WO2006038616A1

WO2006038616A1 - Metal mold cooling structure

Info

Publication number: WO2006038616A1
Application number: PCT/JP2005/018351
Authority: WO
Inventors: Yasuhiro Suzuki
Original assignee: Suzuka Fuji Xerox Co., Ltd.
Priority date: 2004-10-05
Filing date: 2005-10-04
Publication date: 2006-04-13

Abstract

The entire or a part of a path of a cooling fluid is formed by dividing a movable mold and/or a fixed mold into two in a lateral direction, cutting one of or both dividing planes, and joining the dividing planes so as to cool a metal mold composed of the movable mold and the fixed mold. Thus, a flow volume of the cooling fluid is increased while maintaining the strength of the metal mold, and cooling effects are improved.

Description

Specification

Mold cooling structure

Technical field

The present invention relates to the structure of a temperature control circuit (for example, a cooling circuit) of a mold used for molding a resin molded product.

Background art

[0002] The quality of dimensions and the like of a molded resin product that is processed by cooling the molten resin depends on the cooling rate of the molten resin. For example, a resin molded product manufactured by extrusion molding affects the quality such as plate thickness due to the difference in die temperature.

Hereinafter, the production of a molded product by injection molding will be described in detail.

In the manufacture of molded products by injection molding, molten resin is injected into a mold cavity formed by combining a fixed mold and a movable mold, and after cooling, the fixed mold and the movable mold are separated from the mold cavity. It is performed by taking out the solidified molded product.

Here, the molten resin is cooled by cooling the mold and transferring the partial force of the mold in contact with the mold cavity surface and the heat of the molten resin to the mold. For this reason, the fixed mold and the movable mold are provided with a cooling circuit for controlling the temperature of the mold.

[0003] As shown in Fig. 12, this cooling circuit (mold cooling structure) is formed with a plurality of holes 5, 6 by drilling a fixed mold 4 and a movable mold 3 constituting the mold. It is common to open and fill plugs 7 and 8 in unnecessary holes to form passages 5 and 6 through which cooling fluid (medium) such as water and air flows.

In the mold cooling structure shown in FIG. 12, since the cooling fluid flows through the straight passages 5 and 6, a laminar flow forms a thermal boundary film on the heat transfer surface of the passages 5 and 6. There is a problem that the cooling efficiency (the efficiency of heat conduction) of the molten resin is deteriorated.

[0005] As means for solving such a problem, means for generating turbulent flow by providing a partition plate (baffle plate) or a spiral groove in the cooling fluid passage is used (for example, patent documents). (See tributes 1-3).

Patent Document 1: Japanese Patent Laid-Open No. 09-308955 Patent Document 2: Japanese Patent Laid-Open No. 06-262295

Patent Document 3: Japanese Utility Model Publication No. 58-107227

Disclosure of the invention

Problems to be solved by the invention

However, the processing of the partition plate and the spiral groove requires a lot of man-hours and costs. In addition, since the resistance to the cooling fluid increases and as a result the flow rate of the cooling fluid decreases, there is a problem that a large cooling efficiency cannot be expected.

This problem of a decrease in the flow rate can be solved by increasing the diameter of the holes constituting the cooling fluid passage, and the heat transfer area can be increased. However, another problem arises that the strength of the mold is reduced.

[0007] The present invention has been made in order to solve the problem of power, and a mold cooling structure that easily and inexpensively takes a wide heat transfer area and enhances the cooling effect while maintaining the strength of the mold. Is provided.

In the present invention, the “mold” means a mold (movable mold / fixed mold) used for injection molding, an extrusion molding die, a blow molding mold, a vacuum 'pressure molding mold, a hot' mold. Runner hold, nozzles, and processing jigs for parts that require temperature control. Means for solving the problem

[0008] The mold cooling structure according to claim 1 divides the mold into a plurality of parts, cuts a predetermined portion of the divided surface of the parts, and joins the divided surfaces to each other. Since all or part of the cooling fluid is formed, it is possible to form a cooling fluid passage having a complicated shape at a low cost and to improve the cooling efficiency of the mold.

[0009] The mold cooling structure according to claim 2 maintains the strength of the mold in a part of the passage (in the cooling circuit) formed by joining the divided surfaces in claim 1. For this reason, support columns (such as a spacer block) are provided to receive the grease pressure, so that the mold cooling efficiency is improved, even if the passage through which the cooling fluid flows is large, even if the mold strength is not reduced. If you can make it V, it will have an effect.

[0010] The mold cooling structure according to claim 3 is the heat treatment of claim 1 or claim 2, in which the split surfaces are joined by sandwiching a metal having a melting point lower than that of the material constituting the movable mold or the fixed mold. Since they are joined, the divided surfaces can be joined easily, and the cooling efficiency of the mold can be improved at low cost.

[0011] The mold cooling structure according to claim 4 is characterized in that, in claim 1 or claim 2, since the joining of the split surfaces is electric fusion, it is easy to dissimilar and Z or the same kind of mold material strength. Therefore, it is possible to join the divided surfaces to each other and improve the cooling efficiency of the mold at a low cost.

The invention's effect

[0012] The present invention makes it easy to lengthen the passage of the cooling fluid without lowering the strength of the mold, increase the capacity, and increase the heat transfer area. If the cooling efficiency can be improved, there will be an effect!

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail using examples.

Example 1

A first embodiment according to the present invention will be described with reference to FIGS. 1 to 6.

FIG. 1 is a side view of a fixed mold using a mold cooling structure according to the present invention, and FIG. 6 is a side view of a conventional fixed mold. In both cases, the passage of the cooling fluid is indicated by a broken line.

[0015] Conventionally, the fixed mold 1 having the mold cooling structure 2 having a complicated shape shown in FIG. 6 is formed with the shape of the mold cooling structure 2 using, for example, copper, and a nickel plating (electron) is formed thereon. After forming the thick nickel layer and processing the nickel layer to produce the fixed mold 1, the fixed mold 1 was manufactured by putting the fixed mold 1 in a nitric acid solution or the like and dissolving the copper. processing). Such a method requires a lot of cost, and also requires a waste liquid treatment of nitric acid in which copper is dissolved.

On the other hand, the fixed mold 10 shown in FIG. 1 has the same mold cooling structure 14 as the mold cooling structure 2 shown in FIG. ! /

That is, in the fixed mold 10, the upper mold 11 shown in the side view in FIG. 2, the bottom view in FIG. 3, the side view in FIG. 4, and the lower mold 12 shown in the plan view in FIG. Has been configured.

Hereinafter, a method for manufacturing the fixed mold 10 will be described in detail.

First, the upper die 11 and the lower die 12 are processed separately.

The upper mold 11 has a mold cooling structure for the upper half by cutting the dividing surface 13 by milling or the like. 14 is formed.

Similarly, the lower die 12 forms the lower half mold cooling structure 15 by cutting the dividing surface 19, and the cooling fluid inlet 16 and outlet 17 are also cut and drilled using a drill or the like. The cutting and drilling cover may be a discharge cover. Also, if necessary, you can combine the above-mentioned electronic cabinets.

Next, a copper plate 18 is manufactured by hollowing out predetermined portions so as not to obstruct the mold cooling structure formed when the dividing surface 13 of the upper mold 11 and the dividing surface 19 of the lower mold 12 are joined. Then, the copper plate 18 is sandwiched between the dividing surface 13 of the upper mold 11 and the dividing surface 19 of the lower mold 12, and a weight (not shown) is put on the upper mold 11.

Thereafter, heat treatment is performed in the electric furnace at a temperature (for example, about 1200 degrees) lower than the melting temperature of iron (for example, NAK88) constituting the upper mold 11 and the lower mold 12 which is higher than the melting temperature of copper. Then, the copper melts and diffuses into the iron that constitutes the upper mold 11 and the lower mold 12, so that the upper mold 11 and the lower mold 12 can be joined with sufficient strength after cooling. Can be produced.

[0020] The metal used for joining the upper mold 11 and the lower mold 12 sandwiched between the divided surface 13 and the divided surface 19 has a lower melting point than the metal constituting the upper mold 11 and the lower mold 12. Any material that diffuses into the metal may be used. For example, for iron, nickel, silver, gold, manganese, lead, tin, zinc, solder and the like.

[0021] Instead of the copper plate 18, copper or nickel kneaded into a paste may be applied to the joint surface for heat treatment.

[0022] As shown in the present embodiment, when the fixed mold 10 is manufactured, the upper mold 11 and the lower mold 12 are separately processed and joined to form a mold cooling structure 14 having a complicated shape. Can be manufactured easily, and the cooling efficiency of the mold can be improved at low cost.

If there is a concern about insufficient strength in the horizontal direction, it may be reinforced by bolting in the vertical direction. In addition, when the shape is deformed by heat, finishing may be performed later.

Example 2

[0023] Other embodiments according to the present invention will be described in detail below. In order to simplify the description, only differences from the first embodiment will be described, and the same portions are denoted by the same reference numerals and description thereof will be omitted.

[0024] In Example 1, in the case where the upper die 11 and the lower die 12 are made of the same material, different forces, for example, when the upper die 11 is made of nickel and the lower die 12 is made of iron, Since the expansion rate of each metal is different, bonding may not be possible by heat treatment.

In such a case, a pressurization type electric bonding method (elect mouth bonding), which is a bonding method using an electric current, is effective.

A description will be given below of joining using a pressure type electric joining method (for example, the principle of spot welding, projection welding, etc.).

As in FIG. 1, an iron plate or nickel plate 18 is sandwiched between the dividing surface 13 of the upper mold 11 and the dividing surface 19 of the lower mold 12, and a large current flows while applying vertical force pressure. Then, the iron plate or nickel plate 18 melts and diffuses into nickel and iron, so that the upper die 11 and the lower die 12 can be joined.

If necessary, an adhesive such as epoxy may be applied before or after bonding to eliminate the gap between the bonding surfaces. In addition, surface treatment (for example, painting, coating, etc.) may be performed on the flow path (cooling structure) of the internal cooling fluid for the purpose of protection not only at the joint surface.

For the joining, instead of the iron plate or the nickel plate 18, a fine iron wire or a nickel wire may be used. Alternatively, the upper die 11 and the lower die 12 may be directly overlapped and joined using a pressure type electric joining method without using the iron plate or the nickel plate 18. In this case, if the dividing surfaces to be overlapped are provided with irregularities that are not flat, and the current is concentrated on the convex portions, the joining is ensured. Example 3

[0028] In the third embodiment, the mold cooling structure according to the present invention is used for a sprue 1 'runner.

In injection molding, the cooling of the sprue's runner controls the cooling in the molding cycle. Therefore, using the mold cooling structure according to the present invention for the sprue's runner shortens the molding cycle. This is an effective means.

Below, the sprue 1 'runner using this invention is demonstrated in detail. [0029] As shown in Figs. 7 to 9, the sprue 'bush used in the sprue' runner is divided into two parts, a shaft part 20 and a cylindrical part 21, and the outer peripheral surface (split surface) of the shaft part 20 Grooves 22 are formed in a spiral shape.

Thereafter, the shaft portion 20 is inserted into the cylindrical portion 21 and bonded by the heat treatment or pressure type electric bonding method shown in Example 1 or Example 2, so that the mold cooling structure according to the present invention is used. A spruce bush can be manufactured.

The holes 23 and 24 provided in the cylindrical portion 21 are an inlet and an outlet for the cooling fluid.

[0030] The sprue bush produced in this way was incorporated into an injection mold, and the surface temperature of a part of the sprue after 100 shot molding was measured.

In the case of the sprue 1 bush without the temperature control circuit, the force was about 70 degrees. In the case of the sprue 1 bush according to this embodiment, the cooling fluid can flow into the groove 22 formed in a spiral shape. It was cooled to about 40 degrees. Note that air was used as the cooling fluid. After confirming that the molten resin was injected from the heating cylinder of the molding machine (that is, after receiving a signal indicating completion of the primary pressure), the cooling medium air was blown from the hole 24 to be cooled, and the air was discharged through the hole 23 to the atmosphere. Released into. After that, the mold opening signal of the injection molding machine was received and air blowing was stopped.

[0031] In this way, since the cooling of the sprue is improved, the cooling time in the mold of the sprue runner in the injection molding is shortened by about 35% in combination with the runner temperature control of Example 4 described later. be able to.

Although air cooling is used in the third embodiment, cooling using water or heat of vaporization is also possible.

Example 4

[0032] In the fourth embodiment, the mold cooling structure according to the present invention is used for a runner portion.

FIG. 10 shows a cross-sectional view of the runner portion provided on the PL surface of the movable mold 30 and the fixed mold 31.

[0033] As shown in FIG. 10, the runner portion of the fixed die 31 is divided into two parts, an upper die 33 having a recess 32 through which molten resin flows, and a lower die 34. A plurality of grooves 36 are cut along the recess 32. [0034] The upper die 33 is inserted into the recess of the lower die 34 and joined by the joining method shown in Example 1 or Example 2, thereby forming a runner portion with improved cooling efficiency in the lower die 34. can do.

[0035] In the cooling step in the injection molding, when a cooling fluid, for example, air is passed through the groove 36 of the runner portion configured as described above, the molten resin present in the recess 32 can be cooled in a short time.

In fact, when a molded product is produced using a mold having a runner that is powerful in this fourth embodiment, the productivity of injection molding (inside the mold) is higher than that of a mold using a conventional runner. Cooling time of 35%) and production tact improved by about 16%.

[0036] Since the upper mold 33 is inserted into the recess of the lower mold 34, the runner flowing portion and the main body portion of the fixed mold 31 (lower mold 34) are separate parts. There is a slight gap between the body parts. Since this gap acts as a heat insulating layer, the cooling fluid flowing in the groove 36 is a force that drastically reduces the temperature of the runner 32. Fixed temperature 31 The temperature of the main body is not lowered so much. Can be obtained.

Example 5

[0037] In the fifth embodiment, a large-capacity cooling fluid passage is formed using the mold cooling structure according to the present invention.

FIG. 11 shows a side view of the fixed mold 50, in which a mold cooling structure 51 and a post 56 (to be described later) are indicated by broken lines.

[0038] In the fixed mold 50, the upper mold 52 and the lower mold 53 are bonded by using the bonding method shown in the first or second embodiment. Before joining the upper mold 52 and the lower mold 53, the large-capacity space 54 formed by cutting on the respective divided surfaces of the upper mold 52 and the lower mold 53 is formed close to the cavity surface 55. Yes.

Force not shown The large-capacity space 54 is widely cut in the three directions of XYZ, and can flow a large amount of cooling fluid. In other words, large cuts are made in the direction perpendicular to the paper surface of Fig. 11 to form a large-capacity passage.

[0039] The large-capacity mold cooling structure 54 in the fixed mold 50 is provided with a plurality of cylindrical columns 56 for the purpose of reinforcing the strength. This column 56 is planted from the lower mold 53. It functions to support the upper mold 52.

[0040] The powerful configuration allows large volumes of cooling fluid to be sent to near the cavity surface without lowering the mold strength, so that the molten resin can be cooled in a short time, greatly increasing the molding cycle. Can be shortened.

Example 6

[0041] Other embodiments according to the present invention will be described in detail below.

In order to simplify the description, only differences from the fifth embodiment will be described, and the same portions are denoted by the same reference numerals and description thereof will be omitted.

[0042] In Example 5, the force shown when the upper mold 52 and the lower mold 53 are divided in the horizontal direction, as shown in Fig. 13, when the large capacity portion 60 is formed in a part of the upper mold. In some cases, horizontal division alone is not possible! /.

[0043] In the sixth embodiment, the upper die 52 is divided into the vertical direction, the upper die 52 is composed of the parts 61 and 62, and the upper die 52 is formed with a portion 60 having a larger capacity. This is different from the example.

[0044] In this case, the fixed mold 50 is composed of a total of three parts: a lower mold 53 and an upper mold 52 composed of parts 61 and 62, and all of the divided surfaces thereof are the first embodiment or the second embodiment. It is joined by the joining method shown in.

[0045] Due to the powerful configuration, even a very complicated mold cooling structure can be easily manufactured.

Example 7

[0046] The hot runner hold was divided into two parts and cut so that a flow path of molten resin was formed when the respective divided surfaces were joined. Also, the flow path of the molten resin and the curved portion of the flow path were cut so as to form a smooth curve.

The bonding is performed by applying paste-kneaded copper to the divided surfaces, heat-treating using an electric furnace at 1,200 ° C for 5 hours, chemically polishing with nitric acid, and then polishing the threaded portion of the nozzle. . Apply chemical Ni plating on the inside and outside, and bake again at 200 ° C for 4 hours to increase the hardness of the Ni plating, screw it from the top and bottom, reinforce it, and then separately clean the nozzle, heater, thermoelectric A hot runner was completed by assembling pairs. Example 8

FIG. 14 is a front view of an extrusion molding die according to the present invention, and FIG. 15 is a perspective view showing an assembled state of the die shown in FIG.

[0048] As shown in FIG. 14, the die 70 is provided with a space 77 for extruding a U-shaped molded product. A large-capacity space 76 for flowing a cooling fluid such as water is provided at a position close to the space 77 in order to cool the resin passing through the space 77.

This large-capacity space 76 is realized by configuring the die 70 with two parts 71 and 72 as shown in FIG. That is, the part 71 is cut deeply into the vicinity of the space 77, and the part 72 is cut into a substantially convex shape by cutting the plate material so that a sufficiently large space 76 is formed when the part 71 is joined to the part 71. In order to maintain the strength of the die 70 even when the large-capacity space 76 is formed, a plurality of support columns 75 are implanted in the part 72.

[0050] As described in the first embodiment or the second embodiment, the divided surfaces can be joined to the component 71 and the component 72.

Also, water as a cooling fluid is injected into the space 76 from the inlet 73, and the water that has absorbed the heat of the die is discharged from the outlet 74.

[0051] The above-described embodiments have been illustrated for the purpose of explanation, and the present invention is not limited thereto. From the scope of the claims, the detailed description of the invention, and the drawings, those skilled in the art will understand. As long as it is not contrary to the technical idea of the present invention that can be recognized, changes and attachments can be made.

[0052] For example, in Examples 1 to 5, the force shown in the case where the mold cooling structure is formed on the fixed mold may be formed on the movable mold or the fixed mold and the movable mold. .

Further, in the mold insert processing, the insert may be divided into parts and covered, and each part may be joined by the joining method of the present invention to produce a insert having a complicated shape. .

[0053] As the cooling fluid, in addition to water and air, the heat of vaporization of oil or a vaporizable substance (for example, chlorofluorocarbon, halon, alcohol, ether) may be used.

When air is used as the cooling fluid, the valve is opened based on the information that the molten resin has been injected into the mold from the temperature sensor provided near the cavity surface, and air cooling is performed. It can be started when the mold is opened and the molded product is taken out, or air cooling can be performed continuously regardless of the process.

[0054] In the examples, general injection molding (solid injection molding method) was shown, but Asahi Kasei's AGI, GPI, CGM, H ² M, Idemitsu Petrochemical's GIM, Nippon Steel Chemical's PFP, Hollow injection molding methods represented by UK-based thin press, US GAIN Technology, German air-monored, gas-assisted molding methods represented by Contourure, etc., U.S. UCC method, USM method, or Toshiba Machine TAF method developed by Asahi Dow, EX—CELL—O Company method, Hettinger's foam molding, New-SF, GCP method, Allied Chemical's technique, etc. The foam injection molding method represented by U.S. Trecell's MuCell and Asahi Kasei's AMOTEC, the foam molding, the foam injection molding method and the gas-assisted molding method, and the Sumitomo Chemical SP mold, in-mold molding method and Also apply to the method that combines with the gas-assisted molding method. The heat and cool developed and sold by Ono Sangyo, Cisco, and GE Plastics also include molds used for compression molding, injection compression molding, transfer molding, cast molding, vacuum molding, pneumatic molding, It can also be applied to processing jigs that require temperature control of extrusion dies.

[0055] Also, as in heat and cool, the mold temperature is increased with heated steam before injection, the molten resin is injected with water and then cooled with water, or the surface of the mold is heated using high frequency induction heating. The cooling structure of the present invention is also effective for cooling a molding method that aims to improve the appearance by similarly heating the mold surface using a halogen lamp according to the above.

[0056] Furthermore, it is expected that ultrasonic vibration of the cooling fluid will lead to an improvement in the mold release of the molded product and an improvement in the fluidity of the molten resin.

In addition, the cooling effect can be further improved by using microbubble water as the cooling fluid. However, in the case of microbubble water using air as the cooling fluid, there is a concern that dissolved oxygen increases and the mold cooling structure corrodes. For this, an inert gas such as nitrogen is used instead of air, the inside of the mold cooling structure is surface-treated, and a multilayer structure such as iron and copper, iron and SUS, iron and silver, etc. It is possible to cope with this problem by using a medium other than water. It is also effective to use water with a fungicide Means.

[0057] The resin that can be used in the present invention includes ABS, HIPS and other styrenes, PE and PP, olefins, PVC and other burs, polyamides, amides, polyesters, ester, and ethers. All of the thermoplastic resins represented by fats, all of the thermosetting resins represented by urea and phenol, polymer blends and polymer alloys of the resins, and inorganic and Z or organic fibers in the resins. Examples include composites containing minerals.

Industrial applicability

[0058] The present invention relates to a mold used for injection molding, a die part for extrusion molding, a mold for blow molding, a cooling circuit for a mold for vacuum / compression molding, a hot runner manifold and a nozzle, Applicable to machining jigs for parts that require temperature control.

Brief Description of Drawings

FIG. 1 is a sectional view of a fixed mold according to the present invention (Example 1).

FIG. 2 is a side view of an upper mold of a fixed mold according to the present invention (Example 1).

FIG. 3 is a bottom view of the upper mold of the fixed mold according to the present invention (Example 1).

FIG. 4 is a side view of the lower mold of the fixed mold according to the present invention (Example 1).

FIG. 5 is a plan view of the lower mold of the fixed mold according to the present invention (Example 1).

FIG. 6 is a side view for explaining a conventional fixed mold (Example 1).

FIG. 7 is a side view of a sprue bush according to the present invention (Example 3).

FIG. 8 is a side view of a shaft portion of a sprue bush according to the present invention (Example 3).

FIG. 9 is a side view of the cylindrical portion of the sprue bush according to the present invention (Example 3).

FIG. 10 is a side view of a runner according to the present invention (Example 4).

FIG. 11 is a side view of a fixed mold according to the present invention (Example 5).

FIG. 12 is a side view for explaining a conventional mold.

FIG. 13 is a side view of a fixed mold according to the present invention (Example 6).

FIG. 14 is a front view of an extrusion die according to the present invention (Example 8).

FIG. 15 is a perspective view showing an assembled state of an extrusion die according to the present invention (Example 8). Explanation of symbols 10 Fixed type 11 Upper type

12 Lower mold

14 Mold cooling structure 16 Population

17 Exit

Claims

The scope of the claims

[1] Divide the mold into multiple parts,

Cutting a predetermined part of the divided surface of the part,

A mold cooling structure characterized in that all or part of the cooling fluid passage is formed when the divided surfaces are joined.

[2] The mold cooling structure according to claim 1, wherein a column is provided in a part of the passage formed by joining the divided surfaces.

[3] The mold cooling according to claim 1 or 2, wherein the split surfaces are joined by heat treatment with a metal having a melting point lower than that of the material constituting the movable mold or the fixed mold. Construction

[4] The mold cooling structure according to claim 1 or 2, wherein the joining of the divided surfaces is electric fusion.