JPH04305437A - Mold for mutually welding end parts of thermoplastic resin strips - Google Patents

Abstract

PURPOSE:To reduce the generation of the flush of a molded product by providing a protruding surface whose width is slightly smaller than that of a female mold to a male mold and setting the depth of the groove larger than the thickness of a thermoplastic resin strip and constituting the male mold of a material having the coefficient of linear expansion larger than that of the material of the female mold. CONSTITUTION:In such a state that a male mold 1 and a female mold 2 are heated, the gaps between the side walls constituting the groove 20 of the female mold 2 and the side walls of the protruding surface 10 of the male mold 1 become smaller than those at the time of room temp. and the protruding amount of a thermoplastic resin is reduced. In the mold K consisting of the male mold 1 and the female mold 2, the female mold 2 is constituted of an iron material and the width of the upper surface of the groove 20 is set to 300mm and the common difference.upper limit thereof is set to +0 and the common difference.lower limit thereof is set to -0. The male mold 1 is made of an aluminum material and the width of the under surface of the protruding surface 10 is set to 30.0mm and the common difference.upper limit thereof is set to +0 and the common difference.lower limit thereof is set to -0 to set the depth of the groove 20 of the female mold 2 to about 2-3 times the thickness of a belt 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of this application relates to a mold for fusing the ends of thermoplastic resin strips together.

0002

[Prior Art] When joining the ends of belts made of thermoplastic resin, the ends of the belts are butted together, and this butt part is pressed with a mold K and the mold K is heated. , this allows for fusion. The above-mentioned mold K is composed of a male mold and a female mold made of iron. Taking into account the mutual insertion and removal of these molds, the mold K is designed so that when the male mold and the female mold are mated, they form a so-called clearance fit. be.

Therefore, in the heating process for the belt described above, as shown in FIG. 9, the molten resin protrudes from the gap between the male die 1 and the female die 2, and this protruding portion becomes a so-called burr after solidification. Therefore, a step of removing the burrs was required after demolding. The work of removing this burr is very troublesome and takes a lot of time.

0004

[Problems to be Solved by the Invention] Therefore, an object of the invention of this application is to provide a mold for fusing the ends of thermoplastic resin bands to each other, which reduces the occurrence of burrs in molded products. do.

[0005]

[Means for Solving the Problems] The invention according to claim 1 of this application relates to a mold for fusing the ends of a thermoplastic resin band to each other, and the mold is compressed in an assembled state and the thermoplastic resin is melted. It consists of a female mold and a male mold that are heated to such an extent that the female mold has a groove slightly larger than the width of the thermoplastic resin band, and the male mold has a groove that is slightly larger than the width of the thermoplastic resin band. A protruding surface with a width slightly smaller than the groove width is formed, and the depth of the groove is set larger than the thickness of the thermoplastic resin band, so that the male die has a coefficient of linear expansion that is lower than that of the female die. It is made of large material.

[0006]

[Operations] The invention of this application has the following functions. In this invention, since the male die is made of a material with a larger coefficient of linear expansion than the female die, when the male die and the female die are heated, the side wall forming the groove of the female die and the side wall that forms the groove of the female die fit into this. The gap between the side walls of the protruding surfaces of the male mold thus formed is smaller than that at room temperature, and the amount of molten thermoplastic resin protruding from the gap is small.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the invention of this application will be explained below with reference to the drawings showing examples. This example uses a thermoplastic resin conveyor belt (width: 3 mm) with embedded Kevlar fibers.
The invention of this application is adopted to form a loop of Kevlar fiber 3 as shown in Figure 1.
Both ends of the belt 3 in which the number 0 is embedded are formed into finger shapes, and as shown in FIG. 2, the finger-shaped portions are butted against each other and fused together.

In order to join the ends of the belt 3 as described above, a mold K consisting of a male mold 1 and a female mold 2 as shown in FIG. 3 is used. The female mold 2 is made of iron material, and as shown in FIG. ) is set.

The male mold 1 is made of aluminum material, and as shown in the figure, a protruding surface 10 is formed on its lower surface, and the width of this protruding surface 10 is 30.0 mm (tolerance:
Upper limit +0, lower limit -0.02). and,
The depth of the groove 20 of the female mold 2 described above is 2 times the thickness of the belt 3.
It is set to about 3 times as much.

Here, when the press machine 9 shown in FIG. 6 is equipped with a heating/cooling plate 4 serving as a heat source and a cooling source in the pressing part 90 and the mold K described above, the following results are obtained. The ends of the belt 3 can be joined together in this order. ■． The ends of the belt 3 are formed into finger shapes as shown in FIG. ■． As shown in FIG. 4, with the finger-like parts abutted against each other, the abutted parts are fitted into the grooves 20 of the female die 2, and then the male die 1 is assembled to the female die 2. In addition, in this combined state, the state is as shown in FIG. 7, and the fitted state of the male mold 1 and the female mold 2 is a clearance fit. ■． Next, as shown in FIG. 6, the central portion of the mold K (the portion to be joined) is compressed via the heating/cooling plate 4 which has been heated by the press machine 9 described above.

In this example, the male die 1 is made of aluminum (linear expansion coefficient: 23.5 x 10-6), and the female die 2 is made of iron (linear expansion coefficient: 12.1 x 10-6). ), so when the belt 3 is heated to about 180°C where it melts, the fitting state between the protrusion 10 of the male mold 1 and the groove 20 of the female mold 2 is as shown in FIG. This is a so-called stop fit or interference fit. Therefore, compared to the conventional mold K of this type, the occurrence of burrs is extremely small as described in the section of the effect. ■． After a certain period of time has elapsed, when the cooling function of the heating/cooling plate 4 is activated, the two ends, which had been melted, are brought into a bonded state.

[0012] Thereafter, when the belt 3 is removed from the mold K, a loop-shaped belt is completed. In the above embodiment, the male member 1 is made of aluminum material, and the female member 2 is made of aluminum material.
are made of iron, but if the male mold 1 is made of a metal having a larger coefficient of linear expansion than the female mold 2, substantially the same effect can be obtained. For example, there is a combination of magnesium and an amber type alloy.

[0013] In addition, regarding the above embodiment, if at least the surfaces of the male mold 1 and the female mold 2 constituting the molding space were treated with Metaflon, the releasability of the molded product from the mold K was improved. In addition, Metaflon treatment can be made thinner than, for example, chrome plating treatment, so it has less influence on expansion. Further, in the above embodiments, the mold of the present invention was used to join both ends of a conveyor belt, but the invention is not limited thereto, and any thermoplastic strip can be joined in the same way.

Regarding the mold of the above embodiment, the female mold 2
A plurality of grooves 20 may be formed on the male die 1, and a protruding surface 10 corresponding to the grooves 20 may be formed on the male mold 1.

[0015]

Effects of the Invention Since the invention of this application has the above-described configuration, it has the following effects. With this product, only a small amount of molten thermoplastic resin protrudes from the gap between the side wall of the female mold groove and the side wall of the protruding surface of the male mold inserted into it, so burrs occur in the molded product. will be less. That is, it has been possible to provide a mold for fusing the ends of thermoplastic resin bands to each other, thereby reducing the occurrence of burrs in molded products.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of belt ends joined by a mold according to an embodiment of the present invention.

FIG. 2 is a perspective view of a loop-shaped belt formed by a mold according to an embodiment of the present invention.

FIG. 3 is a perspective view of a mold according to an embodiment of the invention.

FIG. 4 is a diagram showing a belt to be joined to a mold according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of a mold according to an embodiment of the invention.

FIG. 6 is a diagram showing a method for manufacturing a loop-shaped belt using a mold according to an embodiment of the present invention.

FIG. 7 is a sectional view showing a state in which a belt is set in a mold according to an embodiment of the present invention.

FIG. 8 is a diagram showing a fitted state of a male die and a female die when the die of the embodiment of the present invention is heated to a resin melting temperature.

FIG. 9 is a diagram showing a fitted state of a male mold and a female mold when a conventional mold is heated to a resin melting temperature.

[Explanation of symbols]

1 Male type 2 Female type 10 groove 20 Projection

Claims (3)

[Claims] 1. Consists of a female mold and a male mold that are compressed in an assembled state and heated to such an extent that the thermoplastic resin melts, and the female mold has a mold that is slightly smaller than the width of the thermoplastic resin band. A groove with a large width is formed, and a protruding surface with a width slightly smaller than the groove width of the female mold is formed on the male mold, and the depth of the groove is set to be smaller than the thickness of the thermoplastic resin band. 1. A mold for welding ends of thermoplastic resin bands to each other, characterized in that the male mold is made of a material having a larger coefficient of linear expansion than the female mold. 2. The thermoplastic resin strip according to claim 1, wherein a plurality of grooves are formed in the female die and a protruding surface corresponding to the grooves is formed in the male die. mold for. 3. The mold for welding ends of thermoplastic resin strips according to claim 1 or 2, wherein the male mold is made of aluminum material and the female mold is made of iron material. .