JPH02190269A - Forced return type single acting hydraulic tool - Google Patents

Abstract

PURPOSE:To facilitate release of a ram from galling phenomenon by providing a switching means to close an oil passage for moving forward a ram and switch it to a passage through which oil is fed only to an annular chamber and a means to escape back oil of the ram. CONSTITUTION:When, during a compression work, the occurrence of galling results in the impossibility for a ram 3 to move backward, a switching valve 8 is operated, a passage B for moving forward the ram is closed, oil is fed only to a passage A, oil is fed to an annular chamber 6, and a slide cylinder 5 and the ram 3 are forcibly moved backward. In this case, the back oil pressure of the ram 3 is increased, and a passage to an oil reservoir 10 is opened. Namely, an oil pressure in a cylinder is lowered through the feed of oil to the oil reservoir 10, and forced backward movement of the ram 3 is not disturted. When, as noted above, sticking is released, the ram 3 is moved backward through the action of a spring 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a single-acting hydraulic compression tool operated by a single hydraulic hose. During compression, a phenomenon commonly referred to as "galling" tends to occur between the die and the material to be compressed.
The object of the present invention is to easily release this and allow the ram to return normally.

[Conventional technology and problems] As a single-acting hydraulic tool, frame F is used as shown in Fig.
, a cylinder C, a ram R, a stem S, and a spring K are known. Cylinder C is fixed to frame F, and stem S is fixed to cylinder C by penetrating its bottom. The ram R is slidably inserted into the cylinder C, and a spring K is inserted between the spring retainer at the top of the stem S and the bottom disk of the ram. The oil press-fitted into the lower end of the passage in the stem is
The ram is moved forward while compressing the spring K to compress the workpiece. When the oil supply pressure is returned to zero after the compression is completed, the force of the spring causes
The ram moves backward while removing the oil (1), allowing the workpiece to be removed.

However, the upper and lower dies (
(not shown), the edges may bite into the workpiece due to slight positional misalignment, the upper and lower dies may stick together due to the protruding excess material, and the ram may not move back with just the spring force. This is the so-called galling phenomenon. In this case, it was necessary to add cumbersome work such as scraping off the excess flesh with a chisel or driving in a wedge. This is a drawback not found in the double-acting type, which has two hydraulic hoses and uses hydraulic pressure for double-acting.

[Means for solving the problem] A sliding tube was attached to the outer periphery of the stem, and oil was sent to the annular chamber formed by the sliding tube to cause the ram to retreat using hydraulic pressure.

In order to do this, a means is required to close the oil passage that controls the advancement of the ram and to switch to a passage for supplying oil only to the annular chamber. This increases the back pressure on the ram, so we added a means to release oil from the back.

[Example] The drawings will be explained. A bottomed cylinder 2 is inserted and fixed into a through hole of a frame 1. The ram 3 is slidably inserted into the cylinder 2 with its skirt. The stem 4 is attached to the bottom of the cylinder through the cylinder, a ring 4a is fixed to the center part, and a spring receiver 4b is provided at the inner end. The bottomed sliding tube 5 has a through hole and a small diameter hole at the bottom. The small diameter hole is slidably inserted into the stem body, and the large diameter hole is slidably inserted into a ring 4a fixed to the stem, thereby forming an annular chamber 6 between them. The sliding tube 5 has a flange 5a on the outer periphery of the bottom, and a spring 7 is inserted between the flange 5a and the spring receiver 4b. A plurality of bottles 3a protrude from the inner surface of the skirt portion of the ram, and the sliding tube 5 is pressed against the bottles by a collar 5a.

The oil that entered the tail end of the stem from the hose H flows through the stem's internal passage A.
through which it leads to the annular chamber 6. A switching valve 8 is attached to six passages B, in which passages B and C are provided in parallel, branching from the passage A and communicating with the cylinder bottom, and the passages can be opened and opened by operating this valve. A relief valve 9 consisting of a ball and a spring is interposed in the passage C.

Separately from the above, there is an oil pool lO at the bottom of the cylinder.
The built-in spring 11 and piston 12 block the passage from the bottom to form a closed chamber.

FIG. 4 is a sectional view taken along line PP in FIG. 1, showing the relative position of the relief valve 9 and the oil pool 10, and FIG. 3 shows details of the oil pool 10.

[Operation] In the present invention configured as described above, as shown in FIG. 1, the passage B is always open and the passage C is closed. Pressure oil from hose H flows into passage B to advance the ram. During this time, the pressure oil flowing through the passage A acts to move the ram backward, but since the ram has a larger pressing cross section than the annular cylinder, it can move forward without any problem. When the compression work is completed, the oil supply switch in the pump is turned off, the oil in the hose becomes unpressurized, and the relief valve 9 is opened. The ram is therefore retracted by the spring.

If "gauling" occurs during compression work and the ram does not move back, the switching valve 8 is operated to close the passage B as shown in FIG. Oil flows only through passage A, forcing the sliding tube and therefore the ram to retreat. At this time, the rear hydraulic pressure of the ram increases and the passage of the oil sump 10/\ opens. That is, the oil pressure in the cylinder is lowered by being sent to the oil reservoir 10, and does not interfere with the forced retreat of the ram. Once the stalemate due to galling is released, the ram will then move back due to the action of the spring 7.

[Effect] Without losing the simplicity of a single-acting hydraulic tool, it is possible to easily escape from the galling phenomenon simply by switching the switching valve and the action of the oil reservoir 10.

[Brief explanation of the drawing]

Figure 1 is a front view of the present invention when it is in normal operation, Figure 2 is a front view when the switching valve is switched, Figure 3 is a cutaway front view of the vicinity of the oil well, and Figure 4 is the P of Figure 1. -P sectional view, and FIG. 5 is a front view of the conventional example. 1...Frame, 2...Cylinder, 3...Ram, 3
a...Bin, 4...Stem, 4a-...Ring, 4
b... Spring receiver, 5... Sliding tube, 5a... Tsuba, 6
...Annular chamber, 7..Spring, 8..Switching valve, 9..
Relief valve, oil pool, spring, piston, hose, A. B. Passage, frame, cylinder, ram, stem, spring.

Claims (1)

[Claims] A frame, a cylinder with a bottom that is inserted and fixed into a through hole of the frame, a ram that is slidably inserted into the cylinder through a skirt part, a ram that is fixed through the bottom of the cylinder and has a spring receiver on the inner end of the ram, and a ring in the center. a stem to which is fixed, a bottomed sliding tube that is slidably inserted into a ring of the stem and has a collar that forms an annular chamber between the stem and can be locked to the ram, and a spring receiver for the stem. A spring inserted between the collar of the sliding tube,
A passage A leads from the outer end of the stem to the annular chamber of the sliding cylinder via the inside of the stem, a passage B branches off from passage A and connects to the bottom of the cylinder, and can be switched between communication and isolation using an attached switching valve; A forced return single-acting hydraulic tool consisting of a passage C that communicates with the bottom of the cylinder via a relief valve, and an oil reservoir that communicates with the bottom of the cylinder and is normally closed by an internal piston and a spring.