JP6400419B2 - Injection mold of hemispherical shoe for swash plate compressor - Google Patents

Description

  The present invention relates to an injection molding used for manufacturing a hemispherical shoe for converting a rotary motion of a swash plate into a reciprocating motion of a piston interposed between a swash plate and a piston in a swash plate compressor used for an air conditioner for an automobile. Regarding molds.

  The swash plate compressor slides a hemispherical shoe on a swash plate mounted at a right angle and obliquely so as to be directly fixed to a rotating shaft or indirectly through a connecting member in a housing where refrigerant exists. The rotational movement of the swash plate is converted into the reciprocating movement of the piston through the shoe to compress and expand the refrigerant. Such swash plate compressors include a double swash plate type that compresses and expands refrigerant on both sides using a double-headed piston, and a single-slope that compresses and expands refrigerant only on one side using a single-headed piston. There is a board type. In addition, the hemispherical shoes include those that slide only on one side of the swash plate and those that slide on both sides of the swash plate. In these swash plate type compressors, sliding with a large relative speed of 20 m or more per second occurs on the sliding surface of the swash plate and the hemispheric shoe, and the hemispheric shoe is used in a very severe environment.

  As for lubrication, the lubricating oil is diluted while dissolved in the refrigerant, circulates in the housing, and is supplied to the sliding portion in the form of a mist. However, when the operation is resumed from the operation stop state, the lubricating oil is washed away by the liquefied refrigerant, and the sliding surface between the swash plate and the hemispherical shoe at the start of the operation becomes a dry lubricating state without the lubricating oil, There is a problem that seizure is likely to occur.

  As a means for preventing this seizure, for example, a polyether ether ketone (PEEK) resin film is directly formed on at least sliding surfaces of a swash plate and a hemispherical shoe by an electrostatic powder coating method (see Patent Document 1). There has been proposed a thermoplastic polyimide coating containing a solid lubricant formed by an electrostatic powder coating method (see Patent Document 2).

  Further, in order to ensure high slidability under high speed and high temperature conditions, a binder made of PEEK resin at at least one sliding contact portion of the swash plate, hemispherical shoe and piston, and a solid lubricant dispersed in the binder The thing which formed the sliding layer which becomes (refer patent document 3) is proposed.

JP 2002-180964 A JP 2003-049766 A JP 2002-039062 A

  In the prior art, in order to improve the lubrication characteristics of the swash plate and the hemispherical shoe, as described above, a method of forming the sliding surface of the swash plate and the hemispherical shoe with a lubricating coating has been proposed. There was no formation of a lubricious coating on the hemispherical shoe, even though a lubricious coating was formed on the plate. The reason for this is that the sliding area of the hemispherical shoe is smaller than that of the swash plate, and the sliding with the spherical seat of the piston is also received. Is guessed.

  For example, when the entire surface of the hemispherical shoe is covered with a resin film for sliding with the swash plate and the piston as in the prior art, the heat dissipation of the frictional heat decreases and the temperature of the hemispherical shoe base material increases, It can happen that the resin coating dissolves. In addition, the formation of a resin film by electrostatic powder coating or coating liquid application exposes the hemispherical shoe to the firing temperature, and there is a concern that the strength may decrease.

  On the other hand, a swash plate with a lubricious coating is not only strict in terms of flatness, parallelism and thickness accuracy of the sliding surface, but also has a low coating cost due to the large coating area of the lubricious coating made of expensive materials. There is a problem that you can not.

  The present invention has been made to address these problems. Even in a dry lubrication state where there is no lubricating oil at the start of operation, seizure does not occur. An object of the present invention is to provide an injection mold for obtaining a hemispherical shoe excellent in durability with suppressed deterioration.

  The injection mold of the swash plate compressor hemispherical shoe according to the present invention is a slant mounted at right angles and obliquely so as to be fixed directly to a rotating shaft or indirectly via a connecting member in a housing where a refrigerant exists. An injection mold used for manufacturing a hemispherical shoe of a swash plate type compressor that compresses and expands a refrigerant by sliding a hemispherical shoe on a plate and converting the rotational motion of the swash plate into a reciprocating motion of a piston through the hemispherical shoe. The hemispherical shoe is made of a hard material, a base material having a hollow portion in the central axis portion, a resin composition, and a surface of a flat portion that slides on the swash plate around the base material and A resin layer formed on the surface of the spherical portion that slides with the piston, and the injection mold includes a movable mold plate and a fixed mold plate, and the movable mold plate and the movable mold plate One of the fixed side templates is A core pin that forms a part of the tee and has a concave spherical surface for forming the spherical portion, and is fitted on the central axis in the horizontal direction of the cavity, and is fitted to the hollow portion of the base material. The other of the template and the fixed-side template has a concave plane for forming the plane portion, which forms part of the cavity, and a gate is disposed coaxially with the core pin. To do.

  The core pin has a small-diameter step portion at the tip, and the step surface of the small-diameter step portion abuts against an end surface of the substrate in a state where the core pin is fitted to the hollow portion of the substrate.

  The movable side plate has the core pin, and the core pin can be moved forward as a protruding pin after the molding die is opened.

  The gate has a gate opening provided at a position recessed from the sliding surface of the hemispherical shoe. The gate is a pinpoint gate.

  The injection mold of the swash plate compressor hemispherical shoe of the present invention is a mold used for manufacturing a hemispherical shoe having a predetermined structure having a spherical surface portion and a flat surface portion on which a resin layer is formed, and is fixed to the movable side mold plate. And one of the movable side mold plate and the fixed side mold plate has a concave spherical surface for forming the spherical portion, which forms part of the cavity, and a horizontal central axis of the cavity. A core pin that fits into the hollow portion of the hemispherical shoe base material is disposed on the other side, and the other has a concave plane that forms part of the cavity and forms the plane portion, and is coaxial with the core pin. Since the molten resin injected from the gate hits the tip of the core pin, the surface of the hemispherical shoe base material is uniformly coated from the axial center of the hemispherical shoe. For this reason, the resin layer formed on the surface of the spherical surface or the flat surface of the hemispherical shoe does not have a weld and becomes a uniform resin layer.

  The hemispherical shoe obtained by using the mold was formed on a base material made of a hard material, a surface of a flat part sliding with the swash plate and a surface of a spherical part sliding with the piston around the base material. Since it has a resin layer, seizure can be prevented even in a dry lubrication state at the start of operation. Further, since the resin layer is not formed on the contact surface between the base material of the hemispherical shoe and the core pin, friction heat is radiated from the portion, and the resin layer can be prevented from being melted due to the temperature rise of the base material. Furthermore, since the injection molding is employed for forming the resin layer, there is no concern of a decrease in strength without being exposed to the firing temperature during production.

  When the core pin has a small-diameter stepped portion at the tip, and the core pin is engaged with the hollow portion of the base material of the hemispherical shoe, the step surface of the small-diameter step portion hits the end surface of the base material. Positioned in the axial direction. Therefore, the base material of the hemispherical shoe having a spherical surface can be easily and accurately arranged in the cavity. Further, in the base material, the axial contact surface with the small-diameter step portion of the core pin becomes an exposed surface on which the resin layer is not formed after the hemispherical shoe is completed, so that heat can also be radiated from this portion.

  Since the movable side plate has a core pin, and the core pin can be moved forward after the molding die is opened as a protruding pin, there is no need to provide a separate protruding pin, and there is no protruding pin mark on the resin layer of the hemispherical shoe. There is no remaining.

  Since the gate opening is provided at a position where the gate opening is recessed from the sliding surface of the hemispherical shoe, it is possible to prevent the gate trace from protruding from the sliding surface of the hemispherical shoe (the surface of the resin layer). Further, since the gate is a pinpoint gate, the gate can be cut in the injection molding process, and damage to the resin layer surface can be prevented as compared with post-processing using a hand tool such as a nipper.

It is a longitudinal cross-sectional view which shows an example of the swash plate type compressor using the hemispherical shoe for swash plate type compressors obtained with the injection mold of this invention. It is the longitudinal cross-sectional view and top view which expand and show the hemispherical shoe of FIG. It is sectional drawing which shows an example of the injection mold of this invention. It is a figure which shows the manufacturing process of the hemispherical shoe using the metal mold | die of FIG.

  An example of a swash plate compressor using a swash plate compressor hemispherical shoe obtained by the injection mold of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a swash plate compressor. The swash plate type compressor shown in FIG. 1 uses carbon dioxide gas as a refrigerant. The swash plate 3 attached obliquely so as to be directly fixed to the rotary shaft 2 in the housing 1 in which the refrigerant exists is inclined. It is converted into a reciprocating motion of a double-headed piston 9 through a hemispherical shoe 4 that slides on both sides of the plate 3, and a refrigerant is generated on both sides of each piston 9 in a cylinder bore 10 formed at equal intervals in the circumferential direction of the housing 1. The swash plate type that compresses and expands. The rotary shaft 2 that is rotationally driven at high speed is supported by a needle roller bearing 11 in the radial direction and supported by a thrust needle roller bearing 12 in the thrust direction. In this configuration, the swash plate 3 may be fixed to the rotary shaft 2 indirectly via a connecting member. Moreover, the aspect attached rather than diagonally may be sufficient.

  Each piston 9 is formed with a recess 9 a so as to straddle the outer periphery of the swash plate 3, and a hemispherical shoe 4 is seated on a spherical seat 13 formed on the axially opposed surface of this recess 9 a, The swash plate 3 is supported so as to be movable relative to the rotation of the swash plate 3. Thereby, conversion from the rotational movement of the swash plate 3 to the reciprocating movement of the piston 9 is performed smoothly. The hemispherical shoe 4 has a spherical portion that slides with the piston 9 (spherical seat 13) and a flat portion that slides with the swash plate 3.

  The structure of the hemispherical shoe for a swash plate compressor obtained by the injection mold of the present invention will be described in detail with reference to FIG. An upper view of FIG. 2 is a longitudinal sectional view showing an example of a hemispherical shoe, and a lower view of FIG. 2 is a plan view thereof. As shown in FIG. 2, the hemispherical shoe 4 includes a spherical portion 4a constituting a part of the sphere, a flat portion 4b in which the sphere is cut in a substantially flat surface on the opposite side of the spherical portion 4a, a spherical portion 4a, It has a substantially hemispherical structure composed of an outer peripheral part 4c connecting the flat part 4b. Further, the hemispherical shoe 4 has a circular planar shape, and the surface of the outer peripheral portion 4c (the surface of the resin layer 6c) is a cylindrical outer peripheral surface. The overall shape of the hemispherical shoe 4 is a shape in which one bottom surface of the cylindrical body is a convex shape constituting a part of the hemisphere. The overall shape of the hemispherical shoe 4 is not limited to this, and it is sufficient if it has a flat surface portion that slides with the swash plate and a spherical surface portion that slides with the piston. It is good also as a shape which does not have.

  The hemispherical shoe 4 uses a member made of a hard material as a base material 5, and a resin layer 6 is formed by injection molding to be described later on the surface of a flat surface portion 4 b that slides with a swash plate and the surface of a spherical surface portion 4 a that slides with a piston. ing. Of the resin layer 6, the resin layer 6a is formed on the surface of the spherical surface portion 4a, the resin layer 6b is formed on the surface of the flat surface portion 4b, and the resin layer 6 is formed on the outer peripheral portion 4c. Layer 6c. Each resin layer is thin (about 0.1 to 0.7 mm), and the shape of the base material 5 is a shape along the entire shape of the hemispherical shoe 4. The diameter of the hemispherical shoe is about 5 to 15 mm.

  In the hemispherical shoe 4, the flat surface portion 4b that slides with the swash plate and the spherical surface portion 4a that slides with the piston are located on the opposite sides in the axial direction. By making the resin layers formed on these surfaces continuous and integrated through the outer peripheral portion 4c and the like, the resin layers on both surfaces are structurally difficult to peel from the substrate. Moreover, it is preferable to make the thickness of the resin layer 6b of the flat surface portion 4b thinner than the thickness of the resin layer 6a of the spherical surface portion 4a. By making the resin layer of the flat part thinner than the resin layer of the spherical part, the resin part of the flat part sliding with the swash plate has high load resistance, and the resin layer of the spherical part sliding with the piston is a piece. Good compatibility with hitting and excellent wear resistance. Furthermore, it is easy to ensure high melt fluidity during injection molding.

  In the form shown in FIG. 2, the base material 5 is formed with a cylindrical space-like hollow portion 5b penetrating the spherical surface portion 4a side and the flat surface portion 4b side at the center axis portion of the circular center. The hollow portion 5b is formed with a resin filling portion 8 filled with a resin composition and a hole portion 7 not filled with the resin composition. The hole portion 7 is a portion into which the core pin is fitted during molding, and is in a state where the surface of the base material is exposed without being filled with resin. Even if frictional heat is generated due to sliding with the swash plate and piston, heat can be transferred from the pores through the base material, and the resin layer does not dissolve and wear and seizure resistance Excellent. Further, the hole portion also has a function as an oil pocket for holding lubricating oil.

  Further, the hemispherical shoe 4 of the form shown in FIG. 2 has an exposed surface 5a which is a non-contact portion with the piston on the outer surface on the spherical surface portion 4a side and is exposed without being covered with the resin layer 6. Have. The non-contact portion is a portion having a shape obtained by cutting a part of the spherical portion 4a with a plane parallel to the flat portion 4b, and is a portion that does not slide-contact with the piston. As will be described later, a hollow portion of the hemispherical shoe 4 is provided by providing a small-diameter stepped portion on the core pin of the injection mold and positioning the stepped surface of the small-diameter stepped portion against the end surface of the base material in the axial direction. An exposed surface 5a corresponding to the step surface is formed at the edge of the core pin fitting side. By having such a non-contact portion and an exposed surface of the base material on the outer surface on the spherical surface portion 4a side, it becomes easy to radiate the frictional heat generated in the spherical surface portion.

  The material of the base material of the hemispherical shoe is not particularly limited as long as it is made of a hard material excellent in mechanical strength and thermal conductivity. For example, a metal material such as steel, aluminum, aluminum alloy, copper, copper alloy, etc. And ceramics. Examples of the steel material include bearing steel (SUJ1-5, etc.), chromium molybdenum steel, carbon steel for mechanical structure, mild steel, stainless steel, high speed steel and the like. These steel materials may be subjected to treatment such as quenching to increase the surface hardness in order to reduce wear damage due to sliding contact with the piston. Among the above, it is preferable to use bearing steel from the viewpoint of reliability.

  Further, as the material of the base material, sintered metals such as iron-based, copper-iron-based, copper-based, and stainless-based materials can also be employed. Since adhesion between the base material and the resin layer can be improved, it is preferable to use a sintered metal containing iron as a main component, and further an iron-based sintered metal having a copper content of 10% by weight or less. By making the base material a sintered metal, it is possible to improve the lubricating oil retention on the surface of the spherical surface, and to improve the adhesion with the resin layer by the anchor effect of the surface irregularities.

  When the base material of the hemispherical shoe is a dense body such as melted metal or ceramics, the surface of the base material is subjected to physical processing such as shot blasting or machining before the resin layer is formed in order to improve the adhesion to the resin layer. It is preferable to roughen it into a concavo-convex shape by a general surface treatment. Also, chemical surface treatment such as acidic solution treatment (mixed with sulfuric acid, nitric acid, hydrochloric acid, etc. or other solutions), alkaline solution treatment (mixed with sodium hydroxide, potassium hydroxide, etc. or other solutions) It is preferable to form a fine uneven shape on the surface of the substrate. The acidic solution treatment is preferable because masking can be omitted. Although the fine uneven shape varies depending on the concentration, processing time, post-treatment, etc., in order to improve the adhesion due to the anchor effect, it is preferable to make the fine unevenness with a concave pitch of several nanometers to several tens of micrometers. The fine uneven shape formed by the chemical surface treatment has a complicated three-dimensional structure such as a porous structure, so that the anchor effect is easily exhibited, and particularly strong adhesion is possible.

  The base resin of the resin composition forming the resin layer is preferably a synthetic resin that can be injection-molded and has excellent lubrication characteristics and heat resistance. Examples of such synthetic resins include aromatic polyetherketone (PEK) resins, polyacetal (POM) resins, polyphenylene sulfide (PPS) resins, injection-moldable polyimide resins, polyamideimide (PAI) resins, polyamides ( PA) resin, injection-moldable fluororesin, and the like. Each of these synthetic resins may be used alone or may be a polymer alloy in which two or more kinds are mixed. Among these synthetic resins, it is preferable to use an aromatic PEK resin. By using an aromatic PEK-based resin, it is possible to obtain a hemispherical shoe that is excellent in heat resistance, oil resistance / chemical resistance, creep resistance, friction wear characteristics, and the like, and that is highly reliable.

  Examples of the aromatic PEK resin that can be used in the present invention include polyether ether ketone (PEEK) resin, polyether ketone (PEK) resin, and polyether ketone ether ketone ketone (PEKEKK) resin. Examples of commercially available PEEK resins that can be used in the present invention include Victrex PEEK (90P, 150P, 380P, 450P, 90G, 150G, etc.), Solvay Specialty Polymers: Keta Spire PEEK (KT-820P, KT). -880P, etc.), manufactured by Daicel Evonik Co., Ltd .: VESTAKEEEP (1000G, 2000G, 3000G, 4000G, etc.). Examples of the PEK resin include Victrex HT manufactured by Victrex, and examples of the PEKKK resin include Victrex ST manufactured by Victrex.

The resin composition forming the resin layer preferably has a melt viscosity of 50 to 200 Pa · s at a resin temperature of 380 ° C. and a shear rate of 1000 s ⁻¹ . When the melt viscosity is within this range, thin injection molding can be smoothly performed on the surface of the base material of the hemispherical shoe. By making thin injection molding possible and eliminating the need for post-processing after molding, manufacturing becomes easy and manufacturing costs can be reduced. In the case of a synthetic resin having an aromatic PEK resin as a main component, it is preferable to employ an aromatic PEK resin having a melt viscosity of 150 Pa · s or less under the above conditions in order to bring the melt viscosity to the above range.

  The resin composition for forming the resin layer includes the above-described aromatic PEK resin, solid lubricants such as polytetrafluoroethylene (PTFE) resin, graphite, molybdenum disulfide, various whiskers, aramid fibers, carbon fibers, etc. It is preferable to make it the resin composition which mix | blended the fibrous reinforcement. Fibrous reinforcing materials and inorganic solid lubricants (graphite, molybdenum disulfide) have the effect of reducing the molding shrinkage of aromatic PEK-based resins, and the internal stress of the resin layer during insert molding with a substrate There is an effect to suppress. In addition, the solid lubricant has low friction even when the lubricating oil is thin, and can prevent seizure.

  In the resin composition for forming the resin layer, means for mixing and kneading the above raw materials is not particularly limited, and only the powder raw material is a Henschel mixer, ball mixer, ribbon blender, ladyge mixer, ultra Henschel mixer. Etc., and further melt-kneaded in a melt extruder such as a twin screw extruder to obtain pellets for molding the resin composition. In addition, a side feed may be used for charging the filler when melt kneading with a twin screw extruder or the like. Using the molding pellets, a resin layer is formed in a manufacturing process using an injection mold described later. In addition, you may perform an annealing process etc. for a physical property improvement after shaping | molding.

  The injection mold of the swash plate compressor hemispherical shoe of the present invention is a mold for producing the hemispherical shoe configured as described above. This injection mold will be described in detail with reference to FIG. FIG. 3 is a cross-sectional view showing an example of an injection mold according to the present invention. As shown in FIG. 3, the injection mold 14 is a mold having a three-plate structure including a movable side mold plate 15, a fixed side mold plate 16, and a fixed side mounting plate 17. The fixed side mold plate 16 has a concave flat surface 16a for forming the flat surface portion of the hemispherical shoe, and the movable side mold plate 15 has a concave spherical surface 15a for forming the spherical surface portion of the hemispherical shoe. The concave spherical surface 15 a and the concave flat surface 16 a are surfaces that constitute a part of the cavity 22. A core pin 18 is disposed on the movable side template 15 on the central axis of the cavity 22 in the horizontal direction. The core pin 18 has a small-diameter stepped shape having a small-diameter step portion 18a at the tip. Further, a gate 21 for filling the cavity 22 with molten resin in communication with the runner 19 and the sprue 20 is disposed on the stationary side template 16. Here, the gate 21 is arranged coaxially with the core pin 18. The cavity 22 may have a concave spherical surface for forming the spherical portion of the hemispherical shoe on the fixed side mold plate, and a concave plane for forming the flat portion of the hemispherical shoe on the movable side mold plate. . Even in this case, a small-diameter stepped core pin is disposed on the central axis in the horizontal direction of the cavity on the movable side mold plate, and a gate is disposed coaxially with the core pin on the fixed side mold plate.

  A process for manufacturing a hemispherical shoe using the injection mold of FIG. 3 will be described with reference to FIG. 4 (a) to 4 (d) are diagrams showing a process for manufacturing a hemispherical shoe using the mold. As shown in FIG. 4A, the base material 5 is disposed in the cavity 22 before injection molding. Specifically, the small-diameter step portion 18 a at the tip of the core pin 18 is fitted into the hollow portion 5 b of the base material 5. The hollow portion 5b of the substrate 5 has a cylindrical space shape, and the small-diameter step portion 18a of the core pin 18 has a columnar shape fitted thereto. Thereby, the base material 5 is positioned in the horizontal direction and the axial direction in the cavity 22. By utilizing such a fitting between the core pin and the hollow portion of the base material, the base material can be easily and accurately positioned in the cavity, and a thin resin layer is easily formed on the surface of the base material. Can be molded with accuracy. In the hollow portion 5b of the base material 5, the portion where the small diameter step portion 18a is fitted becomes the hole portion 7 after the hemispherical shoe is completed, and the portion where the small diameter step portion 18a is not fitted is the resin after the hemispherical shoe is completed. It becomes the filling part 8 (refer FIG. 2). Further, in the base material 5, the abutting surface (axial contact surface) with the step surface of the small-diameter step portion 18a of the core pin 18 becomes an exposed surface 5a on which the resin layer 6 is not formed after the hemispherical shoe is completed (FIG. 2). reference). Before the injection molding, the three-plate structure injection molding die 14 including the fixed side mounting plate 17, the fixed side mold plate 16 and the movable side mold plate 15 is kept at a predetermined temperature of the resin used in a state where the mold is closed. Is held.

  As shown in FIG. 4B, a molten resin 23 obtained by heating the above resin composition to a molten state is injected into the mold by a set injection pressure, and the gate 21 is passed through the runner 19 and the sprue 20. The cavity 22 is filled through. Thereafter, a pressure holding process and a cooling process for a certain time are performed in a state where the mold is closed. The gate 21 of the fixed side mold plate 16 is arranged coaxially with the core pin 18 of the movable side mold plate 15 (on the horizontal central axis of the cavity 22), and its gate port is formed in the cavity 22 after the hemispherical shoe is completed. It is provided in a portion that becomes the resin filling portion 8. As a result, the molten resin injected from the gate 21 collides with the tip of the core pin 18 (tip of the small diameter step portion 18a), and then flows so as to uniformly coat the surface of the base material 5 from the axis of the hemispherical shoe. To do. As a result, the resin layers covering the periphery of the base material can be formed uniformly and without welds, and the resin layer partially loses strength, non-uniformity in sliding characteristics, and adhesion strength to the base material. Non-uniformity or the like does not occur, and the resin layer can be prevented from cracking or peeling off due to sliding with the swash plate or the piston. In addition, when the hollow part 5b of the base material 5 is a non-penetrating shape in the axial direction, the molten resin injected from the gate 21 collides with the bottom part of the hollow part 5b, and a uniform coating is similarly formed.

  Moreover, in the hollow part 5b of the base material 5, the part which is a non-fitting part with the core pin 18 and serves as a resin filling part serves as a cold slug well, and it is possible to prevent cold slug from appearing in the resin layer. By setting the resin filling portion in a range that occupies 1/4 to 3/4 of the axial length of the hollow portion 5b, the above-described effect can be obtained particularly easily. In addition, by setting within this range, a sufficient fitting length can be secured for the fitting portion between the base material 5 and the core pin 18.

  In the form shown in the figure, a large-diameter hollow portion 5c having a larger hole diameter than the other portions is formed at the end of the hollow portion 5b of the base 5 on the resin filling portion side. The hole diameter of the large-diameter hollow part 5c is 1.5 to 3 times the hole diameter of the other part of the hollow part 5b. By forming the large-diameter hollow portion 5c, the gate diameter can be set large, and the fluidity of the molten resin from the gate can be easily ensured. For this reason, although it is thin, it is possible to prevent problems in injection molding such as short shots and to form a uniform resin layer with high adhesion strength.

  In the form shown in the figure, the gate 21 is located on the flat portion side of the hemispherical shoe. Thereby, the flow of the molten resin flows from the flat surface portion side to the spherical surface portion side, and the resin layer of the flat surface portion that receives the most load can be formed thin so as to withstand high surface pressure. Further, since the gate 21 is a pinpoint gate, it is possible to perform gate cutting (in-mold gate cutting) in the injection molding process, and scratches the surface when manually cutting the hemispherical shoe, which is a precision component. There is no fear of.

  Since the gate opening of the gate 21 is provided at a position recessed from the sliding surface of the hemispherical shoe, the gate trace can be prevented from protruding from the sliding surface of the hemispherical shoe (the surface of the resin layer). In particular, the gate 21 can be more reliably prevented from protruding by providing the gate 21 at a position that is deeper than the thickness of the resin layer from the surface position of the substrate 5.

  As shown in FIG. 4C, after the cooling step, the fixed side template 16 is released from the fixed side mounting plate 17 by mold opening, and at the same time, the movable side template 15 is released from the fixed side template 16. Thereby, a runner etc. remove | deviates from a metal mold | die and falls. Further, when the movable side template 15 is opened from the fixed side template 16, the resin in the gate 21 is broken and the gate is cut.

  Finally, as shown in FIG. 4D, the hemispherical shoe 4 is taken out from the cavity by advancing the core pin 18 as a protruding pin. As described above, by using the core pin 18 as a protruding pin so that the molding die can be opened after being opened, there is no need to provide a separate protruding pin, and a protruding pin mark remains on the resin layer of the hemispherical shoe. There is no. Note that the above-mentioned “advance” means that the molded product is advanced from the inside of the mold cavity in the direction of protruding out of the cavity.

  After the resin layer is formed by the above steps, the surface of the resin layer that becomes a sliding surface with the swash plate or the piston may be polished. The polishing process eliminates variations in individual height dimensions and improves accuracy. Moreover, it is preferable to adjust the surface roughness of the surface of the resin layer to 0.05 to 1.0 μm Ra (JIS B0601). By making it within this range, the real contact area on the sliding surface of the resin layer sliding with the swash plate or the piston is increased, the actual surface pressure can be lowered, and the seizure prevention effect is improved. If the surface roughness is less than 0.05 μmRa, the lubricating oil is insufficiently supplied to the sliding surface. The seizure property may be reduced. More preferably, the surface roughness is 0.1 to 0.5 μmRa.

  Oil pockets and dynamic pressure grooves may be formed on the surface of the resin layer serving as a sliding surface with the swash plate or the piston, in addition to the above-described air holes, in order to supplement the lubricating action during the lean lubrication. For example, these shapes can be provided in an injection mold and formed simultaneously with injection molding. Examples of the shape of the oil pocket include a spot-like or streak-like recess. Examples of the spot shape or the stripe shape include a parallel straight line shape, a lattice shape, a spiral shape, a radial shape, and a ring shape. The depth of the oil pocket can be determined as appropriate below the thickness of the resin layer.

  The swash plate type compressor using the hemispherical shoe obtained by the injection mold of the present invention is fixed directly to the rotating shaft or indirectly through a connecting member in a housing in which a refrigerant exists. This is a swash plate type compressor that compresses and expands refrigerant by sliding a hemispherical shoe on an obliquely attached swash plate and converting the rotational motion of the swash plate into a reciprocating motion of a piston through the hemispherical shoe. By using the hemispherical shoe obtained by the injection molding die of the present invention for this swash plate compressor, the lubricating coating can be removed from the swash plate and the piston sliding with the hemispherical shoe. That is, the surface of the swash plate or the like can be incorporated in the swash plate compressor and slid with the hemispherical shoe while the surface of the substrate remains the polished surface. Therefore, by adopting the hemispherical shoe, it is possible to provide a low-cost swash plate compressor that is functionally equivalent.

  By using the injection mold of the hemispherical shoe for the swash plate compressor of the present invention, seizure does not occur even in the dry lubrication state without lubricating oil at the start of operation, and the lubrication characteristics are deteriorated due to frictional heat generation or during production. It is possible to manufacture a hemispherical shoe excellent in durability while suppressing a decrease in strength. Therefore, it can be used as a mold for manufacturing hemispherical shoes for various swash plate compressors. In particular, carbon dioxide gas or HFC1234yf is used as a refrigerant, and it can be suitably used as a mold for manufacturing a hemispherical shoe of a recent swash plate type compressor having a high-speed and high-load specification (for example, the surface pressure exceeds 8 MPa).

DESCRIPTION OF SYMBOLS 1 Housing 2 Rotating shaft 3 Swash plate 4 Hemispherical shoe 5 Base material 6 Resin layer 7 Hole part 8 Resin filling part 9 Piston 10 Cylinder bore 11 Needle roller bearing 12 Thrust needle roller bearing 13 Spherical seat 14 Injection mold 15 Movable Side mold plate 16 Fixed side mold plate 17 Fixed side mounting plate 18 Core pin 19 Runner 20 Sprue 21 Gate 22 Cavity 23 Molten resin

Claims (5)

In the housing in which the refrigerant is present, the hemispherical shoe is slid on a swash plate mounted at right angles and obliquely so as to be directly fixed to the rotating shaft or indirectly through the connecting member, and the hemispherical shoe is passed through the hemispherical shoe. An injection mold used for manufacturing a hemispherical shoe of a swash plate compressor that converts the rotational motion of a swash plate into a reciprocating motion of a piston to compress and expand the refrigerant,
The hemispherical shoe is made of a hard material, and has a base material having a hollow portion at a central shaft portion, a resin composition, a surface of a flat portion that slides around the base material and slides on the swash plate, and the piston and slide. A resin layer formed on the surface of the moving spherical portion,
The injection molding die comprises a movable side template and a fixed side template,
One of the movable side mold plate and the fixed side mold plate has a concave spherical surface for forming the spherical surface portion, which constitutes a part of the cavity, and the base material on the horizontal central axis of the cavity The core pin that fits into the hollow part of
The other of the movable side mold plate and the fixed side mold plate has a concave plane that forms a part of the cavity and forms the plane portion, and a gate is disposed coaxially with the core pin. Injection mold of hemispherical shoe for swash plate type compressors.   The core pin has a small-diameter step portion at a tip, and the step surface of the small-diameter step portion abuts against an end surface of the base material in a state where the core pin is fitted to the hollow portion of the base material. 2. An injection mold for the hemispherical shoe for a swash plate compressor according to 1.   3. The hemispherical shoe for a swash plate type compressor according to claim 1, wherein the movable side plate has the core pin, and the core pin can be advanced as a protruding pin after the molding die is opened. Injection mold.   The swash plate compressor hemispherical shoe for a swash plate compressor according to any one of claims 1 to 3, wherein the gate is provided at a position where the gate port is recessed from the sliding surface of the hemispherical shoe. Injection mold.   The injection mold for a swash plate compressor hemispherical shoe according to any one of claims 1 to 4, wherein the gate is a pinpoint gate.

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