JP2009195935A - Plunger sleeve and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plunger sleeve having superior durability to sliding wear generated with a plunger tip, and a manufacturing method therefore. <P>SOLUTION: A small diameter surface 3a positioned on the injection port 6 side and having relatively small diameter and a large diameter surface 3b positioned on the side away from the injection port 6 compared with the small diameter surface 3a and having diameter larger than the small diameter surface 3a, are formed in the inner periphery of the sleeve body 3 of the plunger sleeve 1. A spray coating layer 7 of ceramic is formed on the large diameter surface 3b, and the sliding surface 4 of the plunger tip 2 is constituted of the inner peripheral surface 7a of the spray coating layer 7 and the small diameter surface 3a of the sleeve body 3 adjacent to the inner peripheral surface 7a in the axial direction. In detail, the sliding surface 4 is constituted of the inner peripheral surface 7a of the spray coating layer 7 in a low speed side region and of the small diameter surface 3a of the sleeve body 3 in a high speed side region, making as boundary a switch position Ps for switching of the plunger tip 2 from low speed sliding to high speed sliding. The small diameter surface 3a is polished to be within the range of prescribed surface roughness. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention mainly relates to a plunger sleeve for die casting and a manufacturing method thereof.

  A plunger of a die casting machine is generally provided with a plunger sleeve and a plunger tip fitted into the plunger sleeve. Here, at the time of die casting, the molten metal is supplied from a pouring port provided in the plunger sleeve, the plunger tip is driven forward by a cylinder or the like, and the molten metal is injected into the cavity of the molding die. Therefore, the plunger sleeve is required to have resistance to melting and abrasion against the molten metal. In addition, high heat insulation is also required in order to suppress the occurrence of inclusions such as broken chills.

  Further, in this type of plunger sleeve, it is necessary to pay attention to air entrainment that occurs when the molten metal is injected from the molten metal port in order to stabilize the molding quality. Therefore, at the beginning of the sliding of the plunger chip, the sliding is performed at a low speed, and thereafter, switching to a high speed sliding is performed for the purpose of obtaining an injection pressure into the mold cavity.

  As this type of plunger sleeve, for example, in Patent Document 1 below, the entire inner peripheral surface of the plunger sleeve that is in contact with the molten metal and on which the plunger tip slides is formed with a sprayed layer made of alloy tool steel such as SKD61. Is disclosed.

Further, in Patent Document 2 below, in a die-casting sleeve in which an inner cylinder is fitted to an inner surface of an outer cylinder, an inner cylinder that comes into contact with molten metal is divided into a tip member on the injection port side and a rear side behind the tip member. A material is disclosed that is divided into members, the tip member is made of a metal material (or a composite material of metal and ceramic), and the rear member is made of a ceramic material.
JP 2007-268568 A JP 2002-192320 A

  In Patent Document 1, the sprayed layer constituting the inner peripheral surface of the plunger sleeve generally has a porous structure, but when viewed from a lubricity surface, the sliding surface of such a porous structure is In the region where the sliding speed is relatively low, the oil film formation is promoted to contribute to the improvement of the lubricity. On the other hand, in the region where the sliding speed is relatively high, the oil film formation is inhibited and the wear resistance is lowered. There is a tendency to invite. In this regard, the plunger sleeve of Patent Document 1 has a problem that wear increases in a region where the plunger tip slides at a high speed because the entire inner peripheral surface (sliding surface) of the plunger sleeve is composed of a sprayed layer. I have it.

  Further, in Patent Document 2, the inner cylinder that contacts the molten metal of the plunger sleeve is divided into a tip member on the injection port side and a rear member on the rear side of the tip member, and the tip member is mechanically impacted. A technique is disclosed in which a metal material (or a composite material of metal and ceramic) is formed from the viewpoint of durability, and a rear member is formed from a ceramic material from the viewpoint of resistance to melting, etc. The problem of lubricity and wear of the sliding part is not considered.

  In view of the above circumstances, an object of the present invention is to provide a plunger sleeve having excellent resistance to sliding wear generated between the plunger tip and a manufacturing method thereof.

  The solution to the above-mentioned problem is a plunger sleeve having a sleeve body and a sliding surface provided on the inner periphery of the sleeve body, on which the plunger chip can slide, and the sliding surface is formed from the low-speed sliding of the plunger chip. It has different surface properties from the switching position to high-speed sliding, and the area on the lower speed side of the sliding surface is composed of the inner surface of the porous layer made of heat insulating material, and is faster than the switching position. The region on the side is achieved by a metal polished surface.

  Here, the “switching position of the plunger tip from low-speed sliding to high-speed sliding” refers to the sliding speed of the plunger tip, and from the speed at the start of sliding, the cross-sectional area of the sliding surface of the plunger sleeve and the molding metal This means the position in the axial direction of the plunger sleeve corresponding to the tip position of the tip when starting the transition to a speed required to obtain a predetermined injection pressure (injection amount) according to the shape and size of the mold cavity. . Therefore, with respect to the “switching position”, the “low speed side region” is located on the side of the plunger sleeve pouring port, and the “high speed side region” is located on the side of the plunger sleeve injection port. In addition, when switching from “low speed sliding” to “high speed sliding” is performed through an area (speed transition area) where the speed increases as shown in a speed diagram of a plurality of stages or inclined shapes, The “switching position” may be a position corresponding to the boundary between the speed region of “low speed sliding” and the speed transition region, or the position corresponding to the boundary between the “high speed sliding” and the speed transition region. It is also good.

  In the plunger sleeve according to the above configuration, the sliding with the plunger tip is performed in a state where a lubricant such as oil is interposed, and the lubricant is different between when sliding at low speed and when sliding at high speed. It was created by paying attention to the point showing the lubricating action. That is, a region on the low speed side (the low speed sliding region of the plunger tip) of the sliding surface of the plunger sleeve is constituted by the inner surface of the porous layer such as ceramics, thereby having a large number of pores inside. The surface opening of the porous layer acts as an oil reservoir, and promotes the formation of an oil film with the sliding surface of the plunger tip, thereby obtaining a good sliding lubrication state. Further, by forming the porous layer with a heat insulating material such as ceramics, it is possible to ensure the heat resistance and heat insulating properties of the sliding surface of the plunger sleeve particularly in the vicinity of the pouring gate. The porous layer can be formed by, for example, spraying a layer or attaching a porous inner cylinder member separate from the sleeve body to the sleeve body. Also, the plunger tip sliding surface of the plunger sleeve is constituted by a metal polished surface in the region on the high speed side from the switching position (the plunger tip high speed sliding region), while ensuring the impact resistance and the plunger tip. It is possible to reduce wear caused by sliding with the sliding surface. That is, in the high-speed sliding area of the plunger tip, the oil film formation promoting effect by making the sliding surface of the plunger sleeve a porous structure can not be expected, but on the contrary, by the oil film cutting caused by the increased surface roughness, This results in increased wear. Therefore, in the present invention, the region on the higher speed side than the switching position of the sliding surface of the plunger sleeve is configured by a metal polished surface, thereby reducing the surface roughness of the region and preventing oil film cutting. Thus, the formation of an oil film in the region is ensured. Thereby, good lubricity is obtained even in the high-speed sliding area of the plunger tip, and wear of the sliding surface is suppressed.

  As described above, according to the plunger sleeve according to the present invention, it is possible to exhibit good sliding characteristics over the entire sliding range of the plunger tip and to suppress the occurrence of wear and seizure as much as possible. A plunger sleeve can be provided. Moreover, the dispersion | variation in an injection aspect can be made small and, thereby, casting quality can be stabilized.

  In addition, in order to obtain a good fluid lubrication effect in a high-speed sliding region, the polished surface is preferably as smooth as possible, in other words, closer to a mirror surface state. For example, parameters (Ra, Rz relating to known surface roughness) , Rk, etc.). Specifically, the surface roughness of the polished surface may be specified to be 0.2 μm or less in terms of Rz, and polishing processing is performed on the high-speed sliding area of the sliding surface so as to be the surface roughness. You may give it. On the other hand, the lower limit of the surface roughness is determined depending on the polishing process employed.

  Further, the metal polished surface may be formed on the inner peripheral surface of the metal inner cylindrical member separate from the sleeve main body, or may be formed on a part of the inner peripheral surface of the sleeve main body. May be. If the polished surface is formed on a metal inner cylinder member that is separate from the sleeve body, only the inner cylinder portion needs to be formed of a material having excellent heat resistance or impact resistance. Expands and leads to reduced material costs. On the other hand, if it is formed on a part of the inner peripheral surface of the sleeve main body, there is no possibility of misalignment with the inner peripheral surface of the thermal spray layer during separate attachment, and the labor of attachment can be saved.

  Also, the solution to the above-mentioned problem is a method of manufacturing a plunger sleeve comprising a sleeve body and a sliding surface provided on the inner periphery of the sleeve body, on which the plunger tip can slide, and of the sliding surfaces, the plunger A step of forming a region on the low speed side from the switching position by thermal spraying at the switching position from the low speed sliding to the high speed sliding of the chip, and a region composed of a metal surface at a high speed side from the switching position. This is achieved by a configuration including a step of polishing the surface.

  According to such a manufacturing method, the same effect as the effect which concerns on the plunger sleeve mentioned above can be acquired.

  The polishing process can also be performed over the entire sliding surface of the plunger sleeve. Here, for example, if honing is applied to the entire sliding surface, the inner peripheral surface of the thermal spray layer in the low speed sliding region and the metal surface in the high speed sliding region can be finished to the same inner diameter, Polishing and centering of the sliding surface can be performed in one step.

  As described above, according to the present invention, it is possible to provide a plunger sleeve having excellent resistance to sliding wear generated between the plunger tip and a manufacturing method thereof.

  Hereinafter, an embodiment of a plunger sleeve and a manufacturing method thereof according to the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a plunger sleeve 1 according to an embodiment of the present invention. The plunger sleeve 1 has a cylindrical shape, a sleeve body 3 into which the plunger tip 2 can be inserted on the inner periphery, and a sliding surface 4 that slidably supports the plunger tip 2 inserted into the inner periphery of the sleeve body 3. Is mainly provided. In addition, a molten metal pouring port 5 is provided at one end of the sleeve body 3 in the axial direction, and an injection port 6 is provided at the end opposite to the pouring port 5 in the axial direction.

  On the inner periphery of the sleeve body 3, as shown in FIG. 1, a small-diameter surface 3a that is located on the injection port 6 side and has a relatively small diameter, and a side that is farther from the injection port 6 than the small-diameter surface 3a (note) A large-diameter surface 3b that is located on the side of the gate 5 and has a larger diameter than the small-diameter surface 3a is formed. Among them, a ceramic sprayed layer 7 as a porous layer is formed on the large-diameter surface 3b, and the inner peripheral surface 7a of the sprayed layer 7 and the sleeve body 3 adjacent to the inner peripheral surface 7a in the axial direction. The small-diameter surface 3a constitutes the sliding surface 4 of the plunger tip 2. Therefore, the inner peripheral surface 7a and the small diameter surface 3a have the same diameter.

  Here, in detail, the sliding surface 4 has an area on the low speed side with the inner peripheral surface 7a of the thermal spray layer 7 and a high speed side at the switching position Ps of the plunger tip 2 from the low speed sliding to the high speed sliding. This region is constituted by the small diameter surface 3a of the sleeve body 3. Accordingly, the inner peripheral surface of the sleeve main body 3, here, the small-diameter surface 3 a and the large-diameter surface 3 b are also adjacent to each other through a step with the switching position Ps as a boundary. In this embodiment, the sliding speed of the plunger tip 2 is switched from the low speed sliding at the start of sliding to the high speed sliding at the time of injection at the switching position Ps.

  The sleeve body 3 is formed of an alloy tool steel such as SKD61 (JIS), and therefore, in this embodiment, the small diameter surface 3a that forms the high speed side region of the sliding surface 4 is also formed of the same metal material as the sleeve body 3. Has been. The small diameter surface 3a is a polished surface and is finished to a predetermined surface roughness. For example, when Rz is used as a parameter relating to the surface roughness, Rz of the small diameter surface 3a is defined to be 0.2 μm or less.

  Hereinafter, an operation of the plunger sleeve 1 in the case of performing die-casting injection molding using the plunger sleeve 1 having the above configuration will be described.

  First, the molten metal is supplied from the pouring port 5 into the plunger sleeve 1 with the end on the injection port 6 side attached to the cavity (not shown) of the molding die. Then, the plunger tip 2 that has been waiting behind the pouring port 5 (for example, the position indicated by the one-dot chain line in FIG. 1) is advanced toward the injection port 6 to be supplied into the plunger sleeve 1. The molten metal is injected into the cavity. Here, a lubricant such as oil is supplied between the plunger tip 2 and the plunger sleeve 1, and there are many on the inner peripheral surface 7 a of the sprayed layer 7 constituting the low speed side region of the sliding surface 4. There are surface openings. Therefore, when the plunger tip 2 slides at a low speed, these surface openings act as an oil reservoir, and a good sliding state with the plunger tip 2 is realized. In addition, since the sprayed layer 7 is formed of ceramics, the heat resistance and heat insulation of the sleeve 1 immediately after pouring of the molten metal, particularly the resistance to erosion immediately below the pouring port 5 is improved.

  During high-speed sliding, the plunger tip 2 slides with the small-diameter surface 3a of the sleeve body 3 in the sliding surface 4. At this time, since the small-diameter surface 3a is a metal-polished surface, oil film cutting is performed. And a good fluid lubrication state is realized. Therefore, sliding friction with the plunger tip 2 is reduced, and thereby the wear resistance or seizure resistance of the plunger sleeve 1 is improved.

  Next, an example of a manufacturing method of the plunger sleeve 1 having the above configuration will be described with reference to FIG.

  First, the sleeve body 3 having the shape shown in FIG. The sleeve body 3 is formed in a hollow cylindrical shape by performing appropriate machining on the material made of the above-described materials. At this time, the small diameter surface 3a and the large diameter surface 3b of the sleeve body 3 are formed through a step. Further, the pouring port 5 is also perforated in advance.

  Next, as shown in FIG. 2B, a thermal spray material 7 such as ceramics is sprayed onto the large diameter surface 3b of the sleeve body 3, thereby forming a ceramic sprayed layer 7 inside the large diameter surface 3b. The sprayed layer 7 formed in this manner contains a large number of internal pores due to its processing mode, and a large number of surface openings are formed on its inner peripheral surface 7a. Further, the thickness of the thermal spray layer 7 is set to be equal to the step provided on the inner periphery of the sleeve body 3, that is, the difference in inner diameter between the small diameter surface 3a and the large diameter surface 3b. In addition, as a material of the thermal spray layer 7, it is also possible to use materials other than ceramics as long as it has at least heat insulation.

  After that, the small-diameter surface 3a of the sleeve body 3 is polished, here, honed, so that the small-diameter surface 3a is finished to a predetermined surface roughness, and its roundness and cylindricity are Finished to a predetermined accuracy. Thereby, the plunger sleeve 1 as a completed product shown in FIG. 1 is formed. The honing process can also be performed on the inner peripheral surface 7a of the sprayed layer 7, whereby the inner peripheral surface 7a of the sprayed layer 7 is smoothed and has the same diameter as the small diameter surface 3a. The surface roughness, roundness, and cylindricity are also finished to the same level or close to those of the small-diameter surface 3a.

  As mentioned above, although one Embodiment of this invention was described, the plunger sleeve which concerns on this invention, or its manufacturing method can be changed arbitrarily within the scope of the present invention.

  For example, in the above embodiment, the case where the high speed side region of the sliding surface 4 is configured by the small diameter surface 3a of the sleeve main body 3 is exemplified for the purpose of reducing the manufacturing cost. Can also be formed on the inner peripheral surface of another member.

  FIG. 3 shows an example thereof. The plunger sleeve 11 according to FIG. 3 is formed with a large-diameter surface 13a having a relatively large diameter on the injection port 16 side of the sleeve body 13 and on the pouring port 15 side. The inner cylinder member 18, which is a separate body from the sleeve body 13, is fitted and fixed to the inside of the large diameter surface 13 a provided on the injection port 16 side and the small diameter surface 13 b having a smaller diameter than the large diameter surface 13 a. The structure of the plunger sleeve 1 according to FIG.

  That is, in this case, since the region on the high speed side of the switching position Ps of the sliding surface 4 is formed by the inner peripheral surface 18a of the inner cylindrical member 18, only the inner cylindrical member 18 is subjected to wear resistance required for die casting injection. The sleeve body 13 can be manufactured at a relatively low cost by forming it with a material satisfying the properties such as property and impact resistance (for example, alloy tool steel such as SKD61). In manufacturing the plunger sleeve 11 having the above-described configuration, the inner cylinder member 18 is first fitted and fixed to the sleeve main body 13 and then the ceramic sprayed layer 17 is formed. Thereafter, the inner cylinder member 18 is formed by honing. A method of polishing the inner peripheral surface 18a and the inner peripheral surface 17a of the sprayed layer 17 at the same time is preferable.

It is sectional drawing of the plunger sleeve which concerns on one Embodiment of this invention. It is a figure explaining the manufacturing process of a plunger sleeve notionally, (a) is sectional drawing of a sleeve main body single-piece | unit, (b) is sectional drawing of the sleeve main body in the stage which formed the sprayed layer inside the large diameter surface. . It is sectional drawing of the plunger sleeve which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plunger sleeve 2 Plunger tip 3 Sleeve main body 3a Small diameter surface 3b Large diameter surface 4 Sliding surface 5 Pouring port 6 Injection port 7 Spraying layer 7a Inner peripheral surface 11 Plunger sleeve 13 Sleeve main body 13a Large diameter surface 13b Small diameter surface 15 Pouring port 16 Injection port 17 Sprayed layer 17a Inner peripheral surface 18 Inner cylinder member 18a Inner peripheral surface Ps Switching position

Claims (3)

A plunger sleeve provided with a sleeve body and a sliding surface provided on the inner periphery of the sleeve body on which a plunger tip can slide;
The sliding surface has different surface properties from each other at the switching position from the low-speed sliding to the high-speed sliding of the plunger tip,
Of the sliding surface, a region on the low speed side from the switching position is configured by an inner surface of a porous layer made of a heat insulating material, and a region on the high speed side from the switching position is configured by a metal polishing surface. sleeve.   The plunger sleeve according to claim 1, wherein the surface roughness of the polished surface is 0.2 μm or less in terms of Rz. A method of manufacturing a plunger sleeve comprising a sleeve body and a sliding surface provided on the inner periphery of the sleeve body and capable of sliding the plunger tip,
Of the sliding surface, a step of forming a region on the low speed side from the switching position by spraying of a heat insulating material at the switching position from the low speed sliding to the high speed sliding of the plunger tip,
A method of manufacturing a plunger sleeve, including a step of polishing a region formed on a metal surface at a higher speed than the switching position.

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