Die casting machine and sleeve lubrication method

Abstract

To provide a die casting machine capable of appropriately applying a lubricant to an inner surface of a sleeve, and to provide a sleeve lubrication method.SOLUTION: A die casting machine includes a sleeve 33, a plunger 15, a lubrication device 200, and a control device. The plunger 15 includes a plunger chip 17 disposed within the sleeve 33 and a rod 16 disposed behind the plunger chip 17. The rod 16 has an outlet hole for discharging a lubricant. The control device controls the lubrication device 200 to discharge the lubricant from the outlet hole into the sleeve 33 when the plunger 15 is retracting, and to stop the discharge of the lubricant when the plunger 15 reaches the discharge stop position.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a die casting machine and a method for lubricating a sleeve. [Background technology]

[0002] Patent Document 1 discloses an example of a conventional die casting machine. This die casting machine has a sleeve and a plunger. The plunger has a plunger tip disposed in the sleeve and a rod disposed behind the plunger tip. The rod is provided with two flow paths having a double-tube structure extending in the axial direction. The inner flow path of the two flow paths is supplied with lubricating liquid, and the outer flow path is supplied with air. The lubricating liquid becomes mist at the outlet end of the inner flow path, and the mist lubricating liquid is discharged into the sleeve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-279645 A Summary of the Invention [Problem to be solved by the invention]

[0004] A conventional die casting machine has an injection mechanism that moves a plunger and a control device that controls the injection mechanism. The control device outputs a signal related to the operation of the injection mechanism, and a lubrication device that discharges lubricating liquid into a sleeve operates based on the signal. Specifically, the lubrication device starts discharging lubricating liquid when a predetermined discharge waiting time has elapsed since receiving a signal indicating the start of retraction of the plunger, continues discharging lubricating liquid for a predetermined discharge duration, and stops discharging lubricating liquid when the discharge duration has elapsed.

[0005] A common power source such as a hydraulic device is used for other drive mechanisms such as the injection mechanism of the die casting machine and the ejection mechanism that pushes the molded product out of the die. If the other drive mechanisms operate while the plunger is retracted by the injection mechanism, some or all of the power may be used by the other drive mechanisms, and the retraction speed of the plunger may temporarily decrease or the plunger may temporarily stop. This may cause unevenness in the lubricating liquid applied to the inner surface of the sleeve, or the lubricating liquid may not be applied to the desired location. In addition, if the discharge waiting time and discharge duration are set assuming a decrease in the retraction speed of the plunger or a stop, and the operating conditions of the other drive mechanisms change and the plunger does not move as expected, the lubricating liquid may leak out of the sleeve.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a die casting machine and a method for lubricating a sleeve, which are capable of appropriately applying a lubricating liquid to the inner surface of the sleeve. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the die-casting machine of the present invention is a die-casting machine having a sleeve to which molten metal is supplied, a plunger for injecting the molten metal in the sleeve, a lubrication device for discharging lubricating liquid into the sleeve, and a control device for controlling the lubrication device, wherein the plunger has a plunger tip arranged in the sleeve and a rod arranged behind the plunger tip, the rod has a discharge hole for discharging the lubricating liquid, and the control device controls the lubrication device to discharge the lubricating liquid from the discharge hole into the sleeve when the plunger is retracting, and stops the discharge of the lubricating liquid when the plunger reaches a discharge stop position. Effect of the Invention

[0008] According to the present invention, when the plunger retracts within the sleeve, the lubricating liquid is discharged into the sleeve from the discharge hole of the plunger rod, and the discharge of the lubricating liquid stops when the plunger reaches the discharge stop position. As a result, compared to a configuration in which the timing of the discharge of the lubricating liquid is controlled by the discharge waiting time or the discharge duration time, the discharge of the lubricating liquid can be stopped at an appropriate position even when the plunger does not move as expected. Therefore, it is possible to prevent the lubricating liquid from leaking outside the sleeve, and the lubricating liquid can be appropriately applied to the inner surface of the sleeve. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a die casting machine according to an embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view of a plunger included in the die casting machine of FIG. 1. [Diagram 3] 3 is a cross-sectional view of the front end of a rod of the plunger in FIG. 2 and its vicinity. [Figure 4] 2 is a cross-sectional view of a die plate and its vicinity in the die casting machine of FIG. 1. [Diagram 5] FIG. 2 is an enlarged cross-sectional view of a mold cavity and its vicinity. [Figure 6] FIG. 2 is an enlarged cross-sectional view of the cavity of the mold and its vicinity (with the plunger in a high-speed forward movement start position). [Figure 7] FIG. 2 is an enlarged cross-sectional view of a cavity of a mold and its vicinity (when the plunger is at the deceleration start position). [Figure 8] FIG. 2 is an enlarged cross-sectional view of a cavity of a mold and its vicinity (when the plunger is at the pressure boosting start position). [Figure 9] 4 is a flowchart (cleaning process) showing an example of a process executed by a control device of the die casting machine of FIG. 1 in a molding mode. [Figure 10] 4 is a flowchart showing an example of a process (lubricant supply process) executed by a control device of the die casting machine of FIG. 1 in a molding mode. [Figure 11]1 is an example of a graph showing pressure applied to a plunger and velocity of the plunger. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a die casting machine according to one embodiment of the present invention will be described with reference to FIGS.

[0011] FIG. 1 is a diagram showing a schematic configuration of a die casting machine according to an embodiment of the present invention. FIG. 1 shows an injection mechanism and a control device of the die casting machine. FIG. 2 is a cross-sectional view of a plunger included in the die casting machine of FIG. 1. In FIG. 2, the connection relationship between the plunger, the sleeve, the lubricating liquid supply device, the gas supply device, and the connection switching device is shown typically. FIG. 3 is a cross-sectional view of the front end of the rod included in the plunger of FIG. 2 and its vicinity. FIG. 4 is a cross-sectional view of the die plate included in the die casting machine of FIG. 1 and its vicinity. FIG. 5 is an enlarged cross-sectional view of the cavity of the die and its vicinity. FIGS. 6 to 8 are enlarged cross-sectional views of the cavity of the die and its vicinity, showing the states in which the plunger is in the high-speed forward movement start position, the deceleration start position, and the pressure increase start position, respectively. FIGS. 9 and 10 are flow charts showing an example of a process executed in a molding mode by a control device included in the die casting machine of FIG. 1. FIG. 9 shows an example of a cleaning process, and FIG. 10 shows an example of a lubricating liquid supply process. FIG. 11 is an example of a graph showing the pressure applied to the plunger and the speed of the plunger. In this specification, the left side in Figs. 1 to 8 is the front, and the right side is the rear.

[0012] The die casting machine 1 according to this embodiment includes an injection mechanism 10, a mold clamping mechanism 30, a molten metal supplying device 50, a lubricating liquid supplying device 60, a gas supplying device 70, a connection switching device 80, and a control device 100. The lubricating liquid supplying device 60, the gas supplying device 70, and the connection switching device 80 constitute a lubrication device 200.

[0013] As shown in Figs. 1 to 3, the injection mechanism 10 has a hydraulically operated piston 11, a cylinder 12 that houses the piston 11, and a plunger 15. The cylinder 12 has a rear oil chamber 13 and a front oil chamber 14 that are partitioned by the piston 11. The plunger 15 is connected to the piston 11. The plunger 15 has a rod 16 that extends forward from a front surface 11a of the piston 11, and a plunger tip 17 that is connected to the front end of the rod 16. The plunger tip 17 has a cylindrical shape.

[0014] The rod 16 is disposed behind the plunger tip 17. The rod 16 has a rod body 161, a ring 162, and a joint 163. The rod body 161, the ring 162, and the joint 163 are disposed in this order from the rear to the front.

[0015] The rod body 161 has a cylindrical shape. The rod body 161 has a main passage 164, a liquid inlet passage 166, and a gas inlet passage 167. The main passage 164 extends linearly from the front end of the rod body 161 to the rear. The liquid inlet passage 166 communicates with the outer circumferential surface 161a of the rod body 161 from the main passage 164. One end of the liquid inlet passage 166 is connected to the vicinity of the rear end of the main passage 164, and the other end opens to the outer circumferential surface 161a. The gas inlet passage 167 communicates with the outer circumferential surface 161a from the rear end of the main passage 164. One end of the gas inlet passage 167 is connected to the rear end of the main passage 164, and the other end opens to the outer circumferential surface 161a. The portion of the main passage 164 to which the gas inlet passage 167 is connected is disposed rearward of the portion of the main passage 164 to which the liquid inlet passage 166 is connected. The gas inlet passage 167 is located rearward of the liquid inlet passage 166 .

[0016] The ring 162 has a cylindrical shape. The outer diameter of the ring 162 is the same as the outer diameter of the rod body 161. The ring 162 has a plurality of fine holes 162e penetrating in the radial direction. The plurality of fine holes 162e are arranged at equal intervals in the circumferential direction. The ring 162 has, for example, eight fine holes 162e arranged at 45 degree intervals. The fine holes 162e are discharge holes for discharging the lubricating liquid.

[0017] The joint 163 has a first portion 163a and a second portion 163b that are integrally formed.

[0018] The first portion 163a has a cylindrical shape. The outer diameter of the first portion 163a is the same as the outer diameter of the rod body 161. The first portion 163a is coaxially connected to the rear end of the plunger tip 17.

[0019] The second portion 163b has a cylindrical shape with a smaller diameter than the first portion 163a. ​​The second portion 163b is coaxially connected to the rear end of the first portion 163a. ​​The second portion 163b is coaxially connected to the front end of the rod body 161. The outer diameter of the second portion 163b is the same as the inner diameter of the ring 162. The axial length of the second portion 163b is the same as the axial length of the ring 162. The second portion 163b is fitted into the ring 162. The outer peripheral surface of the second portion 163b is formed with a connecting groove 163c extending in the axial direction and an annular groove 163d extending in the circumferential direction. The front end of the connecting groove 163c is connected to the annular groove 163d, and the rear end is connected to the main passage 164. The annular groove 163d is connected to a plurality of fine holes 162e.

[0020] The connecting groove 163c, the annular groove 163d, and the plurality of fine holes 162e constitute an outlet passage 165. The outlet passage 165 communicates with the front end of the main passage 164 and the outer circumferential surface 162a of the ring 162.

[0021] The rod 16 has a check valve 168. The check valve 168 is a spring-loaded check valve. The check valve 168 is disposed on the outer circumferential surface 161a of the rod body 161, and is connected to the liquid inlet passage 166. The first pipe 81 is connected to the check valve 168. The check valve 168 allows the flow of fluid from the first pipe 81 to the liquid inlet passage 166, and regulates the flow of fluid from the liquid inlet passage 166 to the first pipe 81. The second pipe 82 is connected to the gas inlet passage 167. The first pipe 81 and the second pipe 82 are, for example, flexible hoses.

[0022] A drive transmission plate 18 is disposed behind the cylinder 12. The drive transmission plate 18 is moved in the front-rear direction by an electric servo motor 19 and a drive transmission mechanism 20 including a drive transmission gear and a ball screw mechanism. When the drive transmission plate 18 is moved forward, the cylinder 12 is pushed and moves forward. The drive transmission plate 18, the electric servo motor 19 and the drive transmission mechanism 20 constitute an electric booster mechanism. Note that instead of such an electric booster mechanism, a hydraulic booster mechanism may be provided that hydraulically pushes the cylinder 12 forward.

[0023] The injection mechanism 10 has an accumulator 21. The accumulator 21 is a hydraulic supply unit that supplies hydraulic oil to the cylinder 12. The accumulator 21 and the rear oil chamber 13 are connected by an oil passage a. A supply valve 22 is disposed in the oil passage a. The supply valve 22 connects and disconnects the accumulator 21 and the rear oil chamber 13. In this embodiment, the supply valve 22 is configured as an electromagnetic valve that drives a valve body by a solenoid. As the supply valve 22, other types of valves, such as one that drives a valve body by a motor, may be used in addition to the electromagnetic valve.

[0024] The front oil chamber 14 of the cylinder 12 and the tank 23 that stores hydraulic oil are connected by an oil passage b. A servo valve 24 is disposed in the oil passage b. The servo valve 24 adjusts the outflow amount of hydraulic oil flowing from the front oil chamber 14 to the tank 23. In this embodiment, the servo valve 24 adjusts the outflow amount (i.e., the amount of hydraulic oil discharged from the front oil chamber 14) to control the forward speed of the plunger 15 (meter-out control). The above-mentioned supply valve 22 may be configured with a servo valve, and the forward speed of the plunger 15 may be controlled by adjusting the amount of hydraulic oil supplied from the accumulator 21 to the rear oil chamber 13 (meter-in control). Hydraulic oil is supplied from the accumulator 21 to the front oil chamber 14 through an oil passage not shown, and hydraulic oil is discharged from the rear oil chamber 13 to the tank 23 through an oil passage not shown, to move the plunger 15 backward. When the plunger 15 is retracted, the hydraulic oil may be supplied to the front oil chamber 14 by using an electric pump instead of the accumulator 21.

[0025] The injection mechanism 10 has an oil pressure sensor 25 that outputs a signal corresponding to the oil pressure Pf in the front oil chamber 14 of the cylinder 12, a position sensor 26 that outputs a signal corresponding to the position L of the plunger 15, and an oil pressure sensor 27 that outputs a signal corresponding to the oil pressure Pb in the rear oil chamber 13 of the cylinder 12. The position sensor 26 can be a known position sensor such as an optical type, a magnetic type, or a magnetostrictive type.

[0026] As shown in Fig. 4, the clamping mechanism 30 has a fixed die plate 31 to which the fixed side die K1 is attached, and a movable die plate 32 to which the movable side die K2 is attached. The fixed die plate 31 has a cylindrical sleeve 33 that is connected to a runner R of the fixed side die K1. The plunger 15 (plunger tip 17) is accommodated in the sleeve 33 so that it can move forward and backward. A supply port 34 is formed in the upper part of the sleeve 33. A cleaning pipe 83 is connected to the sleeve 33. The clamping mechanism 30 moves the movable die plate 32 forward and backward relative to the fixed die plate 31 by a clamping drive unit (not shown), thereby opening and closing (clamping) the fixed side die K1 and the movable side die K2.

[0027] The molten metal supplying device 50 has a ladle 51 and an arm 52. The molten metal supplying device 50 draws up the molten metal M from a melting furnace (not shown), and supplies the molten metal M to the sleeve 33 through the molten metal supply port .

[0028] 5, inside the closed fixed-side mold K1 and movable-side mold K2, a runner R communicating with the sleeve 33, a cavity C communicating with the runner R, and an overflow portion O communicating with the cavity C are formed. The runner R is connected to a gate G opening in the cavity C.

[0029] The lubricating liquid supplying device 60 supplies the lubricating liquid to be applied to the inner surface of the sleeve 33. As shown in Fig. 2, the discharge port of the lubricating liquid supplying device 60 is connected to a first pipeline 81. The lubricating liquid supplying device 60 is a liquid pump that transfers the lubricating liquid. The lubricating liquid supplying device 60 transfers the lubricating liquid from a lubricating liquid storage container (not shown) to the rod 16 through the first pipeline 81.

[0030] The gas supply device 70 supplies high-pressure gas (for example, air). The discharge port of the gas supply device 70 is connected to the connection switching device 80. The gas supply device 70 is, for example, an air compressor.

[0031] The connection switching device 80 selectively connects the discharge port of the gas supply device 70 to the first pipeline 81, the second pipeline 82, and the cleaning pipeline 83. That is, the connection switching device 80 connects the discharge port of the gas supply device 70 to a selected one of the first pipeline 81, the second pipeline 82, and the cleaning pipeline 83. The connection switching device 80 is configured, for example, by combining a plurality of directional control valves.

[0032] When discharging (purging) the lubricating liquid in the first pipe 81, the liquid inlet passage 166, the main passage 164, and the outlet passage 165, the connection switching device 80 connects the outlet of the gas supply device 70 to the first pipe 81. When discharging the lubricating liquid in the main passage 164 and the outlet passage 165 into the sleeve 33, the connection switching device 80 connects the outlet of the gas supply device 70 to the second pipe 82. When cleaning the inner surface of the sleeve 33 and the plunger tip 17, the connection switching device 80 connects the outlet of the gas supply device 70 to the cleaning pipe 83.

[0033] The connection switching device 80 may selectively connect the discharge port of the gas supply device 70 to the second pipeline 82 and the cleaning pipeline 83. In this case, a gas supply device for discharging the lubricating liquid, separate from the gas supply device 70, is connected to the first pipeline 81.

[0034] The control device 100 controls the overall operation of the die casting machine 1. The control device 100 is configured to have a microcomputer for embedded devices having, for example, a CPU, a ROM, a RAM, an EEPROM, various I / O interfaces, and the like. A display device (e.g., a display device) and an input device (e.g., a keyboard, a mouse, a power switch) (not shown) are connected to the control device 100. The control device 100 controls the operations of the injection mechanism 10, the mold clamping mechanism 30, the ejection mechanism (not shown), the molten metal supply device 50, and the lubrication device 200 (the lubricating liquid supply device 60, the gas supply device 70, and the connection switching device 80). The control device 100 measures the hydraulic pressure Pf of the front oil chamber 14 based on a signal output by the hydraulic sensor 25, and measures the hydraulic pressure Pb of the rear oil chamber 13 based on a signal output by the hydraulic sensor 27. The control device 100 measures the position L and the speed V of the plunger 15 based on a signal output by the position sensor 26. The control device 100 controls the operation of various drive mechanisms in various processes such as a mold closing process, a molten metal supply process, an injection process (low-speed injection process and high-speed injection process), a pressure increase process, a mold opening process, a product extrusion process, a lubricant supply process, and a cleaning process.

[0035] In the molding mode, the die casting machine 1 performs the following operations (1) to (7) as a series of operations related to product molding.

[0036] (1) The fixed mold K1 and the movable mold K2 are clamped (mold closing process).

[0037] (2) The molten metal M is supplied to the sleeve 33 of the fixed die plate 31 (molten metal supplying step).

[0038] (3) The plunger 15 is advanced to inject the molten metal M in the sleeve 33 into the cavity C (injection process).

[0039] In the injection process, the hydraulic pressure of the hydraulic oil in the accumulator 21 is increased, the supply valve 22 is opened to supply the hydraulic oil to the rear oil chamber 13 of the cylinder 12, and the hydraulic oil is discharged from the front oil chamber 14 by the servo valve 24, so that the piston 11 is advanced from the retract limit position L0. The amount of hydraulic oil discharged is controlled by the opening of the servo valve 24, and the forward speed of the piston 11 (i.e., the forward speed of the plunger 15) is adjusted. First, the piston 11 is advanced at a low speed, and when the plunger 15 reaches a high-speed forward start position L1 (FIG. 6), the piston 11 is advanced at a high speed, and the molten metal M in the sleeve 33 is injected into the cavity C by the plunger 15. When the plunger 15 reaches a deceleration start position L2 (FIG. 7), the piston 11 is decelerated. The deceleration start position L2 is, for example, a position where the entire cavity C is filled with the molten metal M.

[0040] (4) Pressure is applied to the molten metal M in the cavity C (pressure increase process).

[0041] In the pressure increase process, when the plunger 15 reaches the pressure increase start position L3 (FIG. 8), the electric servo motor 19 is operated to advance the drive transmission plate 18 and press the cylinder 12 (i.e., the piston 11). The pressure increase start position L3 is, for example, a position where the molten metal M fills the entire cavity C and the overflow portion O. The high-speed forward movement start position L1, the deceleration start position L2 and the pressure increase start position L3 are operation switching positions.

[0042] (5) After the pressure boosting step is completed, the fixed mold K1 and the movable mold K2 are opened (mold opening step), and the plunger 15 is advanced to the injection stop position L4 (not shown) which is forward of the pressure boosting start position L3 to push the product forward, while the product is pushed out of the movable mold K2 by the ejection mechanism after the mold opening step is completed (product pushing step). After that, hydraulic oil is supplied to the front oil chamber 14, and hydraulic oil is discharged from the rear oil chamber 13 to move the plunger 15 backward to the backward limit position L0.

[0043] (6) When the plunger 15 is retracted, the lubricating liquid is supplied into the sleeve 33 (lubricating liquid supplying step).

[0044] (7) High pressure air is supplied into the sleeve 33 to clean the inner surface of the sleeve 33 and the plunger tip 17 (cleaning process).

[0045] Next, an example of the lubricating liquid supplying process and the cleaning process executed by the control device 100 in the molding mode will be described with reference to the flowchart of Fig. 9. The lubricating liquid supplying process is executed in the lubricating liquid supplying step, and the cleaning process is executed in the cleaning step.

[0046] The control device 100 waits until the plunger 15 is positioned at the retraction limit position L0 (N in S110). When the plunger 15 is positioned at the retraction limit position L0 (Y in S110), the control device 100 controls the connection switching device 80 to connect the discharge port of the gas supply device 70 to the cleaning pipe 83 (S120). The control device 100 controls the gas supply device 70 to supply high-pressure gas into the sleeve 33 through the cleaning pipe 83 (S130). As a result, gas is supplied into the sleeve 33, and the inner surface of the sleeve 33 and the plunger tip 17 are cleaned.

[0047] The control device 100 controls the lubricating liquid supplying device 60 to supply a predetermined amount of lubricating liquid to the main passage 164 (S140). In the molding mode, the lubricating liquid passage from the first pipe 81 to the check valve 168 (specifically, the first pipe 81 and the portion of the check valve 168 between the connection end of the first pipe 81 and the valve body) is filled with lubricating liquid in advance. The control device 100 controls the connection switching device 80 to connect the discharge port of the gas supplying device 70 to the second pipe 82 (S150).

[0048] The control device 100 waits until the plunger 15 starts to move backward after the injection process to the product extrusion process are completed (N in S160). When the plunger 15 starts to move backward to the backward limit position L0 (Y in S160), the control device 100 waits until the plunger 15 reaches the preset discharge start position Ls (N in S170).

[0049] When the plunger 15 reaches the discharge start position Ls (Y in S170), the control device 100 controls the gas supply device 70 to supply high-pressure gas to the main passage 164 through the second pipe 82 and the gas inlet passage 167 (S180). As a result, when the plunger 15 is retracted, the lubricating liquid in the main passage 164 is discharged (sprayed) into the sleeve 33 through the outlet passage 165 (the fine hole 162e). The control device 100 continues to supply high-pressure gas until the plunger 15 reaches a preset discharge stop position Le (N in S190). The lubricating liquid is discharged from the discharge start position Ls to the discharge stop position Le. This operation is called a "backspray operation." In the backspray operation, the control device 100 controls the gas supply device 70 to adjust the supply amount of high-pressure gas based on the retraction speed of the plunger 15, and discharges the lubricating liquid into the sleeve 33 so that the discharge amount of the lubricating liquid per unit retraction distance of the plunger 15 is uniform. For example, when the retraction speed of the plunger 15 decreases, the supply of high-pressure gas is reduced, and when the plunger 15 temporarily stops, the supply of high-pressure gas is temporarily stopped to adjust the discharge amount of the lubricating liquid. In other words, the control device 100 makes the amount of lubricating liquid applied per unit area on the inner surface of the sleeve 33 uniform. When the plunger 15 reaches the discharge stop position Le (Y in S190), the control device 100 controls the gas supply device 70 to stop the supply of high-pressure gas (S200). This stops the discharge of the lubricating liquid. Then, the control device 100 ends this process.

[0050] Steps S110 to S130 are the cleaning process, and steps S140 to S200 are the lubricating liquid supply process.

[0051] In this embodiment, for example, the distance from the retraction limit position L0 to the injection stop position L4 is set to 350 [mm], the distance from the retraction limit position L0 to the discharge start position Ls is set to 300 [mm], and the distance from the retraction limit position L0 to the discharge stop position Le is set to 100 [mm]. The lubricant is discharged between the discharge start position Ls and the discharge stop position Le. The discharge start position Ls and the discharge stop position Le are appropriately set depending on the configuration of the die casting machine 1 and the type of molded product.

[0052] The die casting machine 1 according to this embodiment includes a sleeve 33 to which the molten metal M is supplied, a plunger 15 for injecting the molten metal M in the sleeve 33, a lubrication device 200 for discharging the lubricating liquid into the sleeve 33, and a control device 100 for controlling the lubrication device 200. The plunger 15 includes a plunger tip 17 disposed in the sleeve 33 and a rod 16 disposed behind the plunger tip 17. The rod 16 includes a fine hole 162e which is a discharge hole for discharging the lubricating liquid. The control device 100 controls the lubrication device 200 to discharge the lubricating liquid from the fine hole 162e into the sleeve 33 when the plunger 15 is retracted, and stops discharging the lubricating liquid when the plunger 15 reaches the discharge stop position Le. As a result, compared to a configuration in which the discharge timing of the lubricating liquid is controlled by the discharge waiting time or the discharge duration time, it is possible to stop discharging the lubricating liquid at an appropriate position even when the plunger 15 does not move as expected. Therefore, leakage of the lubricating liquid to the outside of the sleeve 33 can be suppressed, and the lubricating liquid can be appropriately applied to the inner surface of the sleeve 33.

[0053] The control device 100 also controls the lubricating device 200 to start discharging the lubricating liquid when the plunger 15 reaches a discharge start position Ls, which is forward of the discharge stop position Le, while retracting. In this manner, the lubricating liquid can be more reliably applied to a desired area on the inner surface of the sleeve 33. The control device 100 may also control the lubricating device 200 to start discharging the lubricating liquid when a predetermined discharge waiting time has elapsed since the plunger 15 started to retract.

[0054] In addition, the control device 100 controls the lubricating device 200 to discharge the lubricating liquid so that the amount of the lubricating liquid discharged per unit retreat distance of the plunger 15 is uniform. In this way, unevenness in the lubricating liquid applied to the inner surface of the sleeve 33 can be suppressed.

[0055] Furthermore, in the die casting machine 1, the sleeve 33 may be deformed (bent) due to the heat of the molten metal M, and the deformation of the sleeve 33 may cause the plunger 15 to damage the inner surface of the sleeve 33. Such damage to the inner surface of the sleeve 33 is called "scoring." Scoring locations on the inner surface of the sleeve 33 often have higher sliding resistance than other locations. Scoring locations on the inner surface of the sleeve 33 are unique locations that have a different sliding resistance than other locations.

[0056] Fig. 11 is an example of a graph showing the pressure P applied to the plunger 15 and the speed V (forward speed) of the plunger 15 measured using a die casting machine 1 having a galling portion on the inner surface of the sleeve 33. Fig. 11 shows the pressure P and speed V measured in the injection process and the boosting process. The pressure P is based on the hydraulic pressure Pf in the front oil chamber 14 and the hydraulic pressure Pb in the rear oil chamber 13 of the cylinder 12.

[0057] As shown in FIG. 11, the pressure P and the velocity V fluctuate in a short cycle in the area surrounded by the dashed ellipse. This is presumably because the sliding resistance is different between the galled area and other areas on the inner surface of the sleeve 33, and the sliding resistance at the galled area is not constant, causing a disturbance in the force required for the forward movement of the plunger 15. If the pressure P and the velocity V fluctuate in the injection process, the quality of the molded product may vary. Note that such fluctuations in the pressure P and the velocity V also occur when the plunger 15 is retracting. The pressure P and the velocity V indicate the moving state of the plunger 15, and are measurement information related to the moving state of the plunger 15.

[0058] Therefore, whether or not there is a scuffing spot on the inner surface of the sleeve 33 is determined based on the pressure P or the speed V when the plunger 15 is moving forward (or backward), and when it is determined that there is a scuffing spot, the position of the scuffing spot is identified based on the position L of the plunger 15. Then, by applying a thick layer of lubricant to the scuffing spot, the difference in sliding resistance between the scuffing spot and other parts on the inner surface of the sleeve 33 is reduced, and fluctuations in the pressure P and the speed V can be suppressed.

[0059] That is, the control device 100 judges whether or not there is a scuffing spot on the inner surface of the sleeve 33 based on the measurement information (pressure P or speed V) related to the moving state of the plunger 15. When the control device 100 judges that there is a scuffing spot, it controls the lubrication device 200 to discharge the lubricating liquid so that the amount of lubricating liquid discharged per unit retraction distance of the plunger 15 is greater at the scuffing spot on the inner surface of the sleeve 33 and less at other places than the scuffing spot. The control device 100 may discharge the lubricating liquid only to the scuffing spot. In this way, the variation in the sliding resistance on the inner surface of the sleeve 33 is suppressed, and the quality of the molded product can be stabilized.

[0060] In a die casting machine 1 in which there is no galling portion on the inner surface of the sleeve 33 and the sliding resistance is constant over the entire surface, the fluctuations in pressure P and speed V as shown in Fig. 11 are not observed. Therefore, the control device 100 stores the pressure P measured in advance using a die casting machine 1 in which there is no galling portion on the inner surface of the sleeve 33 as a reference value in the EEPROM, and determines whether there is a galling portion by comparing the measured pressure P with the reference value. The control device 100 may use the speed V instead of the pressure P for the determination.

[0061] The control device 100 may determine whether or not there is a specific location with particularly low sliding resistance on the inner surface of the sleeve 33. When the control device 100 determines that there is a specific location with low sliding resistance, the control device 100 controls the lubrication device 200 to discharge the lubricating liquid so that the amount of lubricating liquid discharged per unit retraction distance of the plunger 15 is small at the specific location and large at locations other than the specific location.

[0062] When the control device 100 determines that there are no peculiar sliding resistance points such as scuffing points on the inner surface of the sleeve 33, it controls the lubrication device 200 to discharge lubricating fluid so that the amount of lubricating fluid discharged per unit retraction distance of the plunger 15 is uniform, or so that the amount of lubricating fluid discharged per unit retraction distance of the plunger 15 is greater when the retraction speed of the plunger 15 is high and is less when the retraction speed of the plunger 15 is low.

[0063] In the above-described embodiment, the injection operation is performed hydraulically and the pressure boosting operation is performed electrically. However, the present invention may also be applied to a configuration in which the injection operation and the pressure boosting operation are performed hydraulically, or a configuration in which the injection operation and the pressure boosting operation are performed electrically.

[0064] Although the embodiments of the present invention have been described above, the present invention is not limited to these examples. Any addition, deletion, or design change of components by a person skilled in the art to the above-mentioned embodiments, or any combination of features of the embodiments, is also included in the scope of the present invention as long as it does not deviate from the spirit of the present invention. [Explanation of symbols]

[0065] 1...Die casting machine, 10...Injection mechanism, 11...Piston, 11a...Front, 12...Cylinder, 13...Rear oil chamber, 14...Front oil chamber, 15...Plunger, 16...Rod, 17...Plunger tip, 161...Rod body, 161a...Outer surface, 162...Ring, 162a...Outer surface, 162e...Slim hole, 163...Joint, 163a...First part, 163b...Second part, 163c...Connecting groove, 163d...Annular groove, 164...Main passage, 165...Outlet passage, 166...Liquid inlet passage, 167...Gas inlet passage, 168...Check valve, 18...Drive transmission plate, 19...Electric servo motor, 20...Drive transmission mechanism, 21...Accumulator, 22...Supply valve, 23...Tank, 24...Servo valve, 25... hydraulic sensor, 26... position sensor, 27... hydraulic sensor, 30... mold clamping mechanism, 31... fixed die plate, 32... movable die plate, K1... fixed side die, K2... movable side die, 33... sleeve, 34... feed port, 50... molten metal supply device, 51... ladle, 52... arm, 60... lubricating liquid supply device, 70... gas supply device, 80... connection switching device, 200... lubrication device, 81... first pipeline, 82... second pipeline, 83... cleaning pipeline, 100... control device, C... cavity, G... gate, R... runner, O... overflow section, M... molten metal, L0... backward limit position, L1... high speed forward start position, L2... deceleration start position, L3... pressure increase start position, L4... injection stop position, Ls... discharge start position, Le... discharge stop position,

Claims

1. A die casting machine comprising: a sleeve to which molten metal is supplied; a plunger for injecting the molten metal in the sleeve; a lubrication device for discharging a lubricating liquid into the sleeve; and a control device for controlling the lubrication device, the plunger having a plunger tip disposed within the sleeve and a rod disposed rearward of the plunger tip; the rod has a discharge hole for discharging the lubricating liquid, The control device controls the lubrication device to discharge the lubricating liquid from the discharge hole into the sleeve when the plunger is retracted, and stops discharging the lubricating liquid when the plunger reaches a discharge stop position.

2. 2. The die casting machine according to claim 1, wherein the control device controls the lubrication device to start discharging the lubricating liquid when the plunger reaches a discharge start position forward of the discharge stop position while retracting.

3. 3. The die casting machine according to claim 1, wherein the control device controls the lubricating device to discharge the lubricating liquid so that an amount of the lubricating liquid discharged per unit retraction distance of the plunger is uniform.

4. The control device, determining whether or not there is a singular location of sliding resistance on the inner surface of the sleeve based on measurement information relating to the moving state of the plunger; A die casting machine as described in claim 1 or claim 2, wherein when it is determined that the unique spot exists, the lubrication device is controlled to discharge the lubricating liquid so that the amount of the lubricating liquid discharged per unit retreat distance of the plunger is different between the unique spot on the inner surface of the sleeve and a spot other than the unique spot.

5. A method for lubricating a sleeve used in a die casting machine having a sleeve to which molten metal is supplied and a plunger for injecting the molten metal in the sleeve, comprising the steps of: the plunger having a plunger tip disposed within the sleeve and a rod disposed rearward of the plunger tip; The rod has a discharge hole for discharging the lubricating liquid, A method for lubricating a sleeve, comprising discharging the lubricating liquid from the discharge hole into the sleeve while the plunger is retracting, and stopping the discharge of the lubricating liquid when the plunger reaches a discharge stop position.

Images