WO2008110031A1

WO2008110031A1 - A method for manufacturing a tubular injection molded part

Info

Publication number: WO2008110031A1
Application number: PCT/CN2007/000775
Authority: WO
Inventors: Lichang Wu
Original assignee: Lichang Wu
Priority date: 2007-03-12
Filing date: 2007-03-12
Publication date: 2008-09-18

Abstract

A method for manufacturing a tubular injection molded part, comprises: making a hollow tube core (13) from rubber material; inserting a core bar (9) and dry sand (10) into the tube core (13) and compressing them with negative pressure; putting the tube core (13) into an injection mold (2); closing the mold and injecting; opening the mold and removing the injection tube (14) with the core (13), and then relieving the negative pressure immediately in order to pour the core bar (9) and dry sand (10) from the tube core (13); finally removing the entire tube core (13) from the injection tube (14).

Description

Production method of tubular injection molded parts

Technical field

The invention relates to a production method of an injection molded part in the injection molding industry, in particular to a production method of a tubular injection molded part, a rubber core core pulling method. technical background

Usually, the lumen portion of the injection molded part is formed by the cavity mandrel (metal rod) on the injection mold in the reciprocating motion of the opening and closing mold, and the cavity thus formed can only be a straight cavity, and the curved pipe or the thick pipe Tube parts with thin tube cavities (such as intake manifolds) cannot be realized by the production method of the above injection molds.

The existing patented technology uses the "fuse core method" to produce injection manifold injection molded parts: This method is a toxic, harmful and banned chemical substance due to the metal elements such as bismuth, lead and cadmium in the low melting point alloy. Environmental pollution is large. Moreover, the process of this method is complicated, the production cost is high, and it is not suitable for large-scale production.

At present, the "welding method" is widely used in foreign countries to produce such parts. The intake manifold is divided into two halves and injection molded separately; then the two halves are welded. The use of the "welding method" requires the purchase of foreign technology and special welding equipment and special solderability engineering plastic particles. However, with this method, the cost investment is large, and the initial investment is expected to be no less than 5 million yuan. Moreover, the risk of using foreign welding methods is large: 1 The so-called "welding technology" is difficult to master, resulting in unstable production processes, resulting in unstable product quality and high production costs. 2 Domestic car factories (joint ventures) believe that welding intake manifold technology is difficult and does not agree with localization, so the support is very difficult. Due to the above reasons, domestic curved and complex pipe injection molded parts cannot be mass-produced, and high-quality, high-efficiency production. Summary of the invention

SUMMARY OF THE INVENTION The object of the present invention is to provide a method for producing a tubular injection molded part, a rubber core core pulling method, which realizes the overall core pulling by integrally producing an injection molded tubular part. The products produced by this method are of stable quality, high reliability and high production efficiency.

In order to achieve the above object, the method for producing a tubular injection molded part of the present invention, the rubber core core pulling method, is achieved by the following steps:

μ), a hollow rubber core made of rubber material, which is flexible and elastic, and is easy to take out from the curved and complicated lumen;

(2), put the core bone into the rubber die in step (1), fill in the dry sand and compact the pressure, take the rigidity, and facilitate injection molding; (3) placing the rubber die under the vacuum compaction state in the step (2) into the injection mold, and molding the injection mold;

(4), mold opening, take the injection pipe fittings together with the core, take out, immediately remove the negative pressure, let the core and dry sand flow out from the rubber die, run out;

(5), by hand grasping the rubber tube of the core part and gently twitching, the entire rubber tube can be completely extracted from the injection tube. At this point, an injection tube is produced, and the rubber tube can be extracted according to the above method. Recycling is used for the production of subsequent injection molded parts.

Preferably, the rubber die in the step (1) is equipped with a conformable tire, and the core is placed in the tire, the upper table is shaken and the negative pressure is compacted, and the rubber tube is compacted. The core is removed from the tire to ensure the size and shape of the rubber die to stabilize the product.

The rubber die of step (1) has at least one core, and the nozzles of the core are all open.

The rubber tube has a core portion at one end, and is designed to have a branch pipe connected to the vacuum system. In the rubber ferrule of the step (1), in order to establish a vacuum system, a plug is inserted into the opening of the core tube of the rubber tube, and the plug is made of a metal material such as steel.

Inserting a plug that is not open at the opening of at least one of the cores of the rubber die, preferably a core having one end of the branch pipe; a core having one end is filled with sand and sand, and the opening of the nozzle of the core is Insert the plug of the opening and tighten the plug above the rubber die to prevent air leakage.

After filling the core and dry sand in the rubber die, after filling the core and dry sand, apply a plastic film on the sand surface, then cover the plastic film with a protective cover, and then vacuum the vacuum. After tightening, the core can be injection molded.

When the rubber die is complicated, it is difficult to design the branch pipe. At this time, the core may also be formed into a tube having micropores having a wire mesh for isolating the sand, and extending the core from the plug of the sand filling nozzle to be connected to the vacuum system.

The vacuum system includes a negative pressure connecting body sequentially connected to the branch pipe, a quick insertion pipe joint, a pipe joint, and the emptying pipe is finally connected to the vacuum pump; and the negative pressure connecting body has a through hole at the core To the role of ventilation.

The two ends of the through hole of the negative pressure connecting body are a net recessed platform and a thread; the net recessed platform is in communication with the rubber die, and the mesh recessed platform has a wire mesh for isolating the sand.

The vacuum pressure of the step (2) is 0. 04~0. 06Mpa can be injection molded.

Preferably, in the step (5), in order to reduce the core pulling resistance, after the sand is exhausted, the rubber die is vacuumed again to establish a negative pressure, and at this time, the rubber tube wall is quickly separated from the injection molded part. The surface of the lumen, which is attracted to each other, makes it easier to pull the core.

The pipe produced by this method has a lumen diameter smaller than the outer diameter of the rubber die in a free state. The contraction amount of the lumen gap is 0.5 to 1.5 mm. The pipe produced by this method has a lumen diameter smaller than the outer diameter of the rubber die in a free state. As for the small size, this involves the hardness of the rubber material used, the vacuum of the vacuum and the pressure during injection molding. These factors are constantly changing with different manufacturers and different products. Therefore, when using this method to produce products, first do a straight tube sample test to determine the amount of shrinkage. As long as the above three factors are stable, the amount of shrinkage is also stable. The outer diameter of the rubber die in the free state should be designed based on the shrinkage determined by the test to meet the requirements of the product cavity size. 5毫米。 The measured amount of shrinkage is about 0. 5 - 1. 5 mm.

The rubber tube is a high temperature resistant 250~28 (TC rubber, such as silicone rubber. It has been found through experiments that the rubber of other ingredients can also meet the requirements of the production of the invention.

After production practice, X† rubber core core pulling method, the advantages of the invention are:

(1) The surface of the tube of the injection molded pipe is smooth and beautiful;

(2) Applicable to the whole injection molding production of pipe parts, the production process is stable, the repeatability is high, and the product quality is stable;

(3) The rubber dies used can be reused and the production cost is low;

(4) Injection molding and core making can be run synchronously next to an injection molding machine, and the production efficiency is high, for example: one person lower core, mold clamping; - person picking, core pulling; one-man core;

(5) The investment is small, the equipment is simple, and it is easy to promote.

The equipment used in the method of the present invention is all existing equipment. Except for the injection molding machine and the injection mold, only one vacuum pump, one vibration table and one rubber tube mold can be mass-produced.

The key advantage of the present invention is that the intake manifold produced by the integral injection molding is more reliable than the welding method, and it is expected to enable a large amount of high-quality, high-efficiency production of the intake manifold plastic parts. Due to the abandonment of the "welding method" technology, and the overall injection molding, there is no welding risk, the price is lower, more acceptable for the car factory and the majority of engine manufacturers. DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the system of the rubber core core drawing method of the present invention.

Mark description: '

1 is vacuum pump, 2 is injection mold, 3 is vacuum tube, 4 is quick-release pipe joint, 5 is negative pressure connection body, 6 is wire mesh, 7 is plug, 8 is clamp, 9 is core, 10 For dry sand, 11 is a plastic film, 12 is a protective cover, 13 is a rubber die, 14 is an injection molded pipe, 15 is a core, and 16 is a branch pipe. detailed description

The invention is further described below in conjunction with the drawings.

1. Design of rubber dies As with the principle of metal casting "lower core", the rubber die 13 should also have a core 15 and the nozzles of the core are open. In this patent, the core head 15 not only functions to support and fix the core, but also functions as sand filling, vacuuming, and sanding. At one end of the core 15 part, a branch pipe 16 is designed for coupling to the vacuum system. As shown, the branch pipe 16 and the negative pressure connection body 5 are coupled by a clamp 8. The other end of the core head has no branch pipe, and its purpose is the top opening for sand filling and sanding.

After the rubber die 13 is made, in order to establish a vacuum system, the rubber die 13 is opened at both ends, and a plug 7 is mounted, which is made of a metal material. It should be noted that, because the functions of the cores 15 at both ends are different, the design of the plugs 7 at both ends is also different: the outlet of the core 15 of the branch 16 is not suitable as a sand filling port, but should be used as a sanding station. The solid end of the contacted dry sand and the clamping end of the core should be inserted into the plug 7 which is not open; the other end is filled with sand and sand, and the plug 7 should be inserted into the opening. Finally, the rubber core 13 is fastened with a clamp 8 to prevent air leakage.

When the rubber die 13 is complicated, it is difficult to design the branch pipe. At this time, the core bone may also be formed into a tubular shape having micropores, a wire mesh thereon for isolating the sand 10, and the core bone 9 is extended from the plug of the sand filling nozzle and connected to the vacuum system. .

2. Select rubber tube material

The heating temperature of ΡΑ-66 engineering plastics is generally 240~260°C, while the domestic high temperature resistant 250~280'C silicone rubber technology is very mature and widely used. Therefore, the use of high temperature resistant silicone rubber material as the core material is completely satisfactory and completely feasible. The invention selects a silicon rubber material produced by a professional manufacturer with high temperature resistance of 250 ° C, has a hardness of 51 degrees, and produces a rubber core 13 on a common vulcanizing machine.

3. Fill in the dry sand and compact the pressure

The invention draws on the principle of metal casting "negative pressure modeling". Dry sand vibration is the key to ensuring the size and shape of the rubber die 13 here. Fill the dry sand 10 from the opening of the sand filling end plug 7. The dry sand 10 used is 40-70 mesh. The core bone is placed in the sand filling process, and the core bone 9 is made of alloy steel rod #10. After the dry sand 10 is filled, the plastic film 11 is placed on the surface of the dry sand 10 to be vacuumed and compacted. The vacuum of the negative pressure reaches 0. 04~0. 06Mpa can be injection molded. After the vacuum is established, the protective cover 12 should be placed over the plastic film 11. The cover 12 is added to place the core into the injection mold 2. Since the heat balance temperature of the injection mold 2 is about 150 ° C, the protective cover 12 functions to protect the plastic film 11; otherwise, the plastic film 11 is thermally deformed, the vacuum system is destroyed, and the production fails.

4. Vacuum system

The main component of the vacuum system is that the negative pressure connecting body 5 has a through hole in the core portion to function as a ventilation. The two ends of the through hole are respectively a hollow socket and a thread. The gutter recess is in communication with the rubber die 13. The net recessed table is used to store the wire mesh 6, as shown in the schematic, to prevent the sand from being drawn into the vacuum pump 1. The other end of the through hole is threadedly coupled to the push-in fitting 4 . Vacuum tube 3 Insert directly into the pipe joint 4. The end of the vacuum tube 3 is connected to the suction port of the vacuum pump 1. The vacuum pump 1 used may be, for example, a 2XZ series two-stage direct-coupled vacuum pump, and the vacuuming time is 1 to 3 minutes. In large-scale production, a vacuum pipe network system can be established, and a vacuum valve is configured to control the opening and closing of the vacuum system.

5. Lower core, mold clamping, core

The injection mold 2 should leave a sufficient, accurate position for the core 15 structural portion of the rubber die 13. The rubber die 13 under the negative pressure compaction state is placed in the mold 2 by dragging a vacuum tube 3 into the mold 2, and the mold can be injection molded.

The heating temperature is determined according to the engineering plastic used. The other parameters are not particularly different from the general injection molded parts. After the mold is opened, the injection molded pipe member 14 is taken out. Immediately after taking the piece, turn off the vacuum pump, pull out the vacuum tube, and the negative pressure is released. Take the protective cover 12, remove the plastic film 11, loosen the clamp nut and pull out the clamp 8, pull out the plug 7, and pour out the dry sand and core.

After the sand has drained, grasp the rubber tube 13 of the end pipe of the branch pipe by hand, and gently pull the rubber die 13 out of the injection molded part. At this point, an injection molded pipe is produced. If the dry sand is poured out, do not pull the core, and then vacuum the rubber die 13 to establish a negative pressure. The rubber dies 13 are all attracted together, making core extraction easier. Reference parameter list

The outer shape and size of the rubber die 13 should conform to the shape and size of the lumen of the injection molded tubular member 14. In one embodiment, the "rubber core core pulling method" is used to successfully produce 10 injection molded pipe fittings on a 250 gram injection molding machine using PA-66 engineering plastics. The technical features of the product are as follows: Pipe length and inner diameter wall thickness

Size

(mm) 120 # 39 4 Example 1

Production method of tubular injection molded parts - rubber core core pulling method

(1), using a silicone rubber material produced by a professional manufacturer of high temperature resistant 26CTC, a hollow rubber tube 13 is formed on the ordinary vulcanizing machine, the rubber core 13 should also have a core head 15, and the core end of one end is provided with a branch pipe 16,

Inserting a plug 7 that is not open at the opening of the nozzle provided with the core of the branch pipe 16, and tightening the outside of the rubber tube 13 with a clamp 8 to prevent air leakage; and installing a negative pressure connecting body 5 at the branch pipe 16, There is a wire mesh 6 on one side to prevent the sand from being drawn into the vacuum pump 1. The other end of the negative pressure connecting body 5 is screwed to the quick-connecting pipe joint 4, the vacuum pipe 3 is directly inserted into the pipe joint 4, and the end of the vacuum pipe 3 is connected to the suction port of the vacuum pump 1;

(2), to the rubber die 13 in the step (1), insert the plug from the other end core 15 into the opening, place the core bone 9, fill the dry sand 10, and use the dry sand 10 for 40-70 mesh, dry After the sand 10 is filled, the plastic film 11 is placed on the surface of the dry sand 10, and the vacuum can be vacuumed. The vacuum pump 1 used can be a 2XZ series two-stage direct-coupled vacuum pump, and the vacuuming time is 1 to 3 minutes. The pressure of the negative pressure is 0. 04~0. 06Mpa, after the negative pressure is established, the protective film cover 12 is covered on the plastic film 11;

(3) placing the rubber die in the step (2) under the negative pressure compaction state into the injection mold, and molding the injection mold;

(4), mold, take the injection pipe fittings together with the core, take off the vacuum pump immediately after taking the parts, pull out the vacuum tube, immediately release the negative pressure, take the protective cover 12, remove the plastic film 11, release the card The hoop nut is withdrawn from the clamp 8, and the plug 7 is pulled out, allowing the core bone 9 and the dry sand 10 to flow out of the rubber die and run out;

(5) After the sand has been drained, do not pull the core first, and then vacuum the rubber tube to establish a negative pressure. The rubber tube wall is adsorbed together, and the rubber tube 13 of the core portion is grasped by hand and gently twitched. The entire rubber die 13 is completely withdrawn from the injection molded pipe. At this point, an injection molded pipe is produced, and the extracted rubber die can be recycled for subsequent production of the injection molded part according to the above method.

Claims

Rights request

1. A method for producing a tubular injection molded part, characterized in that it comprises the following steps:

(1) a hollow rubber core made of a rubber material;

(2), insert the core bone into the rubber die in step (1), fill in the dry sand and compact the pressure;

(3) placing the rubber die under the vacuum compaction state in the step (2) into the injection mold, and molding the injection mold;

The method of producing a tubular injection molded article according to claim 1, wherein the rubber die in the step (1) is provided with a conformable tire, and the core is placed in the tire. The vibrating table shakes the dry sand and compacts it under pressure. After tightening, the core is removed from the tire to ensure the size and shape of the core.

3. The method of producing a tubular injection molded article according to claim 1, wherein the rubber die of the step (1) has at least one core, and the nozzles of the core are open.

4. A method of producing a tubular injection molded article according to claim 3, wherein said rubber die has a core portion at one end and is designed to be connected to a vacuum system.

The method for producing a tubular injection molded article according to claim 3 or 4, wherein the rubber die of the step (1) is inserted into the nozzle opening of the core of the rubber die. The plug is made of a metal material.

The method for producing a tubular injection molded article according to claim 5, wherein at least one end of the rubber die has a plug that is not open at the opening of the core nozzle; and the other end is filled with sand. In the sanding area, insert the opening plug into the opening of the nozzle, and tighten the plug with a clamp on the outside of the rubber tube.

The method for producing a tubular injection molded article according to any one of claims 1 to 4, wherein in the step (2), the rubber core is filled with a core and a dry sand. After the compaction, a plastic film is placed on the surface of the sand, and a protective cover is placed on the plastic film, and the negative pressure is compacted and then injection molded.

The method for producing a tubular injection molded article according to claim 1 or 6, wherein when the rubber core is complicated, when the branch pipe is difficult to design, the core bone can also be made into a microporous hole. The tubular shape has a wire mesh for isolating the sand, and the core is extended from the plug of the sand filling nozzle and connected to the vacuum system.

9. The method of producing a tubular injection molded article according to claim 1, wherein said vacuum system comprises a negative pressure connection body sequentially connected to the branch pipe, a quick insertion pipe joint, a vacuum pipe, and finally connected to the vacuum pump. And the through-hole of the negative pressure connecting body has a through hole for ventilation.

The method for producing a tubular injection molded part according to claim 9, wherein the two ends of the through hole of the negative pressure connecting body are a net recessed platform and a thread; the net socket and the rubber The lumens are interconnected and have a wire mesh therein to isolate the sand. ,

11. The method of producing a tubular injection molded article according to claim 1, wherein in the step (5), in order to reduce the core pulling resistance, after the sand is exhausted, the rubber die is vacuumed again. Under negative pressure, the rubber tube wall quickly disengages from the surface of the injection molded cavity and is attracted to each other to facilitate core pulling.

12. The method of producing a tubular injection molded article according to claim 1, wherein the rubber tube is a rubber having a high temperature resistance of 250 to 280 angstroms, including but not limited to silicone rubber.