JPH01101130A - Continuous resin press molding method for resin sheet - Google Patents

Abstract

PURPOSE:To surely resolve the problem of sink marks in the molded part of draw molding or the molded part with uneven pattern, by a method wherein a molten resin is continuously extruded from a die on one side to prepare a resin sheet, while a molten resin is intermittently extruded from the other side die, and is superimposed upon the former resin sheet intermittently. CONSTITUTION:A molten resin is continuously extruded from a die 1 on one side to form a resin sheet PS, while a molten resin P is intermittently extruded from the other side die 1', and is intermittently superimposed upon the above resin sheet PS. In the intermittent superimposing operation, a unitary thick part T may be intermittently formed in a press molding unit in the longitudinal direction of the resin sheet PS, and the unitary thick part T is used for molding of the sink mark in the case of press molding by the press device 10. When the molten resin P, which is extruded from the die 1' in a sheet, bar, or block shape, has reached a preset extrusion size, the extrusion is stopped, a time limit cutter 14 is set in action to cut off the material.

Description

Detailed Description of the Invention: Industrial Application Field The present invention relates to a continuous resin press for a resin sheet, in which molten resin is extruded from a die to form a resin sheet, and press molding is continuously performed using the heat retained in the sheet. Regarding molding methods.

BACKGROUND ART Conventionally, a continuous press-molding method for resin sheets has been known, in which a molten resin extruded from a die is formed into a sheet and continuously press-molded using the retained heat.

The above molding methods include cutting the resin sheet into unit sheets of fixed length and then press forming (forming), and press forming a continuous sheet and then separating it into each molded product. There is. A representative example of the former is Special Publication No. 59-23691, and an example of the latter is USP No. 41.
No. 05386 is known.

The present invention aims at further improving these prior art examples.

The problem to be solved by the invention is that in the above-mentioned previous example, the previously cured resin sheet was reheated and press-formed at the time of molding. It has the advantage of not only being economical and reducing costs as there is no associated energy loss, but also improving quality by avoiding deterioration of physical properties due to reheating. In products having a side wall, there is a problem that a sinking phenomenon occurs mainly on the side wall. This phenomenon is remarkable in the above-mentioned continuous resin press molding method that utilizes retained heat immediately after sheet molding.

In order to deal with the above problem, the amount of meat sinkage mentioned above is estimated in advance,
One possible method is to increase the thickness of the entire resin sheet and then subject it to press molding. However, this method results in an unnecessarily thickening of the thickness of the part that does not normally cause wall sinkage, which not only lacks economic efficiency, but also increases the weight of the product and makes it expensive.

For this reason, conventionally, after press-forming a product, a separately molded part is tightened with staples, rivets, etc. only at the sink part to reinforce it, but although this method can solve the above-mentioned problem of increased weight, It has the disadvantage of being extremely expensive and requires an additional process.

The present invention was provided with the intention of effectively solving the problem of the shrinkage phenomenon inherent in the continuous resin press molding method in the continuous resin press molding method without adopting the above-mentioned subsequent reinforcement method. It is something.

Means for Solving the Problems The present invention provides a means for solving the above problems in a continuous resin press molding method in which molten resin is extruded through a die to form a resin sheet and press molding is performed while forming the resin sheet. By intermittently extruding molten resin from another additional die and intermittently superimposing it on the resin sheet,
By intermittently forming unit thick parts in the longitudinal direction of the resin sheet in units of press-formed products, and using each unit thick part as a molded part of the sink part during the press molding, This method solves the problem of wall sink easily, reliably, and rationally during the process of continuous resin press molding by simply adding a die and without any subsequent processing.

In another embodiment, the molten resin superimposed on the resin sheet is formed into sheet pieces to form each of the unit thick parts, so that the problem of wall sink during press molding can be solved.

As described above, the present invention intermittently forms the unit thick part of each press-formed product by superimposing the molten resin extruded from another die on the part corresponding to the sink part in the process of forming a resin sheet. By simply forming and press-forming, the problem of sinking in the deep-drawn portion or the relatively deep concavo-convex portion can be reliably solved, and the means for doing so are simple and rational.

When implementing the present invention, only a means for extruding molten resin for intermittent overlapping is added, and the basic line of the continuous resin press molding method, which consistently performs resin sheet formation and press molding, does not require any major changes. Moreover, the reinforcement after press molding as in the conventional example can be omitted, and as mentioned above, an appropriate problem can be solved in the continuous resin press molding method, and the advantages of the continuous resin press molding method can be fully utilized.

In addition, it does not make the parts outside the sink part excessively thick, making it a very effective solution for vehicle parts and the like where weight is an issue.

EXAMPLE Hereinafter, the continuous press molding method of a resin sheet according to the present invention will be explained by taking as an example the case (see FIG. 1) carried out in accordance with the above-mentioned Japanese Patent Publication No. 59-23691 owned by the applicant.

The molten resin is continuously extruded from the die 1 of the extruder, and is passed through a pair of sheet forming rolls 2 kept at a temperature lower than the melting point of the molten resin to form a sheet.
After the S is further rolled around a temperature control roll 3 to obtain the required surface rigidity and heat softening property, it is taken up by a take-up roll 4 and conveyed to a cutting device 5, where it is sequentially cut into unit lengths.

Next, each unit resin sheet PS' is conveyed to the press device 10 by the conveyor 6 and 'f, and is fed into the lower mold 10a of the press device 10 using a sheet feeder, for example, the vacuum feeder 9, and immediately transferred to the upper mold. Press molding is performed by lowering 10b.

The input side of the press device 10, that is, the conveyor 6.

A temperature control furnace 8 is disposed in the conveyance process 7 to control the temperature of the unit resin sheet PS' to a temperature suitable for press immersion and moldability.

Therefore, the present invention provides a continuous resin press molding method in which a molten resin is extruded to form a resin sheet and press-molded as illustrated above, while continuously extruding the molten resin from one die 1 to form a resin sheet PS. , the molten resin P is intermittently extruded from the other die 1° and is then applied to the resin sheet PS.
By the intermittent superposition, the resin sheet PS
A unit thick wall part T is intermittently formed in the longitudinal direction of the press-formed product, and the unit thick wall part T is used as a forming part of a sink part during press forming by the press device 10. It is.

The molten resin P and the resin sheet ps are preferably used in the die 1.
．． For example, the molten resin extruded from the die 1 is placed on the introduction side of the sheet forming roll 2, and the support is supported by the roll while forming the sheet. Due to the tensile force of roll 2, the same roll 2
The resin sheet PS is stretched between the die 1 and the die 1, and the resin sheet PS before passing through the stretched sheet forming rolls is
The molten resin P extruded from the die 1° is superimposed on the top to promote base material fusion.

In addition, the molten resin P intermittently extruded from the other die 1° is made into a resin sheet piece PS'' as shown in the figure, as an example.
It overlaps the surface of the continuous resin sheet ps extruded from one of the dies. On the other side, the molten resin P is made into a lump or rod shape and is superimposed on the surface of the resin sheet s to fuse the base material.

When the molten resin P extruded from the die 1° in the form of a sheet, rod, or block as described above reaches a predetermined extrusion size, the extrusion is stopped and the timed cutter 14 is activated to cut the resin Serve. The resin sheet PS on which the molten resin P has been superimposed is passed through a sheet forming roll 2 consisting of a constant-pressure reduction roll to make the thickness of the overlapped part and the general molded part uniform and to form the surface, as shown in FIG. A unit thick portion T is formed on one surface of the resin sheet ps.

In this case, the opening width of the resin extrusion port of the die 1° can be adjusted and controlled so that the extrusion of the resin sheet piece ps'' can be set arbitrarily, and the width of the opening of the resin sheet PS can be set at the desired position in the width direction. so that the resin sheet pieces PS'' can be overlapped. In FIG. 2, reference numeral 15 indicates a region that will become a press-formed product, and the unit thick wall portion T will be used as a drawing portion of the press-formed product.

Further, FIG. 8 shows a splash board for preventing water from splashing on the side surface of a tire in a vehicle as an example of the press-formed product 12, but this splash board has a deep-drawn part 12a which tends to cause fillet sink where the drive shaft passes. It involves press forming.

As shown in FIG. 9, a unit thick portion T is formed in advance by superimposing the molten resin P at a portion corresponding to such a deep drawn portion 12a. As shown in the same figure, the unit thick portion T is formed to have the same width over almost the entire width in the transverse direction of the resin sheet PS, or is formed to have a smaller width than the transverse width of the sheet, and is formed to have a width smaller than the transverse width of the resin sheet PS. The deep-drawn part 12 of each press-formed product 12 is formed by dividing the press-formed product 12 into two pieces in the direction, and forming two pieces from one end side and the other end side of the unit thick portion T.
Use for press molding in a.

The sheet forming roll 2 is a constant pressure reduction tension roll with a variable gap, and as shown in FIG.
That is, while performing pressure forming of the sheet in the general forming section other than the deep drawing section 12a, the superposition of the resin sheet pieces PS'' is started, and then, as shown in FIG. 3B, the resin sheet pieces PS'' are formed as required. When the length is reached, the cutter 14 is activated to cut it and complete the stacking process, and the sheet forming roll 2 follows the introduction of the stacked part of the resin sheet piece ps'', and the gap becomes a wide gap and is rolled down. The unit thick portion T is formed into a sheet while being fed.

Further, as shown in FIG. 3C, after forming the unit thick portion T, the gap between the sheet forming rolls 2 is again in the state shown in FIG.
Return to step I*) and perform thin sheet molding in the general molding section.

Similarly, the take-up roll 4 uses an adjustable roll that increases the gap in response to the arrival of the unit thick portion T and returns to its original position after passing. For example, one of the take-up rolls 4 may be elastically loaded with a spring or an air cylinder, and the gap may be self-adjusted depending on the thickness of the sheet, or the gap may be controlled to vary in timing.

The cutter of the cutting device 5 is one that automatically returns after cutting, and is controlled to operate intermittently at timings such that each unit resin sheet has a certain length and a unit thick portion exists at a certain position.

As described above, the position, size, and number of the unit thick portions T formed by superimposing the resin sheet pieces ps'' are set according to the position, size, and number of the deep drawn parts 12a of the press-formed product 12.

For example, FIG. 4 shows a resin sheet p formed by the method shown in FIG.
An example in which a single uniform-width unit thick part T is intermittently formed in the longitudinal direction of s for each press-formed product unit, and is cut at a thin part that is a general molded part to form the unit resin sheet PS °, FIG. 5 shows an example in which the pattern shown in FIG. 4 is cut at unit thick portions T to form unit resin sheets PS°.

FIG. 6 shows an example in which a plurality of unit thick parts T are formed for each unit press-formed product, and FIG. 7 shows an example in which a plurality of unit thick parts T are formed for each unit press-formed product by the method shown in FIG. A case will be exemplified in which each unit thick portion is made narrow or wide depending on the size of the deep drawing portion during forming.

The above-described pattern of the unit thick part T can be freely formed by setting the extrusion and superimposition timings without changing the basic structure of the continuous resin press molding line, and only by adding a means for extruding the molten resin P. be.

By using each unit thick part T formed as described above as a molding part of a sink part during press molding by the press device 10, it is possible to continuously perform press molding from extrusion of molten resin to forming a resin sheet. While carrying out the resin press molding method, the problem of sinking in deep drawing parts, etc., which is a problem in the continuous resin press molding method, can be effectively, simply and rationally solved.

In the above embodiment, the case where the resin sheet PS is cut into unit resin sheets PS° of a fixed length and subjected to press molding was explained. Even when cutting into press-formed products after press-forming, it is possible to effectively solve problems while taking advantage of the features of continuous resin press-forming.

As another example of the present invention, in addition to the case where the resin sheet piece PS" extruded from one die 1° is made of the same material as the resin sheet PS, as shown in FIGS. 10A and B, the resin sheet piece PS"
This shows a case in which a glass fiber-containing resin for the purpose of partially reinforcing a product, such as a glass fiber-containing polyolefin resin, is superimposed.As another example, in order to meet the demand for one side to be soft, a polyolefin-based resin sheet piece PS'' is used. As shown in FIG. 10, which shows the case where the elastomer is superimposed, the inner or outer surface of the upsetting side of the press-molded product is coated with a glass fiber-containing resin layer or a soft resin layer.

Effects of the Invention As explained above, the present invention can reduce the unit thick part of a press-molded product by superimposing molten resin extruded from another die on the part corresponding to the sink part during the process of forming a resin sheet. By only forming the material intermittently and subjecting it to press molding, the problem of sinking in the deep drawn portion or the relatively deep concavo-convex molded portion can be reliably solved, and the means for doing so are simple and rational.

According to the present invention, by simply adding a means for extruding molten resin for intermittent superposition, new changes such as additional steps can be made to the basic line of the continuous resin press molding method, which consistently performs resin sheet formation and press molding. Without reinforcement after press molding as in the example, it is possible to effectively utilize the advantages of the continuous resin press molding method as described above and to appropriately solve problems in the same continuous resin press molding method.

In addition, it does not make parts other than the sink area excessively thick, making it an extremely effective solution for vehicle parts where weight is an issue, and it is easy to achieve uniform wall thickness of the entire product as a result of press forming. became.

Further, by carrying out the present invention, the degree of freedom in the taper angle of the deep drawing section and the curvature of the drawing surface can be significantly improved.

In addition, by adding dies and changing the extrusion timing, etc., a simple control method allows you to easily form various patterns of unit thick parts according to the shape of the press-formed product, making it easy to respond to various press-formed products. If properly planned, the versatility of the continuous resin press molding method can be significantly increased.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG. 1 is a side view schematically illustrating the structure of an implementation line of the present invention, FIG. 2 is a plan view of a resin sheet having a unit thick part, and FIGS. 3A and B. , C is a side view illustrating the operation process of superimposing molten resin on a resin sheet;
7 to 7 are side views illustrating formation patterns of unit thick parts in a resin sheet, FIG. 8 is a perspective view illustrating a press-formed product having a deep drawing part, and FIG. 9 is a side view illustrating the formation pattern of unit thick parts in a resin sheet. Figures 10A and 10B are plan views illustrating the production of products from a resin sheet having a unit thick part corresponding to the unit thick part, and Figures 10A and 10B are press forming of the deep drawing part of an example in which glass fiber-containing resin is used as the resin sheet piece. Figure A shows the case where the inner surface of the deep drawing part is covered with a glass fiber-containing resin sheet piece, and Figure B shows the case where the outer surface is covered with the same sheet piece. . 1... Extrusion die for resin sheet, 1°... Extrusion die for molten resin for superposition, 2... Sheet forming roll, 4...
・Take-up roll, 10... Press device, 13... Receiver is roll, P... Molten resin for superposition, ps... Resin sheet, ps'... Unit resin sheet, ps''... Resin Sheet piece, T... unit thick part. Fig. 4 Fig. 6 Fig. 7 Fig. 7 PS' Fig. 8 Fig. 9 Fig. 10 (A) PS' Fig. 10 (B) 1 b ps'

Claims (2)

[Claims] (1) The molten resin is continuously extruded from one die to form a resin sheet, while the molten resin is intermittently extruded from the other die and overlapped with the resin sheet intermittently, so that the resin sheet can be formed in the longitudinal direction of the resin sheet. A continuous resin press molding method for a resin sheet, characterized by intermittently forming unit thick parts of a press molded product, and using each unit thick part as a molding part of a sink part during press molding. . (2) A continuous resin press for a resin sheet according to claim 1, characterized in that the molten resin intermittently extruded from the other die is made into short and small sheets and intermittently overlapped with the resin sheet. Molding method.