JP2006181889A - Mold apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem regarding a weld line that, although the weld line parallel to the axial line makes a product look fine, there is room for improvement since a crack and the like tend to be generated from the end part of the weld line, that particularly in a case such as the end part of the weld line is screwed with another member, owing to the rotational action by the screwing of the other member, there arises the stress accompanied with the rotation in the weld line to cause eventually the crack from the very part, greatly deteriorating the value as product. <P>SOLUTION: In a mold apparatus wherein a plurality of gate holes which let a resin flow into a cavity to form a molded product and runner holes communicant with the gate holes are formed, at least one of the gate holes or runner holes is made different in the inside diameter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mold apparatus in which a plurality of gate holes through which resin flows into a cavity forming a molded product and runner holes communicating with the gate holes are formed.

As an example, in a ballpoint pen tip injection mold for a ballpoint pen that is provided with a substantially cylindrical cavity, the columnar central core of the cavity is composed of a fixed core pin and a movable core pin, and the movable core pin 9 is When the movable core pin is in the retracted position, only the small diameter portion projects into the cavity, and the movable core pin increases as the movable core pin moves from the retracted position to the projected position. A mold apparatus is known that protrudes into a radial cavity and compresses the surrounding fluid resin. And the position of the gate hole of the mold apparatus is formed at a position symmetrical with respect to the central axis of the cavity.
Japanese Patent Laid-Open No. 11-227001.

  In the above prior art, since the gate hole is formed in a line symmetrical position with respect to the central axis of the cavity part, the resin from each gate hole flows uniformly and evenly into the cavity part. . As a result, the weld line serving as the contact surface of the resin that flowed in was generated at a position parallel to the axis of the cavity. Although the weld line parallel to the axis is considered to have a good appearance on the product, cracks from the end of the weld line are likely to occur and there is room for improvement.

  In particular, when another member is screwed to the end portion of the weld line, stress due to the rotation operation is generated in the weld line due to the rotational action caused by the screwing of the other member. ) Cracked and the value of the product was significantly deteriorated.

  The present invention is a mold apparatus in which a plurality of runner holes communicating with a gate hole through which resin flows into a cavity forming a molded product and a gate hole, the at least one gate hole, or The first gist is that the flow velocity or pressure of the resin in the runner hole is made different, and a plurality of gate holes through which the resin flows into the cavity forming the molded product and a plurality of runner holes communicating with the gate hole are formed. A mold apparatus for forming a molded product, wherein the at least one gate hole or the runner hole has a different inner shape, the second gist of which is to make the resin flow into the cavity. And a mold device in which a plurality of runner holes communicating with the gate hole are formed, and a third aspect is that a convex portion or a concave portion is formed on the inner surface of the cavity, and molding is performed. A mold apparatus in which a plurality of gate holes for injecting resin into a cavity forming a plurality of runner holes communicating with the gate holes are disposed, and a core pin is disposed inside the cavity, and the core pin A fourth gist is that a convex portion or a concave portion is formed on the outer surface and / or the inner surface of the cavity.

  The present invention is a mold apparatus in which a plurality of runner holes communicating with a gate hole through which resin flows into a cavity forming a molded product and a gate hole, the at least one gate hole, or The first gist is that the flow velocity or pressure of the resin in the runner hole is made different, and a plurality of gate holes for injecting resin into the cavity forming the molded product and a plurality of runner holes communicating with the gate hole are formed. The second die is that the inner shape of the at least one gate hole or the runner hole is made different, and the gate hole through which the resin flows into the cavity forming the molded product And a mold apparatus in which a plurality of runner holes communicating with the gate hole are formed, and a third aspect is that a convex portion or a concave portion is formed on the inner surface of the cavity. A mold device in which a plurality of gate holes for injecting resin into a cavity forming a plurality of runner holes communicating with the gate holes are disposed, and a core pin is disposed inside the cavity, and the core pin Since the fourth gist is the formation of convex portions or concave portions on the outer surface and / or the inner surface of the cavity, the weld line generated in the molded product can be curved, thereby preventing damage such as cracks as much as possible. It is possible to provide a good product that is prevented.

A sprue hole 4 and a runner groove 5 into which resin flows are formed in a fixed-side mold plate group 3 including a fixed-side mounting plate 1 and a runner plate 2. The runner groove 5 is formed on a surface that comes into contact with a split mold 6 described later.
On the other hand, the movable mold group 7 is composed of the split mold 6, the slide plate 8, the stripper plate 9, the movable attachment plate 10, and the like. The split mold 6 is provided with a pair of split mold cavities 11 so that the split mold cavity 11 can be opened and closed following the opening and closing of the stroke side mold group 3 and the movable side mold group 7. It has become. A cavity portion 12 for forming a molded product is formed on the inner surface of the split cavity 11. Further, the split cavity 11 is formed with a runner hole 13 communicating with the runner groove 5 and a gate hole 14 communicating with the runner hole 13 and the cavity portion 12. Two of these runner holes 13 and gate holes 14 are formed at equal positions. That is, it is formed in a line-symmetric position with respect to the central axis of the cavity portion 12. Further, the inner diameters of the two runner holes 13 and the gate hole 14 are the same, and the flow velocity and pressure of the inflowing resin are made constant.

Here, a convex portion 15 is formed on one portion of the inner surface of the cavity portion 12. This convex part 15 plays the role which forms a through-hole in the side part of a molded article by contact | abutting with the core pin mentioned later.
A core pin 16 that forms a hollow portion in the molded product is fixed to the stripper plate 9 and extends to the inside of the cavity portion 12. And the said convex part 15 formed in the cavity part 12 is provided in the side surface of the core pin 16 so that contact / separation is possible. On the other hand, a tip pin 17 that forms a hollow portion in the molded product is also fixed to the runner plate 2, and its tip can be brought into contact with and detached from the tip of the core pin 16.

  The operation will be described. When the resin flows in from the sprue hole 4, the resin flows into the cavity portion 12 through the runner groove 5, the runner hole 13 and the gate hole 14. At this time, the resin flows uniformly from the gate hole 14 to the vicinity of the convex portion 15, and a weld line is also formed on a straight line. However, when the resin reaches the convex portion 15, the flow of the resin is restricted by the convex portion 15, so that the resin flows toward the lower side of the cavity portion 14 in a non-uniform state. As a result, the weld line A is generated in a curved state (see FIGS. 4 and 5). Further, when the bend line A is curved, the weld line, that is, the contact / adhesion area of both resins is increased, and a product which is not easily cracked is formed.

A second example will be described with reference to FIG. This is an example in which a concave portion or a convex portion is formed on the outer surface of the core pin 16. More specifically, a concave portion 18 is formed on the upper portion of the core pin 16, and a convex portion 19 is formed on the lower portion. These concave portions 18 and convex portions 19 form concave portions and convex portions on the inner surface of the molded product.
The operation will be described. The resin that has flowed in from the gate hole 14 is blocked by the recesses 18 and the protrusions 19 formed in the core pin 16, so that the resin flows into the lower portion of the cavity 12 in a non-uniform state. As a result, a weld line curved from the upper side to the lower side of the cavity portion 12 is generated.

A third example will be described with reference to FIG. This is an example in which the inner shapes of the two runner holes formed in the split cavity 11 are different. More specifically, the inner diameter of the right runner hole 21 is smaller than the inner diameter of the left runner hole 20 in the drawing. By providing a difference in the inner diameter of the runner hole, the resin flows into the cavity portion 12 from each gate hole 14 at a different flow velocity and pressure, and as a result, the cavity portion 12 is bent downward from above. A weld line is generated. More specifically, since the flow velocity and pressure from the runner hole 20 having a large inner diameter increase, the weld line A is generated in a state curved in the right direction in the drawing.
In this third example, the weld lines are curved by changing the inner diameters of the runner holes, but the inner diameters of the runner holes may be the same, and the gate holes may be closed differently.

  A fourth example will be described with reference to FIG. This is an example in which the length of each runner hole is made different to change the position of the gate hole in the axial direction. The split mold cavity 11 is formed with two runner holes 22 and 23 having different lengths. In this example, the left runner hole 22 in the figure is formed longer than the right runner hole 23. Due to the difference in the length of the runner holes, the positions of the gate holes 24 and 25 are also different. That is, the inflow of the resin from the gate hole 25 is accelerated, whereby a curved weld line is generated.

The longitudinal cross-sectional view which shows the 1st example of this invention. The principal part enlarged view of FIG. The schematic diagram which shows the flow of resin. FIG. 4 is a front view of FIG. 3. The schematic diagram which shows a weld line. The principal part longitudinal cross-sectional view which shows a 2nd example. The principal part longitudinal cross-sectional view which shows a 3rd example. The principal part longitudinal cross-sectional view which shows a 4th example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed side mounting plate 2 Runner plate 3 Fixed side type plate group 4 Sprue hole 5 Runner groove 6 Split type 7 Movable side type plate group 8 Slide plate 9 Stripper plate 10 Movable side mounting plate 11 Split type cavity 12 Cavity part 13 Runner hole 14 Gate hole 15 Convex part 16 Core pin 17 Tip pin 18 Concave part 19 Convex part 20 Runner hole 21 Runner hole 22 Runner hole 23 Runner hole 24 Gate hole 25 Gate hole A Weld line

Claims (4)

A mold apparatus in which a plurality of gate holes through which resin flows into a cavity forming a molded product and runner holes communicating with the gate holes are formed, and the resin in at least one of the gate holes or the runner holes Mold device characterized by different flow velocity or pressure. A mold apparatus having a plurality of gate holes through which resin flows into a cavity forming a molded product and runner holes communicating with the gate holes, wherein at least one of the gate holes or the runner holes Mold device characterized by different shapes. A mold apparatus in which a plurality of gate holes through which resin flows into a cavity forming a molded product and runner holes communicating with the gate holes are formed, and a convex portion or a concave portion is formed on the inner surface of the cavity. A mold apparatus characterized by being formed. A mold apparatus in which a plurality of gate holes through which resin flows into a cavity forming a molded product and runner holes communicating with the gate holes are formed, and a core pin is disposed inside the cavity, and A mold apparatus, wherein convex portions or concave portions are formed on an outer surface of a core pin and / or an inner surface of a cavity.

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