JPH03120022A - Method and apparatus for manufacturing resin molded items - Google Patents

Abstract

PURPOSE:To eliminate mixing of air with the joints of a plurality of resin- molding parts to simply finish the appearance of the joints beautifully by welding the joints together in a metal mold through molten resin. CONSTITUTION:Joints 2, 12 are formed in respective end parts of two resin- molding parts 1, 11. Because stepped section-changing parts 4 are formed in the inner surface side end parts of the resin-molding parts 1, 11, the joints 2, 12 are constituted so as to be thinner than their vicinity. Also, the margins 3, 13 of the joints 2, 12 are formed into edge shapes thinning at ends like 'beveling' in welding. The joints 2, 12 are welded together by molten resin R injected from an injection molding machine. Thus, an integral cowling C is formed, no sinking and warping occur in the section-changing parts of the resin-molding parts after welding, and it is possible to obtain a resin molded item with a beautiful appearance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a resin molded product and an apparatus for manufacturing the same. The present invention relates to a method and an apparatus for producing a desired resin molded product.

(Prior art) Traditionally, there are two methods for manufacturing resin molded products: one is to obtain the desired product by integrally molding the desired product (hereinafter referred to as the "integrated molding method"), and the other is to mold multiple parts separately. There is a method (hereinafter referred to as the split-type molding method) in which the desired product is obtained by first molding the molded parts and then welding the molded parts together to obtain the desired product.

In the above-mentioned integral molding method, a mold large enough to accommodate the product that can be manufactured as a whole is manufactured, and molten resin is injected into the mold to manufacture the desired product. do. Products manufactured using this method have no joints and have a beautiful appearance.

However, since the entire product is integrally molded, if the product is large, the mold becomes very large, and as a result, the molding apparatus as a whole also becomes large. Furthermore, in this case, a large space is required to install the device. Furthermore, technically speaking, larger molds are
It is difficult to achieve high hardness over a wide molding surface,
Furthermore, when the shape of the product is complicated, it becomes very difficult to form the dividing point and the shape of the divided parts due to manufacturing technology, when dividing the upper mold and the lower mold, which fit together and become integral during molding.
In some cases, it can be very difficult to make molds. Further, even in the case of a shape that can be manufactured, a huge amount of cost is required to manufacture the device including the mold etc. for the reasons mentioned above.

On the other hand, in the split molding method, as described above, the entire product is integrally molded by welding a plurality of separate molded parts between their ends to be connected. For this reason, the joint portion appears on the outside. However, on the other hand, there is an advantage that there is no need to manufacture a large mold that can accommodate the entire product, and therefore no large molding equipment is required. In addition, with this method, the entire molding can be performed with a welding device that welds the joints, so the molding device that molds each molded part and the mold for each component only need to be relatively small. 6 As mentioned above, each of the above two molding methods has its own advantages. -For boat fishing, the integral molding method is suitable for relatively small products or products with a relatively simple shape. The split molding method is used to produce relatively large and shaped parts. 3
It is used when manufacturing internal products.

Incidentally, one of the products manufactured by resin molding is the cowling for motorcycles.In recent years, these cowlings have often been made to cover the entire area from the top of the handlebar to the bottom of the engine in order to reduce air resistance and improve aesthetics. In addition, the shape has become more complex in order to reduce air resistance as much as possible.

Like this, large size? For the reasons mentioned above, the above-mentioned split molding method is used to manufacture cowlings having irregular shapes.

The main methods of welding motorcycle cowlings used in the current split molding method are the first method shown in Figs. 11 and 12, and the first method shown in Figs. 13 and 1.
There is a second method as shown in FIG.

In the first welding method, as shown in FIGS. 11 and 12, the parts to be connected are attached to the ends of two molded parts 51 and 61, one from the outside and the other from the inside. Joint part 52.6 where the plate thickness protruding in the direction is halved
2 are respectively formed, and with these joint parts 52 and 62 joined, multiple parts of the joined parts are welded using an ultrasonic welding machine (the welded parts are indicated by X marks in the figure). It was all stopped.

In the second welding method, as shown in FIGS. 13 and 14, two molded parts 51, 61 are joined with their joint parts 52, 62 facing each other, and an inner surface ( The reinforcing plate 55 is brought closer to the rear surface (so-called backing),
The overlapping portions (overlapping portions) 56 and 66 were welded together using an ultrasonic welder (the welded portions are indicated by X marks in the figure) and fixed together.

In all of the conventional welding methods described above, the end surfaces of the two joints are butted against each other on the outer surface of the joint, and the overlapping portion is spot-welded using an ultrasonic welding machine.

Therefore, a gap (referred to as a recess; for example, a recess 54) is formed on the outer surface of the joint between the two joint parts.

Therefore, after welding, a recess (54
) was filled with adhesive to close the gap, and after drying, the solidified adhesive protruding from the outer surface of the joint was scraped off and polished to give a smooth finish.

Thereafter, the cowling with the joints finished and integrated is sent to a painting process where it is painted with a desired color to become a final product (component; cowling).

As a prior art of this type, there is a ``fairing manufacturing method'' (Japanese Patent Publication No. 60-26754) that aims to prevent a decrease in the strength of the divided part at the welded part of a molded part and to prevent deviations and steps from occurring in this part. There is a public notice).

[Problems to be Solved by the Invention] By the way, in the above-mentioned split molding method, by protruding and forming a joining part with half the plate thickness at each end of the resin molded parts to be joined, the resin molding is completed. A wall thickness change portion occurs at the boundary between the part adjacent to the joint of the component and the joint. On the other hand, spot welding is performed mainly at the center of the joint, and welding is not performed at this thickness change area. This results in warping, which impairs the beauty of the product.

Furthermore, as mentioned above, the recess (
Since the final finishing step was to fill in the gaps (gap) with adhesive, the following inconveniences also occurred.

In other words, if the recesses are filled with adhesive and then painted after baking, the air mixed in the adhesive expands due to the heat during painting, causing the paint film to peel off and pins to the painted surface. Holes etc. may occur. In this case, the beauty of the product would be impaired, so the recesses were repaired with adhesive, dried, the outer surface was smoothed, and the product was repainted.

However, products that require the above-mentioned modifications are only discovered after being heated during the painting process, so after discovery, the process is returned to the above-mentioned bonding process and the series of processes described above are repeated again. This results in duplication of processes and worsens productivity.

To improve this, we currently have a correction process before the painting process, in which the joints are preheated to expand the air trapped in the adhesive, and products that have air trapped in the joints are selected in advance and then re-applied. Add correction processing to that part using the adhesive described above.

Then, only the products that have been cleared of mixed air are sent to the next painting process, and the baking process is completed by painting.

However, when looking at actual manufacturing, a high percentage of all products require the above-mentioned modifications or re-modifications, resulting in increased production costs and, above all, a situation in which a large amount of space is required for the modification process. The current situation is that this is occurring. Particularly in the repair process, the adhesive must be stored for the drying time (approximately 12 hours), and a product with a large volume like a cowling requires a large amount of space.

The purpose of this invention is to eliminate the intrusion of air into the joints by welding the joints of a plurality of resin molded parts with molten resin in a mold, and to eliminate the above-mentioned disadvantages in the painting process. Another object of the present invention is to provide a method for manufacturing a resin molded product and an apparatus therefor, which can easily finish the appearance of a joint part beautifully.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a resin molded product in which a plurality of resin molded parts are welded and integrated using molten resin, and in which each end of the resin molded parts to be connected is , forming a joint that is thinner than the thickness of the neighboring parts, covering the joint of the resin molded parts from both sides with a mold consisting of an upper mold and a lower mold, and pouring molten resin into the mold. A method for manufacturing a resin molded product, characterized in that the joint parts to be joined are integrated by injection and welding using the molten resin, and a holding table for holding a plurality of resin molded parts in a predetermined position during welding. is provided near the holding base, and covers the joint formed at the end of the resin molded part and is thinner than the thickness of the joint near the end, and also creates a space between the inner wall of the resin molded part and the joint when mated. An injection molding method comprising a mold consisting of an upper mold and a lower mold to form a mold, an operating means for relatively fitting and disengaging these molds during welding, and an injection port communicating with the space. A manufacturing apparatus for resin molded products is provided.

[Effect]

By the manufacturing method having the above configuration, a joint part that is thinner than the thickness of the adjacent part is formed at each end of a plurality of resin molded parts to be connected, and a mold consisting of an upper mold and a lower mold is used. The molten resin was injected into the space formed in the mold, and the molten resin welded the joints together to integrate them.
The joint portion can be smoothly joined according to the space within the mold.

Furthermore, since the entire surface portion of the joint is bonded using molten resin, no sinkage or warpage occurs due to the stress caused by bonding.

Furthermore, between the joints to be joined in the mold,
Since welding is performed using molten resin, there is no possibility of air entering the joint.

Furthermore, the series of manufacturing methods described above can be carried out by the manufacturing apparatus having the above configuration. That is, a plurality of resin molded parts to be joined are held in a predetermined position by a holding table, and in this state, the actuating means is activated so that each joint formed at the end of the resin molded parts is It is covered from both sides by a mold consisting of a mold and a lower mold. Molten resin is injected from an injection molding machine into the space inside the mold, thereby welding the joints of the resin molded parts together.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method and apparatus for manufacturing a resin molded article according to the present invention will be described below with reference to the drawings (FIGS. 1 to 10), taking the case of manufacturing a cowling for a motorcycle as an example.

1 and 2 show the shapes of the joints of resin molded parts (resin molded parts constituting the cowling) according to the first and second embodiments, and both show the shapes of the joints of the resin molded parts to be welded. FIG. 3 is a perspective view of a state in which the joint portions are in contact with each other, viewed from the inner surface (back surface) side.

In Fig. 1, 1.11 are two resin molded parts to be joined, and these two resin molded parts 1,
At each end of 11 a joint 2.12 is formed.

In the case of this embodiment, the joint 2.12 is connected to the resin molded part 1.
．． By forming the step-shaped cross-section changing part 4 at the end of the inner surface of 11, the vicinity thereof (the side opposite to the joint part of the cross-section changing part 4;
The thickness is thinner than the thickness of both ends (in FIG. 1). Furthermore, the edge 3.13 of the joint 2.12 is formed into an edge shape that becomes thinner at the end, like a groove J in welding.

In addition, in FIG. 2, 2.12 is a joint, and in the case of this joint 2.12, unlike the joint in FIG. It is formed so that the thickness gradually becomes thinner towards the end.

Then, the joint parts 2 and 12 in FIGS. 1 and 2 are welded by a manufacturing device described later with molten resin R injected from the injection molding machine, thereby forming an integral cowling C. be done.

The cowling C formed by this welding has a thickness that is thinner than the thickness of the joint parts 2 and 12 in the vicinity, regardless of whether the joint parts 2 and 12 are welded in either of the configurations shown in FIG. 1 or 2. Therefore, after welding, the joint part 2.12 of the resin molded part 1.11 has the same thickness as the neighboring part. Further, the above-mentioned welding is performed by welding the entire surface of the joint portion (more precisely, the entire surface of the contact surface and the inner surface (back surface)) using molten resin.

Therefore, there is no need for post-processing (finishing), and almost no sink marks or warpage occur at the cross-sectional change portion 4 of the joint portion 2.12.

In particular, if the cross-sections of the joints 2 and 12 are gradually changed as shown in FIG. 2, the concentration of internal stress, etc. on the cross-sectional change portion 4 will be better than in the case of the configuration shown in FIG. As a result, the cross-sectional change portion 4 is less likely to have sink marks or warpage.

By the way, the apparatus shown in FIGS. 9 and 10 is a manufacturing apparatus (welding apparatus) for welding the resin molded part 1.11 having the above-described configuration.

In FIGS. 9 and 10, reference numeral 31 denotes a base of the apparatus placed on the floor 30, and a C-shaped frame 3 is placed on this base 31.
2 is disposed, and a slide bed 33 is further disposed on this C-shaped frame 32.

On this slide bed 33, a holding stand 34 for holding the cowling C is slidably placed by a hydraulic cylinder 37, and a lower mold 35b constituting the mold 35 is arranged on the upper part of the holding stand 34. ing. Therefore, the lower mold 35
b, by expanding and contracting this hydraulic cylinder 37, the holding table 34 and the top of the slide vent 33 below the holding table 34 are moved in the front-rear direction of the device (in FIG. (left and right).

Further, in the upper part of the C-shaped frame 32, a cylinder portion of a hydraulic cylinder 36, which serves as an operating means for fitting and disengaging the mold 35, is arranged such that its rod portion can be freely expanded and contracted downward. .

An upper mold 35a is disposed at the tip of the rod 36a of the cylinder 36. Therefore, this upper mold 35
a by expanding and contracting the rod 36a of the hydraulic cylinder 36, as shown by the solid line and the two-dot chain line in FIG.
It is configured to be movable in the vertical direction.

In addition, near the center of the back side of the C-shaped frame 32, there is a
An injection molding machine 38 is provided, and this injection molding machine 38
An injection port 38a is connected to a sprue (not shown) near the fitting surface 35c of the mold 35.

Incidentally, in the case of this embodiment, the mold 35 is fitted with an inner space formed by fitting the mold 35 so that the joint portion 212 (see FIGS. 1 and 2) has the same thickness as its surrounding area. is formed to be equal to the thickness near the end of the resin molded part.

In addition, in FIG. 9, 39 holds the cowling C on the holding stand 3.
This is the workbench used when attaching and detaching the 4.

Therefore, when welding the joints 2 and 12 of the resin molded parts 1 and 11 using the apparatus having the above configuration, first, the hydraulic cylinder 36 is contracted as shown by the two-dot chain line in FIG. the upper mold 35a is raised upward, and the hydraulic cylinder 37 is extended to move the lower mold 35b (holding table 34) to the ninth position.
Move it to the left end in the diagram. In this state, the lower mold 35
The resin molded part 1.11 to be welded is placed on top of b. At this time, as shown in FIG. 10, the resin molded parts 1 and 11 are held in a predetermined position on the holding table 34 by a plurality of support arms 34a provided below the holding table 34.

Then, by contracting the hydraulic cylinder 37, the holding table 34 is moved to a predetermined position on the right side in FIG.

In this way, when the holding base 34 is set at the predetermined position,
The rod 36a of the hydraulic cylinder 36 is extended to lower the upper mold 35a. When the upper mold 35a is completely lowered, the joint 2.12 of the resin molded part 1.11
(See Figures 1 and 2) are the upper mold 35a and the lower mold 35.
covered from above and below by b.

Through the above series of operations, the joint 2.12 (Fig. 1, 2
(See figure) Welding preparation is completed.

In a state where welding preparations are completed, the joint parts 2, 12 of the two resin molded parts 1.11 are formed by the upper mold 35a and the lower mold 35b, as shown in the cross-sectional view of FIG. 1
2 is sandwiched from above and below, and at this time, a space S is created between the inner wall of the mold 35a and the joint parts 2 and 12, and a space S is created between the inner wall of the mold 35a and the joint parts 2 and 12
A small gap S' is formed between the joint portion 12 and the joint portion 12.

When the welding preparation is completed in this way, the apparatus injects the molten resin R (see FIGS. 1 and 2) from the injection port 38a of the injection molding machine 38. This molten resin R is applied to resin molded parts 1.
A resin different from 11 may be used as long as it can be welded, but it is preferable to use the same resin as resin molded parts 1.11, or a resin with reinforcing fibers such as carbon fiber mixed into the resin. may be used.

The injected molten resin R flows into the space S and the gap S' between the joint parts 2 and 12 from a sprue (not shown) in the mold 35, and welds the joint parts 2 and 12 to form the two resins. Integrate molded parts 1.11.

Then, welding is completed by solidifying the molten resin R (see FIGS. 3 and 4).

Note that the series of operations described above are controlled by an operator's operation and a control device (not shown).

By the way, instead of the above-mentioned joints 2.12, as shown in the cross-sectional view of FIG. 4 and the enlarged cross-sectional view of the main part of FIG. 3. Near 13, resin molded parts 1. ] By forming the protrusion 5 that is equal to the thickness of the part near the joint part 2.12 of 1 or slightly protruding, when the joint part 2.12 is clamped with the mold 35 described above, the upper end of this protrusion 5 is formed. When the inner wall surface of the mold comes into contact with
It is possible to prevent the joint parts 2 and 12 from floating up within the mold 35, and it is possible to hold (press) them at a predetermined position within the mold.

As a result, it is possible to prevent the joint parts 2 and 12, especially the edges 3 and 13, from rising during injection molding, and the joint parts 2 and 12 can be prevented from lifting up during injection molding.
It is possible to prevent the molten resin R from flowing into the portion where the mold 35 and the mold 35 should come into contact.

Further, during welding, the outer peripheral surface of the protrusion 5 is also welded to the molten resin R, increasing the welding area, thereby further integrating the resin molded parts 1 and 11.

Note that, as shown in FIG.
3 and the joint portion 2.12, a plurality of them may be formed near the center of the joint portion 2.12, and the entire surface of the joint portion 2.12 may be pressed against the inner wall surface of the mold 35.

In the above embodiment, a plurality of projections 5 are formed in a cylindrical shape, but as shown in FIG. 7, a square projection 5A may be formed on the edge 3.13, and this shape is not particularly limited It is not something that will be done.

In addition, as shown in FIG.
If the welding surface of the joint 2.12 is formed in a wave shape, the welding area can be increased, compared to the case where the welding surface of the joint 2.12 is formed into a flat surface as shown in FIG. 1 or 2. Therefore, even if the lengths of the joints 2 and 12 are shortened, the same welding strength can be obtained.

Generally, after a plurality of resin molded parts 1 and 11 are integrated in the above-mentioned method, a desired coloring process is applied to complete the resin molded product. However, materials that do not require a painting process (for example, polypropylene, etc.) ), in the gap formed between the abutting joints 2 and 12 of a plurality of resin molded parts 1.11 of the same color (see Figs. 2 to 8),
By injecting and welding molten resin R of another color, a line of the color of molten resin R can be formed in this gap between the colors of the resin molded parts 1.11.

Furthermore, even when the resin molded parts 1 and 11 of different colors are integrated by welding, if the welding is done with the same molten resin R as either of the resin molded parts 1.11, the joining parts 2, 12 Beautiful resin molded products can be obtained.

In the mold 35 described in the above embodiment, the molten resin injected from the injection port 38a provided near the fitting surface 35c of the mold 35 passes through a runner provided in the mold 35 and enters the space. By forming a large number of these runners, the resin can be oriented in the same direction as the resin molded part 1.11. It is also possible to further improve the strength and aesthetics of .12.

Furthermore, since this embodiment is configured to weld the two-part cowling C, the effective width of the mold 35 is also the same as the width of the joint 2.12 (see FIGS. 3 and 4). It is sufficient to have a width that is sufficient to reliably press the molded parts 1 and 11 and to prevent the molten resin R from flowing out to the outside of the joint portion 2.12. Therefore, the mold itself may be small, and the manufacturing cost of the mold 35 is also reduced.

Furthermore, if an uneven shape is formed on the surface of the upper mold 35a within a range that does not cause sink marks or the like, the uneven shape can be formed on the surface of the joint part 2° 12, and the outer surface of the resin molded product will have an uneven shape. It is also possible to form a pattern.

Note that the present invention is not limited to an apparatus for welding resin molded parts having a two-part structure as described above;
It is also possible to configure so that a plurality of resin molded parts can be welded.

〔Effect of the invention〕

As described above, the present invention provides a method for forming joints formed at the ends of a plurality of resin molded parts, which are thinner due to the thickness of the adjacent parts, using a mold to form a space between the inner wall of the mold and the joints. Since welding is performed by injecting molten resin into the joint, it is possible to prevent air from entering the joint.

For this reason, there is no need to set up a correction process as in the past, and the productivity of resin molded products is significantly increased.
The manufacturing space required for the correction process is also eliminated.

This also allows production costs to be significantly reduced.

In addition, since the joints of resin molded parts can be welded using molten resin between the thickness and the grooves of the resin molded parts, there will be no sinkage or warpage in the cross-sectional areas of the resin molded parts after welding, and the appearance will be improved. It becomes possible to produce beautiful resin molded products.

The manufacturing equipment for implementing this manufacturing method also includes a holding stand that holds the resin molded part, and a small mold that can cover the joint formed at the end of the resin molded part and the adjacent parts. Since it is sufficient to include an injection molding machine that injects molten resin, not only the mold but also the entire manufacturing apparatus can be made smaller.

Therefore, the device itself can be provided at low cost.

[Brief explanation of drawings]

1 to 10 are diagrams for explaining a manufacturing method and a manufacturing apparatus according to an embodiment of the present invention, and FIGS. 11 to 14 are diagrams showing a conventional example. FIG. 1 is a perspective view showing the structure (shape) of a joint of a resin molded part used in an embodiment of the present invention, viewed from the inner surface (back surface) side, and FIG. 2 is a different embodiment from FIG. 1. FIG. 2 is a perspective view showing the configuration (shape) of the joint of the resin molded component when viewed from the inner surface (back surface) side. FIG. 3 is a cross-sectional view showing the relationship between the joint and the mold in a state where the joint is covered with the mold, FIG. 4 is the same cross-sectional view showing a different embodiment from FIG. The figure is an enlarged sectional view of the main part of FIG. 4. FIG. 6, FIG. 7, and FIG. 8 are perspective views, viewed from the inner surface (back side), showing the structure of the joint portion of the resin molded component in an embodiment other than that shown in FIG. 1. FIG. 9 is a side view showing the configuration of a manufacturing apparatus according to an embodiment of the present invention, and FIG. 10 is a sectional view taken along line AA in FIG. 9. FIG. 11 is a perspective view showing a first conventional welding method, FIG. 12 is a sectional view of the welding part, and FIG. 13 is a perspective view showing a second conventional welding method. FIG. 14 is a sectional view of the welded portion. l, 11...Resin molded part 2, 12...Joint part 3.13...Edge part 4...Changed cross section part 5
...Protrusion 30...Floor surface 31...
Base 32...C-shaped frame 33...
- Slide bed 34... Holding stand 35... Mold 35a... Upper mold 35b... Lower mold 37 - Hydraulic cylinder 38a... Injection port R... Molten resin 36. ... Hydraulic cylinder 38 ... Injection molding machine C ... Cowling S ... Space 4 Fig. S space 3 Fig. 6 )) Fig. 4 Fig. 5 Fig. 52 Fig. 17 2 3 1 12th item 74th figure

Claims (2)

[Claims] (1) A method for manufacturing a resin molded product in which a plurality of resin molded parts are welded and integrated using molten resin, and each end of the resin molded parts to be connected has a thickness that is thinner than that of the vicinity thereof. The joint part of the resin molded parts is covered from both sides by a mold consisting of an upper mold and a lower mold, and molten resin is injected into the mold to form a joint part of the resin molded parts. A method for manufacturing a resin molded product, characterized in that the parts to be joined are integrated by welding. (2) A holding stand that holds a plurality of resin molded parts in a predetermined position during welding, and a joint that is provided near the holding stand and is thinner than the thickness of the resin molded parts formed at the end thereof. A mold consisting of an upper mold and a lower mold that covers the joint part and forms a space between the inner wall of the joint part and the joint part when mated, and a mold that relatively fits and disengages these molds during welding. 1. An apparatus for manufacturing a resin molded product, characterized in that an injection molding machine having an injection port communicating with the space is provided.