JPS6311313A - Molding process of plastic molded product having curved hole and mold therefor - Google Patents

Abstract

PURPOSE:To enable a molded product to be produced, even when a diameter of a curved hole is same as those of straight holes on both ends thereof by molding the plastic product having a curved hole in its center and straight holes on both sides thereof by a two-stage injection molding. CONSTITUTION:A mold 1 is composed of a first mold 2 for molding a roughly molded article B and a second mold 3 for molding a short tube C. In the first mold 2, the straight rod 8 constituting an inner rod 7 is butted onto a curved rod 10, and the injection molding is carried out, thereby obtaining the roughly molded article B. Then, a straight rod 8 and the curved rod 10 are retracted respectively in side positions, whereby the roughly molded article B is taken out. The taken out article B is set in a recessed groove 22 of the second mold 3, and the tip of a straight rod 25 is advanced and rolled into the curved hole (a) of the roughly molded article B, and then a short tube C is molded by injection molding. A molded product A is obtained, by welding the short tube C onto the roughly molded article B. Then, the straight rod 25 is drawn out, and in the product A, an inner hole is formed which connects the curved hole (a) having a specified curvature with straight holes (b) and (d) having respectively predetermined lengths on both sides thereof. Screw thread parts Bs, Cs on both ends of the molded product A may be also shaped by machine work after molding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for molding a plastic molded product having a curved hole, such as a casing cap (hereinafter referred to as a wire guide) for guiding a wire or the like, and a mold for the molding.

[Conventional technology]

As the wire guide, there is one having a structure shown in FIG. 11, for example. The inner hole P of this wire guide WG has a curved hole P1 with a predetermined radius of curvature, and a straight line aP2 at both ends. P3
It cannot be formed by one injection molding, so the molding method is generally to divide it into two along a plane including the axis as shown in Fig. 2(b).

As shown in (C), two rough-shaped products Wa and Wb are formed,
A method of joining the two rough-shaped products using an adhesive or the like has been adopted.

[Problem that the invention seeks to solve]

When using the above-mentioned molding method, it takes time and effort to bond, and there is a risk that the bonded portion may peel off during use, and there are problems such as spoiling the appearance during bonding.

For this reason, the inventor of the present invention first invented a mold that can be manufactured by one injection molding (Japanese Patent Application No. 1983-
101653), in this case, it can be applied if one of the straight holes P2 or P3 has a larger diameter than the curved hole P2. It is difficult to apply this method when P3 and the curved hole P1 are required to have the same diameter, or when the straight hole is long.

In view of this, an object of the present invention is to divide the manufacturing process into two steps to enable manufacturing even when the curved hole and the straight holes at both ends thereof have the same diameter. .

[Means for solving problems]

A first method of the invention for achieving the above object is to construct an inner rod by butting together a straight rod of a required length and a curved rod of a predetermined radius of curvature, and use this inner rod to form a curved hole and a straight hole at one end. A first step of injection molding a rough-shaped product having an inner hole with continuous holes, and a step of storing the rough-shaped product, inserting a straight rod of the required length into the open end of the curved hole, and connecting it to the rough-shaped product to form a short pipe. The gist of the present invention is to form an inner hole in which linear holes of a required length are connected on both sides of a required radius of curvature by a second step of injection molding.

A second invention relates to a mold for carrying out the above method, and a first mold for injection molding a rough-shaped product having a curved hole with a predetermined radius of curvature and a straight hole at one end thereof. and a second mold for receiving the rough-shaped product and integrally injecting a short tube with a straight hole connected to the open end of the curved hole into one end of the rough-shaped product; The molding die is equipped with a pair of movable molds having female molds forming the external shape of the rough-shaped product on their mating surfaces, and an inner rod that forms the inner hole of the rough-shaped product, and the inner rod has a straight rod of a required length and A curved rod with a predetermined radius of curvature is butted together 5=, and the straight rod and the curved rod are provided with transition means for selectively shifting between the abutting position and the retracted position along their respective axes, and the second forming The molds have a pair of movable molds each having a concave groove on the mating surface for accommodating the above-mentioned rough-shaped product and a female mold for forming a short pipe on the open end side of the curved hole of the rough-shaped product, and a straight mold for forming the short pipe inner hole. The gist is that the straight rod is provided with a transition means for selectively shifting between an advanced position and a retracted position in which the straight rod is inserted into the inner hole of the rough-shaped product.

[Effect]

In the first step, a rough-shaped product having an inner hole with a curved hole and a straight hole on one side thereof is injection molded, and in the second step, a straight hole is provided on one side of the rough-shaped product, that is, on the opening end side of the curved hole. Since the short tube was injection molded to be welded to the rough-formed product,
The rough-shaped product and the short tube become one body, and the inner hole has a shape of a curved hole and straight holes connected to both sides of the curved hole.

〔Example〕

1 to 5 relate to the first embodiment. In the first step, the molded product to be formed in this example is first formed into a rough-formed product B.
is injection molded, and then in the second step, the short tube C is integrally molded with the rough-shaped product B by injection molding.
is provided with a curved hole a having a predetermined radius of curvature and a straight hole d of a required length on one side thereof, and the short pipe C is provided with a straight hole d of a required length connected to the curved hole a.

That is, molded product A is formed by integrally molding the above-mentioned rough-formed product B and short tube C, whereby straight holes d of the required length are connected to both sides of a curved hole a with a predetermined radius of curvature. be.

The molding die 1 of this embodiment consists of a first mold 2 as means for forming the rough-shaped product B, and a second mold 3 as a means for forming the short tube C.

The first mold 2 includes upper and lower movable molds 4 and 5, and a female mold 6 that follows the external shape of the rough-shaped product B is formed on the mating surfaces 4a and 5a of both molds 4 and 5. 7 is a sprue connected to this female mold 6. An inner rod 7 for forming the inner hole of the rough-shaped product B is provided on the mating surfaces of both molds 4.5. This inner rod 7 includes a straight rod 8 of a required length, a curved rod 10 of a prescribed radius of curvature, and respective transition means 9.
, 11.

The straight rod transfer means 9 consists of a hydraulic cylinder, for example, and the straight rod 8
is reciprocated along the axis between a position where it butts against the curved rod 10 and a retracted position where it is pulled out from the female die 6.

The bent rod transition means 11 includes a rack plate 12 to which the bent rod 10 is attached at the tip, and a binion 13 that meshes with the rack plate 12, and the rack plate 12 is bent together with the bent rod 10 into a curved shape with the predetermined radius of curvature. It fits into a guide groove 14 with the same radius of curvature formed on one of the movable molds 5, and by driving the pinion 13, the curved rod 10 is brought into abutting position with the straight rod 8 and a retracted position where it is pulled out from the female mold 6. Transfer back and forth. 15 is a support shaft on which the pinion 13 is attached, and is used for appropriate driving! (not shown).

Further, 16 is a cover that covers the transfer means 11.

In order to maintain the straight rod 8 and the curved rod 10 in a correctly abutted state, preferably, one of them is formed into a pointed shape as shown in the figure, and the other end is formed into a hollow shape into which the straight rod 8 and the curved rod 10 are fitted.

The second mold 3 similarly includes upper and lower movable molds 20 and 21,
The mating surfaces 20a and 21a of both molds have a concave groove 22 for storing the rough-shaped product B, and a female groove 22 for forming the short pipe C on one side of the rough-shaped product B to be stored, that is, on the open end side of the curved line 7 and the hole a. A mold 23 is formed. This mating surface 20a, 2], a is provided with a straight rod 25 that forms the inner hole d of the short pipe C, and the straight rod 25 is connected to a transition means 26, for example, a hydraulic cylinder, so that the straight rod 2
It reciprocates between an advanced position where the tip of the molded product B is inserted into the inner hole a of the rough-shaped product B, and a retracted position where it is extracted from the female mold 23.

Reference numeral 27 denotes a rough-formed product support rod provided as necessary, to which a transfer means 28 consisting of, for example, a hydraulic cylinder is connected, and its tip is inserted into the supplied rough-formed product B to ensure that the rough-formed product B is moved into the groove 22.
keep it within.

29 in the figure is a runner. In addition, during injection molding of the short tube C, the tip of the rough-shaped product B is made into a small diameter part Ba so that it can be welded and integrated with the rough-shaped product B, and if necessary, the outer surface is provided with irregularities, and the female mold 23 Come inside.

In the above configuration, first, the straight rod 8 and the curved rod 10 constituting the inner rod 7 are butted against each other in the first mold 2, and injection molding is performed by well-known means to form the rough-shaped product B.

Next, the straight rod 8 and the curved rod 10 are respectively retreated to their retracted positions, the rough-shaped product B is taken out and set in the groove 22 of the second mold 3, and the straight rod 25 is moved forward to place the tip of the rough-shaped product B into the rough-shaped product B. curved hole a
A short tube C is formed by injection molding. The short tube C is welded to the rough shaped product B to obtain the product A. Thereafter, by pulling out the straight rod 25, a curved hole a having a predetermined radius of curvature is formed in the product A, and an inner hole e is formed in which straight holes a and d of a required length are connected on both sides of the curved hole a. In addition, in Fig. 5, Bs, Cs
are threaded portions formed at both ends of the molded product A, and although the illustrated example shows an example in which they are formed during injection molding, these may also be formed by machining after molding.

Next, FIGS. 6 to 10 show a second embodiment. 1st above
In the example, the molding of the rough-shaped product B and the short tube C were performed separately, but in this example, the rough-shaped product 82 (see Fig. 10) is formed in the first step as in the previous example. , and an example in which the short tube C is formed in the second step and the first and second steps are performed simultaneously.

The molding die 30 includes a pair of upper and lower movable molds 31 and 32, and a female die 33 for molding a rough-shaped product and a groove 34 for storing a rough-shaped product are formed on the mating surfaces 31a and 32a of both molds with a gap between them. are provided in parallel to each other, and the aforementioned female die 35 for forming a short tube is continuously provided in the groove 34. That is, the first mold 2 and the second mold 3 of the previous example are installed in series, and the female mold 33 for molding a rough-shaped product has a straight rod 8, similar to the previous example.
A bent rod 10 and its respective transition means 9, 11, and a straight rod 25 and its transition means 26 for the short tube forming female mold 35.
Equipped with. These have the same structure as the previous example, are given the same reference numerals, and description thereof will be omitted. Further, this molding die 30 is provided with a transfer blade 36 on the mating surfaces of both movable dies 31 and 32 as a means for conveying the rough-shaped product. This blade 36 is attached to the rough-shaped product B2 when the rough-shaped product B2 is formed, and the blade 36 is transferred to the storage groove 34, and the transfer means 37 is constituted by, for example, a hydraulic cylinder.

Note that the procedure for attaching the blade 36 to the rough-shaped product B2 is as described in No. 9.
As shown in the figure, the blade 36 is, for example, a flat trapezoid buried in the upper surface of the rough-shaped product B2, and prevents it from falling during transportation, fixes the coarse-shaped product B2, and allows the blade 36 to be pulled out. It is preferable that the blade attachment mark 36a (FIG. 10) to be formed later be to the extent that it does not cause any trouble or can be easily maintained. The figure shows a blade 36 whose upper surface is aligned with the upper surface of IJI type B2 as shown in FIG. It is provided to protrude from the surface 32a.

In the figure, 38 indicates each female mold 3 for forming the rough-shaped product B2 and the short pipe C.
3. It is a common runner connected to 35, and 40 is a concave groove 3.
This is a support rod for rough shapes supplied to No. 4. This support rod 40 may be moved forward and backward by a separate transition means, but in order to simplify the structure, a bracket 41 is used to move the straight rod 8 forward and backward.
shows the structure connected to.

In the above configuration, the two movable molds 31 and 32 are put together, the straight rod 8 and the curved rod 10 are inserted into the female mold 33 for molding a rough-shaped product, and when the rods 8 and 10 are butted together, the molten plastic is melted from the runner 38. is press-fitted into the female mold 33 to form a rough-shaped product B2. In this case, as shown in FIG. 9, the rough-shaped product B2 is injection-molded with the transfer blade 36 attached thereto. At the same time, molten plastic is also supplied to the female mold 35 for forming short tubes.
This will be discussed later.

Next, both movable types 31 and 32 are opened, and straight rod 8 and curved rod 1 are opened.
0 to the retracted position, and the transfer blade 36 is advanced one pitch, that is, the attached rough-shaped product B2 is moved to the storage groove 3.
4, polymerize the moving molds 31 and 32, and form a coarse product B2.
is stored in the concave groove 34, and the support rod 40 is advanced together with the straight rod 8 by the transition means 9 and inserted into the inner hole of the rough-shaped product B2, and at the same time, the curved rod 10 and the short tube forming female mold 35 are inserted. Move the rod 25 forward. Next, the transfer blade 36 is pulled out against the joining with the rough-formed product B2 and moved back one pitch.

After that, injection molding of the short pipe C is carried out together with the rough-shaped product B2 through the runner 38. In this case, the tip of the rough-shaped product B2 is the small diameter part Ba that protrudes into the female mold 35 as explained in the previous example.
The short tube C is welded to the rough-shaped product B2 to form a product, that is, a molded product A2.

Thereafter, the above-mentioned operation is repeated and the molded product A2 formed is sent out from the mold 30 by the transfer blade 36.

The sent-out molded product A2 is prevented from going back at the outer edge of the mold 30, and is pulled out by the returning movement of the transfer blade 36.

In this case, the runner D remaining in the runner 38 is suitable for -13.
= It is cut at the supply port by appropriate means, adheres to the rough-shaped product B2 and the short pipe C, and is transferred. Therefore, mobile type 31, 32
A concave groove for housing the runner D is provided, but it is not shown.

Although the above embodiment shows an example in which one transfer blade 36 is used as a means for conveying the rough-shaped product B2, it is also possible to provide two parallel transfer blades with a gap between them. Often, the design can be changed without departing from the spirit of the invention.

〔Effect of the invention〕

According to the present invention, a plastic molded product such as a casing cap with a curved hole in the center and straight holes at both ends is formed by injection molding in two steps, so it is not divided into upper and lower parts than in the past. It is extremely efficient compared to the method of molding and gluing the same, and since it does not have an adhesive surface, it has advantages such as there is no risk of peeling as in the conventional method.

[Brief explanation of drawings]

1 to 5 relate to the first embodiment, FIG. 1 is an overall plan view of the molding die with the upper movable die omitted, and FIG. 2 is the first embodiment.
A cross-sectional view along the line I-I in the figure, Fig. 3(a), (
b) are the lines II-II and 11+ in Fig. 1, respectively.
4 is a partially cutaway plan view of the roughly shaped product, FIG. 5 is a partially cutaway plan view of the molded product, and FIGS. 6 to 10 are related to the second embodiment. , Figure 6 is an overall plan view of the molding die with the upper movable mold omitted, Figures 7 and 8 are
9 and 9 are cross-sectional views taken along lines IV-IV, V-V, and Vl-Vl in FIG. 6, respectively, FIG. 10 is a perspective view of a molded product, and FIG. 11 is a conventional manufacturing method of a molded product. It is an explanatory diagram of the procedure. 1 is a molding mold, 2 is a first mold, 3 is a second mold, 4.5
6 is a moving type, 6 is a female type, 7 is an inner rod, 8 is a straight rod, 9 is a straight rod transition means, 10 is a curved rod, 11 is a curved rod transition means, 20, 21
22 is a concave groove, 23 is a female type, 25 is a straight rod, 26
30 is a straight rod transition means, 30 is a mold for molding, 31.32 is a movable mold, 33.35 is a female mold, 34 is a groove, 36 is a transfer blade, 37 is a blade transition means, A and A2 are molded products , B
, B2 is a rough-shaped product, and C is a short tube. Figure 7 Figure 11

Claims (4)

[Claims] (1) An inner rod is constructed by a straight rod of the required length and a curved rod of a predetermined radius of curvature, and this inner rod is used to form a rough-shaped product that has an inner hole with a curved hole and a straight hole at one end. The required radius of curvature is achieved by the first step of injection molding the rough-shaped product, and the second step of inserting a straight rod of the required length into the open end of the curved hole, connecting it to the rough-shaped product, and injection molding a short pipe. 1. A method for molding a plastic molded product having a curved hole, the method comprising forming an inner hole with straight holes of a required length on both sides of the hole. (2) A forming means for performing the first step of forming a rough-shaped product and a forming means for performing a second step of forming a short tube are arranged adjacent to each other, and the rough-shaped product is transferred to the forming means for the second step by a conveying means. Claim 1 is characterized in that the molding means of the first step and the second step are provided with a common runner, and the rough-shaped product and the short tube are simultaneously injection molded. A method of molding a plastic molded product having a curved hole as described above. (3) A first molding die for injection molding a rough-shaped product having a curved hole with a predetermined radius of curvature and a straight hole connected to one end thereof, and a first mold for injection molding the rough-shaped product, which is connected to the open end of the receiving curved hole. and a second molding die for integrally injection molding a short tube with a straight hole on one end of the rough-shaped article, and the first molding die forms the outer shape of the rough-shaped article on the mating surface. It is equipped with a pair of movable molds forming a female mold and an inner rod forming an inner hole of the rough-shaped product, and the inner rod is made by butting a straight rod of a required length and a curved rod with a predetermined radius of curvature, and the straight rod and the curved rod are formed by butting each other. The rods are provided with transition means for selectively shifting between the abutting position and the retracted position along their respective axes, and the second molding die has a concave groove for storing the rough-shaped product on the mating surface, and a groove for storing the rough-shaped product on the mating surface. It consists of a pair of movable molds with a female mold that forms a short pipe on the open end side of the curved hole, and a straight rod that forms the inner hole of the short pipe. 1. A mold for molding a plastic molded product having a curved hole, characterized in that the mold is provided with a transition means for selectively shifting the position. (4) The first mold and the second mold are integrally formed,
A blade for transferring rough-shaped products is arranged on the mating surfaces of both molds, and the rough-shaped products are injection-molded with the blade attached, and are fed into the rough-shaped product storage groove of the second mold by the transfer of the blade. Claim 3 is characterized in that a common runner is connected to each of the first and second female molds, and a coarse-shaped product and a short rod are simultaneously molded in one shot. A mold for forming a plastic molded product having the curved hole described above.