JPS62299319A - Manufacture of cylindrical part with surface tissue from thermoplastic resin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention provides a method for manufacturing a rod-shaped part with a surface texture, particularly a grab rod with a rack for an unprotected loom, from a thermoplastic resin. Regarding.

[Conventional technology]

Such a grab bar is known, for example, from German Patent No. 171
It is described in Publication No. 0293. The grab bar in this publication is composed of a tooth-shaped inner part made of, for example, compression molded synthetic resin, and a holding part with a U-shaped cross section that surrounds this inner part from three sides and is attached to it. ing. In this case, a high bending strength is achieved, on the one hand, by the connection of the hollow holding part with the inner part, and, on the other hand, by the non-cutting shaping of the inner part in compression molding.

This bending strength is further increased because on both sides of the inner part there are threaded webs approximately at the height of the teeth that contact the inner face of the U-shaped holding part. In the case of such grab bars, there is an impeccable adhesion between the inner part and the holding part, as well as the longitudinal strength of the tooth-shaped inner part, which has to absorb all the forces that occur during the drive of the grab bar in the direction of movement of the grab bar. is very important.

A disadvantage of such racks is that their manufacturing process is complex. This rack is made from two parts which must be connected to each other, for example by gluing. Generally, the inner part or rack is made of synthetic resin, and the holding part that supports it on three sides is made of metal as a hollow part with a U-shaped cross section.

Another grab bar configuration is known from DE 35 27 202 A1. In order to better absorb the forces occurring during the drive of the grab bar, the rack is made of thermoplastic tape reinforced with fibers laminated to each other and connected to each other by compression and heat treatment, the fiber direction being synthetic. It is located in the longitudinal direction of the resin tape. The required tooth shape is then obtained by various height-dependent punchings in each plastic tape.

In other words, cutting work on this rack during manufacturing can also be avoided.

This glove dedication is the above-mentioned patent number 171 of the Federal Republic of Germany.
Compared to the grab bar of Publication No. 0293, it has the advantage of being lightweight without the need for a two-part structure, but the longitudinal strength obtained thereby cannot satisfy even more severe conditions. Furthermore, the method of manufacturing the grab bar is very complicated.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for manufacturing a tooth-shaped grab rod with high strength while maintaining lightness at the lowest possible manufacturing cost.

[Means for solving problems]

According to the invention, this object is achieved by the measures specified in the characterizing part of claim 1. Advantageous embodiments of the invention are set out in the embodiment section of the patent claims.

The main part of the method of the invention is an injection step, known per se, which increases the strength of the material in cooperation with the subsequent stamping step. The molecular chains oriented in the longitudinal direction of the product during injection likewise begin to crystallize very quickly in the same direction, since the temperature of the melt is just above the crystallization temperature of the synthetic resin. In the subsequent stamping process, this basic structure is superimposed with the structure generated in the local flow process caused by the stamping ram, and the melt crystallizes into the so-called Shish-Kabab structure, which is unique to its Strength is characterized by greater stiffness and strength.

(Example〕 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a die 1 and a ram 2 in a perspective view, and here, for the sake of simplicity, the injection nozzle, the riser and the injection molding machine itself are not shown. The ram 2 closes the die 1 from above when injecting the synthetic resin melt 3.
a s and is used as a ram carrier for the stamping ram 2b required in the subsequent process with a groove shape on the surface.

Next, the method of the present invention will be explained with reference to FIG.

In the first step shown in FIG. 2a, injection molding is carried out in a known manner. The heated thermoplastic resin 3 is then injected into the main mold.

The thermoplastic resin 3 is in a temperature range just above its crystallization temperature. The main mold consists of a die 1 with a U-shaped cross section and a flat ram 2a which closes the open side of the die 1 and is supported by a ram carrier.

The injection nozzle and riser are selected to ensure a continuous flow of the synthetic resin melt 3 and promote orientation of the polymer. The flow process that occurs during injection causes an orientation of the polymers extending in the longitudinal direction of the injection molded article, which improves the strength properties of the material. The large pressure required for injection must be applied by the ram force FS on the fixed die 1 on the one hand and on the movable ram 2 on the other hand.

Figure 2b shows that the flat ram 2a and the stamping ram 2 have been completely lifted from the die 1 in the second step to take up the position required for the stamping step shown in figure 2c.
It shows that the displacement is by the ram distance S between b and b.

A stamping pressure Fp is applied to the synthetic resin melt 3 by the stamping ram 2b.
When molding by giving a
The surface groove shape is oriented in accordance with the shape of the surface.

In the subsequent third step, the synthetic resin melt 3 is transferred to the stamping ram 2.
It is cooled while maintaining the pressure applied by b. Maintaining this pressure promotes crystallization of the material and creates a serial structure. This serial structure positively influences the mechanical properties of the material in the direction of orientation.

Depending on the selected surface profile of the stamping ram 2b, it is also conceivable that from the beginning only one ram, the stamping ram 2b, is used in the entire process.

This eliminates the need to replace the ram, and replaces ram 2 with die 1.
This eliminates the need for lifting from the ram and prevents oriented molecular chains from becoming unoriented during the pressure relief caused by ram exchange.

Figure 3a is a schematic cross-sectional view of a rack 4 made by the method according to the invention. The orientation 5 of the molecular chains according to the surface profile is shown schematically. The orientation 5 then follows the shape of the teeth 6 of the rack 4, which strengthens the areas that are highly loaded during operation of the rack 4.

In order to increase the strength of the rack 4, lateral webs 7 can also be provided, which requires only slight changes in the shape of the marking ram 2b.

Although the example of a grab rack has been described, the invention can be applied in many other fields in the production of rods or rod-shaped parts with a suitable surface profile.

The advantage of the method of the invention is not only the simplicity of the method and the ease of manufacture of its products, but also the fact that the products made with this method can be made of light weight and great strength.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the die and ram; FIGS. 2a, 2b, and 2c are cross-sectional views of the die and ram in various steps; FIGS. FIG. 1... Dice, 2... Ram, 2a... Flat ram, 2b... Engraved ram, 3... Synthetic resin melt.

Claims (1)

[Claims] 1. A method for manufacturing a rod-shaped part with a surface texture from a thermoplastic resin, especially a grab rod with a rack for an unprotected loom, comprising: a) a whole consisting of a die (1) and a ram (2); injecting the thermoplastic resin heated to a temperature somewhat above the crystallization temperature into a closed flat main mold; b) injecting the desired structure in the same die (1) after separating the injection unit; A method for manufacturing a rod-shaped part with a surface texture from a thermoplastic resin, characterized by: modeling under pressure using a stamping ram (2b) equipped with c) cooling while maintaining the pressure. 2. A method according to claim 1, characterized in that the injection nozzle and the riser ensure a continuous flow of synthetic resin melt during injection. 3. The method according to claim 1 or 2, characterized in that the riser is attached so that the orientation of the melt in the semi-finished product is in the direction of the load that the bar-shaped part will receive in the future. . 4. The method according to claim 1, wherein the melt has a temperature in the range of the crystallization temperature of the material during injection. 5. a) A thermoplastic resin heated to a temperature slightly higher than the crystallization temperature is injected into a completely closed flat main mold consisting of a die (1) and a ram (2), and b) an injection unit. from the thermoplastic resin by molding in the same die (1) under pressure with a stamping ram (2b) with the desired structure after separation, and c) cooling while maintaining the pressure. In an apparatus for producing bar-shaped parts with a surface texture, a common ram carrier is provided with a flat ram (2a) for closing the die (1) during injection and a stamping ram (2b) with a shape corresponding to the desired profile. ) is arranged and the ram carrier is displaceable relative to the die (1) in such a way that a flat ram (2a) or a stamped ram (2b) is alternately located opposite the die (1). A device for manufacturing rod-shaped parts with surface texture from plastic resin.