JPH031129B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for molding a resin molded article with a skin.

(Prior Art and Problems to be Solved by the Invention) Conventional skinned resin molded products have been manufactured by manually attaching a skin to the surface of a resin base material. This manufacturing method has problems in that it is inefficient, takes time, and increases manufacturing costs. Therefore, in order to improve this problem, an in-mold molding method has been devised in which the skin is set in a mold, a synthetic resin is injection molded on the back side of the mold, and the molding and the pasting of the skin are performed simultaneously. However, since a large injection pressure is applied to the skin, if a cloth made of synthetic fibers such as polyester fiber or nylon fiber, or a sheet made of polyvinyl chloride resin or polyethylene resin is used as the skin, the resin heat, injection pressure, etc. As a result, the problem remains that the skin becomes crushed and the appearance deteriorates.

Structure of the Invention (Means for Solving the Problems) The present invention comprises a step of filling each spot of at least two injection mechanisms disposed in a lower mold with molten resin, and a step of filling a molten resin between the upper mold and the lower mold. A step of arranging the skin, a step of clamping the upper mold and the lower mold to form a cavity, and raising the piston member of each injection mechanism to inject the molten resin onto the back of the skin inside the cavity. A method for molding a resin molded product with a skin is adopted, which includes the steps of aligning the upper end surface of the piston member to be substantially flush with the cavity, and after the molten resin has solidified, opening both molds and removing the resin molded product with a skin. In particular, the above-mentioned problems are solved.

(Function) When the piston member of each injection mechanism is raised to inject molten resin into the back surface of the skin inside the cavity,
Since the pot and the piston member form a flow path for the molten resin, a wide flow path corresponding to the runner and gate can be obtained, and can be formed with a small injection pressure.

Further, from the beginning to the middle of the injection, the skin is softened and stretched by the heat of the molten resin, is pressed against the inner surface of the upper mold, and is pulled in the flow direction by friction with the molten resin. However, in the present invention, each piston member of at least two injection mechanisms is raised to perform injection from multiple locations.
Compared to the case where there is only one injection point, the flow rate and flow length of the molten resin and the local concentration of heat applied to the epidermis are reduced, and excessive softening of the epidermis and deformation due to tension are prevented or alleviated.

Furthermore, at the end of injection, the cavity is filled with molten resin, so the maximum injection pressure is applied to the entire molten resin and skin. At this time, normally equal pressure is applied to each part, but if the shape of the resin molded product is irregular, such as having stepped parts,
The pressure is not applied uniformly and tends to concentrate locally, crushing the epidermis. However, in the present invention, pressure is applied from multiple injection points, so even if the resin molded product has an irregular shape, the pressure applied to each part can be made uniform and the pressure can be prevented from concentrating.
Partial collapse of the epidermis can be prevented.

Further, since the upper end surface of the piston member is aligned substantially flush with the cavity and forms a part of the cavity, a molded product without any runner or gate portion attached after molding is formed. Therefore, there is no need to remove the runner or gate portion after molding.

(Example) Hereinafter, an example embodying the present invention will be described with reference to the drawings.

As shown in FIG. 8, the resin molded article 61 with a skin formed according to this embodiment includes a base material 62 made of polypropylene resin (PP), and a cloth skin 63 made of polyester fiber attached to the surface of the base material 62. It consists of. The base material 62 is composed of diagonal portions 64 on both left and right sides, two flat portions 65, and a stepped portion 66 that vertically separates the flat portions 65.

Further, as shown in FIG. 1, the main parts of the resin molding apparatus used in this example are a frame part A, a mold part B attached to each frame part A, and the vicinity of the frame part A. A hydraulic unit C is installed in the mold section B to operate the clamping cylinder and drive device, which will be described later, a material supply unit D is attached to the frame body A and supplies molten resin, and a hydraulic unit C is installed in the mold section B. Resin molded product 61
and a skin supply device E for supplying the skin 63. First, each of these parts A to E will be explained in detail in order.

The frame body part A includes a lower base 1 and a lower base 1.
Four pillars 2 vertically extending above, a ceiling member 3 horizontally fixed to the upper ends of the pillars 2, and a protruding base 5 having one end fixed to the pillars 2 and supported by a diagonal frame 4. It consists of

The mold section B includes a mold clamping cylinder 6 attached to the lower base 1, and a slide base 7 that is guided by the pillar 2 and reciprocated in the vertical direction by an operating rod 6a of the mold clamping cylinder 6. , a vertical member 8 fixed on the slide base 7, and a lower mold (movable mold) fixed on the upper end of the vertical member 8.
9, an upper mold (fixed mold) 10 fixed to the lower surface side of the ceiling member 3, two left and right injection mechanisms 11 provided on the lower mold 9, and a molded product removal mechanism 12. A cavity 2 corresponding to the shape of the resin molded product 61 is provided between the lower mold 9 and the upper mold 10.
6 is formed, and the two injection mechanisms 11 are respectively connected to the lower mold 9.
These are disposed at locations forming the lower surfaces of the two flat portions 65 of the resin molded product 61. Further, two pressure detectors 51 and 52 are provided on the lower surface portion of the upper mold 10 facing each of the injection mechanisms 11,
It is designed to detect the injection pressure of molten resin.

Each of the left and right injection mechanisms 11 includes a heat insulating member 11a fixed to the lower surface side of the lower mold 9, as shown in FIG.
Pot 13 fixed inside the heat insulating member 11a
It consists of a ring-shaped heater 14 that heats the pot 13 to 200 to 220 DEG C., and a piston member 16 inserted into the pot 13 so as to be slidable in the vertical direction.

The piston member 16 includes a first piston 16a equipped with a high-frequency heating coil 15 on its outer periphery;
It consists of a second piston 16b screwed onto the lower end of the first piston 16a via a seal 17. A circulation passage 18 having an inlet and an outlet in the second piston 16b is formed inside both pistons 16a and 16b. The reason why the piston member 16 consists of the first piston 16a and the second piston 16b is to attach the high-frequency heating coil 15, and if the coil 15 can be attached to the inner circumferential surface of the pot 13, the piston member 16 can be attached to the inner peripheral surface of the pot 13. It may be a member.

Further, a hydraulic cylinder 23 having an actuating rod 22 is connected to the piston member 16 via a heat insulating member 21 and a connecting member 19. Both injection mechanisms 1
One hydraulic cylinder 23 is both held by a holding member 24.

The upper surface of the piston member 16 is substantially flush with the lower surface of the cavity 26 when the piston member 16 is raised;
It becomes a part of forming the cavity 26. Further, when descending, a cylindrical space 25 is formed between the upper surface and the pot 13. Molten resin is supplied to the space 25 from a material supply unit D, which will be described later.

Furthermore, although the first piston 16a is always warmed by the high-frequency heating coil 15 on the outer periphery, after the resin molded product 61 is molded, the first piston 16a is
It is cooled by sending cooling water to 8 in the direction of the arrow. When the resin molded product 61 is solidified by this cooling and cooling is no longer necessary, the passage 18
compressed air is sent to and the cooling water is removed. Therefore, the piston member 16 is connected to the high frequency heating coil 15.
The temperature rises again due to the action of

On the other hand, the resin molded product removal mechanism 12 includes an upright rod 27 attached to the lower base 1 as shown in FIG. an actuating rod 28 that can come into contact with the actuating rod 28;
The push-up pin 30 is connected to the upper end of the push-up pin 30 and is urged downward by a coil spring 29. The resin molded product removing mechanism 12 is for pushing up the resin molded product 61 using the push-up pin 30 when the lower mold 9 is lowered, and detaching the resin molded product 61 from the lower mold 9.

The hydraulic unit C is connected to a mold clamping cylinder 6, a hydraulic cylinder 23, and an injection cylinder 45 (described later) through parts not shown, and is used to operate these cylinders, and a normal hydraulic unit can be used. .

As shown in FIG. 1 and FIG. 3, which is a partial plan view thereof, the material supply unit D is arranged on a plate 36.
A plasticizing cylinder 42, a motor 38 that drives a screw in the plasticizing cylinder 42, a hopper 32 that supplies resin in the form of a pellet inside the plasticizing cylinder 42, a supply plunger 41 that stores plasticized resin therein, and a supply plunger. A cylinder device 45 for driving 41 piston rods 44 is installed. The cylinder device 45 supplies molten resin from the supply plunger 41 into the space 25 of the injection mechanism 11.

The protruding base 5 fixed to the lower base 1 is connected to the plate 3 via a ball screw mechanism.
6 is attached, and a motor 37 for rotating the screw 35 of the ball screw mechanism is fixed. Therefore, the entire material supply unit D mounted on the plate 36 can be reciprocated along the screw 35 of the ball screw mechanism by operating the motor 38.

The plasticized and melted resin material in the plasticizing cylinder 42 passes through the check valve 39 and is stored in the supply plunger 41, and when the cylinder device 45 is actuated and the piston rod 44 is pressed while the plate 36 is advanced. As shown in FIG. 4, the liquid is supplied into the space 25 of each injection mechanism 11 through an injection port 43.

Further, a large hopper tank 31 and a shutter 34 which is opened and closed by a cylinder 33 are arranged above the hopper 32, and pellet-shaped resin material corresponding to the capacity of the cavity 26 is released by opening and closing the shutter 34. It is now being supplied in small quantities.

The skin supply device E includes a support frame 53 for sandwiching and horizontally supporting the skin 63 of the resin molded product 61, and moves the support frame 53 and the skin 63 reciprocally between the lower mold 9 and the upper mold 10. The drive mechanism (not shown) is provided on the side of the mold section B.

Note that a recess 54 for holding the support frame 53 is formed at each edge of the lower mold 9 and the upper mold 10.

Next, a method of molding the skinned resin molded product 61 using the resin molding apparatus configured as described above will be described.

[Filling process of molten resin] First, as shown in FIG. 4, with the lower die 9 lowered, the motor 37 is driven to rotate the screw 35, and the material supply unit D provided on the plate 36 is It is advanced between the lower mold 9 and the upper mold 10.
At this time, in the material supply unit D, approximately one charge of pellet-like resin material is supplied from the hopper tank 31 into the hopper 32, and then sent into the plasticizing cylinder 42 where it is plasticized and melted by the screw inside the cylinder 42. , are stored in supply plunger 41 through check valve 39.
Then, when the injection port 43 reaches the space 25 of the left injection mechanism 11 provided in the lower mold 9, the forward movement of the material supply unit D is stopped.

Subsequently, the cylinder device 45 is actuated to press the piston rod 44 to fill the space 25 with the molten resin in the supply plunger 41 for about one injection in the injection mechanism 11 on the left side.

Next, the motor 37 is reversed to move the material supply unit D backward, so that the injection port 43 is connected to the injection mechanism 1 on the right side.
When the material supply unit D reaches the space 25 of No. 1, the retraction of the material supply unit D is stopped.

Then, as in the case on the left side, the cylinder device 45
is operated to fill the molten resin in the supply plunger 41 into the space 25 of the injection mechanism 11 on the right side.

The total amount of molten resin supplied into the left and right spaces 25 as described above is approximately equal to the amount required to form the base material 62 of the resin molded product 61 within the cavity 26.

Thereafter, the motor 37 is further reversed to move the material supply unit D back from between the upper mold 10 and the lower mold 9. At the same time, for the next filling, the aforementioned process of supplying and melting the resin material from the hopper tank 31 to the inside of the supply plunger 41 is performed.

[Skin Arrangement Step] The skin 63 is placed on the support frame 53 in advance as shown in FIG.
Place it between the two. As mentioned above, space 2 on both the left and right sides
After supplying the molten resin into the mold 5 and retracting the material supply unit D, as shown in FIG. to be placed.

[Shape clamping process] Next, as shown in FIG.
is operated to raise the lower die 9 and clamp it against the upper die 10 to form the cavity 26. At this time, the supporting frame 53 of the skin supplying device E has both molds 9,
It fits into a recess 54 formed on the edge of the holder 10 and is held therebetween. In addition, the skin 63 held between the support frame 63
is sandwiched between the two shapes 9 and 10, and is deformed within the cavity 26 into a shape that substantially corresponds to the shape of the same cavity.

Note that both molds 9 and 10 are constantly cooled by flowing cooling water through cooling water passages 20 provided inside the molds, but the molten resin is not allowed to flow through the heat insulating member 12 before injection. Since it is located inside the pot 13, it is difficult to cool down. Furthermore, the pot 13 is heated to about 200-220°C by a ring-shaped heater 14, and the piston member 16 is constantly warmed by a high-frequency heating coil 15.
The molten resin never solidifies.

[Process of Injecting Molten Resin] Next, as shown in FIG.
The molten resin in 3 is transferred to the skin 6 in the cavity 26.
Inject into the back side of 3.

At this time, since the pot 13 and the piston member 16 form a material flow path, a wide flow path corresponding to a runner and a gate is obtained, and molding can be performed with a small injection pressure.

In addition, from the beginning to the middle of the injection, the molten resin injected from the injection mechanism 11 on the left side is transferred to the epidermis 6.
3, flows on both sides, a flat part 65 on the left side of the base material 62, an oblique part 64 on the left side, and a step part 66
We will fulfill the parts that should become. On the other hand, the molten resin injected from the injection mechanism 11 on the right side hits the skin 63 and then the flat part 65 on the right side of the base material 62,
It fills the right side oblique part 64 and the part to become the stepped part 66, and merges with the molten resin injected from the left injection mechanism 11 at the stepped part 66.

The skin 63 is softened by the heat of the molten resin and becomes easy to stretch, and is pressed against the inner surface of the upper mold 10,
It is pulled in the direction of flow by friction with the molten resin. However, in this embodiment, each piston member 16 of the two injection mechanisms 11 is raised to perform injection from two locations, so the flow rate and flow length of the molten resin and the skin 6
The local concentration of heat given to 3 is reduced, and the epidermis 63
Excessive softening and deformation due to tension are prevented or alleviated. Therefore, the appearance of the epidermis 63 is maintained well.

In particular, when a cloth made of polyester fiber is used as the outer skin 63 as in this embodiment,
Even when cloth made of synthetic fibers such as nylon fibers, sheets made of polyvinyl chloride resin, polyethylene resin, etc. are used, the deformation of the skin 63 is effectively prevented, resulting in a good appearance. is obtained.

Furthermore, at the end of the injection, the cavity 26 is filled with the molten resin, so the maximum injection pressure is applied to the entire molten resin and the skin 63. At this time, normally equal pressure is applied to each part, but if the resin molded product 61 has an irregular shape such as having a stepped part 66 as in this example, the pressure is not applied uniformly and may be localized. There is a risk that the epidermis 61 may be crushed by concentrating on the particles. However, in this embodiment, pressure is applied from two injection points, so even if the resin molded product 61 has an irregular shape, the pressure applied to each part can be made uniform and the pressure can be prevented from concentrating. It is possible to prevent crushing. Therefore, when using the skin 61 which is easily deformed by pressure as in this embodiment, this embodiment is particularly effective in preventing the skin from being crushed.

Also, at the end of the injection, the piston member 61
The implantation is complete when the upper end surface of the cylindrical tube is substantially flush with the cavity 26 to form a portion of the cavity 26. Therefore, since the resin molded product 61 is molded to which the runner and gate parts do not adhere after molding,
There is no need to remove the runner or gate part after molding.

Incidentally, during the injection of the molten resin, the injection pressure can also be controlled by using pressure detectors 51 and 52 provided on the upper mold 10.

That is, the pressure detectors 51 and 52 on both the left and right sides detect the pressure of the molten resin immediately above each injection mechanism 11, and when the resin pressure on both sides is unbalanced, the hydraulic pressure in the injection mechanism 11 on the side where the pressure is higher is increased. It is possible to control the cylinder 23 to lower its injection pressure, or to control the hydraulic cylinder 23 in the injection mechanism 11 whose pressure is lower to increase its injection pressure. In this embodiment, as described above, fundamentally non-uniform resin pressure is unlikely to occur, but by controlling the injection pressure using the pressure detectors 51 and 52 as described above, the pressure of the molten resin can be made even more uniform. can be maintained. Therefore, the epidermis 63 is completely protected.

During the injection, the upper mold 10 and lower mold 9 are constantly cooled, so the molten resin injected into the cavity 26 begins to solidify. However, since the piston member 16 is constantly warmed by the high-frequency heating coil 15, the molten resin near the upper end surface of the piston member 16 does not begin to solidify. Therefore, upon completion of injection, cooling water is sent to the circulation passage 18 within the piston member 16 to cool the piston member 16 and solidify the molten resin.

Through the above injection process, the molten resin comes into contact with the back surface of the skin 63 and solidifies to become the base material 62 and is attached to the skin 63. In particular, since cloth is used as the skin 63 in this embodiment, the molten resin penetrates into the weave. Therefore, the skin 63 and the base material 62 are firmly joined by the anchor effect.

[Removal process of resin molded product] When the molten resin solidifies and the resin molded product 61 is formed, the mold clamping cylinder 6 is operated to lower the lower mold 9 and the mold is opened, as shown in FIG. conduct. Then, the upright rod 27 of the lower base 1 comes into contact with the actuating rod 28 of the resin molded product removal mechanism 12, and
Since the push-up pin 30 is raised against the elastic force of the coil spring 29, the resin molded product 61 is automatically released from the lower mold 9.

At this time, in both injection mechanisms 11, the hydraulic cylinders 23 are operated to lower the piston 16, and compressed air is sent to the circulation passage 18 to remove the cooling water remaining inside, so that the piston 16 is cooled by the cooling water. Abort. Therefore, the piston 16
is heated again by the high-frequency heating coil 15 and returns to its original state.

[Process of cutting unnecessary parts of the skin] As shown in FIG. 8, the released resin molded product 6
1 has an unnecessary portion of the skin 63 that was sandwiched between the two shapes 9 and 10 attached thereto. Therefore, by cutting and removing the unnecessary portions after releasing the mold, the skinned resin molded product 61 is completed.

Through the above steps, the skinned resin molded product 61
One cycle of molding is completed.

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, and may be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) The injection mechanism 11 can be provided at any location on the lower die 9 depending on the size and shape of the resin molded product, and the number is not limited as long as it is a plurality of at least two.

(2) The pressure detectors 50, 51 and the control of the injection pressure by them may be omitted.

Effects of the Invention As detailed above, the present invention exhibits the excellent effect of being able to prevent deformation of the skin attached to a resin molded product and maintaining the good appearance of the molded product. .

[Brief explanation of the drawing]

Fig. 1 is a front view showing the entire molding apparatus used in the embodiment of the present invention together with a partial cross section;
The figure is an enlarged sectional view of the main parts of the same device, Figure 3 is a plan view of the material supply unit of the same device, and Figures 4 to 8 show each step of the method for molding a resin molded product with a skin using the same device. 4 is a cross-sectional view of the main part showing the molten resin filling process, FIG. 5 is a cross-sectional view of the main part showing the skin arrangement process, FIG. 6 is a cross-sectional view of the main part showing the mold clamping process, and FIG. FIG. 8 is a cross-sectional view of a main part showing a step of injecting molten resin, and FIG. 8 is a cross-sectional view of a main part showing a step of removing a resin product. 9... Lower mold, 10... Upper mold, 11... Injection mechanism, 13... Pot, 16... Piston member, 2
6...Cavity, 61...Resin molded product with skin, 63...Skin.

Claims (1)

[Claims] 1. A step of filling each pot 13 of at least two injection mechanisms 11 disposed in the lower mold 9 with molten resin, a step of arranging a skin 63 between the upper mold 10 and the lower mold 9, and a step of filling the upper mold 10 with a skin 63. and the lower mold 9 to form the cavity 26, and the piston member 16 of each injection mechanism 11 is raised to inject molten resin into the back surface of the skin 63 inside the cavity 26,
A process of aligning the upper end surface of the piston member 16 substantially flush with the cavity 26, and opening both molds 9 and 10 after solidifying the molten resin to form a resin molded product 61 with a skin.
A method of molding a resin molded product with a skin, which includes a step of removing the skin.