JPH04254004A - Cylinder - Google Patents

Abstract

PURPOSE:To facilitate maintenance of a cylinder used at high temperature by lengthening the life of a seal member in the cylinder. CONSTITUTION:Though a seal member 14 of a cylinder 1 used at a high temperature is deteriorated by a high temperature in its early stages, the deterioration is prevented by forming a circular passage 15 in the periphery of a seal member 14 in the cylinder 1 and letting a cooling fluid flow in the circular passage 15 to cool the seal member 14.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a cylinder that can be used at high temperatures.

0002

[Prior Art] In recent years, cylinders for the core of molds in die-casting machines, injection machines, etc. have come to be directly attached to the machine body due to the need to make the entire device smaller and lighter. Due to conduction heat from the main body, it can now be heated up to about 100 degrees Celsius. For this reason, U made of fluororubber with good heat resistance is used as a sealing member between the cylinder case and the pinton rod and between the cylinder case and the piston.
Now uses packing. On the other hand, as the working fluid for operating the core cylinder as mentioned above, oil is generally not used, as it can cause a fire if it comes into contact with a hot mold if it leaks outside, and 95% water is used as the working fluid. A water/glycol solution containing a certain amount of water and glycol is used.

0003

[Problems to be Solved by the Invention] However, when a sealing member made of fluororubber as described above comes into contact with moisture in water or glycol liquid while being heated to a high temperature,
A chemical reaction occurs and deteriorates in a short period of time, resulting in a seal failure. When such a seal failure occurs, the working fluid leaks to the outside from between the cylinder case and the piston rod, so in the past, the seal member was frequently replaced before it deteriorated. There is a problem that maintenance becomes troublesome.

0004

[Means for Solving the Problems] These problems are solved by a cylinder case having a front wall at the front end, a piston slidably housed in the cylinder case, and a cylinder connected to the piston at the front of the cylinder case. A cylinder including a piston rod passing through a through hole formed in a wall, and a sealing member attached to an inner periphery of the through hole, wherein an annular passage is formed in a front wall surrounding the sealing member, and This problem can be solved by forming a passage in the cylinder case for supplying and discharging cooling fluid to and from the annular passage to cool the sealing member.

[0005]

[Operation] When the cylinder is used under high temperature conditions, the sealing member that seals between the through hole and the piston rod is also heated to a high temperature. Therefore, the sealing member may deteriorate rapidly due to this high temperature or due to the synergistic effect of the high temperature and other effects, such as contact with moisture. However, if an annular passage is formed around the seal member as in the present invention and a cooling fluid is allowed to flow through the annular passage, the seal member can be cooled and its temperature lowered, thereby preventing deterioration. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a cylinder for the core of a mold that is attached to a die-casting machine, an injection machine, etc. Since this cylinder 1 is directly attached to a high-temperature machine, it is heated to over 100 degrees Celsius. This cylinder 1 has a cylinder case 3 in which a cylinder chamber 2 is formed, and this cylinder case 3 includes a cylindrical cylinder tube 4, a front cover 5 fixed to the front end of the cylinder tube 4, and a cylinder case 3. A sleeve 6 is clamped and fixed to both the front end of the tube 4 and the front cover 5, and the cylinder tube 4
and a rear cover 7 fixed to the rear end of the vehicle. The cylinder case 3 has a front wall 8 formed of a sleeve 6 and the front end of the cylinder tube 4 at its front end, and a through hole 9 extending in the axial direction is formed in the center of the front wall 8. A piston 11 that divides the cylinder chamber 2 into a front cylinder chamber 2a and a rear cylinder chamber 2b is slidably housed in the cylinder chamber 2 of the cylinder case 3, and the front end of the piston 11 is connected to the cylinder case 3. Coaxial piston rods 12 are integrally connected. The piston rod 12 passes through the through hole 9, and its tip is connected to the core of the mold. An annular groove 13 is formed on the inner surface of the through hole 9 by the sleeve 6 and the cylinder tube 4, and a U packing 14 as a sealing member is attached to the annular groove 13. This U packing 14 is made of fluororubber with good heat resistance and seals between the front wall 8 of the cylinder case 3 and the piston rod 12. An annular passage 15 is formed at the front end of the cylinder case 3 surrounding the U-packing 14, and the opening at the front end of the annular passage 15 is closed by a ring 17 fixed by welding. Also, ring 17
A seal ring 18 made of silicone resin is interposed between the annular passage 15 and the sleeve 6, thereby doubly preventing fluid leakage within the annular passage 15.

Further, the rear cover 7 has a cylindrical portion 21 inserted into the cylinder tube 4, and a space between the outer periphery of the central portion of the cylindrical portion 21 and the inner periphery of the central portion of the cylinder tube 4 surrounds the cylinder chamber 2. A ring path 22 is formed. This annular passage 22 and the annular passage 15 communicate with each other through a first passage 23 formed in the cylinder tube 4, and this annular passage 22 and an outlet port 24 formed on the outer periphery of the rear cover 7 communicate with each other. The two passages 25 communicate with each other. Reference numeral 26 denotes an inlet port opened on the outer periphery of the cylinder case 3, and this inlet port 26 and the annular passage 15 communicate with each other through a third passage 27. The annular passage 22, first passage 23, second passage 25, and third passage 27 described above collectively constitute a passage 28 formed in the cylinder case 3 and supplying and discharging cooling fluid to and from the annular passage 15. A pair of U-packings 31 and 32 made of fluororubber are attached to the outer periphery of the piston 11 to seal between the piston 11 and the cylinder case 3.
A seal ring 33 made of Teflon is installed between 1 and 32. Note that 34 is a dust seal and 35 is an O-ring. Further, 41 is a fluid source that supplies working fluid to the cylinder 1, and for the purpose of avoiding the occurrence of fire under high temperatures as mentioned above, water/glycol liquid with a water content of 95% or more is used as the working fluid here. I am using it. After passing through the switching valve 42, the fluid discharged from this fluid source 41 passes through one of the supply and discharge passages 43 and 44 to the front cylinder chamber 2a, or passes through the other supply and discharge passage 45 and passage 46 to the rear cylinder chamber 2b. is supplied to Relief valves 49 and 50 and check valves 51 and 52 are provided in branch passages 47 and 48, each of which has one end connected to the middle of supply and discharge passage 43 and supply and discharge passage 45, respectively, and these branch passages 4
The other ends of 7 and 48 merge and are connected to the inlet port 26. The aforementioned relief valves 49 and 50 as a whole are supply and discharge passages 43 and 4 that supply and discharge working fluid to and from the cylinder 1.
A control valve 53 is configured to take out the working fluid from the supply/discharge passages 43 and 45 whose pressure has exceeded the set pressure and guide it to the passage 28 when any one of the pressures 5 becomes equal to or higher than the set pressure. Note that the outlet port 24 is connected to a tank 54.

Next, the operation of one embodiment of the present invention will be explained. When clamping the mold of the machine, the working fluid discharged from the fluid source 41 is transferred to the switching valve 42 and the supply/discharge passage 4.
5. It flows into the rear cylinder chamber 2b through the passage 46, and the piston 11 and piston rod 12 are moved forward. On the other hand, the return fluid in the front cylinder chamber 2a is returned to the tank 54 through the passage 44, the supply/discharge passage 43, and the switching valve 42. Then, when the piston 11 and the piston rod 12 move forward to the stroke end, back pressure is built up in the supply and discharge passage 45, and the internal pressure of the supply and discharge passage 45 becomes equal to or higher than the set pressure. This results in
The relief valve 50 is opened, and the working fluid that has been flowing into the rear cylinder chamber 2b is transferred to the branch passage 48 and the inlet port 26.
, flows into the annular passage 15 through the third passage 27. Here, since the U-packing 14 is exposed to a high temperature of more than 100 degrees Celsius and moisture in the working fluid, there is a risk that it will deteriorate over time and the seal will break, causing the working fluid to leak to the outside. However, as described above, the working fluid (cooling fluid) flows into the annular passage 15 and cools the U-packing 14 and its surroundings, so the deterioration rate of the U-packing 14 is significantly reduced.
The service life is significantly longer than without cooling. Therefore, instead of using fluororubber U-packing as a sealing member, it is also possible to use a lower quality one.
Manufacturing costs can be reduced. Note that in this embodiment, fluororubber is used in consideration of safety. The working fluid that has cooled the U-packing 14 in this way flows through the first passage 2.
3, the U-packings 31 and 32 and the seal ring 33 flow into the annular passage 22 and are attached to the piston 11.
to cool down. The working fluid then returns to the tank 54 after passing through the second passage 25 and the outlet port 24 . Here, the fluid supplied to the annular passage 15 and the annular passage 22 is supplied to the cylinder 1.
Since the fluid is used to operate the fluid, there is no need to provide a special fluid source, and the structure can be simplified. Moreover, since the fluid is taken out from between the switching valve 42 and the cylinder chamber 2, some of the fluid in the supply/discharge passages 43 and 45, which is normally reciprocated and hardly replaced, passes through the annular passage 15. The liquid then returns to the tank 54, thereby allowing the fluid in the supply and discharge passages 43, 45 to be partially refreshed. On the other hand, when releasing the mold of the machine, the switching valve 42 is switched to supply working fluid to the front cylinder chamber 2a through the supply/discharge passage 43. At this time, the return fluid in the rear cylinder chamber 2b returns to the tank 54 through the supply/discharge passage 45. Then, when the piston 11 and the piston rod 12 retreat and reach the stroke end, the internal pressure of the supply/discharge passage 43 rises above the set pressure, and the relief valve 49
is opened and working fluid is supplied to the annular passage 15 and the annular passage 22. As a result, U packings 14, 31, 32,
Seal ring 33 is cooled.

In the above-mentioned embodiment, the annular passage 1 is used for the cylinder 1 which is used under quite severe conditions.
5 is provided to cool the U-packing 14, the present invention may be applied to cylinders used under more severe conditions or cylinders used under milder conditions than those of the embodiments. Further, in the above embodiment, the fluid for operating the cylinder 1 was supplied to the annular passage 15, but in this invention, fluid such as air, water, oil, etc. is supplied to the annular passage 15 from a separate system. It may also be supplied to

0010

As explained above, according to the present invention, since the sealing member is cooled, its lifespan is extended and maintenance is facilitated.

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view, partially represented by symbols, showing an embodiment of the present invention.

[Explanation of symbols]

1...Cylinder 3...Cylinder case 8...Front wall
9...Through hole 11...Piston
12... Piston rod 14... Seal member
15... Annular passage 28... Passage

Claims (1)

[Claims] Claim 1: A cylinder case having a front wall at the front end;
A piston that is slidably housed in a cylinder case;
In a cylinder including a piston rod connected to the piston and passing through a through hole formed in a front wall of a cylinder case, and a seal member attached to the inner periphery of the through hole, the inside of the front wall surrounding the seal member. 1. A cylinder characterized in that an annular passage is formed in the cylinder case, and a passage for supplying and discharging cooling fluid to and from the annular passage is formed in the cylinder case to cool the sealing member.