CN114536695A

CN114536695A - Flexible demoulding device

Info

Publication number: CN114536695A
Application number: CN202210202472.XA
Authority: CN
Inventors: 葛晓宏; 吕福恒; 张志文; 朱秋华; 李辉; 王金伙; 朱一梁
Original assignee: Xiamen University of Technology
Current assignee: Xiamen University of Technology
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2022-05-27
Anticipated expiration: 2042-03-03
Also published as: CN114536695B

Abstract

The invention discloses a flexible demolding device which comprises a female die and a male die, wherein the female die and the male die are arranged correspondingly, the male die is provided with an injection molding opening, a concave cavity is formed in the female die, the injection molding opening is communicated with the inner side of the concave cavity, a core is arranged on the male die and is positioned on the inner side of the concave cavity, the core is provided with a through hole, a metal core is arranged in the through hole, a gap is formed between the metal core and the inner wall of the core, a plurality of micro steel balls are arranged in the gap, a plurality of telescopic pieces are arranged in the female die, and output shafts of the telescopic pieces are in contact with the male die. Through setting up the core, the core is flexible material, can loose core fast after moulding plastics, and the drawing of patterns time that has significantly reduced has improved the work efficiency of the drawing of patterns.

Description

Flexible demoulding device

Technical Field

The invention belongs to the technical field of injection mold equipment, and particularly relates to a flexible demolding device.

Background

Injection molding is a method for producing and molding industrial products, and in the injection mold industry, blow molding and rotational molding are generally used for molding hollow round or arc-shaped composite parts. In injection moulding, the demoulding process of the mold core is more complicated, the demoulding process occupies a large amount of time, the forming period of the product is longer, the production efficiency of enterprises is lower, and if the demoulding time in injection moulding is reduced, the production efficiency can be greatly improved.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a flexible demolding device, wherein a core is arranged and made of a flexible material, and can be used for quickly pulling a core after injection molding is finished, so that the demolding time is greatly shortened, and the demolding working efficiency is improved.

The invention provides the following technical scheme:

the utility model provides a flexible drawing of patterns device, includes die and terrace die, the die corresponds the setting with the terrace die, the terrace die is provided with the mouth of moulding plastics, be provided with the cavity in the die, the mouth of moulding plastics is inboard with the cavity and communicates, be provided with the core on the terrace die, the core is located the inboard of cavity, the core is provided with the through-hole, be provided with metal core in the through-hole, be provided with the clearance between the inner wall of metal core and core, be provided with a plurality of miniature steel balls in the clearance, be provided with a plurality of extensible members in the die, the output shaft and the terrace die contact of extensible member.

Preferably, the metal core material is metal iron, metal core's inboard is provided with the cavity, be provided with the iron core in the cavity, the surface winding of iron core has metal coil, metal coil's all is connected with the wire, the other end of wire is connected with the terminal, the terminal is located metal core's upper end, the terminal is connected with the DC power supply electricity.

Preferably, the outer surface of the metal core is provided with a plurality of channels, the channels are communicated with the lower side of the metal core, the miniature steel balls are positioned on the inner side of the channels, and the width of the channels is larger than the diameter of the miniature steel balls.

Preferably, the channels have a cosine function of their trajectory, the channels being arranged uniformly over the surface of the metal core.

Preferably, the core includes stiff end and flexible core, the stiff end is connected with flexible core, flexible core's material is polytetrafluoroethylene.

Preferably, the fixed end is provided with a first fixed hole, the upper end of the metal core is provided with a second fixed hole, when the metal core is inserted in the metal core, the first fixed hole is over against the second fixed hole, and fixed pins are inserted in the first fixed hole and the second fixed hole.

Preferably, the surface of the fixed end is provided with a limiting plate, the upper side of the male die is provided with a cover plate, and the cover plate is used for fixing the limiting plate.

Preferably, this device still includes the liquid nitrogen container, the liquid nitrogen is held in the liquid nitrogen container, the liquid nitrogen container is connected with the spray gun, the spray gun can peg graft in the through-hole of core, the spray gun is used for letting in nitrogen gas to the through-hole of core and cools down the core.

Preferably, the cosine function of the channel trajectory is y = a · cos α, where a is the correlation coefficient.

Preferably, the upper end of the metal core is provided with a hanging ring, and the hanging ring is used for plugging and unplugging the metal core.

Preferably, the diameter of the core is R, and the diameter of the through hole on the core is R, then a = β · R/R, where β is a correction factor, and the value range is 0.89-0.93.

Preferably, the diameter of the micro steel ball is d, the width of the channel is 0.80-0.95d, the depth of the channel is 0.48-0.62d, and the unit mm of d is obtained.

Preferably, the length of the curve of the channel is s, and the number of the micro steel balls in each channel is n = t (s/2 d), wherein t is less than or equal to 0.5.

Preferably, in order to reduce the demolding time and improve the demolding efficiency, the invention also discloses a flexible demolding method, which comprises the following steps:

s1, core assembly, namely inserting the metal core into the core, wherein the miniature steel balls are filled between the metal core and the core, and then the core and the male die are fixed to realize the assembly and the fixation of the core;

s2, closing the die and carrying out injection molding, namely assembling the male die and the female die with the die, and carrying out injection molding and pressure maintaining on the interior of the die by using an injection molding machine after the die closing is finished;

s3, once core pulling is carried out, after the pressure maintaining is finished, the metal core is pulled out, the separation between the metal core and the core is realized, the core obtains larger space, and the novel demolding treatment is facilitated;

s4, cooling the core, and introducing a cooling substance into the through hole of the core after the primary core pulling is finished, so that the flexible core is rapidly contracted to realize the separation between the core and the plastic product;

s5, secondary core pulling, namely after cooling, firstly jacking the male die by using the telescopic piece to primarily separate the core from the plastic product, and then fully drawing out the core to realize the demoulding of the core;

and S6, taking out the micro steel balls, and taking out the micro steel balls scattered in the plastic product after the secondary core pulling is finished.

Preferably, the cooling time of the core is not less than 30 seconds in the core cooling process, and the cooling substance is liquid nitrogen or liquid water.

Preferably, the time interval between the primary core pulling and the core cooling is not more than 45 seconds.

Preferably, after the metal core is inserted into the core, the clearance between the metal core and the hole wall of the core is less than or equal to 1.5 mm.

Preferably, in the taking out of the micro steel balls, the magnets extend into the plastic product to take out the micro steel balls.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the flexible demolding device, the core is arranged, the core is made of the flexible material, the through hole is formed in the middle of the core, and the core can be rapidly pulled after injection molding is finished, so that demolding time is greatly shortened, and demolding efficiency is improved.

(2) According to the flexible demolding device, the iron core and the coil are arranged in the metal core, and after the coil is electrified, a magnetic field can be generated, so that the miniature steel ball is conveniently adsorbed, the metal core is further conveniently inserted into the through hole of the core, the use process is extremely convenient and fast, and the operation process is simple.

(3) According to the flexible demolding device, the liquid nitrogen tank is arranged, the mold core is cooled after injection molding is finished, the mold core is quickly separated from a plastic product by utilizing the principle of expansion with heat and contraction with cold, and great convenience is provided for taking out the mold core in the next step.

(4) According to the flexible demolding device, the channel and the miniature steel ball are arranged, the track of the channel is a cosine function, the rolling path of the miniature steel ball is increased during core pulling, the friction force between the metal core and the mold core is reduced, and great convenience is brought to core pulling.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic view of the overall structure of the present invention.

FIG. 2 is a schematic view of the connection of the inventive core to a metallic core.

FIG. 3 is a schematic view of a metallic insert of the present invention.

FIG. 4 is a schematic view of the internal structure of the metallic insert of the present invention.

FIG. 5 is a schematic view of a second metallic core of an embodiment of the present invention.

In the figure: 1. a female die; 2. a male die; 3. a concave cavity; 4. a fixing pin; 5. a core; 6. a fixed end; 7. a flexible core; 8. a first fixing hole; 9. a metal core; 10. a channel; 11. a miniature steel ball; 12. an iron core; 13. a metal coil; 14. a wire; 15. a binding post; 16. a telescoping member; 17. an injection molding port; 18. a limiting plate; 19. a cover plate; 20. and a second fixing hole.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described in detail and completely with reference to the accompanying drawings. It is to be understood that the described embodiments are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive efforts based on the embodiments of the present invention, are within the scope of protection of the present invention.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The first embodiment is as follows:

as shown in fig. 1-5, a flexible demolding device comprises a female die 1 and a male die 2, wherein the female die 1 and the male die 2 are arranged correspondingly, the male die 2 is provided with an injection port 17, a cavity 3 is arranged in the female die 1, the injection port 17 is communicated with the inner side of the cavity 3, a core 5 is arranged on the male die 2, the core 5 is positioned at the inner side of the cavity 3, the core 5 and the cavity 3 are used for molding a plastic product, the core 5 is provided with a through hole, a metal core 9 is arranged in the through hole, the metal core 9 is used for providing a supporting force during an injection molding process, so that the core 5 keeps a certain shape and is not easy to deform, a gap is arranged between the metal core 9 and the inner wall of the core 5, a plurality of micro steel balls 11 are arranged in the gap, and the micro steel balls are positioned in the cavity to ensure the dimensional accuracy inside the plastic product during the filling and pressure maintaining stages of injection molding, the die is characterized in that a plurality of telescopic pieces 16 are arranged in the die 1, an output shaft of each telescopic piece 16 is in contact with the male die 2, the telescopic pieces 16 are convenient for demoulding the mold core 5, the telescopic pieces 16 are electric telescopic rods or hydraulic cylinders, and the number of the telescopic pieces 16 is at least four.

The metal core 9 is made of metal iron, a cavity is formed in the inner side of the metal core 9, an iron core 12 is arranged in the cavity, a metal coil 13 is wound on the surface of the iron core 12, the metal coil 13 is connected with a wire 14, the other end of the wire 14 is connected with a terminal 15, the terminal 15 is located at the upper end of the metal core 9, the terminal 15 is electrically connected with a direct-current power supply, when the terminal 15 is electrified and current flows in the metal coil 13, the metal coil 13 generates a magnetic field, the metal core 9 can conveniently adsorb the miniature steel balls 11, and the metal core 9 and the miniature steel balls can be conveniently placed in through holes of the metal core 5.

The outer surface of the metal core 9 is provided with a plurality of channels 10, the channels 10 are communicated with the lower side of the metal core 9, the miniature steel balls 11 are located on the inner side of the channels 10, the width of the channels 10 is larger than the diameter of the miniature steel balls 11, the miniature steel balls 11 can roll in the channels 10 conveniently, the upper end of the metal core 9 is provided with a hanging ring, the hanging ring is used for plugging and unplugging the metal core 9, and the use process is convenient.

The core 5 includes stiff end 6 and flexible core 7, stiff end 6 is connected with flexible core 7, flexible core 7's material is polytetrafluoroethylene. The fixed end 6 is provided with a first fixed hole 8, the upper end of the metal core 9 is provided with a second fixed hole 20, when the metal core 9 is inserted in the core 5, the first fixed hole 8 is just opposite to the second fixed hole 20, a fixed pin 4 is inserted in the first fixed hole 8 and the second fixed hole 20, and the fixed pin 4 is used for fixing the metal core 9 and the core 5. The surface of the fixed end 6 is provided with a limiting plate 18, the upper side of the male die 2 is provided with a cover plate 19, and the cover plate 19 is used for fixing the limiting plate 18.

This device still includes the liquid nitrogen jar, the liquid nitrogen has been held in the liquid nitrogen jar, the liquid nitrogen jar is connected with the spray gun through the connecting pipe, the spray gun can be pegged graft in the through-hole of core, the spray gun is used for letting in nitrogen gas to the through-hole of core and cools down the core, makes core 5 can contract fast, carries out quick separation with plastic products.

Example two

With reference to the first embodiment and fig. 5, the channels 10 are uniformly arranged on the surface of the metal core 9 according to the cosine function curve of the track of the channel 10, and the track of the channel 10 is set as the cosine function curve, so that the movement distance of the micro steel balls 11 during core pulling is prolonged, interference friction between the adjacent micro steel balls 11 is avoided, and the metal core 9 can be smoothly pulled out. The cosine function of the channel trajectory is y = a · cos α, where a is the correlation coefficient. The diameter of the core 5 is R, the diameter of the through hole on the core 5 is R, then a = β · R/R, where β is a correction coefficient and has a value range of 0.89-0.93, and when the value range of β is less than 0.89, the curvature of the channel trajectory is small, and when the metal core 9 is drawn out, the micro steel balls 11 easily slide, friction occurs between the micro steel balls 11, and the metal core 9 is not easily drawn out smoothly.

The diameter of the miniature steel ball 11 is d, the width of the channel is 0.80-0.95d, the depth of the channel is 0.48-0.62d, and the unit mm of d is obtained. The length of the curve of the channel is s, the number n of the micro steel balls in each channel is = t · s/2d, wherein t is less than or equal to 0.5, when t is less than or equal to 0.5, the micro steel balls 11 can be guaranteed to roll smoothly in the channel, when the relation is met, the micro steel balls 11 can slide smoothly in the channel, meanwhile, in the injection molding process, the contact area between the micro steel balls 11 and the mold core 5 can be maximized, a large supporting force is kept to the maximum extent, and the mold core is not prone to deformation.

EXAMPLE III

With reference to the second embodiment, the cosine function of the channel trajectory is y = a · cos α, which can be further described as y = β · R/R · cos α, where β is a correction coefficient, the value range is 0.89-0.97, R is 20mm, and R is 10mm, performing an insertion and extraction experiment on the metal core 9, and testing the smoothness of the insertion and extraction process. The method comprises the steps of collecting data of a force variation curve, collecting a small value 10 group, collecting an average number a1, collecting a large value 10 group, collecting an average value a2, representing the force variation condition with k = a1/a2, wherein the larger the k value is, the more obvious the force variation is, when the metal core is drawn out, the friction interference occurs between the miniature steel balls, and the smaller the k value is, the metal core can be drawn out smoothly.

When the value of beta is 0.60, k is 4.2; when the value of beta is 0.79, k is 2.1; when the value of beta is 0.89, k is 1.5; when the value of beta is 0.93, k is 1.3; when the value of beta is 0.97, k is 1.09; when the value of beta is 1.0, k is 1.95. Based on the above results, the effect is better when the value range of beta is 0.89-0.97.

Example four

A flexible demolding method, comprising the following steps:

In the cooling process of the mold core, the cooling time of the mold core is not less than 30 seconds, the cooling substance is liquid nitrogen or liquid water, and when the liquid water is adopted, the temperature of the water is not higher than 20 ℃, so that the mold core can be fully cooled, and the mold core and the plastic can be fully separated. The time interval between the primary core pulling and the core cooling is not more than 45 seconds, the temperature of the core and a plastic product is prevented from being reduced due to the fact that heat in the mold volatilizes, the cooling effect of the core is not affected, and after the time interval between the primary core pulling and the core cooling is more than 45 seconds, the core shrinking effect is not obvious, and the subsequent secondary core pulling process is affected.

After the metal core is inserted into the core, the clearance between the metal core and the hole wall of the core is less than or equal to 1.5mm, the deformation of the core in the injection molding process is reduced, and the size precision of the plastic product is ensured.

The mold core includes stiff end and flexible mold core, the stiff end is connected with flexible mold core, flexible mold core's material is polytetrafluoroethylene. In the process of taking out the miniature steel balls, the magnets are used for extending into the plastic products to take out the miniature steel balls, and the taking-out process is extremely convenient.

The device obtained by the technical scheme is a flexible demoulding device, a female die 1 and a male die 2 are matched before injection molding, a metal core 9 is inserted in a core 5, at the moment, a miniature steel ball is arranged in a channel of the metal core 9, then, injection molding is carried out, in the injection molding process, molten high-density polyethylene (HDPE) is injected into a die by an injection molding machine in a pressing mode, the core inside the die is a Polytetrafluoroethylene (PTFE) flexible core 5, the shape of the inner die core is ensured by expanding the miniature steel ball 11 filled in an inner through hole, after pressure maintaining is finished, the Polytetrafluoroethylene (PTFE) core 5 is demoulded by secondary loose core, finally, flexible demoulding is realized, the demoulding process is that the metal core 9 is firstly extracted, then liquid nitrogen is filled for cooling, finally, the core 5 is extracted, a telescopic piece is firstly started between the extracted cores 5, the telescopic piece is used for ejecting out the male die, and then the core 5 is completely extracted, as the metal core is withdrawn from the Polytetrafluoroethylene (PTFE) core, more space is available, providing great convenience for withdrawing the core 5. The metal core is tightly assembled with a Polytetrafluoroethylene (PTFE) flexible core during mold closing. The miniature steel balls are positioned between the mold core 5 and the metal mold core 9, and the dimensional precision inside the plastic part can be ensured in the filling and pressure maintaining stages of injection molding.

During the extraction of the metallic core 9, the metallic coil 13 is in a de-energized state, and during the preparation phase of the injection molding, the metallic core 9 is inserted into the core 5, the metallic coil 13 is in an energized state.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention; any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a flexible drawing of patterns device, its characterized in that, includes die (1) and terrace die (2), die (1) corresponds the setting with terrace die (2), terrace die (2) are provided with the mouth of moulding plastics (17), be provided with cavity (3) in die (1), the mouth of moulding plastics (17) and cavity (3) inboard intercommunication, be provided with core (5) on terrace die (2), core (5) are located the inboard of cavity (3), core (5) are provided with the through-hole, be provided with metal core (9) in the through-hole, be provided with the clearance between the inner wall of metal core (9) and core (5), be provided with a plurality of miniature steel balls (11) in the clearance, be provided with a plurality of extensible member (16) in die (1), the output shaft and the terrace die (2) contact of extensible member (16).

2. The flexible demolding device according to claim 1, wherein the metal core (9) is made of metal iron, a cavity is arranged inside the metal core (9), an iron core (12) is arranged in the cavity, a metal coil (13) is wound on the surface of the iron core (12), the metal coils (13) are connected with conducting wires (14), the other end of each conducting wire (14) is connected with a binding post (15), the binding post (15) is located at the upper end of the metal core (9), and the binding post (15) is electrically connected with a direct current power supply.

3. Flexible stripper device according to claim 1, characterized in that the outer surface of the metal core (9) is provided with a plurality of channels (10), said channels (10) communicating with the lower side of the metal core (9), said micro-balls (11) being located inside the channels (10), the width of said channels (10) being greater than the diameter of the micro-balls (11).

4. The flexible demolding device as claimed in claim 3, further comprising a liquid nitrogen tank, wherein liquid nitrogen is contained in the liquid nitrogen tank, the liquid nitrogen tank is connected with a spray gun, the spray gun can be inserted into the through hole of the mold core, and the spray gun is used for introducing nitrogen into the through hole of the mold core to cool the mold core.

5. A flexible stripper device according to claim 1, characterized in that said core (5) comprises a fixed end (6) and a flexible core (7), said fixed end (6) being connected to said flexible core (7), said flexible core (7) being made of teflon.

6. Flexible demolding device according to claim 5, wherein the fixing end (6) is provided with a first fixing hole (8), the upper end of the metal core (9) is provided with a second fixing hole (20), the first fixing hole (8) is opposite to the second fixing hole (20) when the metal core (9) is inserted in the core (5), and fixing pins are inserted in the first fixing hole (8) and the second fixing hole (20).

7. A flexible ejection device according to claim 5, wherein the cosine of the path trajectory is y = a · cos α, where a is the correlation coefficient.