JP2018015773A - Plunger tip structure of die cast machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively cool a molten metal adjacent to a front surface of a plunger tip.SOLUTION: A plunger tip structure of a die cast machine comprises: a plunger tip body 12 disposed at a front end of a plunger of the die cast machine M; cooling holes 13 formed in the plunger tip body 12, and defining channels in which coolants flow; coolant discharging tubes 23 inserted into the respective cooling holes 13; a salient part 14 arranged at a front end of the plunger tip body 12; and cooling hole expanded parts 15 formed in the salient part 14 by expanding the cooling holes 13. The cooling holes 13 are formed to linearly extend in an axial direction of the plunger tip body 12, as well as in parallel to each other. The cooling hole expanded parts 15 are formed by extending the respective cooling holes 13 forward.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a plunger tip structure of a die casting machine.

  In die casting, a plunger tip that pushes molten metal into a cavity is generally used. A coolant such as cooling water or cooling oil circulates inside the plunger tip. The refrigerant exchanges heat with the molten metal via the plunger tip. The molten metal cooled by heat exchange is solidified.

JP-A-9-103864 Japanese Utility Model Publication No. 6-41953 JP 2006-212696 A Japanese Utility Model Publication No. 6-29757

  A disc-shaped cast member called a relatively thick biscuit is formed at a front portion adjacent to the front surface of the plunger tip. It is important to reduce the cycle time that the biscuit is cooled and solidified as soon as possible.

  Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide a plunger tip structure of a die casting machine that can effectively cool a molten metal adjacent to the front surface of the plunger tip.

According to one aspect of the invention,
A hollow cylindrical plunger tip body provided at the plunger front end of the die casting machine;
A cooling hole that is formed inside the plunger tip body and defines a flow path through which the coolant flows;
A refrigerant discharge pipe inserted into the cooling hole;
A convex portion provided at the front end of the plunger tip body;
A cooling hole enlarged portion formed by enlarging the cooling hole in the convex portion;
The cooling holes are provided to extend linearly in the axial direction of the plunger tip body, and are provided in parallel.
The cooling hole expanding portion is formed by extending the cooling hole in a front end direction. A plunger tip structure of a die casting machine is provided.

  According to the present invention, the molten metal adjacent to the front surface of the plunger tip can be effectively cooled.

It is a schematic vertical side view which shows a die-casting machine. It is a vertical side view of a plunger tip. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. It is a vertical side view of the plunger tip which concerns on a modification. FIG. 5 is a cross-sectional view taken along line B-B in FIG. 4.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic longitudinal sectional side view showing a die casting machine to which a plunger tip according to this embodiment is applied. The die casting machine M of the present embodiment is a horizontal injection type, and its front, rear, left, right, and upper directions are as illustrated. One end side (right side in the figure) of the horizontal central axis C of the plunger tip 1 is the front side, and the other end side (left side in the figure) is the rear side. It should be noted that these directions are merely defined for convenience of explanation. The die casting machine M of this embodiment is used for die casting a product that is a vehicle part such as a clutch housing or a transmission case. However, the type of product is arbitrary. The present invention can also be applied to a vertical injection type die casting machine.

  In the figure, reference numeral 2 indicates a fixed mold, and reference numeral 3 indicates a movable mold that can move back and forth with respect to the fixed mold 2 or can move close to and away from it. The fixed mold 2 is fixed to a fixed platen 4 of the die casting machine M, and the movable mold 3 is fixed to a movable platen (not shown) of the die casting machine M. In addition, a diverter 8 is fixed to the movable mold 3.

  The fixed die 2 includes a cylindrical diverter bush 5 into which a diverter 8 is fitted and inserted when the movable die 3 is combined with the fixed die 2, and a cylindrical spout sleeve disposed adjacent to the front of the diverter bush 5. 6 is fixed. A cylindrical machine sleeve 7 disposed adjacent to the front of the gate sleeve 6 is fixed to the fixed platen 4. In the machine sleeve 7, the plunger tip 1 is slidably arranged back and forth. The diverter bush 5, the gate sleeve 6 and the machine sleeve 7 are arranged coaxially with the central axis C of the plunger tip 1.

  The die casting machine M also includes a plunger P for moving the plunger tip 1 back and forth, and a plunger drive unit (not shown) that drives the plunger P back and forth. The plunger P is formed in a rod shape with a circular cross section and extends in the front-rear direction. The plunger drive section has a hydraulic chamber into which the plunger P is inserted so as to be movable in the front-rear direction. The plunger P moves forward when the hydraulic pressure in the hydraulic chamber rises, and moves backward when the hydraulic pressure in the hydraulic chamber falls. The plunger tip 1 is provided at the front end of the plunger P.

  During casting, the hydraulic pressure in the hydraulic chamber rises and the plunger P moves forward, and the plunger tip 1 provided at the front end of the plunger P pushes the molten metal H in the machine sleeve 7 toward the flow divider 8. The extruded molten metal H is first received by the diverter 8 and guided to an elongated runner passage 9 formed between the fixed mold 2 and the movable mold 3. Next, the molten metal H is filled in a pressurized state into a cavity 10 as a product casting chamber formed between the fixed mold 2 and the movable mold 3 through the runner passage 9. The product is cast-molded by cooling and solidifying the molten metal H in the cavity 10.

  A relatively thick disc-shaped biscuits B as shown by phantom lines in the figure are formed between the front surface 11 of the plunger tip 1 that has been moved to the forefront when the molten metal is extruded, and the diverter 8. Cooling and solidifying the biscuit B as soon as possible is important for shortening the cycle time.

  Next, the plunger tip 1 will be described with reference to FIGS.

  As shown in FIGS. 2 and 3, the plunger tip 1 includes a hollow cylindrical plunger tip body 12 provided on the plunger P of the die casting machine M, and a flow path through which the coolant flows, formed inside the plunger tip body 12. The cooling hole 13 is defined, the convex portion 14 provided at the front end of the plunger tip body 12, and the cooling hole enlarged portion 15 formed by enlarging the cooling hole 13 inside the convex portion 14.

  The plunger tip body 12 is made of a metal having high wear resistance, heat resistance, and heat transfer, such as die steel, chrome molybdenum steel, nickel alloy, and the like. A fitting hole 16 for fitting the plunger P is formed at the rear end of the plunger tip body 12. A front end portion (front end portion) of the plunger P is inserted into the insertion hole 16, whereby the plunger tip body 12 is fixedly provided on the front end portion of the plunger P.

  The cooling holes 13 are provided so as to extend linearly in the axial direction of the plunger tip body 12 and are provided in parallel. All the cooling holes 13 are opened in the axial direction within the fitting holes 16. Each cooling hole 13 is connected to a refrigerant passage 20 of the plunger P described later when the plunger P is inserted into the insertion hole 16.

  The convex portion 14 is formed in a hemispherical shape having a smaller diameter than the plunger tip body 12 and protrudes forward. The base end (rear end) of the convex portion 14 is formed in a circular cross section having a smaller diameter than the plunger tip body 12. The center O of the convex portion 14 is disposed on the central axis C of the plunger tip 1. Further, the outer peripheral front end surface 17 of the plunger tip body 12 is exposed outward in the radial direction from the convex portion 14. The outer peripheral front end surface 17 is formed in a ring shape and at a right angle to the outer peripheral surface 18 of the plunger tip body 12. Thereby, the biscuit B is formed in a substantially disk shape, and the outer peripheral end face of the biscuit B is formed flat. When the biscuit B is gripped by being sandwiched in the axial direction by a robot arm or the like (not shown), it can be gripped easily and stably. The convex portion 14 is formed integrally with the plunger tip body 12 and is made of the same material as the plunger tip body 12.

  The cooling hole enlarged portion 15 is formed by extending each cooling hole 13 forward. The cooling hole enlargement portion 15 has a different forward extension length depending on its position. Specifically, the cooling hole expanding portion 15 formed at a position where the protruding amount of the convex portion 14 is large is larger than the cooling hole expanding portion 15 formed at a position where the protruding amount of the protruding portion 14 is small. It is extended long forward. Thereby, heat exchange with the molten metal H and a refrigerant | coolant is favorably performed also in the position where the convex part 14 protruded largely forward.

  Moreover, the cooling hole expansion part 15 is formed so that it may become thin as it goes ahead. Thereby, the cooling hole expansion part 15 can be extended further forward, ensuring the thickness of the required wall between the cooling hole expansion part 15 and the convex part 14 outer surface.

  The minimum thickness between the cooling hole enlarged portion 15 and the outer surface of the convex portion 14 is set to the thinnest dimension within a range that can withstand the pressure of the molten metal H in front. Thereby, heat exchange with the molten metal H and a refrigerant | coolant is performed favorably.

  Moreover, the front end of the cooling hole enlarged portion 15 is formed in a curved surface shape. Thereby, the refrigerant | coolant discharged ahead from the refrigerant | coolant discharge pipe 23 mentioned later can be made to fold back, expanding smoothly radially.

  The plunger P is fixed in a liquid-tight manner in the insertion hole 16. Further, a coolant passage 20 for circulating the coolant through the cooling hole 13 is provided in the plunger P.

  The refrigerant passage 20 is formed in a passage hole 24 formed in the plunger P so as to extend in the axial direction. A plurality of refrigerant passages 20 are provided corresponding to the respective cooling holes 13 of the plunger tip body 12. The passage hole 24 is connected to the cooling hole 13 coaxially.

  The refrigerant passage 20 is connected to a discharge side of a pump (not shown) and sends a refrigerant 21 to the front end side of the cooling hole 13, and a return path 22 takes in the refrigerant from the rear end side of the cooling hole 13 and returns it to the suction side of the pump. Is provided.

  The forward path 21 is formed in a refrigerant discharge pipe 23 disposed in each passage hole 24. The refrigerant discharge pipe 23 is disposed at the center of the passage hole 24. The front end of the refrigerant discharge pipe 23 protrudes forward from the plunger P. The front end of the refrigerant discharge pipe 23 is located in the cooling hole expanding portion 15 and is spaced rearward from the front end of the cooling hole expanding portion 15.

  The return path 22 is formed between the inner surface of each passage hole 24 and the outer peripheral surface of the refrigerant discharge pipe 23.

  Next, the operation of this embodiment will be described.

  The refrigerant in each refrigerant discharge pipe 23 is discharged forward in the cooling hole expanding portion 15. The refrigerant discharged from each refrigerant discharge pipe 23 hits the front end of the cooling hole expanding portion 15, and then is folded back while expanding radially along the inner surface of the cooling hole expanding portion 15. At this time, there is a molten metal H between the convex portion 14 and the flow divider 8, and heat exchange between the molten metal H and the refrigerant is performed via the convex portion 14. The front surface 11 having the convex portion 14 is in contact with the molten metal H in a larger area than the front surface (flat) of the conventional plunger tip. For this reason, heat exchange between the molten metal H and the refrigerant is performed efficiently. Furthermore, the amount of the molten metal H between the plunger tip 1 and the diverter 8 is reduced as compared with the conventional art because the convex portion 14 protrudes into the molten metal H. For this reason, the molten metal H is solidified more rapidly than before, and the biscuits B are rapidly formed.

  The refrigerant folded back from the front end of the cooling hole expanding portion 15 flows backward through the cooling hole 13 outside the refrigerant discharge pipe 23 and flows to the return path 22 of the plunger P. At this time, the refrigerant flows backward while exchanging heat with the plunger tip body 12, the plunger tip body 12 is cooled, and the molten metal H that contacts the outer peripheral front end surface 17 is cooled. Thereby, the outer peripheral part of biscuit B is also formed rapidly.

  As described above, the plunger tip 1 includes the convex portion 14 provided at the front end of the plunger tip body 12 and the cooling hole enlarged portion 15 formed by enlarging the cooling hole 13 inside the convex portion 14. 13 is provided extending linearly in the axial direction of the plunger tip body 12 and provided in parallel. The cooling hole expanding portion 15 is formed by extending the cooling hole 13 forward. The molten metal adjacent to the front surface 11 can be effectively and quickly cooled. Specifically, the contact area between the coolant and the plunger tip body 12 can be increased as compared with the conventional case where one large cooling hole is formed in the plunger tip, and the cooling effect (heat radiation effect) of the molten metal H can be increased. Can be improved. Moreover, while the contact area of the molten metal H and the convex part 14 can be increased by the part which the convex part 14 protrudes in the molten metal H, the quantity of the molten metal H used as the biscuit B can be reduced, and the cooling effect ( Heat dissipation effect). And the molten metal H can be cooled and solidified quickly, and cycle time can be shortened.

  Further, since the meat of the plunger tip body 12 exists between the adjacent cooling holes 13 and this meat functions as a support, the strength of the plunger tip body 12 is higher than that of forming one large cooling hole as in the prior art. improves.

  Further, the convex portion 14 is formed in a hemispherical shape, and the cooling hole enlarged portion 15 formed at a position where the protruding amount of the protruding portion 14 is large is formed at a position where the protruding amount of the protruding portion 14 is small. Therefore, the minimum thickness of the convex part 14 from the cooling hole expansion part 15 to the molten metal H can be approximated, and the heat exchange between the molten metal H and the refrigerant is efficient. Well and as equally as possible.

  Further, the base end of the convex portion 14 is formed in a circular shape with a smaller diameter than the plunger tip body 12, and the center of the base end is disposed on the central axis of the plunger tip body 12, and is radially outward from the convex portion 14. Since the outer peripheral front end surface 17 of the plunger tip body 12 is formed at right angles to the outer peripheral surface 18 of the plunger tip main body 12, the outer peripheral end surface of the biscuit B is formed flat. When sandwiched and gripped in the axial direction, it can be gripped easily and stably.

  Next, the modification which added the change to the plunger chip | tip 1 is demonstrated. In addition, about the structure similar to the above-mentioned, the same code | symbol is attached | subjected and description is abbreviate | omitted.

(Modification)
As shown in FIGS. 4 and 5, the outer surface 29 of the convex portion 28 may be formed by combining a plurality of curved surfaces 31, 32, 33. Specifically, the convex portion 28 is preferably formed in a truncated cone shape or a truncated cone shape whose diameter decreases toward the front. At this time, the first curved surface 31 is preferably formed so as to round a ridge line between the front end surface 29 a of the convex portion 28 and the outer peripheral surface 29 b of the convex portion 28. The second curved surface 32 may be formed so as to round a ridge line between the outer peripheral surface 29b of the convex portion 28 and the outer peripheral front end surface 37 of the plunger tip body 12a. Still further, the third curved surface 33 may be formed so as to round a ridge line between the outer peripheral front end surface 37 of the plunger tip body 12b and the outer peripheral surface 39 of the plunger tip body 12b. The shape and size of the convex portion 28 can be freely set. For example, when the front end surface 29a is formed flat as shown in the figure without changing the forward protrusion amount of the convex portion 28, the amount of the molten metal H that becomes the biscuit B can be further reduced, and the molten metal H is solidified quickly. Can be made.

12 Plunger tip body 13 Cooling hole 14 Convex part 15 Cooling hole enlarged part 23 Refrigerant discharge pipe M Die casting machine

Claims (5)

A hollow cylindrical plunger tip body provided at the plunger front end of the die casting machine;
A cooling hole that is formed inside the plunger tip body and defines a flow path through which the coolant flows;
A refrigerant discharge pipe inserted into the cooling hole;
A convex portion provided at the front end of the plunger tip body;
A cooling hole enlarged portion formed by enlarging the cooling hole in the convex portion;
The cooling holes are provided to extend linearly in the axial direction of the plunger tip body, and are provided in parallel.
The cooling chip expanding portion is formed by extending the cooling hole forward. A plunger tip structure of a die casting machine, wherein: The convex portion is formed in a hemispherical shape,
The cooling hole enlarged portion formed at a position where the protruding amount of the convex part is large is extended to the front longer than the cooling hole enlarged part formed at a position where the protruding amount of the convex part is small. A plunger tip structure of a die-casting machine characterized by this. The plunger tip structure of a die casting machine according to claim 1 or 2, wherein the cooling hole enlarged portion is formed so as to become thinner toward the front.   The plunger tip structure of a die casting machine according to any one of claims 1 to 3, wherein a front end of the cooling hole enlarged portion is formed in a curved surface shape. The base end of the convex portion is formed in a circular shape with a smaller diameter than the plunger tip body, and the center of the base end is disposed on the central axis of the plunger tip body,
5. The outer peripheral front end surface perpendicular to the outer peripheral surface of the plunger tip body is formed in the plunger tip main body radially outward from the convex portion. 6. The plunger tip structure of the die casting machine.

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