CN101549546B - Temperature changing unit of micro injection molding die - Google Patents

Abstract

The utility model relates to a micro-injection molding mold temperature changing device, which belongs to the technical field of micro-injection molding molds. The mold temperature changing device includes a liquid-absorbing core heat pipe, a semiconductor cooling chip, a copper plate, a water tank, a thermocouple and a temperature controller. One side of the liquid-absorbing core heat pipe is inserted into the mold cavity plate, and the other side is inserted into the copper plate; both sides of the copper plate Both are in contact with the semiconductor refrigerating sheet, and the other side of the semiconductor refrigerating sheet is in contact with the water tank; the upper and lower surfaces of the semiconductor refrigerating sheet are coated with a heat-conducting layer; the thermocouple is in contact with the surface of the mold cavity and its temperature is fed back to the temperature controller. The computer controls the direction of the semiconductor refrigeration sheet current to determine the heating or cooling of the mold. The temperature changing device can realize variable temperature control on micro-injection molding molds and precise and uniform temperature control on templates. The device has a compact structure, which can flexibly adapt to the limited space in the injection molding machine and the mold, and reduce the thermal deformation of the template. The temperature changing device can be applied to the injection molding process of tiny plastic parts, and solves the problem of mold temperature control in the micro injection molding process.

Description

A temperature-changing device for micro-injection molding molds

technical field

The invention belongs to the technical field of micro-injection molding molds, and relates to a micro-injection molding mold temperature-changing device. the

Background technique

Micro-injection molding is an emerging technology that has developed rapidly in recent years. It is a manufacturing technology that can repeatedly produce complex plastic parts with precise microstructures. It has broad application prospects in the field of micro-electromechanical systems (MEMS). Compared with silicon-based material components currently used in the field of micro-electromechanical systems, the use of micro-injection molds to form components in MEMS has the advantages of low manufacturing cost, short production cycle, simple molding process, and easier guarantee of component quality. the

During the filling process of injection molding, when the polymer melt is in contact with the cavity wall of the low-temperature mold, the heat transfer between the melt and the cavity wall will cause the melt to lose heat rapidly, and the melt will form a condensation layer on the cavity wall , the condensed layer continues to expand to the inside, making the melt flow channel section continuously reduced, the melt flow resistance increases, and filling is difficult. Micro-injection molding plastic parts are small in size and high in precision. The mass is usually below 1 gram or has a micron-scale microstructure on it. The influence of the condensation layer will be more significant, so high mold temperature is usually used. In addition, high mold temperature can also eliminate other molding defects such as weld lines and molecular orientation, and improve the uniformity of products. However, the increase of mold temperature will inevitably increase the cooling time of plastic parts in the mold, prolonging the production cycle. Therefore, the ideal temperature adjustment system is that the mold can heat up quickly when filling the mold, and the mold temperature can quickly drop to the demoulding temperature when cooling, that is, the mold can realize variable temperature control. the

At present, the mold temperature change methods mainly include the following types: electric heating water cooling, infrared heating water cooling, induction heating water cooling, thin film resistance heating water cooling, composite mold wall adiabatic-heating, etc. Among them, the electric heating water cooling method is widely used, the structure is simple, and the cost is low. Its disadvantage is that the electric heating ring has a large thermal resistance, and it is easy to cause local overheating. There is a certain temperature gradient, and the heating is uneven, which is easy to cause template Thermal stress deforms, and the heating coil needs to be cooled at the same time during cooling, resulting in large heat loss. However, infrared heating water cooling and induction heating water cooling need to open the mold before filling the mold, heat the mold cavity manually or with a robot, and then quickly close the mold and fill it, increasing the operation steps, and after starting the mold closing and injection molding, it is impossible to control the template temperature. In addition to the disadvantages of electric heating and water cooling, thin film resistance heating water cooling and composite mold wall adiabatic heating have complex structures, require new materials with good thermal conductivity and good insulation, and are difficult to manufacture. the

Contents of the invention

The technical problem to be solved by the present invention is to provide a temperature-changing device for a micro-injection molding mold, which overcomes the shortcomings or deficiencies of the above-mentioned mold temperature-changing device, and promotes the development of micro-injection molding mold technology. the

Technical scheme of the present invention is as follows:

The utility model relates to a micro-injection mold temperature-changing device, which includes a liquid-absorbing core heat pipe, a semiconductor cooling sheet, a copper plate, a water tank, a thermocouple and a temperature controller.

In the temperature changing device, one side of the liquid-absorbing core heat pipe is inserted into the mold cavity plate, and the other side is inserted into the copper plate; both sides of the copper plate are in contact with the semiconductor cooling plate, and the other side of the semiconductor cooling plate is in contact with the water tank; The upper and lower surfaces of the cold sheet are coated with a heat conducting layer. the

The thermocouple is in contact with the surface of the mold cavity to feed back its temperature to the temperature controller. By controlling the direction of the current of the semiconductor refrigeration sheet, the heating and cooling of the mold and precise temperature control are realized. Add an insulating layer around the cavity block in the mold cavity plate to reduce heat loss and improve heat transfer efficiency. the

In actual use, multiple semiconductor cooling chips can be used in combination and placed on both sides of the copper plate. the

The effect and benefit of the present invention are: adopting the device can realize the variable temperature control of the micro-injection molding mold and the accurate and uniform temperature control of the template. The device has a compact structure, can flexibly adapt to the limited space in the injection molding machine and the mold, reduce the thermal deformation of the template, and avoid the influence of the temperature control system on the injection molding machine system. The mold temperature changing device can be applied to the injection molding process of tiny plastic parts, and solves the problem of mold temperature control in the micro injection molding process. In summary, the present invention will further improve the technical level of micro-injection molds and promote the application of micro-injection products in the field of micro-mechanical systems. the

Description of drawings

Figure 1 is a schematic diagram of the temperature changing device. the

Fig. 2(A) is a schematic diagram of the structure of the microfluidic chip. the

Fig. 2(B) is an enlarged view of the section A-A of Fig. 2(A). the

Fig. 3 is a schematic diagram of the overall assembly of the microfluidic chip mold. the

In the figure: 1. liquid-absorbing core heat pipe; 2. semiconductor cooling plate; 3. water tank; 4. mold cavity plate; 5. temperature controller; 6. computer; 7. copper plate. the

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with technical solutions and accompanying drawings. the

This embodiment is used for microfluidic chip injection molding molds for typical micro-injection molding parts. The chip structure is shown in Figure 2. The shape is a flat plate structure with two double cross-shaped microchannels on it. A rectangle that is 80 µm deep and 80 µm wide. the

Embodiment steps are as follows:

Step 1: Select different specifications of liquid-absorbing core heat pipe 1 and semiconductor cooling plate 2 according to the size of the mold cavity block, copper plate 7 and water tank 3 of corresponding size, and assemble as shown in Figure 3, and insert one side of the liquid-absorbing core heat pipe 1 into the mold In the cavity plate 4, the other side is inserted into the copper plate 7; both sides of the copper plate 7 are in contact with the semiconductor cooling plate 2; The cooling water is used for semiconductor cooling fin 2 to dissipate heat. the

Step 2: The thermocouple is in contact with the surface of the mold cavity, and its temperature is fed back to the temperature controller 5. When the temperature of the cavity is lower than the heating temperature set by the computer 6, the side of the semiconductor cooling plate 2 in contact with the copper plate 7 dissipates heat, and the heat Through the liquid-absorbing core heat pipe 1, it is transmitted to the mold cavity plate 4 to heat it, and when the set temperature is reached, operations such as chip injection and pressure maintenance are performed;

step 3

The computer 6 sets the cooling temperature, and the temperature controller 5 controls the direction of the current of the semiconductor refrigeration sheet 2. The side in contact with the copper plate 7 absorbs heat, and the mold cavity plate 4 is cooled by the liquid-absorbing core heat pipe 1. When the cooling temperature is reached, Carry out operations such as chip ejection. the

step 4

As shown in Figure 1, the temperature control curve is set by the computer 6 program, and steps 2 and 3 are repeated to realize the variable temperature control of the mold. the

Claims (3)

1. temperature changing unit of micro injection molding die, comprise imbibition core heat pipe (1), conductor refrigeration sheet (2), water tank (3), thermocouple and temperature controller, copper coin (7), it is characterized in that: a side of imbibition core heat pipe (1) is inserted in the mold cavity plate (4) in this changing device, and opposite side inserts in the copper coin (7); Copper coin (7) both sides all contact with conductor refrigeration sheet (2), and the opposite side of conductor refrigeration sheet (2) contacts with water tank (3); The upper and lower surface applied heat-conducting layer of conductor refrigeration sheet (2); Thermocouple contacts with the mold cavity surface and feeds back its temperature to temperature controller, mold cavity plate (4) is heated or cooling with definite by computer (6) control semiconductor chilling plate (2) sense of current.

2. a kind of temperature changing unit of micro injection molding die as claimed in claim 1, its feature also is: multi-disc semiconductor chilling plate (2) coupling places it in copper coin (7) both sides.

3. a kind of temperature changing unit of micro injection molding die as claimed in claim 1, its feature also is: add heat insulation layer in mold cavity plate (4) around the die cavity piece.

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