JP2010194719A - Sprue bush and method for producing sprue bush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sprue bush high in reliability and excellent in cooling performance, and a method for manufacturing the sprue bush. <P>SOLUTION: In a column 5 wherein a sprue hole 15 is formed in the middle, spiral cooling passages 19 and 21 in which cooling mediums circulate are formed to surround the sprue hole 15. The sprue bush 1 can be obtained based on slice data on a cooling passage 11 by processing a groove which forms the cooling passage in each of a plurality of metal plates, laminating the groove-processed metal plates in a prescribed order, diffusion-bonding the laminated metal plates, and shape-processing a metal block obtained by the diffusion bonding. By forming the thickness of the metal plate to such a thickness which allows a through-hole perpendicular to the metal plate as a part of a groove to be protrusive, the smooth spiral cooling passages 19 and 21 without steps can be formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sprue bush and a sprue bushing manufacturing method, and more particularly, to a sprue bushing having a cooling path in a cylindrical portion having a sprue hole and a sprue bushing manufacturing method.

  When manufacturing a resin molded product using a metal mold | die, the shortening of molding time is calculated | required from the point of productivity improvement. As a method for shortening the molding time, for example, molten resin is filled in a cavity space of a mold, and the mold is opened after cooling. In injection molding for manufacturing a resin molded product, a cavity space filled with resin is formed. There is a method of increasing the cooling rate by providing a cooling water channel in the vicinity of the molding surface of the mold. It is effective to provide this cooling water channel in the vicinity of the molding surface of the mold that forms the cavity space, and many techniques have been proposed so far. In injection molding and the like, cooling of the sprue that guides the molten resin injected from the injection device to the mold is also important for shortening the molding time.

  As a method of cooling the sprue, there is a method of providing a cooling water channel in the sprue bushing in the same manner as the mold. For example, in the conventional sprue bushing, a cylindrical cooling path is formed around the entire sprue, so that it is difficult for the cooling water to flow and the resin cannot be cooled effectively, and a technology for providing a spiral temperature control path in the sprue bushing Has been proposed (see, for example, Patent Document 1 and Patent Document 2).

JP 2003-220633 A JP 2003-245961 A

  The sprue bush described in Patent Document 1 is formed by inserting an outer cylindrical body through a bush body having a groove formed on an outer wall surface so as to cover the bush body. A hole is formed in the outer cylinder, and the hole communicates with a groove formed in the outer wall surface of the bush body. The outer cylindrical body is provided with a flange portion inside one end, and this flange portion is fixed to one end outer peripheral portion of the bush body by brazing or diffusion bonding. Similarly, the other end portion of the outer cylinder is fixed to the other end step portion of the bush body by brazing or diffusion bonding. According to this method, although it is considered that cooling water does not leak to the outside from the joint portion between the bush body and the outer cylinder, the outer wall surface of the bush body in which the inner wall surface of the outer cylinder body and the groove are formed Is not joined, the cooling water flows through the gap between the inner wall surface of the outer cylinder and the outer wall surface of the bushing body in which the groove is formed, and the cooling water flowing through the groove may be insufficient.

  The sprue bush described in Patent Document 2 is provided with a sealed space portion formed of an inner cylinder body and an outer cylinder body on the outer peripheral surface of the bush body, and is in contact with the inner cylinder body in the sealed space. Thus, a pipe formed in a spiral shape in the axial direction is provided. One end of this pipe is located in the vicinity of the head of the sprue bush, receives cooling water therefrom, and flows down in a pipe spirally provided in the axial direction. The cooling water flowing down in the pipe is released to the end of the sealed space, and the opened cooling water is raised in the sealed space toward the head of the sprue bush and discharged. The sprue bushing having such a structure, when viewed in the radial direction from the sprue hole, circulates through the wall surface of the bushing body, the inner cylinder forming the sealed space, the pipe, the cooling water flowing through the pipe, and the sealed space. An outer cylinder that forms the cooling water and the sealed space is located. Since many members are interposed between the cooling water and the sprue flowing through the pipe as the cooling source, considering the thermal conductivity of these members and the film heat transfer coefficient between the members, it is not always necessary. The thermal coefficient is not high.

  Although some sprue bushes having a spiral cooling water channel as described above have been proposed, it cannot be said that reliability and cooling performance are sufficiently high.

  An object of the present invention is to provide a sprue bushing having high reliability and excellent cooling performance and a method for manufacturing the sprue bushing. Another object of the present invention is to provide a sprue bushing manufacturing method capable of manufacturing a sprue bushing with high reliability and excellent cooling performance at low cost.

  According to the first aspect of the present invention, a spiral cooling passage through which a cooling medium flows is provided inside a cylindrical portion having a sprue hole formed in the center so as to surround the sprue hole. A sprue bush characterized by the above.

According to a second aspect of the present invention, based on the slice data of the cooling path, a groove processing step for processing a groove for forming a cooling path in each of a plurality of metal plates, and a metal plate obtained in the groove processing step are defined as predetermined. Laminating step of laminating in order, diffusion bonding of the metal plate obtained in the laminating step, obtaining a metal block, processing the metal block obtained in the joining step, and shape processing step of obtaining a sprue bush, And the thickness T of the metal plate is a thickness that satisfies the formula (1).
T <L / cos θ (1)
Where L: diameter of cooling path (mm) θ: angle of inclination of cooling path (°)

  According to a third aspect of the present invention, in the sprue bushing manufacturing method according to the second aspect, in the grooving step, the grooving is performed from both the front surface and the back surface of the metal plate.

  According to a fourth aspect of the present invention, there is provided a sprue bushing manufacturing method according to the second or third aspect, wherein the plurality of sprue bushings are manufactured. A plurality of sprue bushing grooves are machined in a metal plate, and after the joining process, before the shaping process, the metal block obtained in the joining process is cut into a plurality of blocks, and the obtained blocks are each shaped. A plurality of sprue bushings are manufactured.

  The sprue bush according to the present invention is provided with a spiral cooling path through which a cooling medium flows so as to surround the sprue hole inside the cylindrical part having a sprue hole formed in the center. Since the cooling medium flowing through the path and the member forming the cylindrical portion are in direct contact, the heat transfer coefficient is high and the cooling performance is excellent. Further, since the spiral cooling path is formed directly inside the cylindrical portion, there is no leakage of the cooling medium and there is no short path, and the reliability is high. Further, since the cooling path is formed in a spiral shape, the heat transfer area is large, the cooling performance is excellent, and the pressure loss is small.

  In the sprue bushing manufacturing method according to the present invention, after forming grooves for forming a cooling path in a plurality of metal plates, these are laminated, diffusion bonded, and finally processed in shape, so that a sprue hole is formed. A sprue bush having a spiral cooling path surrounding the sprue hole can be obtained inside the cylindrical portion. In particular, each metal plate at the time of diffusion bonding is partially a flat metal plate although the grooves are partially processed, so that the bonding strength of the joined body obtained by diffusion bonding can be sufficiently increased. it can. As a result, a spiral cooling path free from water leakage and short paths can be reliably formed. Further, by setting the metal plate to a predetermined thickness, groove processing is easy and a smooth spiral cooling path without a step can be obtained.

  Further, according to the present invention, since the metal plate has a predetermined thickness, in the grooving process, as a part of the grooving, it is possible to drill through-holes orthogonal to the metal plate, and the front and back surfaces of the metal plate Since groove processing can be performed from both sides, a relatively thick metal plate can be used. Even in this case, a smooth spiral cooling path without a step can be obtained.

  Further, according to the present invention, since a plurality of sprue bushings can be obtained at the same time, the manufacturing cost can be reduced while being efficient.

It is a figure which shows the sprue bush 1 as 1st Embodiment of this invention, (a) is a perspective view which shows an external appearance, (b) is a figure which shows typically the cooling path 11 provided in the bush part 5. FIG. . It is a flowchart which shows the manufacture procedure of the sprue bush 1 of FIG. It is a figure for demonstrating the manufacture point of the cooling path 11 of the sprue bush 1 of FIG. It is a top view of the metal plate 31e in FIG. It is a perspective view of the metal plate 31e in FIG. 6A is a plan view cut along the one-dot chain line in FIG. 4, and FIG. 6B is a perspective view cut along the one-dot chain line in FIG. FIG. 2 is a plan view of a spiral cooling path 19 of the sprue bush 1 of FIG. 1, for explaining the relationship between the thickness of a metal plate 31 and a through hole. It is a figure for demonstrating the point which manufactures the four sprue bushes 1 of this invention simultaneously, Comprising: The groove | channel 35a which forms a part of the cooling path 11 of the four sprue bushes 1a-1d in the metal plate 37 of 1 sheet. It is a figure which shows the state which processed -35d and 36a-36d.

  FIG. 1 is a view showing a sprue bush 1 as a first embodiment of the present invention, where (a) is a perspective view showing an appearance, and (b) is a schematic view of a cooling path 11 provided in the bush portion 5. FIG.

The sprue bush 1 is a member used in an injection mold or the like, and includes a gate portion 3 and a bush portion 5 positioned below the gate portion 3. The gate portion 3 is a member having a thick block shape, and a nozzle touch portion 7 to which a nozzle (not shown) is connected is provided at the center portion, and the sprue bush 1 is fixed to the mold on both sides. Bolt holes 9a, 9b
Is provided. Further, a cooling medium supply port 13 for connecting a cooling path 11 provided in the bush portion 5 to supply a cooling medium such as cooling water to the cooling path 11 and a cooling medium discharge port 15 for discharging the cooling medium from the cooling path 11 are provided. Is provided.

  The bush portion 5 has a cylindrical shape and is formed integrally with the gate portion 3. A sprue hole 15 through which molten resin flows is formed in the central portion of the bush portion 5. Further, a cooling passage 11 shown in FIG. 2 is provided inside the bush portion 5 so as to surround the sprue hole 15. The cooling path 11 is used for cooling the sprue bush 1 by flowing a cooling medium therein, and has a spiral shape. The cooling path 11 is directly provided in the bush portion 5. The procedure for forming the cooling path 11 will be described later.

  The cooling path 11 includes a cooling medium introduction path 17 connected to the cooling medium supply port 13 for introducing the cooling medium, two spiral cooling paths 19 and 21, a communication path 23 connecting the two spiral cooling paths 19 and 21, and A cooling medium discharge path 25 for discharging the cooling medium is provided. The two spiral cooling paths 19 and 21 each have one pitch. The cooling medium introduction path 17 and the cooling medium discharge path 25 are arranged in a straight line passing through the sprue hole 15 with the sprue hole 15 interposed therebetween. The spiral cooling path 21 having one end connected to the cooling medium introduction path 17 and the spiral cooling path 19 having one end connected to the cooling medium discharge path 25 are located at 180 ° different positions in the plan view (transverse section). These are connected by a connecting pipe 23. It goes without saying that the connecting pipe 23 is provided at a position where it does not contact the sprue hole 15.

  FIG. 2 is a flowchart showing a manufacturing procedure of the sprue bushing 1 of FIG. 3 to 6 are views for explaining the manufacturing procedure of the cooling path 11 provided in the bush portion 5 of the sprue bush 1 of FIG. 1, and FIG. It is a figure which shows typically the state which laminated | stacked the given some metal plate. 4 and 5 are a plan view and a perspective view of a single metal plate 31e that has been grooved. 6A is a plan view and FIG. 6B is a perspective view cut along the one-dot chain line in FIG.

  The sprue bush 1 generally creates slice data of the sprue bush 1 (step S1), and processes grooves that form cooling paths in a plurality of metal plates based on the slice data (step S2). The front and back surfaces of the metal plate are polished (step S3), laminated in a predetermined order (step S4), the laminated metal plates are diffusion-bonded (step S5), and the metal block after diffusion bonding is shaped (step S6). ) Manufacture. Each procedure will be described in detail below.

  First, in step S1, slice data is created based on the three-dimensional CAD data of the outer shape of the sprue bush 1 and the shape of the cooling path 11. The slice data is created using a computer in which a program for creating slice data is installed in advance. The computer determines the thickness of the metal body 31 from the input three-dimensional CAD data according to the installed program, and creates slice data for each metal body 31. The slice data includes an outer shape of the sprue bush 1, a reference hole for positioning (not shown) when the cooling path 11 and the metal plate 31 are stacked. In addition, when it is anticipated that the thickness of the metal plate 31 will decrease in the diffusion bonding in step S5 described later, it is preferable to consider this point in advance and create slice data for each metal plate 31.

  The thickness of the metal plate 31 (31 a to 31 h) is determined based on the shape of the cooling path 11. Basically, the shape of the cooling path 11 is simple, the metal plate corresponding to the part that does not need to be divided and processed into a plurality of metal plates is thickened, and the shape of the cooling path 11 corresponds to the part that is not simple. As the metal plate, a relatively thin metal plate is used in order to accurately form the shape. Since the cooling medium introduction path 17 and the cooling medium discharge path 25 have a linear shape, this portion is a single metal plate 31a. This shortens the processing time. However, in consideration of the standard of metal plates, availability, and price, a plurality of metal plates may be used.

  On the other hand, since the spiral cooling paths 19 and 21 and the communication path 23 are curvilinear in shape and not simple, relatively thin metal plates 31b to 31h are used. As a result, a smooth spiral water channel without a step can be formed. At this time, it is necessary to determine the plate thickness while paying attention to the following points. In the next step, the metal plate 31 is processed with grooves 33 and 34 forming the cooling path 11. In order to smoothly form the grooves 33 and 34 forming the spiral cooling channels 19 and 21 without any step, it is necessary to process each metal plate 31 from the front and the back. At this time, if the through-hole orthogonal to the metal plate 31 cannot be drilled, the groove cannot be machined. For this reason, the metal plate 31 needs to have a thickness that allows a through hole perpendicular to the metal plate 31 to be drilled, which is necessary for groove processing.

  FIG. 7 is a diagram in which the spiral cooling path 19 is developed in a plane, and is a diagram for explaining the relationship between the thickness of the metal plate 31 and the through hole. The horizontal axis in FIG. 7 represents the length of the spiral cooling passage 19 in the circumferential direction, and the vertical axis represents the height of the spiral water passage 19. FIG. 7 shows an example in which three types of metal plates are selected. Here, the diameter (inner diameter) of the spiral water channel 19 is L, and the inclination angle when the spiral water channel 19 is developed on a plane is θ.

When a metal plate having a thickness t1 is selected, the region surrounded by a1b1c1d1 needs to be cut by machining. When this metal plate is viewed in plan, a hole surrounded by b1b2d1d2 can be seen. Similarly, when a metal plate having a thickness t2 is selected, the region surrounded by e1f1g1h1 needs to be cut by machining. When this metal plate is viewed in plan, a hole surrounded by f1f2h1h2 can be seen. On the other hand, when a metal plate having a thickness t3 is selected, the region surrounded by i1j1k1l1 needs to be cut by machining. Even if this metal plate is viewed in plan, the through hole cannot be seen. Such a relationship is expressed by Equation (1), where T is the thickness of the metal plate.
T <L / cos θ (1)
Where L: diameter of cooling path (mm) θ: angle of inclination of cooling path (°)
If the metal plate satisfies the formula (1), a through hole for groove processing can be drilled. A metal plate having such a thickness is selected, and the standard of the metal plate, availability, price, The plate thickness may be determined in consideration of processing accuracy and processing time. Although the processing accuracy increases as the plate thickness decreases, the processing time increases because the number of processing increases.

  As the metal plate 31 to be used, a metal material used for manufacturing a mold such as an SK material, an SKS material, an SKD material, tool steel, and stainless steel can be used. These may be appropriately selected according to the required strength and the like.

  In step S2, a groove for forming the cooling path 11 in each metal plate 31 and a positioning reference hole (not shown) for lamination are processed. The machining can be easily performed by using a known CAD / CAM and a machining center, an NC machine tool, or a CNC machine tool based on the slice data obtained in step S1. In step S2, the outer shape of the sprue bush 1 and the sprue hole 15 are not processed.

  In step S3, the joint surface of each metal plate 31 that has been subjected to the groove processing or the like obtained in step S2, specifically, both the front and back surfaces of each metal plate 31 are polished. This polishing is performed for the purpose of improving the bonding strength when the metal plates 31 that are subsequent processes are diffusion bonded, and can be performed by a known polishing apparatus and polishing method. The degree of polishing is preferably such that the center line average roughness Ra is 1.0 μm or less from the viewpoint of improving the adhesion between the metal plates 31 and the bonding strength.

  Next, in step S4, the metal plates 31 are laminated in a predetermined order. Since the metal plate 31 has a reference hole (not shown) for positioning, accurate positioning can be performed by using a reference pin (not shown).

  The laminated metal plates 31 are joined in step S5. Bonding is performed by diffusion bonding. The diffusion bonding procedure is as follows. When the coupling force between the metal plates 31 is weak, the cooling medium leaks from the cooling path 11, and diffusion bonding with strong bonding force is used for joining the metal plates 31. Diffusion bonding is a method in which the metal plates 31 are brought into close contact with each other and bonded by utilizing the diffusion of atoms generated on the bonding surface. In accordance with an ordinary method, a laminated body of the laminated metal plates 31 is installed in a heating furnace, and the laminated body is obtained. It can carry out by applying a load to and heating a laminated body.

  In general, when diffusion bonding is performed, if the materials of the bonding surfaces are different, an insert material may be inserted between the bonding surfaces to increase the bonding strength. The insert material is effective for increasing the bonding strength between the bonding surfaces, but when there are grooves 33 and 34 forming the cooling path 11 as in the present embodiment, the insert material enters the grooves 33 and 34, There is a risk of blocking the flow path. For this reason, it is preferable to use the metal plate 31 of the same material for the joining of the metal plate 31 having a particularly small cooling path 11 and perform diffusion joining without using an insert material.

  At the time of diffusion bonding, another metal plate is arranged in a state having a predetermined gap from the outer wall surface of the metal plate 31 so as to surround the entire outer wall surface of the laminated metal plate 31, and these are installed in the heating furnace. It is preferable to apply a load in the vertical direction (stacking direction) only to the metal plates 31 stacked using a press device while heating the inside of the heating furnace, and pressurize the stacked metal plates 31. By performing diffusion bonding in a state in which the entire outer periphery of the metal plate 31 is constrained in this way, it is possible to keep the pressurizing pressure low, and the amount of horizontal deformation of the stacked metal plates 31 is constrained. Deformation of the laminated metal plates 31 at the time of diffusion bonding can be suppressed. As a result, the position of the cooling path 11 and the like in the metal block after the diffusion bonding is almost the same as the state before the bonding, and the cooling furnace 11 is placed at a predetermined position with high accuracy in the mold after shape processing of these. be able to.

  In the next process, the metal block obtained in step S5 is processed into a shape and finished as a sprue bush (step S6). Shape processing can be easily and accurately performed by using a known CAD / CAM and machining center, NC machine tool, or CNC machine tool, as in a general resin molding die.

  As described above, the sprue bush 1 shown in the present embodiment has a high heat transfer coefficient and excellent cooling performance because the cooling path 11 is directly provided in the bush portion 5. Moreover, since the cooling path 11 is formed in a spiral shape, the heat transfer area is large, the cooling performance is excellent, and the pressure loss is small. Further, the spiral cooling path 11 has no dead space and is difficult to accumulate water scale. Further, since the cooling plate 11 is formed by diffusion-bonding the metal plate 31 in which the groove forming the cooling passage 11 is processed, the spiral cooling passages 19 and 21 free from water leakage and short paths can be reliably formed.

  Further, a plurality of sprue bushings 1 can be manufactured at the same time in the manufacturing procedure of the sprue bushing 1. FIG. 8 is a view for explaining a procedure for manufacturing four sprue bushings 1a to 1d at the same time. A part of the cooling path 11 of the four sprue bushings 1a to 1d is formed on one metal plate 37. The state which processed the groove | channels 35a-35d and 36a-36d to form is shown. As in the case of manufacturing one sprue bushing 1, after forming grooves that form part of the cooling passages 11 of the four sprue bushings 1a to 1d in a plurality of metal plates, the metal is laminated and diffusion bonded. Get a block. Then, the metal block is divided into four by wire cut electric discharge machining to obtain four blocks. Each metal block is processed to obtain sprue bushings 1a to 1d. Thereby, the plurality of sprue bushes 1a to 1d can be manufactured easily and efficiently.

DESCRIPTION OF SYMBOLS 1 Sprue bush 3 Gate part 5 Bush part 7 Nozzle touch part 9a, 9b Bolt hole 11 Cooling path 13 Cooling medium supply port 15 Cooling medium discharge port 17 Cooling medium introduction path 19 Spiral cooling path 21 Spiral cooling path 23 Connection path 25 Cooling medium discharge path 31 Metal plate 33 Groove 34 Groove 35 Groove 36 Groove 37 Metal plate

Claims (4)

  A sprue bush, characterized in that a spiral cooling passage through which a cooling medium flows is provided so as to surround the sprue hole inside a cylindrical part having a sprue hole formed in the center. Based on the cooling path slice data, a groove processing step for processing a groove for forming a cooling path in each of a plurality of metal plates,
A laminating step of laminating the metal plates obtained in the groove processing step in a predetermined order;
Diffusion bonding of the metal plate obtained in the lamination step, a bonding step to obtain a metal block,
Processing the metal block obtained in the joining step, and obtaining a sprue bush,
The sprue bushing manufacturing method according to claim 1, wherein the thickness T of the metal plate satisfies a formula (1).
T <L / cos θ (1)
Where L: diameter of cooling path (mm) θ: angle of inclination of cooling path (°)   The method for manufacturing a sprue bush according to claim 2, wherein in the grooving step, the grooving is performed from both the front surface and the back surface of the metal plate. A sprue bushing manufacturing method for manufacturing a plurality of sprue bushes,
In the groove processing step, a plurality of sprue bushing grooves are processed on a single metal plate,
After the joining step, before the shape processing, the metal block obtained in the joining step is cut into a plurality of blocks,
4. The method of manufacturing a sprue bush according to claim 2, wherein each of the obtained blocks is processed to manufacture a plurality of sprue bushes.

Images