JPS621122B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder, and more particularly to a multi-stage cylinder having a second piston inside a first piston.

Conventionally, as the above-mentioned cylinder, for example, one described in Japanese Utility Model Publication No. 53-6981 is known. This thing forms a sealed space inside the main piston whose front and rear ends are closed by a front end wall and a rear end wall, stores a small piston in this sealed space, and further includes a front end wall and a front end wall. A ventilation hole is formed in each case.

Since this product is used as a buffer for opening and closing the door, pressurized air is injected into the interior. As a result, in the first half of the extrusion process, both pistons move together and the small piston moves at high speed and with a large output, and in the second half of the extrusion process, only the small piston moves and moves at low speed and with a small amount. Conversely, during the first half of the drawing process, both pistons move, resulting in high-speed, large-output movement.
In the latter half of the drawing process, only the small piston moves, resulting in low speed and small output movement.

It is also possible to supply a fixed amount of liquid to such a cylinder and use it as a cylinder for the core of a mold such as a die casting machine or an injection molding machine.
In this way, in the first half of the extrusion process, the main piston moves to produce a low speed and high output, and in the latter half, only the small piston moves to produce a high speed and small output.
On the contrary, it is thought that the movement is performed at low speed and high output during the first half of the drawing process, and at high speed and low output during the latter half.
For this reason, cylinders that operate in this manner move at high speed during the first half of the extrusion process and the second half of the drawing process, where large forces are not required, to save time, and also use a large output during the second half of the extrusion process and the first half of the drawing process. There is a problem in that it cannot be used as a core cylinder for molds such as die casting machines and injection molding machines that require the production of molds.

These problems are caused by a cylinder body that has a cylinder chamber formed inside, a cylinder that is slidably housed in the cylinder chamber of the cylinder body, and is coaxial with the cylinder body and opens at both ends, and can be placed at any axial position. a first piston in which a through hole with the same inner diameter is formed; a second piston that is slidably housed in the through hole of the first piston and whose axial length is shorter than that of the first piston; A ring-shaped rear stopper attached to the rear end and having an inner diameter slightly smaller than the through hole and capable of coming into contact with the second piston, and a liquid supply passage provided at a position facing the rear end surface of the second piston. ,
This problem can be solved by the first piston having a protrusion at its front end that protrudes radially inward and can come into contact with the front end surface of the second piston.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, reference numeral 1 denotes a cylindrical cylinder tube having a predetermined axial length and a predetermined diameter.
Reference numeral 2 denotes a front cover fixed to the front end of the cylinder tube 1, and this front cover 2 includes a small diameter portion 3 whose outer diameter is approximately the same as the inner diameter of the cylinder tube 1, and a small diameter portion 3 that is continuous with the small diameter portion 3. It consists of a large diameter part 4 with a larger diameter. This small diameter portion 3 is inserted and fixed into the front end portion of the cylinder tube 1.
5 is an O-ring, and this O-ring 5 is designed to seal the gap between the cylinder tube 1 and the front cover 2. Reference numeral 6 denotes a through hole formed in the center of the front cover 2 in the axial direction thereof. This through hole 6 is connected to a first diameter portion 7 formed on the large diameter portion 4 side of the front cover 2;
A second portion formed on the small diameter portion 3 side of the front cover 2
A third diameter portion 9 which communicates the diameter portion 8 with the first diameter portion 7 and the second diameter portion 8 and has a smaller diameter than the first and second diameter portions 7 and 8.
It consists of and. Reference numeral 10 denotes a plurality of holes that communicate the first diameter portion 7 and the second diameter portion 8. Reference numeral 11 denotes a front supply hole formed in the large diameter portion 4 of the front cover 2 substantially perpendicular to the axial direction of the front cover 2, and one end of this front supply hole 11 is connected to a supply pipe (not shown). , the other end communicates with the second diameter portion 8 of the through hole 6. Reference numeral 12 denotes a cylindrical member whose rear end is inserted into the first diameter portion 7, and this cylindrical member 12 is connected to a ring member 14 attached to the front end surface of the front cover 2 by bolts 13 and a large diameter of the front cover 2. It is held between the parts 4 and 4. 15
is an axial hole coaxial with the through hole 6 formed in the cylindrical member 12, and this axial hole 15 communicates with the first diameter portion 7 of the through hole 6. Reference numeral 16 denotes a rear cover fixed to the rear end of the cylinder tube 1, and the rear cover 16 has a small diameter portion 17 whose outer diameter is approximately the same as the inner diameter of the cylinder tube 1, and a small diameter portion 17.
and a large diameter part 18 which is continuous with the small diameter part 17 and has a larger diameter than the small diameter part 17. This small diameter portion 17 is inserted and fixed into the rear end portion of the cylinder tube 1. 19 is an O-ring, and this O-ring 19 seals the gap between the cylinder tube 1 and the rear cover 16. The aforementioned ring member 14, front cover 2, cylinder tube 1, and rear cover 16 collectively constitute a cylinder body 20. A cylinder chamber 21 is formed within this cylinder body 20. A hole 22 is formed in the front end surface of the small diameter portion 17 of the rear cover 16 and serves as a liquid supply passage facing the rear end surface of a second piston 56, which will be described later. It is located opposite 8. Reference numeral 23 denotes a rear supply hole formed in the large diameter portion 18 of the rear cover 16, substantially perpendicular to the axial direction of the rear cover 16, and one end of this rear supply hole 23 is connected to a supply pipe (not shown). The end communicates with the hole 22. 24
is a first piston body whose axial length is shorter than the axial length of the cylinder tube 1 by a predetermined length, and the first piston body 24 is slidably housed in the cylinder chamber 21. A through hole 25 coaxial with the cylinder body 20 and open at both ends is formed therein. The inner diameter of the through hole 25 is the same at any axial position, and is formed to have the same diameter as the second diameter portion 8 of the through hole 6. 26 is an oil cutting groove formed on the outer peripheral surface of the first piston body 24. A front stopper 27 is fixed to the front end surface of the first piston body 24 by a bolt 28, and this front stopper 27 has a shaft hole 29 coaxial with the through hole 25 of the first piston body 24 in the center thereof. . This shaft hole 29
is the inner diameter of the third through hole 6 of the front cover 2.
The inner diameter of the diameter portion 9 is approximately equal to the inner diameter. Therefore, the radially inner end of the front stopper 27 forms a protrusion 30 that protrudes radially inward from the front end of the first piston body 24 by a predetermined length. 31 is a U-packet, and this U-packet 31 seals the gap between the cylinder tube 1 and the first piston body 24. Reference numeral 32 designates a plurality of holes formed at the radially outer end of the front stopper 27, and these holes 32 communicate with the cylinder chamber 21 and a chamber 33 that accommodates the U-packet 31.
Reference numeral 34 indicates a plurality of holes formed in the protruding portion 30, and the holes 34 communicate the cylinder chamber 21 and the through hole 25 of the first piston body 24. 35 is a ring-shaped rear stopper fixed to the rear end surface of the first piston body 24 by a bolt 36, and has a plurality of fluid passage grooves extending in the axial direction formed on the inner surface;
This rear stopper 35 has a shaft hole 37 coaxial with the through hole 25 of the first piston body 24 in its center. The inner diameter of this shaft hole 37 is the same as that of the first piston body 24.
The inner diameter of the through hole 25 is slightly smaller than the inner diameter of the through hole 25. 38 is a U-packet, and this U-packet 38 seals the gap between the cylinder tube 1 and the first piston body 24. Reference numeral 39 denotes a plurality of holes formed at the radially outer end of the rear stopper 35, and these holes 39 communicate with the cylinder chamber 21 and the chamber 40 that accommodates the U packing 38. The aforementioned front stopper 27 and first piston body 24 constitute a first piston 41 as a whole, and this first piston 4
1 is slidably housed in the cylinder chamber 21 of the cylinder body 20, and the rear end surface of the rear stopper 35 is in contact with the front end surface of the rear cover 16. 42 is a second piston body that is slidably housed in the through hole 25 of the first piston body 24 and whose axial length is shorter than the axial length of the first piston 41 by a predetermined length. The second piston body 42 has a through hole 43 coaxial with the first piston 41 inside thereof. 44,4
5 is the outer peripheral surface of the front and rear ends of the second piston body 42 and the first
These U gaskets 4 are respectively interposed between the inner circumferential surface of the piston body 24.
4 and 45 seal the gap between the first piston body 24 and the second piston body 42. 46 is a piston rod, and this piston rod 46 has a first diameter portion 47 having approximately the same diameter as the inner diameter of the third diameter portion 9 of the through hole 6 of the front cover 2, and a first diameter portion 47 that is continuous with the first diameter portion 47 and has a second piston body. 42, a second diameter part 48 having the same diameter as the through hole 43, and a second diameter part 4 continuous with the second diameter part 48.
8. The third diameter portion 49 has a diameter smaller than 8. 50 is an end body, and this end body 50 is screwed into the third diameter portion 49 of the piston rod 46 and fixed thereto. This end body 50 is connected to the second
The piston body 42 is pressed against a step surface between a first diameter section 47 and a second diameter section 48 of a piston rod 46, and its rear end surface is pressed against the step surface between the first diameter section 47 and the second diameter section 48 of the piston rod 46.
can come into contact with the front end surface of the Therefore,
The piston rod 46 has its first diameter portion 47 loosely fitted into the through hole 6 of the front cover 2, the shaft hole 15 of the cylindrical member 12, and the shaft hole 29 of the front stopper 27, and its second diameter portion 48 is inserted into the through hole 43 of the second piston body 42, and its third diameter portion 49 is fixed to the end body 50. Reference numeral 52 denotes a plurality of holes formed at the radially outer end of the end body 50, and these holes 52 are connected to a chamber 53 that accommodates the cylinder chamber 21 and the U packing 45.
communicate with. Reference numeral 54 denotes a plurality of holes formed at the radially outer end of the pad 51, and these holes 54 are connected to the through hole 25 of the first piston body 24 and the U packing 4.
4. The piston rod 46, the stopper 51, the second piston body 42, and the end body 50 described above are collectively
A piston 56 is configured. This second piston 56
slides inside the first piston 41 along its axial direction, and the stopper 51 can come into contact with the protrusion 30 of the front stopper 27 .
57 is the cylindrical member 12 and the piston rod 46;
It is a U seal that seals the gap between the 5
Reference numeral 8 denotes an oil seal that seals the gap between the cylindrical member 12 and the piston rod 46.

Next, the operation of one embodiment of the present invention will be explained.

First, pressure fluid at a constant pressure is supplied from the rear supply hole 23 into the hole 22 of the rear cover 16 via a supply pipe (not shown). The pressure fluid flowing out from this hole 22 first acts on the rear end surface of the second piston 56 and pushes out only the second piston 56 at high speed. At this time, the first piston 41 hardly moves. When the mold provided at the tip of the piston rod 46 reaches approximately the set position, the load acting on the piston rod 46 increases and becomes larger than the extrusion force of the second piston 56, so the movement of the second piston 56 is stopped. do. In the early stage of the extrusion process, only the second piston 56, which has a small pressure-receiving area, moves, so the piston rod 46 moves at high speed with a small output as shown in Figures 2 and 3, reducing the amount of pressure required to set the mold. This will save time. After the mold is set, preparation for pouring the molten metal can begin, for example. Next, when only the first piston 41 moves without any load and the inner end of the rear stopper 35 comes into contact with the second piston 56, the latter half of the extrusion process is reached. In the latter stage of this extrusion process, the first and second pistons 41, 56
unite and move slightly forward to clamp the mold. At this time, the pressure receiving area is both pistons 41,
56, the piston rod 46 moves at low speed with high output, generating sufficient output for mold clamping.

Next, pressure fluid at a constant pressure is supplied from the front supply hole 11 into the second diameter portion 8 of the through hole 6 of the front cover 2 via a supply pipe (not shown). As a result, only the first piston 41 moves rearward without any load at first. Since the piston rod 46 and the mold do not move during the movement period of only the first piston 41, other work can be done at the same time, and no time is wasted. Then, the protrusion 30 of the first piston 41 is connected to the second piston 56.
When it is caught, the first piston 41 and the second piston 56 integrally move rearward within the cylinder chamber 21, and the first half of the drawing process begins. In the first half of the drawing process, the pressure receiving area is the total area of the front end surfaces of both pistons 41 and 56, so the piston rod 46 moves at low speed with high output as shown in FIGS. , even if seizing occurs between the mold core and the material, they can be easily separated. Next, when the rear end surface of the rear stopper 35 comes into contact with the front end surface of the rear cover 16 and the movement of the first piston 41 is stopped, the latter half of the drawing process begins. In the latter half of the drawing process, the first piston 41 stops and a certain amount of pressure fluid is supplied to the cylinder chamber 21 for a certain period of time. 25 toward the rear at high speed with a small output, and return the mold from near the set position to the standby position while shortening the time. The second piston 56 is stopped when the rear end surface of the end body 50 comes into contact with the front end surface of the rear cover 16. As described above, one cycle of this cylinder extrusion and drawing process is completed, and this cycle is repeated thereafter.

Since the present invention is constructed as described above, when used as a cylinder for the core of a mold in an aluminum die-casting machine, a plastic injector, etc., when setting the mold, the extrusion speed is increased to shorten the time. Also, when clamping the mold, increase the pushing force, and conversely, when pulling out the core of the mold after pouring the molten metal, the core and material will seize, so increase the cylinder's pulling force. After the mold is separated from the material, the pulling speed is increased to shorten the cycle time of the machine as a whole.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the cylinder according to the present invention, Fig. 2 is a graph showing the relationship between the extrusion force of the cylinder and the extrusion stroke, and Fig. 3 is a graph showing the relationship between the extrusion speed and the extrusion stroke of the cylinder. FIG. 4 is a graph showing the relationship between cylinder pulling force and drawing stroke, and FIG. 5 is a graph showing the relationship between cylinder drawing speed and drawing stroke. 20 is the cylinder body, 21 is the cylinder chamber, 22
25 is a through hole, 30 is a protrusion,
35 is the rear stopper, 41 is the first piston,
56 is a second piston.

Claims (1)

[Claims] 1 A cylinder body with a cylinder chamber formed inside, and a through hole that is slidably housed in the cylinder chamber of the cylinder body, is coaxial with the cylinder body, is open at both ends, and has the same inner diameter at any axial position. a first piston formed with a first piston;
a second piston that is slidably housed in the through hole of the piston and has a shorter axial length than the first piston; and a second piston that is attached to the rear end of the first piston and has an inner diameter slightly smaller than the through hole. a ring-shaped rear stopper that can come into contact with the
a liquid supply passage provided at a position opposite to the rear end surface of the second piston, and the first piston has a protrusion at its front end that can protrude radially inward and come into contact with the front end surface of the second piston. A cylinder comprising: