CN103302813B - Plastic cement products negative pressure injection forming mold and method thereof - Google Patents

Abstract

The present invention relates to plastic-injection field shaping technique, particularly relate to plastic cement products negative pressure injection forming mold and method thereof, include front mould, rear mold, front mould inside is provided with multiple die cavity, the front end face of front mould is provided with add-in card, add-in card offers multiple passage corresponding with multiple die cavity respectively, each passage is communicated with corresponding die cavity respectively, be interconnected by the ventilation tank circuit between multiple passage, the ventilation tank circuit is communicated with extraneous air compressibility, the present invention can make die cavity carry out injection moulding under negative pressure state, injection moulding plastic raw material can be full of die cavity fast, injection moulding efficiency is high, and avoiding oxygen and plastic material in die cavity to produce reaction makes plastic material burn, improve performance and the surface quality of plastic cement products, can injection molding more accurate, the product of the less and thin wall type of size, malleation blowing method can be utilized to be blown out by product, and prevent product to be bonded on front mould, prevent deformation of products and damage, the demoulding is easy.

Description

Plastic product negative pressure injection molding mold and method thereof

Technical field:

The invention relates to the technical field of plastic injection molding, in particular to a negative pressure injection molding mold for plastic products and a method thereof.

Background technique:

Injection molding of plastic products is a processing method used in the mass production of some parts with complex shapes. Specifically, it refers to injecting heated and melted materials into the mold cavity under high pressure, and after cooling and solidifying, molded products are obtained. Existing injection molding molds are all injected and demolded under normal pressure. During injection molding, due to the presence of air in the cavity, the plastic raw material cannot quickly fill the cavity, the injection speed is slow, and the oxygen in the cavity will interact with the plastic. The reaction of raw materials will burn the plastic raw materials, affect the performance and surface quality of plastic products, and make it impossible to process more precise, small-sized and thin-walled products by injection molding; when demoulding, because the product is easy to stick to the front mold, it is not easy Demoulding, and the ejector pin is used to directly eject the product, which may easily lead to product deformation and damage.

Invention content:

The purpose of the present invention is to provide a negative pressure injection molding mold for plastic products that can improve product performance and surface quality and injection molding efficiency in view of the deficiencies in the prior art, and also provide a plastic product negative pressure injection molding method for this molding mold .

In order to achieve the above object, the technical scheme adopted in the present invention is:

The plastic product negative pressure injection molding mold includes a front mold and a back mold matched with the front mold. The back mold is set on the rear end surface of the front mold. There are multiple cavities inside the front mold. The additional plate, the additional plate is provided with a plurality of air holes corresponding to the multiple cavities, each air hole communicates with the corresponding cavity, and the air holes communicate with each other through the air channel, and the air channel and the air channel are connected to each other. External air compression system connection.

The inside of the front mold is provided with a plurality of mold cores, the mold cores are detachably arranged inside the front mold, and the mold cavity is arranged in the mold cores.

The mold core includes an outer core and at least one combined inner core arranged inside the front end of the outer core, the combined inner core and the outer core are mutually enclosed to form a mold cavity, an adjusting screw is threadedly connected to the air hole, and the rear end of the adjusting screw The top is pressed on the combined inner core at the front end, the adjusting screw is a hollow tubular structure, and the two ends of the hollow inner cavity of the adjusting screw communicate with the air hole and the mold cavity respectively.

The outer core is screwed inside the front mold through an external thread.

The ventilation grooves are arranged on the front end surface of the additional plate, and a plurality of air inlet grooves are provided on the rear end surface of the additional plate, and each air inlet groove is distributed with a plurality of air holes communicating with it.

The plurality of air intake slots are evenly arranged in parallel.

The additional board is provided with a ventilation interface, and the ventilation tank communicates with the external air compression system through the ventilation interface, and a reversing valve is connected between the ventilation interface and the external air compression system.

A hot runner device is provided on the front end surface of the additional plate.

The present invention also provides a plastic product negative pressure injection molding method, comprising the following steps:

A. Use the air compression system to generate a negative pressure suction state, suck out the air in the mold cavity, and form a negative pressure in the cavity;

B. Inject the plastic raw material in molten state into the cavity from the sprue of the forming mold, so that the plastic raw material fills the cavity to form a product;

C. When demoulding, use the air compression system to generate a positive pressure blowing state, and blow air into the cavity of the forming mold to make the product separate from the front mold.

The air compression system communicates with the cavity of the forming mold through a ventilation pipeline system, and the air compression system is switched between a negative pressure suction state and a positive pressure blow state through a reversing valve.

The beneficial effects of the present invention are: the present invention comprises a front mold and a rear mold, the rear mold is arranged on the rear end surface of the front mold, a plurality of cavities are arranged inside the front mold, an additional plate is arranged on the front end surface of the front mold, and the additional plate There are a plurality of ventilation holes corresponding to the plurality of cavities, and each ventilation hole is connected with the corresponding cavity, and the plurality of ventilation holes are connected to each other through the ventilation groove, and the ventilation groove is connected to the external air compression system. The present invention uses the air compression system to suck out the air in the mold cavity to form a negative pressure, and then injects the molten plastic raw material into the mold cavity to form a product. When demoulding, the air compression system is used to blow air into the mold cavity , so that the product is separated from the front mold, the invention can make the cavity be injected under negative pressure, the injection plastic material can quickly fill the cavity, the injection molding efficiency is high, and avoid the reaction of oxygen in the cavity with the plastic material to cause the plastic material to burn. Improve the performance and surface quality of plastic products, and be able to process more precise, small-sized and thin-walled products by injection molding; can use positive pressure blowing to blow out the product to prevent the product from sticking to the front mold, preventing product deformation and damage, Easy to demould.

Description of drawings:

Fig. 1 is a schematic diagram of the internal structure of the present invention.

Figure 2 is a rear view of the attachment plate of the present invention.

Fig. 3 is a structural schematic diagram of the mold core of the present invention.

detailed description:

The present invention will be further described below in conjunction with accompanying drawing and preferred embodiment, see shown in Fig. 1～3, plastic product negative pressure injection molding mold comprises front mold 1, the rear mold 2 that cooperates with front mold 1, and rear mold 2 sets On the rear end face of the front die 1, the inside of the front die 1 is provided with a plurality of cavities 10; Vent holes 31 , each vent hole 31 communicates with the corresponding cavity 10 respectively, and the plurality of vent holes 31 communicate with each other through the vent channel 32 , and the vent channel 32 communicates with the external air compression system. The present invention first uses the air compression system to suck out the air in the mold cavity 10 to form a negative pressure, and then injects the molten plastic raw material into the mold cavity 10 to form a product. The air is blown in the middle, so that the product is separated from the front mold 1. The present invention can make the cavity 10 perform injection molding under a negative pressure state, and the injection molding plastic material can quickly fill the cavity 10, and the injection molding efficiency is high, and the oxygen in the cavity 10 and the plastic material are avoided. The reaction will burn the plastic raw material, improve the performance and surface quality of the plastic product, and can injection process more precise, small-sized and thin-walled products; the product can be blown out by positive pressure blowing to prevent the product from sticking to the front mold 1 On, to prevent product deformation and damage, easy demoulding.

The inside of the front mold 1 is provided with a plurality of mold cores 4, the mold cores 4 are arranged in the front mold 1 in a detachable manner, and the cavity 10 is arranged in the mold cores 4, which is convenient for replacing different mold cores 4 to produce different products, achieving Interchangeable effect, can be applied to products of different shapes and specifications, strong versatility and cost saving. The outer core 41 is threaded inside the front mold 1 through an external thread, which is convenient for assembly and disassembly, and the position of the cavity 10 can be adjusted by rotating the outer core 41 .

The mold core 4 includes an outer core 41 and at least one combined inner core 42 arranged inside the front end of the outer core 41. The combined inner core 42 and the outer core 41 are enclosed to form a cavity 10. Through different combined inner cores 42 and outer The core 41 or its combination can change the shape or size of the cavity 10, and can be applied to products of different shapes and specifications, which has strong versatility and saves costs. The air hole 31 is threadedly connected with an adjustment screw 5, and the rear end of the adjustment screw 5 is pressed against the combined inner core 42 at the front end. 31. The cavity 10 is connected, which is conducive to ventilation. By rotating the adjusting screw 5, the position of the combined inner core 42 can be adjusted, thereby adjusting the length of the cavity 10, which can eliminate errors, and can be used for products of different lengths. It has strong versatility and is easy to process. Convenience and cost savings.

Ventilation groove road 32 is arranged on the front end face of additional plate 3, and the rear end face of additional plate 3 is provided with a plurality of air inlet grooves 33, and each air inlet groove 33 is distributed with a plurality of air holes 31 communicating with it, and the air grooves The combination of the passage 32, the air hole 31 and the air intake groove 33 forms a ventilation pipeline system, so that the air pressure is evenly distributed, and the air pressure of each air hole 31 is the same. A plurality of air intake slots 33 are evenly arranged in parallel to make the air pressure distribution more uniform. The additional board 3 is provided with a ventilation interface 34, the ventilation channel 32 communicates with the external air compression system through the ventilation interface 34, and a reversing valve is connected between the ventilation interface 34 and the external air compression system, and the air compression system passes through the reversing valve. Switch between the pressure suction state and the positive pressure blow state.

A hot runner device 6 is provided on the front end surface of the additional plate 3 . The additional plate 3 is sealed and connected with the front mold 1 and the hot runner device 6 respectively through the sealing ring 7 to prevent air leakage.

The present invention also provides a negative pressure injection molding method for plastic products. The air compression system communicates with the mold cavity 10 through the ventilation pipeline system, and the air compression system is between the negative pressure suction state and the positive pressure blowing state through a reversing valve. To switch, the specific steps are as follows:

1. Use the air compression system to generate a negative pressure suction state, suck out the air in the cavity 10 of the forming mold, and form a negative pressure in the cavity 10, such as forming a vacuum in the cavity 10;

2. Inject the molten plastic raw material into the cavity 10 through the sprue of the forming mold, so that the plastic raw material fills the cavity 10 to form a product;

3. After the product in the cavity 10 is cooled and solidified, when demolding, the reversing valve switches direction, and the air compression system is used to generate a positive pressure blowing state, and the air is blown into the cavity 10 of the forming mold to separate the product from the front mold 1.

The air compression system can stop the suction work after the negative pressure is sucked into the cavity 10, and then perform the injection molding work in step 2; Carry out the injection molding work of step 2 while the air is in the air, and stop the suction work after the injection molding work is completed, and the injection molding effect is good.

Utilize the method of the present invention to make cavity 10 carry out injection molding under the negative pressure state, injection molding plastic raw material can fill cavity 10 quickly, injection molding efficiency is high, and avoid the reaction of oxygen in cavity 10 and plastic raw material to make plastic raw material burn, improve The performance and surface quality of plastic products can be processed by injection molding with relatively precise, small size and thin-walled products; the present invention uses a positive pressure blowing method to blow out the product, preventing the product from sticking to the front mold 1, preventing product deformation and damage , Easy to demould.

Of course, the above descriptions are only preferred embodiments of the present invention, so all equivalent changes or modifications made according to the structures, features and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims (4)

1. plastic cement products negative pressure injection forming mold, include front mould (1), the rear mold (2) matched with front mould (1), rear mold (2) is arranged on front mould (1) rear end face, front mould (1) inside is provided with multiple die cavity (10), it is characterized in that: the front end face of described front mould (1) is provided with add-in card (3), add-in card (3) offers multiple passage (31) corresponding with multiple die cavity (10) respectively, each passage (31) is communicated with corresponding die cavity (10) respectively, be interconnected by the ventilation tank circuit (32) between multiple passage (31), the ventilation tank circuit (32) is communicated with extraneous air compressibility, front mould (1) inside is provided with multiple core rod (4), and it is inner that core rod (4) is removably arranged on front mould (1), and die cavity (10) is arranged in core rod (4), core rod (4) includes outer core (41) and is arranged at least one combination inner core (42) of outer core (41) inside, front end, mutually enclose between combination inner core (42) and outer core (41) and form die cavity (10), the set screw that has been threaded in passage (31) (5), the top, rear end of set screw (5) is pressed on combination inner core (42) foremost, set screw (5) is hollow tubular structures, and the two ends of set screw (5) hollow lumen are communicated with passage (31), die cavity (10) respectively.

2. plastic cement products negative pressure injection forming mold according to claim 1, it is characterized in that: the described ventilation tank circuit (32) is arranged on the front end face of add-in card (3), the rear end face of add-in card (3) offers many air inlet ducts (33), every bar air inlet duct (33) is distributed with multiple passage (31) be communicated with it.

3. plastic cement products negative pressure injection forming mold according to claim 2, is characterized in that: described many air inlet ducts (33) uniform parallel arrangement.

4. plastic cement products negative pressure injection forming mold according to claim 1, it is characterized in that: described add-in card (3) is provided with ventilation interface (34), the ventilation tank circuit (32) is communicated with extraneous air compressibility by ventilation interface (34), is connected with reversal valve between ventilation interface (34) and extraneous air compressibility.