side receiving plate 32 (not shown), there is a driving device which enables the vertical movement of the eject pins 35, 36, 37.

  FIG. 2 is a cross-sectional view of a state in which the injection molding die 10 is tightened. As shown in FIG. 2, when the fixed mold 20 and the movable mold 30 are overlapped, the spool 22 is completed, and the cavity 38 and the bottom surface of the movable mold 30 constitute the runner 23, the gate 24 and the space 25 for forming the product. Be done.

  FIG. 3 is a plan view of the product 40 produced by the injection mold 10. The product 40 is a plate-like body whose upper surface is substantially rectangular. On the top surface of the product 40, circular through holes 41 are provided at the four corners, and four rectangular through holes 42 are provided at the center. Further, on the bottom surface, there is a concave portion 43 formed by the tip portion 34a (see FIG. 1) of the undercut pin 34.

  FIG. 4 is a plan view of a molded article 50 manufactured by the injection molding die 10. The molded article 50 is in a state in which the resin is allowed to flow into the mold-clamped injection mold 10 (see FIG. 2) and then cured. The product 40 is obtained by cutting the gate portion 53 of the molded product 50. The molded product 50 further includes a spool 51, a runner 52, and a gate 53. The spool portion 51, the runner portion 52, and the gate portion 53 are resin that remains in the spool 22, the runner 23, and the gate 24, which are passages of resin, and is cured. The gate portion 53 has a groove 54 formed by cutting in the blade portion 33 a of the gate cut pin 33. In addition, when the product 40 is taken out of the movable mold 30 for reference, the portions 55, 56 pressed by the eject pins 36, 37 are shown.

  Next, the manufacturing process of the product 40 will be described with reference to FIGS. 5 to 8. In addition, in FIGS. 6-8, the fixed type | mold 20 is not shown in figure.

  First, resin flows into the clamped injection molding die 10. The resin is then held under pressure, cooled and cured. FIG. 5 is a cross-sectional view of a state in which the resin is caused to flow into the clamped injection molding die 10. The spool portion 51 is formed by the spool bush 21 and the movable side cavity mold 31, and the runner portion 52, the gate portion 53 and the product 40 are in a space constituted by the bottom surface of the fixed mold 20 and the cavity 38 (see FIG. 2). It is formed. The runner portion 52 is located between the spool portion 51 and the gate portion 53, and the gate portion 53 is in the vicinity of the tip of the gate cut pin 33. A product 40 is formed on the left side of the gate cut pin 33. At this time, the tip 34a of the undercut pin 34 is embedded in the product.

After the resin cures, the movable mold 30 is moved to open the injection mold 10. FIG. 6 is a cross-sectional view of the injection molding die 10 in an open state (the fixed mold 20 is not shown). From the movable mold 30, the upper portion of the molded article 50 including the spool 51, the runner 52, the gate 53, and the product 40 is exposed.

  Next, as shown in FIG. 7, the spool 51, the runner 52 and the gate 53 are removed from the movable die 30. FIG. 7 is a cross-sectional view of the injection molding die 10 with the spool 51 and the like removed (the fixed die 20 is not shown). In order to remove the spool 51 and the like, first, the gate cut pin 33 is raised to cut the gate 53. Subsequently, the eject pin 35 is raised, the bottom of the spool 51 is pushed, and the spool 51, the runner 52, and the gate 53 are removed from the movable cavity mold 31.

  Finally, as shown in FIG. 8, the product 40 is removed from the movable mold 30. FIG. 8 is a cross-sectional view of the injection mold 10 with the product 40 removed (the fixed mold 20 is not shown). To remove the product 40, raise the eject pins 36, 37 and push the bottom of the product 40. The product 40 is now removed from the movable cavity mold 31. At this time, the tip 34 a of the undercut pin 34 is detached from the product 40, and the recess 43 remains in the product 40.

  As described above, in the injection molding die 10, the injection molding die 10 is opened, and gate cutting is performed in a state where the product 40 is fixed by the undercut pin 34. That is, since an escape place for the resin (a portion other than the product 40 of the molded product 50) is secured in the fixed mold 20 direction, almost no force is applied to the gate cut pin 33 for compressive deformation of the molded product 50. Therefore, the injection mold 10 can be gate-cut with a small force while having a simple structure. Similarly, in the method of manufacturing the product 40 using the injection molding die 10, the injection molding die 10 can be gate-cut with a small force while having a simple structure. Further, according to the manufacturing method using the injection molding die 10, the gate cut is performed after the pressure holding and cooling steps, so that the dimensions of the product 40 can be cut stably in a stable state.

Second Embodiment
FIG. 9 is a cross-sectional view of an injection molding die 90 shown as a second embodiment of the present invention. The injection mold 90 comprises a fixed mold 91 and a movable mold 30. The fixed mold 91 is provided with a protrusion 92 facing the blade portion 33 a of the gate cut pin 33. The movable mold 30 is the same as the movable mold 30 included in the injection molding mold 10. The molded product manufactured by the injection molding die 90 has a recess immediately above the blade portion 33a, which further facilitates gate cutting.

10, 90 ... injection mold,
20, 91 ... fixed type,
21 ... spool bush,
22 ... spool,
23 ... runner,
24 ... gate,
25 ... Space to form a product,
30 ... movable type
31 ... Movable side cavity type,
32: Movable side receiving plate,
33: Gate cut pin,
33a ... blade portion,
33b flat part,
34 ... Undercut pin,
34a ... tip portion,
35, 36, 37 ... Eject pin,
38 ... cavity,
40 ... products,
41, 42 ... through holes,
43: Recess,
50 ... molded articles,
51: Spool unit,
52 ... runner section,
53: Gate section,
54 ... groove,
55, 56 ... The part pressed by the eject pin,
92 ... protrusion.

Claims (3)

In an injection mold having a fixed mold and a movable mold,
The movable type is
With a gate cut pin that cuts the product and the gate,
An undercut pin that projects into the cavity and the upper end is wider;
An injection mold comprising: an eject pin for pushing a product to release the product from the movable mold.   The injection mold according to claim 1, wherein the fixed mold has a protrusion facing the gate cut pin. A step of injecting a resin into the injection molding mold in which the fixed mold and the movable mold are clamped, filling the tip of the undercut pin with the product, holding the pressure, cooling and curing the resin;
Moving the movable mold to open the injection mold and exposing the upper part of the molded article including the product from the movable mold;
A step of raising a gate cut pin to cut a gate portion of the molded product and removing a portion other than the product of the molded product from the movable mold with an eject pin;
And a step of sequentially removing the product from the tip of the undercut pin and the movable die by another eject pin.