JP3745615B2 - Oil leakage prevention device for hydraulic cylinder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for preventing oil leakage from a rod that advances and retreats in a hydraulic cylinder.
[0002]
[Prior art]
The rod of the hydraulic cylinder is hydraulically sealed by a known technique such as a plurality of chevron packings, and if necessary, a sealing member such as an oil seal or a dust seal is provided outside the packing, and an oil film remaining on the surface of the rod I tried to remove the dust. In some cases, a drain chamber is provided between the packing and the seal member so that the oil leaked into the drain chamber by the seal member is guided to the tank through a pipe line.
[0003]
[Problems to be solved by the invention]
However, in such a conventional technique, the oil film of the rod cannot be scraped off sufficiently, and particularly when the hydraulic cylinder is used in a vacuum atmosphere such as a vacuum lamination molding apparatus, the oil leakage increases and the oil leakage occurs. It becomes easy to vaporize in the vacuum chamber, and the molded product is contaminated in the vacuum chamber. Further, even if the drain chamber is provided, the pipeline from the drain chamber to the tank is thin and long, and further, there is no pressure, so it is difficult to smoothly introduce oil leakage into the tank.
[0004]
[Means for Solving the Problems]
Therefore, the oil leakage prevention device for the hydraulic cylinder of the present invention removes the oil film when the rod retracts to the outer cylinder of the packing that makes the rod of the hydraulic cylinder hydraulically compact . Inner seal material that is effective for the inner surface, an intermediate seal material that is opposite to the inner seal material and effective for removing the oil film when the rod is extended, and an outer seal material that has a greater sealing force than the intermediate seal material A pneumatic chamber that is provided in order from the inner side toward the outer side and that is provided between the intermediate sealing material and the outer sealing material and communicates with a pneumatic passage that is supplied with pressurized air; A drain chamber provided between the inner sealing material and the intermediate sealing material and supplied with air from the pneumatic chamber via the intermediate sealing material, and via a drain communicating with the drain chamber Tank that collects leaked hydraulic oil together with air Characterized in that is provided.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a seal portion of a rod of a hydraulic cylinder embodying the present invention and a portion for collecting leaked oil in a tank. FIG. 2 is a longitudinal sectional view of a vacuum lamination molding apparatus incorporating a hydraulic cylinder according to the present invention.
[0006]
As shown in FIG. 2, the hydraulic cylinder 6 includes a cylindrical cylinder 7, a piston 8 fitted into the cylinder 7 so as to be able to reciprocate, and a rod 9 fixed to the piston 8. Hydraulic pipes are connected to the upper and lower chambers of the cylinder 7 partitioned by the piston 8, and the rod 9 rises when pressure oil is supplied to the lower chamber, and the rod 9 rises when pressure oil is supplied to the upper chamber. Descends. Here, an example in which the hydraulic cylinder 6 is incorporated in the vacuum lamination molding apparatus 1 will be described. The four hydraulic cylinders 6 are attached to the upper surface of the fixed platen 2, and the tip of the rod 9 is fixed to the movable platen 3. Pressure oil is supplied to the chamber (pressure chamber 27) under the hydraulic cylinder 6 to raise the movable platen 3, the pressure oil in the chamber under the hydraulic cylinder 6 is returned to the tank, and the movable platen 3 is lowered by its own weight. Let Accordingly, no pressure oil is supplied to the chamber above the hydraulic cylinder 6 and only the hydraulic oil leaked from the pressure chamber 27 to the upper chamber through the piston 8 is guided to the tank. A hot plate 4 is fixed to the opposing surface of the fixed platen 2 and the movable platen 3, and another hot plate 4 is disposed at equal intervals between the fixed plate 2 and the hot platen 4 of the movable platen 3. When the movable platen 3 is raised by 6, the molded product 5 placed on the hot plate 4 is raised together with the hot plate 4 and pressed against the fixed platen 2. The movable part is covered with a fixed platen 2 and a vacuum cover 10, and the inside is deaerated to form a vacuum chamber. The temperature of the hot plate 4 is adjusted by an electric heater or a heat medium, and the heat and hydraulic pressure are controlled. The molded product 5 is molded in a vacuum by the pressing force of the cylinder 6.
[0007]
The detail of the seal part of the rod in the A part of FIG. 2 is shown in FIG. The rod 9 of the hydraulic cylinder 6 penetrates a part of the cylinder 7 that is fixed to the stationary platen 2, and the packing 11 has a chevron-shaped cross-section opening through the packing presser 12 to the pressure chamber 27 side. It is mounted hydraulically. The packing 11 is made of rubber, leather or the like whose inner diameter is the same as the outer diameter of the rod 9. The number of the packing 11 is increased or decreased according to the hydraulic pressure supplied to the pressure chamber 27.
[0008]
A bush 20 is embedded and fixed to the outside (reverse pressure chamber 27 side) where the rod 9 of the cylinder 7 passes and the packing 11 is mounted. The bush 20 has a cylindrical shape penetrating the rod 9, and a plurality of grooves are formed on the inner peripheral surface thereof, and the sealing materials 13, 14, 15 are arranged in the grooves with the drain chamber 18 and the pneumatic chamber 16 interposed therebetween. It is installed. The sealing material 13, 14, 15 is preferably made of fluororesin in terms of heat resistance and slidability, but rubber or the like may be used depending on the application of the hydraulic cylinder 6. Next, the shape and characteristics of the sealing material will be described. The sealing material 13 is adjacent to the outer side of the packing 11 and is used for original sealing to remove oil film and dust. The inner (pressure chamber 27 side) lip is shorter than the outer lip, and the rod 9 is raised. It is effective for removing the oil film. The oil leaked by the sealing material 13 flows into the drain chamber 18 adjacent to the outside of the sealing material 13. The sealing material 14 is located between the drain chamber 18 and the pneumatic chamber 16, and supplies an appropriate amount of air pressure of about 0.1 to 0.3 Mp supplied from the pneumatic passage 17 communicating with the pneumatic chamber 16 to the drain chamber 18. It has a pneumatic sealing characteristic that causes leakage, and has a cross-sectional shape in which the sealing material 13 is reversed as shown in the figure, which is effective for removing the oil film when the rod 9 is lowered. The oil leaked by the sealing material 14 when the rod 9 is lowered flows into the drain chamber 18 together with the air supplied from the pneumatic chamber 16 in an appropriate amount, merges with the oil leaked from the sealing material 13 and passes through the drain 19. It is collected in the tank 21. The sealing material 15 is located outside the pneumatic chamber 16 and in the vicinity of the end face of the bush 20, and is disposed so that the opening having a U-shaped section faces inward. The sealing material 15 is for air sealing like the sealing material 14, but the sealing force is greater than that of the sealing material 14. In addition, the cross-sectional shape of the sealing material 15 may be the sealing material 14 as long as the function can be achieved, or the cross-sectional shape of the sealing material 14 may be the sealing material 15. However, the opening having a U-shaped cross section faces the surface of the rod 9. Thus, the cross-sectional shape and installation direction of the sealing material can be selected as appropriate. Further, the number of each sealing material may be increased as necessary, or the sealing material 14 may be omitted.
[0009]
A protective tube 23 is installed on the upper portion of the tank 21 through which oil leakage including air flows from the drain 19. A filter 22 is provided inside the protective tube to remove large bubbles mixed in the leaked oil from the drain 19. The filter 22 is made of a wire mesh, a perforated iron plate, or the like and is a bowl-shaped object provided at a position higher than the highest oil level 26. A defoaming device 28 is constituted by the protective tube 23 and the filter 22. The protective tube 23 is attached to the upper back surface of the tank 21 so that its length extends below the lowest oil surface 25 in the tank 21. An opening 24 is provided on the upper side surface of the protective tube 23 at a position higher than the highest oil level 26 in the tank 21.
[0010]
The hydraulic oil in the tank 21 is converted into pressure oil by a pump (not shown), supplied to the pressure chamber 27 via various valves (not shown), and the rod 9 is lifted to execute the pressing process of the molded product 5. It becomes the lowest oil level 25 during this pressing step. On the other hand, when the molded product 5 is carried in and out (FIG. 2) before and after the pressing process, the hydraulic oil in the pressure chamber 27 returns to the tank 21 and reaches the maximum oil level 26. The hydraulic oil that has passed through the filter 22 containing fine bubbles remains in the vicinity of the oil level inside the protective tube 23, and the bubbles are separated from the hydraulic oil and discharged from the opening 24 during the pressing process that takes several hours. When the oil level rises after the pressing process is finished, hydraulic oil without bubbles enters the protective tube 23 from below.
[0011]
The supply of compressed air to the pneumatic passage 17 may be performed at any time, but a valve that operates in response to a signal from the control device of the vacuum lamination molding apparatus 1 is provided between the compressed air source and the pneumatic passage 17, and during the pressure-clamping process. Alternatively, it is preferable to supply pressurized air during an arbitrary period by a timer in order to prevent generation of excessive air bubbles in the hydraulic oil and a decrease in the degree of vacuum in the vacuum chamber.
[0012]
【The invention's effect】
Since the present invention is configured as described above, it does not leak from the hydraulic cylinder to the outside, and does not contaminate the inside of the vacuum lamination molding apparatus or the molded product. In addition, since the oil leakage recovered by the air is effectively separated from the air, the hydraulic equipment is not adversely affected by cavitation and malfunction.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a seal portion of a rod of a hydraulic cylinder for implementing the present invention and a portion for collecting oil leakage in a tank.
FIG. 2 is a longitudinal sectional view of a vacuum lamination molding apparatus incorporating a hydraulic cylinder according to the present invention.
[Explanation of symbols]
1 ……… Vacuum lamination molding device 2 ……… Fixed platen 3 ……… Movable platen 4 ……… Heat plate 5 ……… Molded product 6 ……… Hydraulic cylinder 7 ……… Cylinder 8 ……… Piston 9… ... Rod 10 ... Vacuum cover 11 ... Packing 12 ... Packing retainers 13, 14, 15 ... Sealing material 16 ... Pneumatic chamber 17 ... Pneumatic passage 18 ... Drain chamber 19 ... Drain 20 ... Bush 21 ... Tank 22 ... Filter 23 ... Protection tube 24 ... Opening 25 ... Minimum oil level 26 ... Maximum oil level 27 ... Pressure chamber 28 ... Defoaming device

Claims (3)

A sealing material 13 effective for removing an oil film when the rod is retracted is provided on the outer cylinder 7 of the packing 11 that makes the rod 9 of the hydraulic cylinder 6 fluid-tight. The sealing material 14 which is opposite to the material 13 and is effective for removing the oil film when the rod is extended, and the sealing material 15 having a sealing force larger than that of the sealing material 14 are sequentially provided from the inside toward the outside. As well as
A pneumatic chamber 16 provided between the sealing material 14 and the sealing material 15 and communicated with a pneumatic passage 17 to which pressurized air is supplied;
A drain chamber 18 provided between the sealing material 13 and the sealing material 14 and supplied with air from the pneumatic chamber 16 through the sealing material 14 ;
An oil leakage prevention device for a hydraulic cylinder, characterized in that a tank 21 is provided for collecting hydraulic oil that has leaked through a drain 19 communicated with the drain chamber 18 together with air. The oil leakage prevention device for a hydraulic cylinder according to claim 1, wherein the hydraulic cylinder (6) is used in a vacuum atmosphere . The oil leakage prevention device for a hydraulic cylinder according to claim 1 or 2 , wherein the sealing materials (13, 14, 15) are made of a fluororesin .

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