CN108189352B

CN108189352B - Injection mold convenient to cool

Info

Publication number: CN108189352B
Application number: CN201711470064.8A
Authority: CN
Inventors: 邱建华
Original assignee: Chongqing Yinsheng Mold Co ltd
Current assignee: Chongqing Yinsheng Mold Co ltd
Priority date: 2017-12-29
Filing date: 2017-12-29
Publication date: 2020-10-27
Anticipated expiration: 2037-12-29
Also published as: CN108189352A

Abstract

The application relates to the field of plastic injection, and particularly discloses an injection mold convenient to cool, which comprises an upper mold and a lower mold, wherein a cooling water channel and a plurality of capillary cooling pipes are arranged in the upper mold and the lower mold and surround a mold cavity; the water inlet is communicated with the water pump through a liquid inlet pipe, the liquid inlet pipe comprises an inlet section, a throat and a diffusion section, the inlet section is communicated with the water pump, the diffusion section is communicated with the cooling water channel, one end of the capillary cooling pipe is communicated with the inlet section, and the other end of the capillary cooling pipe is communicated with the throat; the periphery of the capillary cooling pipe is provided with a throttling device, the throttling device comprises an expansion chamber surrounding the periphery of the capillary cooling pipe, a slide way communicated with the expansion chamber and a needle valve throttling the capillary cooling pipe, a piston is arranged in the slide way and connected with a valve core of the needle valve, and a heated expansion substance is filled in the expansion chamber. During injection molding, the speed of temperature reduction of the high heat area and the low heat area is more uniform, so that the deformation of an injection molding piece is avoided.

Description

Injection mold convenient to cool

Technical Field

The invention relates to the field of plastic injection, in particular to an injection mold convenient to cool.

Background

The injection molding piece is generally processed by injection molding through an injection mold, the mold is generally provided with an upper module and a lower module, an injection molding cavity is formed in the middle of the upper mold and the lower mold after the upper mold and the lower mold are combined in a closed mode, and due to the fact that molten plastic grains are added during pouring, structures such as a mold core and a mold are easy to deform, cooling needs to be accelerated after pouring is completed, and the injection molding piece is formed more quickly. At present, some cooling systems are provided, through holes are formed in a mold, and water is injected into the through holes to cool the mold, but the cooling effect of the structure is poor, so that cooling points are unevenly distributed, injection molded parts are likely to deform, and the rejection rate is increased.

In addition, in the process of molding the injection molded part, the upper mold and the lower mold are matched with each other, after the injection molded part is molded, the upper mold is dismounted firstly, and then the lower mold is removed to obtain a finished product. Since the plastic product is not completely adhered to the lower mold side during the removal of the upper mold, there is a portion adhered to the upper mold, resulting in strain deformation of the product. The existing solution is to prolong the cooling time of the product and increase the packing force of the mould plastic on the rubber product, and the method prolongs the molding cycle of the product and reduces the production efficiency of the product.

Disclosure of Invention

The invention aims to provide an injection mold convenient to cool so as to ensure that the temperature reduction speed of a region with lower heat and a region with higher heat is more uniform during injection so as to avoid the deformation of an injection molding part.

In order to achieve the above purpose, the basic scheme of the invention is as follows:

the injection mold convenient to cool comprises an upper mold and a lower mold, wherein the upper mold and the lower mold are buckled to form a mold cavity, cooling water channels are further arranged in the upper mold and the lower mold, the cooling water channels surround the mold cavity, a water inlet and a water outlet which are communicated with the cooling water channels are formed in the upper mold and the lower mold, a plurality of capillary cooling pipes are further arranged in the upper mold and the lower mold, and the capillary cooling pipes are arranged between the cooling water channels and the mold cavity; the water inlet is communicated with the water pump through a liquid inlet pipe, the liquid inlet pipe comprises an inlet section, a throat and a diffusion section, the cross sectional areas of the inlet section and the diffusion section are larger than that of the throat, the inlet section is communicated with the water pump, the diffusion section is communicated with the cooling water channel, one end of the capillary cooling pipe is communicated with the inlet section, and the other end of the capillary cooling pipe is communicated with the throat; the throttling device comprises an expansion chamber surrounding the periphery of the capillary cooling pipe, a slide way communicated with the expansion chamber and a needle valve used for throttling the capillary cooling pipe, a piston is arranged in the slide way, and the piston is connected with a valve core of the needle valve; the expansion chamber is filled with a heated expansion substance, the volume of the heated expansion substance expands, and the opening degree of the needle valve is increased; the volume of the heated expansion substance shrinks, and the opening degree of the needle valve is reduced.

This scheme injection mold convenient to cooling's principle lies in:

after the injection of the molten plastic into the mold cavity is completed, the water pump is started to pump cooling water into the cooling water channel, and the cooling water passes through the cooling water channel and is discharged from the water outlet, so that the upper mold and the lower mold can be cooled by the cooling water. The water pump injects water into the cooling water channel through the water inlet after passing through the liquid inlet pipe, the liquid inlet pipe comprises an inlet section, a throat and a diffusion section, the cross sectional areas of the inlet section and the diffusion section are both larger than that of the throat, and when the water pump pumps cooling water into the inlet section, the throat has a blocking effect on water flow due to the fact that the throat contracts relative to the inlet section, and therefore the pressure in the inlet section is increased; and because the pressure in the inlet section is increased, cooling water is accelerated to enter the throat, so that the flow velocity in the throat is increased, and according to the Bernoulli law, the fluid flow velocity is faster, the pressure is smaller, and the pressure in the throat is reduced. Because the two ends of the capillary cooling pipe are respectively communicated with the inlet section and the throat, pressure difference is formed between the two ends of the capillary cooling pipe, cooling water enters the capillary cooling pipe from the inlet section and then returns to the throat, and therefore the cooling water flows in the capillary cooling pipe.

Since the capillary cooling tubes are located between the cooling water channels and the mold cavity, the capillary cooling tubes will absorb the heat of the molten plastic in the mold cavity more quickly. And the surface area of the capillary cooling pipe contacted with cooling water is large, so that heat can be absorbed more quickly. The heat in the mold cavity varies from place to place due to the different thickness of the molten plastic in the mold cavity. Because the heat which can be taken away by cooling water is limited when the cooling water passes through the capillary cooling pipe, the heat dissipation is relatively slow at the place with higher heat, namely the heat dissipation is slow at the place with thicker molten plastic; and the place with lower heat dissipates heat fast, namely the place with thinner molten plastic dissipates heat fast, so the temperature of each capillary cooling tube is different in the heat dissipating process.

Because the expansion cavity surrounds the capillary cooling pipe and is internally provided with the thermal expansion substance, the temperature of the capillary cooling pipe directly influences the volume of the thermal expansion substance. When the capillary cooling pipe is located at a position with higher heat, the temperature of the capillary cooling pipe is higher, and the volume of the heated expansion substance is increased, so that the heated expansion substance enters the slide way and extrudes the piston, and the piston pushes the valve core of the needle valve to increase the opening degree of the needle valve; the flow rate of the cooling water in the capillary cooling tube increases and thus the capacity of the capillary cooling tube to remove heat increases. The capillary cooling pipe is located at the position where the heat is reduced, the temperature of the capillary cooling pipe is also lower, and the volume of the heated expansion substance is relatively smaller, so that the extrusion force of the heated expansion substance on the piston is small, the opening degree of the needle valve is small, the flow of cooling water in the capillary cooling pipe is reduced, and the capacity of the capillary cooling pipe for taking away the heat is weakened. Therefore, because the heat at each position in the die cavity is different, the cooling capacity of each capillary cooling pipe is also different, namely the higher the heat is, the higher the cooling capacity of the capillary cooling pipe is enhanced, and the lower the heat is, the lower the cooling capacity of the capillary cooling pipe is reduced, thereby enabling each position of the die to be in a lower temperature difference range.

The beneficial effect that this scheme produced is:

the cooling speed of the capillary cooling pipe is high for the area with high heat, and the cooling speed of the area with low heat is low, so that the phenomenon that the temperature of the area with low heat is reduced quickly, the temperature of the area with high heat is reduced slowly, the temperature difference of a workpiece in a die cavity is large, the stress concentration phenomenon of the workpiece occurs, and the workpiece is deformed.

And (II) because the contact area between the capillary cooling pipe and the cooling water is large, the capillary cooling pipe can quickly absorb the heat of the molten plastic in the mold cavity, so that the cooling efficiency can be improved.

The first preferred scheme is as follows: as a further optimization of the basic solution, the thermally expansive substance is mercury; the thermal expansion coefficient of mercury is large, and mercury is liquid all the time in the expansion process, so that mercury is not easy to deform when being extruded by the piston, and pressure generated on the piston when mercury expands is large, so that the piston can be pushed to slide.

The preferred scheme II is as follows: as a further optimization of the first preferred scheme, a ring body made of heat insulating materials is sleeved outside the capillary cooling pipe, the expansion chamber is arranged in the ring body, and an opening communicated with the expansion chamber is arranged on the side wall of the ring body, which is in contact with the capillary cooling pipe. The ring body is made by thermal insulation material, and the expansion chamber is located in the ring body to the ring body has thermal-insulated effect to mercury in the expansion chamber, and only is equipped with the opening on the lateral wall that the ring body and capillary cooling tube contacted, thereby mercury in the expansion chamber will be through opening and capillary cooling tube direct contact, makes the volume of mercury mainly influenced by capillary cooling tube temperature, reduces other interference factor.

The preferable scheme is three: as a further optimization of the second preferred embodiment, the inner diameter of the capillary cooling pipe is 2-3 mm; if the inner diameter of the capillary cooling pipe is too small, the resistance of the cooling water flowing in the capillary cooling pipe is large, and if the inner diameter of the capillary cooling pipe is too large, the temperature in the capillary cooling pipe cannot be rapidly increased, so that the response speed of the valve core of the needle valve is slow, and the adjustment of the heat absorption capacity of the capillary heat absorption pipe is not facilitated.

The preferable scheme is four: as a further optimization of the third preferred embodiment, the capillary cooling pipe is made of copper, and the copper has a good heat conduction effect, so that the rate of heat transfer to the cooling water can be increased by using copper as the capillary cooling pipe, and the heat dissipation efficiency is increased.

The preferable scheme is five: as a further optimization of the preferable scheme four, the inner wall of the capillary cooling pipe is provided with a plurality of heat conduction columns so as to increase the contact area between the capillary cooling pipe and the cooling water and improve the heat absorption efficiency of the cooling water in the capillary cooling pipe.

Drawings

FIG. 1 is a schematic structural view of an embodiment of an injection mold of the present invention that facilitates cooling;

fig. 2 is an enlarged view of a portion a in fig. 1.

Detailed Description

The present invention will be described in further detail below by way of specific embodiments:

reference numerals in the drawings of the specification include: the device comprises an upper die 10, a die cavity 20, a lower die 30, a water inlet 31, a water outlet 32, an inlet section 33, a throat 34, a diffusion section 35, a cooling water channel 36, a capillary cooling pipe 37, a heat dissipation column 38, a ring body 41, a piston 42, a valve core 43, an expansion chamber 44 and a slide way 45.

The embodiment is basically as shown in figures 1 and 2:

the injection mold convenient to cooling of this embodiment includes mould 10 and lower mould 30, goes up and forms die cavity 20 after mould 10 and the lock of lower mould 30, is equipped with the passageway of moulding plastics on going up mould 10, can inject molten plastics into the film cavity through the passageway of moulding plastics. The upper die 10 and the lower die 30 are also internally provided with cooling water channels 36, the cooling water channels 36 surround the die cavity 20, the upper die 10 and the lower die 30 are both provided with a water inlet 31 and a water outlet 32, and two ends of the cooling water channels 36 are respectively communicated with the water inlet 31 and the water outlet 32; thereby introducing cooling water from the water inlet 31, the cooling water will pass through the cooling water channel 36 and then be discharged from the water outlet 32, and the cooling water will surround the mold cavity 20 to cool the mold and the molten plastic, so as to cool and solidify the molten plastic. A plurality of capillary cooling pipes 37 made of copper are arranged in the upper die 10 and the lower die 30, the capillary cooling pipes 37 are arranged between the cooling water channel 36 and the die cavity 20, and cooling water flows through the capillary cooling pipes 37 to accelerate the cooling of the die and the molten plastic. The inner diameter of the capillary cooling pipe 37 is 3mm, so that the flow rate of cooling water passing through the capillary cooling pipe 37 is small, and the temperature of the cooling water in the capillary cooling pipe 37 can be rapidly increased; in addition, the inner wall of the capillary cooling pipe 37 is provided with a plurality of heat conduction columns to increase the contact area between the capillary cooling pipe 37 and the cooling water. The water inlet 31 is provided with a liquid inlet pipe, cooling water in the cooling channel is pumped by a water pump, and the water inlet 31 is communicated with the water pump through the liquid inlet pipe. The liquid inlet pipe comprises an inlet section 33, a throat 34 and a diffuser section 35, the cross-sectional areas of the inlet section 33 and the diffuser section 35 are three times that of the throat 34, and the inlet section 33 and the diffuser section 35 are both transited to the throat 34 through taper holes; the inlet section 33 communicates with a water pump, and the diffuser section 35 communicates with a cooling water passage 36. When fluid flows in from the inlet section 33 of the liquid inlet pipe, the throat 34 has a blocking effect on the fluid due to the contraction of the throat 34, so that the pressure of the fluid in the inlet section 33 is increased, the fluid is accelerated to enter the throat 34, the flow speed in the throat 34 is increased, and the pressure of the fluid at the throat 34 is reduced. One end of the capillary cooling pipe 37 is communicated with the inlet section 33, and the other end of the capillary cooling pipe 37 is communicated with the throat 34, so that when cooling water passes through the liquid inlet pipe, pressure difference exists between two ends of the capillary cooling pipe 37, and therefore the cooling water enters the capillary cooling pipe 37 and flows in the capillary cooling pipe 37 to cool the mold.

The throttling device is arranged on the periphery of the capillary cooling pipe 37 and comprises a needle valve and a ring body 41 sleeved on the periphery of the capillary cooling pipe 37, a valve core 43 of the needle valve extends into the capillary cooling pipe 37, the opening degree of the needle valve is smaller as the length of the valve core 43 of the needle valve extending into the capillary cooling pipe 37 is longer, and conversely, the opening degree of the needle valve is larger as the length of the valve core 43 of the needle valve extending into the capillary cooling pipe 37 is shorter. The ring body 41 is made of heat insulating ceramic so as to lower its heat conductive performance. An expansion chamber 44 is arranged in the ring body 41, an opening which is in contact with the expansion chamber 44 is arranged on the side wall of the ring body 41 which is in contact with the capillary cooling pipe 37, mercury is filled in the expansion chamber 44, the mercury is in contact with the capillary cooling pipe 37 through the opening, and when the temperature of the capillary cooling pipe 37 changes, the volume of the mercury also changes. In addition, the ring body 41 is externally arranged to slide and communicated with the expansion chamber 44, and when the volume of mercury expands, the mercury enters the slide way 45; and a piston 42 is provided in the slide 45, the piston 42 being slidable in the slide, so that when the volume of mercury expands, the mercury presses the piston 42, thereby pushing the piston 42 to slide in the slide. The valve body 43 of the needle valve is welded with the piston 42 into a whole, and when the piston 42 slides, the valve body 43 of the needle valve is pushed to move, namely when the temperature of the capillary cooling pipe 37 changes, the opening degree of the needle valve also changes.

The concrete working process of the injection mold convenient for cooling of the embodiment is as follows:

injecting molten plastic into the mold cavity 20, starting a water pump to pump cooling water into the liquid inlet pipe, wherein when the cooling water is pumped into the liquid inlet pipe, the pressure of the inlet section 33 is increased, and the pressure in the throat 34 is smaller, so that a pressure difference is formed at two ends of the capillary cooling pipe 37, and the cooling water circulates in the capillary cooling pipe 37 while entering the cooling channel; so that the cooling water channels 36 and the capillary cooling tubes 37 have a cooling effect on both the mould and the molten plastic in the mould cavity 20. The capillary cooling pipe 37 is provided between the cooling water passage 36 and the mold cavity 20, and the surface area of the capillary cooling pipe 37 in contact with the cooling water is large, so that heat can be absorbed more quickly.

Because of the different thicknesses of the molten plastic at different locations within the mold cavity 20, the amount of heat present at various locations within the mold cavity 20 is different. Since the cooling water has a limited amount of heat to be carried away when passing through the capillary cooling tubes 37, heat dissipation is relatively slow at places with high heat; and the heat is quickly dissipated at the place with lower heat, so the temperature of each capillary cooling pipe 37 is different in the heat dissipation process. When the capillary cooling pipe 37 is located at a position where the heat quantity is high, the temperature of the capillary cooling pipe 37 is high, the opening degree of the needle valve is increased when the volume of mercury is increased, and the flow rate of cooling water in the capillary cooling pipe 37 is increased, so that the heat quantity carrying capacity of the capillary cooling pipe 37 is enhanced. When the capillary cooling tube 37 is in the position where the heat is reduced, the temperature of the capillary cooling tube 37 is also low, and the volume of mercury is relatively small, the opening degree of the needle valve is small, so that the flow rate of cooling water in the capillary cooling tube 37 is reduced, and the ability of the capillary cooling tube 37 to take away the heat is reduced. Therefore, because the heat quantity at each position in the mold cavity 20 is different, the cooling capacity of each capillary cooling pipe 37 is also different, that is, the higher the heat quantity is, the higher the cooling capacity of the capillary cooling pipe 37 is enhanced, and the lower the heat quantity is, the higher the cooling capacity of the capillary cooling pipe 37 is reduced, so that each position of the mold can be in a lower temperature difference range.

Example two:

the second embodiment is different from the first embodiment only in that in the second embodiment, the throttling device includes a temperature sensor, a solenoid valve and a controller, the temperature sensor and the solenoid valve are both electrically connected with the controller, the temperature sensor extends into the capillary cooling tube, and a valve core of the solenoid valve extends into the capillary cooling tube. The temperature sensor can monitor the temperature in the capillary cooling pipe in real time and send feedback signals to the control gas, and the controller sends execution signals to the electromagnetic valve, so that the depth of the electromagnetic valve extending into the capillary cooling pipe can be changed, and the flow of cooling water in the capillary cooling pipe can be changed.

The foregoing is merely an example of the present invention and common general knowledge of known specific structures and features of the embodiments is not described herein in any greater detail. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims

1. Injection mold convenient to cooling, including last mould and lower mould, go up mould and lower mould lock back formation die cavity, still be equipped with the cooling water passageway in last mould and the lower mould, the cooling water passageway centers on around the die cavity, and goes up the mould and be equipped with in the lower mould and feed through with the cooling water passageway water inlet and delivery port, its characterized in that: a plurality of capillary cooling pipes are arranged in the upper die and the lower die and are arranged between the cooling water channel and the die cavity; the water inlet is communicated with the water pump through a liquid inlet pipe, the liquid inlet pipe comprises an inlet section, a throat and a diffusion section, the cross sectional areas of the inlet section and the diffusion section are larger than that of the throat, the inlet section is communicated with the water pump, the diffusion section is communicated with the cooling water channel, one end of the capillary cooling pipe is communicated with the inlet section, and the other end of the capillary cooling pipe is communicated with the throat; the throttling device comprises an expansion chamber surrounding the periphery of the capillary cooling pipe, a slide way communicated with the expansion chamber and a needle valve used for throttling the capillary cooling pipe, a piston is arranged in the slide way, and the piston is connected with a valve core of the needle valve; the expansion chamber is filled with a heated expansion substance, the volume of the heated expansion substance expands, and the opening degree of the needle valve is increased; the volume of the heated expansion substance shrinks, and the opening degree of the needle valve is reduced.

2. The easy-to-cool injection mold of claim 1, wherein: the thermally expansive substance is mercury.

3. The easy-to-cool injection mold of claim 2, wherein: the capillary cooling pipe is sleeved with a ring body made of heat insulating materials, the expansion chamber is arranged in the ring body, and an opening communicated with the expansion chamber is formed in the side wall, in contact with the capillary cooling pipe, of the ring body.

4. The easy-to-cool injection mold of claim 3, wherein: the inner diameter of the capillary cooling pipe is 2-3 mm.

5. The easy-to-cool injection mold of claim 4, wherein: the capillary cooling tube is made of copper.

6. The easy-to-cool injection mold of claim 5, wherein: and a plurality of heat conducting columns are arranged on the inner wall of the capillary cooling pipe.