Speed control valve of die cast machine and die cast machine

Abstract

To improve abrasion resistance while reducing material costs.SOLUTION: A speed control valve 30 is a speed control valve of a die cast machine that controls molten metal injection speed. The speed control valve 30 includes: a housing 35 formed with a valve hole 350 therein; a spool 34 that slides inside the valve hole 350; and a sleeve 36 fixed to the inside of the valve hole 350 and supporting the spool 34 so as to be slidable. The sleeve 36 includes: inside sleeves 361, 362 that contact the spool 34 at at least any position at the time of sliding of the spool 34; and a frame 363 provided so as to surround the periphery of the inside sleeves 361, 362. The inside sleeves 361, 362 and the frame 363 are separate bodies. A material of the inside sleeves 361, 362 has a hardness higher than that of the frame 363.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a speed control valve for a die casting machine and a die casting machine. [Background technology]

[0002] Patent Document 1 discloses a die-casting machine in which one of two cylinder chambers is connected to a hydraulic pressure source and the other is connected to a speed control valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7168707 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a speed control valve for a die casting machine and a die casting machine that have improved wear resistance while reducing material costs. [Means for solving the problem]

[0005] [1] A speed control valve for a die-casting machine that controls the injection speed of molten metal, comprising: a housing having a valve hole formed therein; a spool that slides within the valve hole; and a sleeve fixed within the valve hole and slidably supporting the spool, wherein the sleeve has a contact portion that contacts the spool at least at some position when the spool slides; and an outer circumferential portion that surrounds the contact portion, wherein the contact portion and the outer circumferential portion are separate bodies, and the material of the contact portion is harder than the material of the outer circumferential portion.

[0006] [2] The speed control valve for a die casting machine described in [1] above, characterized in that the contact portion contacts the spool at a contact surface provided on the inner peripheral side, and one or both axial ends of the contact surface are tapered.

[0007] [3] A die-casting machine comprising a hydraulic power source and an injection means connected to the hydraulic power source, wherein the injection means has a cylinder and a piston that divides the interior of the cylinder into two chambers, one of the two divided chambers being connected to the hydraulic power source, and the other of the two divided chambers being connected to the speed control valve described in claim 1 or 2. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a speed control valve for a die casting machine and a die casting machine that have improved wear resistance while reducing material costs. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of a die-casting machine. [Figure 2] FIG. 2 is a schematic diagram showing the die casting machine with the piston in the forward position. [Figure 3] FIG. 3 is a schematic diagram showing the die casting machine with the piston retracted. [Figure 4] FIG. 4(a) is a cross-sectional view showing a housing included in a speed control valve, FIG. 4(b) is a diagram showing a sleeve included in the speed control valve, and FIG. 4(c) is a diagram showing a speed control valve in which the sleeve is assembled to the housing. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment will be described below with reference to the drawings. In the description, the same elements or elements having the same functions are designated by the same reference numerals, and redundant description will be omitted.

[0011] FIG. 1 is a schematic diagram showing an example of a die-casting machine 1. The die-casting machine 1 is a device that produces a casting by filling a mold with molten metal (hereinafter referred to as "molten metal") and molding it. The molten metal is, for example, an aluminum alloy. The die-casting machine 1 is also called a die-casting device or a casting molding device. The die-casting machine 1 includes, for example, an injection unit 10 (injection means), a hydraulic drive unit 20 (hydraulic pressure source), a speed control valve 30, a hydraulic oil storage tank 40, a hydraulic pressure supply unit 45, and a controller 70.

[0012] The injection unit 10 is a part that operates a plunger (not shown) that injects molten metal into a cavity (not shown). The injection unit 10 is a hydraulically driven injection means, and is connected to a hydraulic drive unit 20 and a speed control valve 30. The injection unit 10 has a cylinder 11 and a piston 12.

[0013] The cylinder 11 forms a space for the advancement and retreat of the members included in the injection part 10. The cylinder 11 is formed in a cylindrical shape so as to extend along the front-rear direction in which the piston 12 moves.

[0014] The piston 12 has a rod portion 12a extending in the front-rear direction in which it operates, and a head portion 12b provided integrally with the rod portion 12a at one end side of the rod portion 12a. Hereinafter, in the front-rear direction in which the piston 12 operates, the side on which the head portion 12b is provided will be referred to as the "rear" and the opposite side will be referred to as the "front."

[0015] Within the cylinder 11, a space is formed behind the head portion 12b of the piston 12, and this space is referred to as the "head-side hydraulic chamber 11b." Within the cylinder 11, a space is formed in front of the head portion 12b of the piston 12, and this space is referred to as the "rod-side hydraulic chamber 11a." In this way, the piston 12 divides the interior of the cylinder 11 into two chambers (the head-side hydraulic chamber 11b and the rod-side hydraulic chamber 11a). The head-side hydraulic chamber 11b is connected to the hydraulic drive unit 20. The rod-side hydraulic chamber 11a is connected to the speed control valve 30.

[0016] The hydraulic drive unit 20 is a part that supplies hydraulic oil to the injection unit 10. The hydraulic drive unit 20 has, for example, an injection accumulator 21, a pressure-boosting accumulator 22, and a switching valve 23.

[0017] The injection accumulator 21 is a device that delivers hydraulic oil to the injection unit 10 during the injection process. The injection accumulator 21 has, for example, a sealed container 21a, a hydraulic oil chamber 21b, a gas chamber 21c, and an airtight member 21d. The sealed container 21a forms spaces that become the hydraulic oil chamber 21b and the gas chamber 21c, and houses the airtight member 21d. The hydraulic oil chamber 21b stores hydraulic oil. The gas chamber 21c stores pressurized gas. Nitrogen gas, for example, is supplied to the gas chamber 21c from a gas supply unit 50. The airtight member 21d airtightly separates the hydraulic oil chamber 21b and the gas chamber 21c inside the sealed container 21a and is movably arranged therein. The hydraulic oil chamber 21b of the injection accumulator 21 is connected to the head-side hydraulic chamber 11b via a switching valve 23. When pressurized gas is supplied to the gas chamber 21c, the airtight member 21d is pressed and moved. As the airtight member 21d moves, hydraulic oil for injection is supplied from the hydraulic oil chamber 21b to the head-side hydraulic chamber 11b.

[0018] The boosting accumulator 22 is a device that delivers hydraulic oil to the injection unit 10 during a boosting process to apply pressure to the molten metal in the cavity (not shown). The boosting process is a process of boosting the pressure of the molten metal in the cavity (not shown) after the injection process. The boosting accumulator 22 includes, for example, a sealed container 22a, a hydraulic oil chamber 22b, a gas chamber 22c, and an airtight member 22d. The sealed container 22a forms spaces that become the hydraulic oil chamber 22b and the gas chamber 22c, and houses the airtight member 22d. The hydraulic oil chamber 22b stores hydraulic oil. The gas chamber 22c stores pressurized gas. Nitrogen gas, for example, is supplied to the gas chamber 22c from a gas supply unit 60. The airtight member 22d is movably disposed within the sealed container 22a and airtightly separates the hydraulic oil chamber 22b from the gas chamber 22c. The hydraulic oil chamber 22b of the pressure-boosting accumulator 22 is connected to the head-side hydraulic chamber 11b of the injection unit 10. When pressurized gas is supplied to the gas chamber 22c, the airtight member 22d is pressed and moved. As the airtight member 22d moves, pressure-boosting hydraulic oil is supplied from the hydraulic oil chamber 22b to the head-side hydraulic chamber 11b.

[0019] The switching valve 23 is a member that switches the accumulator that supplies hydraulic oil to the head-side hydraulic chamber 11b of the injection unit 10. The switching valve 23 switches between a state in which injection hydraulic oil is supplied from the injection accumulator 21 to the injection unit 10 and a state in which boosting hydraulic oil is supplied from the boosting accumulator 22 to the injection unit 10. The switching valve 23 may be any valve that can switch between these two states. The switching valve 23 operates based on an operation command from the controller 70.

[0020] The speed control valve 30 is a speed control valve for the die casting machine 1 that controls the injection speed of the molten metal. The speed control valve 30 includes a servo motor 31, an encoder 32, a coupling 33, a spool 34, a housing 35, and a sleeve 36. The speed control valve 30 is a nested type in which multiple parts are stacked coaxially.

[0021] The servo motor 31 is a motor that rotates a rotary shaft. An encoder 32 is attached to the servo motor 31 with the rotary shaft connected thereto. The encoder 32 detects the rotation angle of the rotary shaft of the servo motor 31. The servo motor 31 and the encoder 32 are electrically connected to a controller 70 by wiring. The servo motor 31 operates based on commands from the controller 70. The detection signal of the encoder 32 is used to convert the position of the spool 34 and is used for feedback control by the controller 70.

[0022] Coupling 33 is configured to convert the rotational motion of the rotary shaft of servo motor 31 into linear motion by transmitting it to a rotary-linear motion conversion mechanism (not shown), and transmits it to spool 34 via connecting rod 37. This causes spool 34 to perform linear motion (lateral movement), thereby opening and closing the valve.

[0023] The spool 34 is configured to perform linear motion (lateral movement) in response to power transmitted from the servo motor 31 via the connecting rod 37 and the coupling 33. The spool 34 has a cylindrical shape (stepped cylindrical shape) in which large-diameter portions and small-diameter portions are alternately arranged along the axial direction. The spool 34 has large-diameter end portions 34a, 34b at both axial ends, a central large-diameter portion 34c at the center in the axial direction, a front small-diameter portion 34d provided between the front large-diameter end portion 34a and the central large-diameter portion 34c, and a rear small-diameter portion 34e provided between the central large-diameter portion 34c and the rear large-diameter end portion 34b. The large-diameter end portions 34a, 34b and the central large-diameter portion 34c have, for example, the same diameter. The front small-diameter portion 34d and the rear small-diameter portion 34e have, for example, the same diameter.

[0024] The housing 35 is a cylindrical housing with a valve hole 350 (space) formed therein. The spool 34 slides laterally within the valve hole 350. As shown in FIG. 4( a), the valve hole 350 is configured so that, from front to rear, a first small-diameter space 351, a second large-diameter space 352, a third small-diameter space 353, a fourth large-diameter space 354, a fifth small-diameter space 355, a sixth large-diameter space 356, and a seventh small-diameter space 357 are continuous. The first space 351, the third space 353, the fifth space 355, and the seventh space 357 have the same diameter. The second space 352, the fourth space 354, and the sixth space 356 have the same diameter.

[0025] 1, the housing 35 is formed with a tank connection port 358 that connects the second space 352 and the hydraulic oil storage tank 40 to each other, a cylinder connection port 359 that connects the fourth space 354 and the rod-side hydraulic chamber 11a to each other, and a hydraulic connection port 360 that connects the sixth space 356 and the hydraulic pressure supply device 45 to each other. As is clear from the fact that the tank connection port 358, the cylinder connection port 359, and the hydraulic connection port 360 are shown in the cross-sectional view of FIG. 1 but not in the cross-sectional view of FIG. 4(a), they are formed only in a partial region in the circumferential direction of the housing 35.

[0026] The sleeve 36 is fixed within the valve hole 350 and is configured to slidably support the spool 34. The sleeve 36 is provided so as to surround the outer periphery of the spool 34. Details of the sleeve 36 will be described later.

[0027] The hydraulic oil storage tank 40 is a tank that stores hydraulic oil and is connected to the valve hole 350 via a tank connection port 358. The tank connection port 358 is constantly filled with hydraulic oil. The hydraulic supply device 45 is connected to the valve hole 350 via a hydraulic connection port 360 and is a device that supplies hydraulic oil at a predetermined pressure and flow rate. When the piston 12 retracts, the hydraulic supply device 45 supplies hydraulic oil for the retreat stroke. The hydraulic supply device 45 may be configured by a pump, a variable pressure control valve, a variable flow rate control valve, an electric motor, or the like.

[0028] The controller 70 is a device that controls at least some of the elements included in the die-casting machine 1. The controller 70 is configured by one computer or multiple computers. A display device 80 may be connected to the controller 70. The display device 80 is a device for outputting (displaying) the results calculated by the controller 70 to an operator of the die-casting machine 1. The display device 80 may be any device that is capable of displaying information, and is, for example, a liquid crystal display.

[0029] (Spool operation) 1, the fourth space 354, which is connected to the cylinder connecting port 359, is blocked by the central large diameter portion 34c of the spool 34. More specifically, the third space 353 and the fifth space 355 are both blocked from the fourth space 354. This position of the spool 34 is the zero point position, origin, or all-port closed position of the spool 34.

[0030] 2 (the position where the piston 12 is advanced), the spool 34 has moved rearward (to the right in the figure) compared to the zero-point position. In this state, the central large-diameter portion 34c of the spool 34 is located rearward of the fourth space 354, so the cylinder connection port 359 and the tank connection port 358 are in communication with each other via the fourth space 354, the third space 353, and the second space 352. This allows the hydraulic oil in the rod-side hydraulic chamber 11a of the injection unit 10 to flow (return) to the hydraulic oil storage tank 40.

[0031] 3 (the position where the piston 12 is retracted), the spool 34 has moved forward (to the left in the figure) compared to the zero point position. In this state, the central large diameter portion 34c of the spool 34 is located forward of the fourth space 354, so the cylinder connection port 359 and the hydraulic connection port 360 communicate with each other via the fourth space 354, the fifth space 355, and the sixth space 356. This allows hydraulic oil to flow (be supplied) to the rod-side hydraulic chamber 11a of the injection section 10 in accordance with the pressure from the hydraulic supply device 45.

[0032] (Sleeve details) Fig. 4(a) is a cross-sectional view showing a housing 35 included in the speed control valve 30, Fig. 4(b) is a view showing a sleeve 36 included in the speed control valve 30, and Fig. 4(c) is a view showing the speed control valve 30 in which the sleeve 36 is assembled to the housing 35. As shown in Fig. 4(b), the sleeve 36 has inner sleeves 361 and 362 (contact portions) and a frame 363 (outer periphery). The inner sleeve 361, the inner sleeve 362, and the frame 363 are separate bodies.

[0033] The internal sleeves 361, 362 are portions that come into contact with the spool 34 when the spool 34 slides (moves laterally). The internal sleeves 361, 362 come into contact with the spool 34 at contact surfaces 361x, 362x provided on the inner periphery thereof, respectively. The internal sleeves 361, 362 come into contact with the spool 34 at least at some position when the spool 34 slides.

[0034] The inner sleeve 361 is a cylindrical portion, and one or more holes are formed circumferentially at predetermined axial positions. In the cross-sectional view shown in Fig. 4(b), four lands 3611, 3612, 3613, and 3614 are shown from front to rear, with a hole 3615 formed between the lands 3611 and 3612, a hole 3616 between the lands 3612 and 3613, and a hole 3617 between the lands 3613 and 3614. These holes 3615, 3616, and 3617 are portions through which hydraulic oil passes.

[0035] One axial end or both ends of the contact surface 361x of the land portions 3611, 3612, 3613, and 3614 are tapered. Specifically, a tapered portion 3611a is formed on one axial end (here, the rear end) of the land portion 3611, which tapers radially outward (becomes thinner) as it approaches the rear end. Tapered portions 3612a, 3612a are formed on both axial ends of the land portion 3612, which taper radially outward (becomes thinner) as it approaches the end (front end or rear end). A tapered portion 3613a is formed on one axial end (here, the front end) of the land portion 3613, which tapers radially outward (becomes thinner) as it approaches the front end. A tapered portion 3614a that tapers radially outward (becomes thinner) as it approaches the front end is formed on one axial end side (here, the front end side) of the land portion 3614. By forming such a tapered shape, it is possible to smoothly guide the spool 34 when it starts to come into contact with the spool 34.

[0036] The inner sleeve 362 is a portion provided forward of the inner sleeve 361. A tapered portion 362a is formed on one axial end side (here, the rear end side) of the contact surface 362x of the inner sleeve 362, which tapers radially outward (becomes thinner) as it approaches the rear end.

[0037] The frame 363 is a cylindrical portion provided to surround the periphery of the inner sleeves 361, 362. The frame 363 has, from the front to the rear, a first portion 3631, a second portion 3632, a third portion 3633, a fourth portion 3634, a fifth portion 3635, a sixth portion 3636, and a seventh portion 3637. As shown in FIG. 4(c), the second portion 3632, the fourth portion 3634, and the sixth portion 3636 have one or more holes formed in the circumferential direction.

[0038] As shown in Figure 4(c), the first part 3631 is arranged to surround the periphery of the internal sleeve 362, the third part 3633 is arranged to surround the periphery of the land portion 3611 of the internal sleeve 361, the fifth part 3635 is arranged to surround the periphery of the land portion 3613 of the internal sleeve 361, and the seventh part 3637 is arranged to surround the periphery of the land portion 3614 of the internal sleeve 361.

[0039] As shown in FIG. 1 , the tapered shapes of the internal sleeves 361, 362 are provided at locations that can be contact initiation positions with the large diameter portion of the spool 34. That is, the rear end of the internal sleeve 362 can be contact initiation positions with the end large diameter portion 34a of the advancing spool 34, so a tapered portion 362a is formed at the rear end. Similarly, the land portion 3611 of the internal sleeve 361 can be contact initiation positions with the central large diameter portion 34c of the advancing spool 34, so a tapered portion 3611a is formed at the rear end. Similarly, the land portion 3612 of the internal sleeve 361 can be contact initiation positions with the central large diameter portion 34c of the retracting spool 34, and the rear end can be contact initiation positions with the central large diameter portion 34c of the advancing spool 34, so tapered portions 3612a are formed at the front and rear ends. Similarly, a tapered portion 3613a is formed at the front end of the land portion 3613 of the internal sleeve 361 because the front end can be the position where contact with the central large diameter portion 34c of the rearwardly approaching spool 34 begins. Similarly, a tapered portion 3614a is formed at the front end of the land portion 3614 of the internal sleeve 361 because the front end can be the position where contact with the end large diameter portion 34b of the rearwardly approaching spool 34 begins.

[0040] The housing 35 is made of ordinary cast iron (FCD400, etc.). Since the housing 35 does not have any sliding parts with other components, it only needs to be strong enough to hold the oil passages and other components, and wear resistance is not necessary. Furthermore, since the housing 35 is relatively large compared to the other components in the speed control valve 30 of the present application, an inexpensive material is preferred.

[0041] The frame 363 is made of steel (SS400, S45C, etc.). Like the housing 35, there are no sliding parts, but steel is used because it needs to be strong enough to hold the internal sleeves 361 and 362 and to withstand hydraulic pressure. Since the frame 363 is also a relatively large part, it is preferable to use inexpensive general steel.

[0042] The materials for the inner sleeves 361, 362 and the spool 34 are preferably nitride materials such as SCM and SACM, or hot work tool steel such as SKD61. Because the oil passage is opened and closed by the sliding of the spool 34 relative to the inner sleeves 361, 362, the clearance between the inner sleeves 361, 362 and the spool 34 is narrow, and a large force acts as a result of the sliding. Therefore, a material with high hardness is used.

[0043] As described above, in this sleeve configuration, the material of the inner sleeves 361, 362 is harder than the material of the frame 363. This difference in configuration is due to the fact that the inner sleeves 361, 362 are required to be wear-resistant and resistant to erosion, while the frame 363 is not required to have such functions and its main function is to support the spool 34 and guide it between the spool 34 and the housing 35 (manifold). Specifically, the material of the inner sleeves 361, 362 may be a nitride material such as SCM or SACM, or a hot work tool steel such as SKD61. As described above, the material of the frame 363 may be general steel such as SS400 or S45C. In this way, the use of the right material for the right purpose (multi-material) enables convenience and additional functions. The use of general steel improves availability and delivery time. The inner sleeves 361, 362 can be designed so that only the portions that come into contact with the spool 34 are as small as possible, thereby improving the flexibility of processing and the heat treatment properties (the smaller the portion, the easier it is for heat to enter).

[0044] Next, the operation and effect of the speed control valve for the die casting machine and the die casting machine according to this embodiment will be described.

[0045] The speed control valve 30 according to this embodiment is a speed control valve for a die-casting machine that controls the injection speed of molten metal, and includes a housing 35 having a valve hole 350 formed therein, a spool 34 that slides within the valve hole 350, and a sleeve 36 that is fixed within the valve hole 350 and slidably supports the spool 34. The sleeve 36 has inner sleeves 361, 362 that contact the spool 34 at least at some position when the spool 34 slides, and a frame 363 that is provided to surround the inner sleeves 361, 362. The inner sleeves 361, 362 and the frame 363 are separate bodies, and the material of the inner sleeves 361, 362 is harder than the material of the frame 363.

[0046] The sliding surface of the sleeve against the spool requires wear resistance and durability. Meanwhile, there is no particular need for high wear resistance in the sleeve other than the sliding surface of the spool. However, conventionally, parts other than the sliding surface of the spool have been constructed of expensive materials, such as nitrided materials and hot-work tool steel, which are advantageous for improving wear resistance. The sleeves of Gigacast machines have sometimes undergone special heat treatment to further improve wear resistance. The inventors focused on this point and came up with a configuration in which only the hardness of the material of the inner sleeves 361, 362 that contact the spool 34 is increased. That is, in the speed control valve 30 according to this embodiment, the sleeve 36 is constructed with separate parts that contact the spool 34 and those that do not, and only the part that contacts the spool 34 has high hardness. With this configuration, only the parts that require high wear resistance, which increases costs, require high hardness, thereby improving wear resistance while reducing costs.

[0047] Furthermore, since the sleeve 36 is configured as a separate component as described above, a clearance is created between the inner sleeves 361, 362 and the frame 363, and when the spool 34 deforms due to temperature variations or the like, the clearance allows the sleeve to deform to some extent, thereby reducing the sliding resistance of the spool 34. Furthermore, since the sleeve 36 is configured as a separate component as described above, the processability of the inside of the sleeve is improved, and it becomes possible to process it according to required characteristics.

[0048] Furthermore, if the sleeve is an integrated type, when wear progresses, even if only a small portion is worn, it is necessary to replace the entire sleeve, which weighs nearly 100 kg, which poses problems in terms of cost and workability. In this regard, by configuring the sleeve 36 as a separate unit as described above, it becomes possible to replace only the worn portion (internal sleeves 361, 362), which is advantageous in terms of cost and workability compared to the conventional integrated configuration.

[0049] Furthermore, prototyping large valve parts is generally time-consuming and can make it difficult to increase the variety of prototypes. However, by configuring the sleeve 36 as a separate component as described above, the part becomes smaller, making prototyping easier and allowing for an increase in the number of prototypes.

[0050] Furthermore, when the sleeve is an integrated type, it is difficult to perform complex internal processing, and the design often results in a simple, large internal space. In this regard, by configuring the sleeve 36 as a separate component as described above, it becomes possible to miniaturize the component and increase the number of processing methods, thereby enabling the creation of a more complex (highly functional) shape.

[0051] Furthermore, if the sleeve is an integrated unit, the loss would be significant if the sleeve had to be discarded during production due to a processing error or careless damage. In this regard, by configuring the sleeve 36 as a separate unit as described above, the component can be made smaller, and the loss due to a processing error or the like can be limited.

[0052] In the speed control valve 30 of the die-casting machine 1 described above, the inner sleeves 361, 362 contact the spool 34 at contact surfaces 361x, 362x provided on the inner periphery, and one or both axial ends of the contact surfaces 361x, 362x may be tapered. When the sleeve supports the spool at multiple sliding surfaces, some of the sliding surfaces may separate from the spool due to the opening and closing of the valve. When the separated sliding surfaces and the spool subsequently come into contact with each other again, the tapered ends of the contact surfaces 361x, 362x allow the tapered shape to appropriately guide the spool 34 at the time of re-contact, thereby enabling the spool 34 to be driven effectively.

[0053] The die-casting machine 1 according to this embodiment includes a hydraulic drive unit 20 and an injection unit 10 connected to the hydraulic drive unit 20. The injection unit 10 has a cylinder 11 and a piston 12 that divides the interior of the cylinder 11 into two chambers, one of which (head-side hydraulic chamber 11b) is connected to the hydraulic drive unit 20, and the other of which (rod-side hydraulic chamber 11a) is connected to the speed control valve 30. This configuration makes it possible to provide a die-casting machine that can more significantly exhibit the effects of the speed control valve 30. [Explanation of symbols]

[0054] 1...die casting machine, 10...injection section (injection means), 11...cylinder, 11a...rod side hydraulic chamber (the other of the two chambers), 11b...head side hydraulic chamber (one of the two chambers), 12...piston, 30...speed control valve, 34...spool, 35...housing, 36...sleeve, 40...hydraulic oil storage tank (hydraulic source), 350...valve hole, 361, 362...inner sleeve (contact section), 361x, 362x...contact surface, 363...frame (outer periphery).

Claims

1. A speed control valve for a die casting machine that controls the injection speed of molten metal, a housing having a valve hole formed therein; a spool that slides within the valve hole; a sleeve fixed within the valve bore and slidably supporting the spool, the sleeve has a contact portion that contacts the spool at least at a position when the spool slides, and an outer circumferential portion that surrounds the contact portion, the contact portion and the outer circumferential portion are separate from each other, The material of the contact portion is harder than the material of the outer circumferential portion. A speed control valve for a die casting machine.

2. 2. The speed control valve for a die casting machine according to claim 1, The contact portion contacts the spool at a contact surface provided on an inner circumferential side thereof, One or both axial ends of the contact surface are tapered. A speed control valve for a die casting machine.

3. A hydraulic source; an injection means connected to the hydraulic power source, the injection means has a cylinder and a piston that divides the interior of the cylinder into two chambers, One of the two partitioned chambers is connected to the hydraulic pressure source, The other of the two partitioned chambers is connected to the speed control valve according to claim 1 or 2. The die casting machine is characterized by:

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