CN107297856B

CN107297856B - Injection molding method of soft rubber arch product

Info

Publication number: CN107297856B
Application number: CN201710598018.XA
Authority: CN
Inventors: 张智杰; 马立平
Original assignee: Goertek Inc
Current assignee: Goertek Techology Co Ltd
Priority date: 2017-07-20
Filing date: 2017-07-20
Publication date: 2020-05-29
Anticipated expiration: 2037-07-20
Also published as: CN107297856A

Abstract

The invention discloses an injection molding method of a soft gum arch product. The injection molding method of the soft gum arch product comprises the following steps: providing a mould, wherein the mould comprises a cavity for forming a soft rubber arch product and an arch parting surface, the mould is provided with a pouring gate and two exhaust channels, and the two exhaust channels are respectively positioned on two sides of the length direction of the arch parting surface and are communicated with the cavity; injecting the molten soft rubber material into the mold cavity in sections, and controlling the injection speed of the molten soft rubber material to be 10-15 mm/s during the injection at the tail section; when the two ends of the arched parting surface in the length direction are filled with the molten plastic material at last, the mold cavity is filled with the molten plastic material; and maintaining the pressure of the die. The invention aims to solve the technical problem that gas generated in the injection molding process of the existing soft rubber arch-shaped product cannot be discharged.

Description

Injection molding method of soft rubber arch product

Technical Field

The invention relates to the technical field of injection molding, in particular to an injection molding method of a soft gum arch product.

Background

In the injection molding process of plastic products, TPU and other soft rubber materials have good fluidity and are easy to generate gas and other gases during heating or injection. Especially, when the plastic product is a soft plastic arch product, the gas generated in the injection molding process cannot be effectively discharged in time due to the structural shape particularity of the arch product.

The gas such as gas produced in the forming process can not be effectively discharged, bad exhaust can be produced in the die cavity, the burn defect on the surface of the plastic product is caused, and the pollution to the die is increased. Meanwhile, the dust-laden gas can also generate reverse pressure to reduce the film filling speed, so that the machine table is unstable in operation, the debugging period is long, the difficulty is high, the maintenance frequency of the die is increased, and the service life of the die is also shortened.

At present, the whole parting surface of the die is additionally exhausted, so that the gas is discharged to a certain extent. However, the determination of the size of the whole parting surface for opening the exhaust is difficult to realize, and the burrs of the soft rubber product are serious and the size of the product is unstable.

Therefore, there is a need for improved methods of injection molding soft gum dome articles.

Disclosure of Invention

The invention aims to provide a new technical scheme of an injection molding method of a soft gum arch product.

According to one aspect of the present invention, a method of injection molding a soft gum dome article is provided. The injection molding method of the soft gum arch product comprises the following steps: providing a mould, wherein the mould comprises a cavity for forming a soft rubber arch product and an arch parting surface, the mould is provided with a pouring gate and two exhaust channels, and the two exhaust channels are respectively positioned on two sides of the length direction of the arch parting surface and are communicated with the cavity; injecting the molten soft rubber material into the mold cavity in sections, and controlling the injection speed of the molten soft rubber material to be 10-15 mm/s during the injection at the tail section; when the two ends of the arched parting surface in the length direction are filled with the molten plastic material at last, the mold cavity is filled with the molten plastic material; and maintaining the pressure of the die.

Optionally, when the mould is subjected to pressure maintaining, the pressure maintaining speed is controlled to be 4mm/s-10 mm/s.

Optionally, one end of the exhaust channel, which is far away from the cavity, is communicated with a gas treatment unit.

Optionally, the exhaust channel includes an exhaust groove having one end communicating with the cavity, and the exhaust groove is located at one end of the arched parting surface in the length direction.

Optionally, the mold comprises a fixed mold and a movable mold, the cavity is arranged on the fixed mold, and the exhaust groove is arranged on the fixed mold.

Optionally, the exhaust passage further comprises an air guide hole, and the exhaust groove is communicated with the outside through the air guide hole.

Optionally, the pore diameter of the air guide hole is 5 mm.

Optionally, the gate comprises two side gates.

Optionally, two side gates are located on the arched parting surface, and the two side gates equally divide the length of the arched parting surface into three sections.

Optionally, an injection machine is further provided, the injection machine comprises a material tube, and the temperature of the material tube is controlled to be 210 ℃ to 230 ℃ when the molten soft rubber material is injected into the mold cavity.

The inventor of the invention finds that in the injection molding process of the soft rubber arch product, the gas generated in the injection molding process can not be effectively discharged in time due to the structural shape particularity of the arch product. This can lead to poor venting in the mold cavity, resulting in burn defects on the surface of the plastic article and increased contamination of the mold. Meanwhile, the accumulated gas can also generate reverse pressure to reduce the film filling speed, so that the machine table is unstable in operation, the debugging period is long, the difficulty is high, the maintenance frequency of the die is increased, and the service life of the die is also shortened. Therefore, the technical task to be achieved or the technical problems to be solved by the present invention are never thought or anticipated by those skilled in the art, and therefore the present invention is a new technical solution.

In the injection molding method of the soft gum arch product provided by the invention, the injection molding method is specially designed according to the characteristics of the structure and the appearance of the soft gum arch product. The mould includes die cavity and arch die joint, and two exhaust passage are located the both sides position of arch die joint respectively and communicate with the die cavity. In the process of continuously injecting the molten soft rubber material into the mold cavity, the two ends of the arched parting surface are filled with the molten plastic material at last, and the mold cavity is filled with the molten soft rubber material at the moment. In the injection process, the exhaust channel can not be blocked by the molten soft rubber, and gas can be discharged in time through the two exhaust channels and can not remain in the cavity.

The molten soft rubber material is injected into the mold cavity in sections, and the injection speed of the molten soft rubber material is controlled to be 10-15 mm/s during the injection at the tail section. The injection speed of the tail section cannot be too high, so that the generated gas can be discharged through the two exhaust channels in time and cannot be remained in the arch-shaped cavity.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a schematic diagram of a method of injection molding a soft gum dome article according to one embodiment of the present invention;

fig. 2 is a schematic structural view of a mold provided in an embodiment of the present invention.

Wherein, 10: a cavity; 11: an arched parting surface; 12: a gate; 13: an exhaust groove; 14: and air vents.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

The invention provides an injection molding method of a soft gum arch product, which is used for molding the soft gum arch product. Gas such as gas generated in the heating and injection molding processes of the soft rubber material can be discharged in time, and the gas cannot remain in the mold cavity of the mold. For example, the soft gum may be TPU (Thermoplastic polyurethane elastomers) or other soft gum materials. The soft gum dome product includes an arcuate shape in its length direction. For example, the soft gum dome may be or approximate an arch bridge configuration, banana configuration, or other dome configuration.

Referring to fig. 1, the injection molding method includes the steps of:

a mold for molding a soft gum dome product is provided. Referring to fig. 2, the mold includes a cavity 10 for molding a soft gum dome product and a dome-shaped parting plane 11. The cavity 10 is designed according to the specific shape of the soft gum arch product required. The arched parting surface 11 is used for taking out a soft rubber arched product molded in the cavity 10. For example, the arcuate parting plane 11 may be a plane structure, wherein two opposite edges of the arcuate parting plane 11 are parallel arcs or approximately parallel arcs.

A gate 12 and two exhaust channels are provided on the mold. Molten soft gum material is injected into the cavity 10 of the mold through the gate 12. The two exhaust passages are respectively positioned on two sides of the length direction of the arched parting surface 11. Moreover, one end of each exhaust channel is communicated with the cavity 10, so that gas generated in the heating and injection molding process of the soft rubber material can be exhausted out of the cavity 10 in time. For example, as shown in fig. 1, the two exhaust passages are located on both sides of the arcuate parting plane 11 in the arc length direction and communicate with the cavity 10.

The other end of the exhaust passage is communicated with the outside to exhaust the gas in the mold cavity 10. Preferably, a gas processing unit may be disposed at the outside, and an end of the exhaust passage away from the cavity 10 may be communicated with the gas processing unit. For example, the end of the exhaust channel remote from the mould cavity 10 may be in communication with a suction device to create suction. For another example, an end of the exhaust passage away from the cavity 10 may be communicated with an exhaust gas treatment device to treat exhaust gas such as gas.

Then, the molten soft plastic such as TPU is injected into the cavity 10 of the mold in sections. The molten soft gum material has different injection speeds and injection pressures at different locations. During the final injection, the injection speed of the molten soft rubber compound is controlled between 10mm/s and 15 mm/s.

After the final injection is performed for a certain period of time, when the two ends of the arched parting surface 11 in the length direction are filled with the molten plastic material, the molten soft plastic material is filled in the cavity 10 of the mold. In the process of continuously injecting the molten soft plastic material into the mold cavity 10, the molten plastic material is filled at the two ends of the arched parting surface 11. Thus, the generated gas can be discharged in time.

After the molten soft gum material fills the cavity 10 of the mold, the mold is subjected to pressure holding. Thus, the deformation amount and the size of the product can be controlled. The temperature reduction of the molten soft rubber and the backflow phenomenon caused by the internal stress in the molten soft rubber can be prevented.

Therefore, in the process of continuously injecting the molten soft plastic into the mold cavity 10, the two ends of the arched parting surface 11 are filled with the molten plastic at last. The exhaust channel can not be blocked by the melting soft glue, and the generated gas can be discharged in time through the two exhaust channels and can not remain in the arch-shaped cavity 10.

The injection speed at the end is controlled between 10mm/s and 15 mm/s. The injection speed of the tail section is not too high, so that the generated gas can be discharged through the two exhaust channels in time and cannot remain in the cavity 10 of the mold.

Gas generated in the injection process can be discharged through the two exhaust channels in time, and cannot remain in the cavity 10 of the mold, so that the molding defect of the soft rubber arch product can be avoided. Meanwhile, the corrosion to the die can be avoided, the maintenance frequency of the die is greatly reduced, and the actual service life of the die is prolonged. The injection molding method is simple to operate and easy to process, and can reduce the production cost.

In consideration of the physical properties of the raw materials in the molten state and the particularity of the molding of the dome-shaped product, the pressure holding speed is strictly required. Alternatively, when the mold is subjected to pressure holding, the pressure holding speed can be controlled to be 4mm/s-10 mm/s. Therefore, the pressure maintaining speed is not too high, and the defects of serious burrs and unstable size on the surface of a product are avoided. The pressure maintaining speed is not too slow, and the product does not have the defects of difficult full filling and shrinkage.

Because the soft rubber arch product has more complex shape and structure and more appearance defects, the molten soft rubber can be injected into the cavity 10 at least in four sections. For example, the molten soft plastic may be injected into the cavity 10 in five stages.

In the invention, the two exhaust passages are respectively positioned at two ends of the length direction of the arched parting surface 11 and are communicated with the cavity 10. The specific structure and manner of formation of the two exhaust passages may be varied.

In one example, referring to fig. 2, each of the vent channels may include a vent groove 13 having one end communicating with the cavity 10. Each of the exhaust grooves 13 is located at a position on one side of the arcuate parting plane 11. When the films are combined, the other side of the exhaust groove 13 is sealed, and only two ends are conducted. One end of which is communicated with the cavity 10. Thus, the gas generated in the cavity 10 can enter the exhaust groove 13 to be exhausted in time.

In this embodiment, referring to fig. 2, the exhaust passage may further include an air guide hole 14. One end of the air guide hole 14 is communicated with the exhaust groove 13, and the other end of the air guide hole 14 is communicated with the outside. The exhaust groove 13 is communicated with the outside through the air guide hole 14. For example, the air vent 14 may be formed through the mold from the air vent groove 13 until communicating with the outside.

The pore diameter of the air-guide hole 14 may be set to 5 mm. Therefore, the exhaust channel can continuously exhaust the gas generated in the cavity 10 in time, and no gas is left in the cavity 10 of the mold.

In this embodiment, the mold may include a stationary mold and a movable mold. Referring to fig. 2, the cavity 10 may be provided on the stationary mold. The exhaust groove 13 may be provided on the surface of the fixed mold. For example, the air vent 14 may penetrate the fixed mold or the movable mold to communicate with the outside.

Of course, a part of the cavity 10 may be provided on the stationary mold and another part may be provided on the movable mold. When the mold is closed, the complete cavity 10 is formed.

Molten soft rubber is injected into the cavity 10 through the gate 12. The position of the gate 12 may be various, as long as it can realize that the molten plastic material finally fills up the two end positions in the length direction of the arched parting surface 11. Preferably, referring to fig. 2, the gates 12 may include two side gates. Two of the side gates are provided on the side surface of the cavity 10. For example, the side gates may be circular, rectangular, or other shapes in cross-section. Therefore, the material handle is easy to remove, the gate mark is small, and the influence on appearance quality is small.

When the molten soft rubber material is injected into the cavity 10, the molten soft rubber material can be relatively synchronously and uniformly filled at the two ends of the arched parting surface 11 in the length direction. Further, referring to fig. 2, two of the side gates are located on the arcuate land 11. The two side gates are uniformly distributed along the length direction of the arched parting surface 11. The two side gates equally divide the length of the arcuate parting surface 11 into three sections. For example, as shown in fig. 2, two of the side gates may divide the arc length of the arcuate parting surface equally into three segments. Therefore, the molten soft rubber can be synchronously and uniformly filled at the two ends of the arched parting surface 11 in the length direction at the end.

Molten soft glue needs to be injected into the cavity 10. Preferably, the injection molding method is further provided with an injection machine to inject molten soft gum into the mold cavity 10. The specific structure of the injection machine can adopt the prior art. The injection machine may include a feed tube. According to the physical property table of the raw materials, when the molten soft rubber is injected into the die cavity 10, the temperature of the charging barrel is controlled to be 210-230 ℃. For example, the soft gum may be a TPU soft gum. In order to avoid serious burrs on the surface of the molded soft rubber arch product, the temperature of the charging barrel can be set to be lower limit as much as possible in the specific implementation process.

Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. An injection molding method of a soft rubber arch product is characterized by comprising the following steps:

providing a mould, wherein the mould comprises a cavity (10) for molding a soft rubber arch product and an arch parting surface (11), the mould is provided with a pouring gate (12) and two exhaust channels, and the two exhaust channels are respectively positioned at two sides of the length direction of the arch parting surface (11) and are communicated with the cavity (10);

injecting the molten soft rubber material into the mold cavity (10) in sections, and controlling the injection speed of the molten soft rubber material to be 10-15 mm/s when injecting the molten soft rubber material at the tail section;

when the two ends of the arched parting surface (11) in the length direction are filled with molten plastic materials at last, the mold cavity (10) is filled with the molten soft plastic materials;

maintaining the pressure of the die; when the mould is subjected to pressure maintaining, the pressure maintaining speed is controlled to be 4-10 mm/s;

the exhaust channel comprises an exhaust groove (13) with one end communicated with the cavity (10), and the exhaust groove (13) is positioned at one end of the length direction of the arched parting surface (11);

the gate (12) comprises two side gates; the two side gates are positioned on the arched parting surface (11), and the two side gates divide the length of the arched parting surface (11) into three equal sections;

an injection machine is provided, the injection machine comprising a barrel, the temperature of the barrel being controlled at 210-230 ℃ when injecting molten soft gum into the mould cavity (10).

2. The method for injection molding of soft gum dome products according to claim 1, wherein the end of the exhaust channel remote from the cavity (10) is in communication with a gas treatment unit.

3. The injection molding method of a soft gum arch product according to claim 1, wherein the mold comprises a fixed mold and a movable mold, the cavity (10) is arranged on the fixed mold, and the exhaust groove (13) is arranged on the fixed mold.

4. The injection molding method of soft gum arch product according to claim 1, wherein the exhaust channel further comprises an air guide hole (14), and the exhaust groove (13) is communicated with the outside through the air guide hole (14).

5. The method for injection molding of soft gum dome products according to claim 4, characterized in that the pore size of the gas-guiding hole (14) is 5 mm.