JP2593883Y2 - Multi-stage ram lift - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an improvement of a multi-stage ram type lift.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, various types of multi-stage ram lifts in which a plurality of rams 20, 30,... This type of multi-stage ram type lift has recently been used more and more widely because it has an advantage that the depth of the storage pit can be set small when the lift body is buried under the floor.

[0003]

However, the above-described conventional multi-stage ram type lift generally has a plurality of rams 20, 30,...
(The outer ram is the first ram 20, and the inner ram is the second ram 3.
It is called 0. Since there is no mechanism for controlling the order of lifting and lowering, there is a difference in the time required to ascend and descend to a certain predetermined position, which may hinder the interlocking with other devices, and If the small-diameter second ram 30 is stopped suddenly during ascent and descent, a large surge pressure is generated in the cylinder 10, which may cause a shock to the mounted heavy object W and the hydraulic circuit, which may cause the heavy object to drop or the hydraulic circuit to be damaged. Had issues.

That is, the lifting order of the conventional multi-stage ram type lift will be described with reference to FIG. 5 when no load is applied and FIG. 6 when a load is applied halfway as follows.

[0005] "Normal ascending / descending order under no load" First, in the normal ascending / descending order under no load, both the first ram 20 and the second ram 30 in FIG. When the oil is press-fitted into the cylinder 10 from the state (A), the first ram 20 and the second ram 30 usually rise together as a state (B). When the first ram 20 rises to the rising end, the first ram 20
When the oil comes into contact with a stopper or the like and cannot be raised, and the oil is press-fitted into the cylinder 10, only the second ram 30 is raised this time to be in a state (C). When the lift is lowered, the state is returned from the state shown in FIG. 5C to the state shown in FIG. 5A via the state shown in FIG.

"Special lifting sequence under no load" However, since the above-mentioned lifting operation sequence is not guaranteed by a special mechanism for that purpose, in some cases, only the second ram 30 is raised in the initial stage of lifting. (The first ram 20 stops), and the second ram 30 rises to the rising end,
The first ram 20 may rise with the second ram 30 in some cases. In other words, the ram may go up and down via the state shown in FIG. 5 (D). The cause is the difference between the weights of the first ram 20 and the second ram 30 and the ram and its metal. Is higher on the first ram 20 side and the second ram 30 side.

"Normal ascending sequence with halfway load""FIG.6" is to embed a lift below the floor F to lift a heavy object W placed on the floor F. When oil is press-fitted into the cylinder 10 from the state (A) in which both the first ram 20 and the second ram 30 are lowered to the lowermost end, no load is initially applied, and therefore, as described above, usually the first The ram 20 and the second ram 30 are integrally raised together to be in the state (B1a), but in some cases, only the second ram 30 may be raised to be in the state (D1). Then, when the second ram 30 comes into contact with the heavy object W in the state (D1), the second ram 30 temporarily stops rising by the load, and the first ram 20 rises to the state (B1b). Is the same as (B1a). Then, when a load is applied to both the first ram 20 and the second ram 30 in the state of (B1a) and (B1b), the first ram 20 and the second ram 30 rise together as one. (B)
State. Then, when the first ram 20 rises to the rising end, the first ram 20 comes into contact with a stopper or the like to be unable to ascend, and further, the oil is discharged from the cylinder 10.
Then, only the second ram 30 rises to the state (C) as in the case of no load.

However, if the load is largely offset in the state (D1), the first ram 20 and the second ram 30 are integrated from the state (D1). To the state (E) in some cases. That is, when the first ram 20 is displaced by the offset load and the sliding portion of the first ram 20 cannot slide with the second ram 30, the first ram 2 cannot be lifted at the time when the second ram 30 does not finish moving up.
0 may rise.

[Load Normal Lowering Order] When lowering under load, first the second ram 30
Descends, and when the second ram 30 finishes descending, the first ram 20 descends together with the second ram 30.

"Special load descending sequence" However, when the load is an uneven load, the first ram 20 and the second ram 30 descend integrally, and after the first ram 20 finishes descending, the second ram 30 May fall.

That is, in the conventional multi-stage ram type lift, the ascending and descending order of each ram may rarely be out of order as described above, and if this ascending and descending order occurs in a special case, the ascending and descending speed is also affected. However, there is a problem that the control becomes complicated and interlocking with other devices may be hindered.

Further, this type of multi-stage ram type lift uses a heavy load W
When descending from a high place to a low place, as described above, first, it descends from the small diameter second ram 30 side, so the descending speed is high at a high place and the lift is suddenly stopped when only the second ram 30 descends. The two conditions that the second ram 30 has a small diameter and a high descent speed are combined, so that a considerably large surge pressure is generated in the cylinder 10. The large surge pressure causes the second ram 30 to stop more suddenly than necessary, causing an impact force on the mounted heavy load W against inertia, and the heavy load W may be displaced and displaced. It is also assumed that the large surge pressure naturally affects the hydraulic circuit connected to the cylinder 10 and causes the hydraulic circuit to be damaged.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a multi-stage ram type lift in which the ascending and descending order is controlled and large surge pressure is hardly generated even at the time of sudden stop.

[0014]

SUMMARY OF THE INVENTION In accordance with the above objects, the construction of the present invention, which has the features of the above-mentioned claims, has an upper opening 11 for solving the above-mentioned problem.
A first ram 20 is housed in a cylinder 10 having a first metal 12 fixed inside 1, the first ram 20 is formed in a cylindrical shape, a second metal 22 is provided inside an upper opening 21, and a lower opening end is provided. An orifice bottom plate 24 having a small through hole 23 is fixed to the first ram 20 and a second ram 30 is accommodated in the first ram 20 by technical means.

[0015]

Therefore, the multi-stage ram lift according to the present invention, when ascending, the orifice bottom plate 24 resists the inflow of oil, regardless of the presence or absence of a load.
And the first ram 20 rises to the rising end, and then only the second ram 30 acts to rise.

When a load is applied to the second ram 30 at the time of lowering, first, the second ram 30 to which the load is directly applied is first applied.
Only the second ram 30 and the first ram 20
When the second ram 30 descends to the state where it is stored in the first ram 20 (the second ram 30 descends to the lowermost end with respect to the first ram 20), the first ram 20 and the second ram 30 thereafter descend integrally. Works.

In the case of descending with no load, as will be described later, the shape of the small through hole 23 of the orifice bottom plate 24 is devised so that only the second ram 30 descends before the first ram 20 without fail. However, in a normal use state, when the load is lowered with no load from the middle, the second ram 30 is moved to the first ram 2 when the load is reduced.
Since the rams 20 and 30 are normally completely housed in the cylinder 0, the weights of the two rams 20 and 30 work together to push out the oil in the cylinder 10.
There is no difference that 0 and 30 drop together.

Further, when there is no load from the beginning of the descent, if the shape of the small through hole 23 of the orifice bottom plate 24 is not devised,
The descending order is not always controllable, but in this case it is usually at the time of return after the function of the lift is completed, so the control of the ascending and descending order in this step is not so important.

Further, since the orifice bottom plate 24 communicates the inside of the first ram 20 with the cylinder 10 through the small through hole 23, when the second ram 30 is stopped suddenly, the oil flows into the small small through hole 2.
3, a buffering effect can be exhibited, and the influence on piping and the like can be reduced. In addition, the buffering effect can be exhibited even when an impact is applied to the heavy object W at the time of sudden stop.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, reference numeral 10 denotes a cylinder. The cylinder 10 has an upper opening 11, and a first metal 12 is fixed inside the upper opening 11. The bottom of the cylinder 10 is hermetically sealed by a bottom plate 13, and an oil inlet / outlet 14 is provided at an appropriate position (in the illustrated example, at a peripheral surface). Then, the pump 5 of the pump unit 50 shown in FIG.
1 is operated to press the oil in the tank 52 into the cylinder 10 from the entrance 14 to raise the rams 20 and 30 to be described later.
By operating the ram 3, the rams 20 and 30 can be returned.
It is the same as in the prior art that the angle is lowered. In FIG. 3, reference numeral 54 denotes a filter, reference numeral 55 denotes a check valve, and reference numeral 56 denotes a flow rate adjusting valve.

The first ram 20 is housed in the cylinder 10 in a vertically movable manner, and the second ram 30 is housed in the first ram 20 in a vertically movable manner. Same as a lift. The outer peripheral surface of the first ram 20 is slidable while maintaining the airtightness with respect to the first metal 12, so that the first ram 20 can be moved up and down. The first ram 20 is formed in a cylindrical shape, and a second metal 22 is provided inside the upper opening 21.
The outer peripheral surface is slidable while maintaining the airtightness of the second metal 22 so as to be able to move up and down. The second ram 30 has a pillar or a bottom 29 or a cover 28 (in the illustrated example, the cover has both the bottom 29 and the cover 28) so that oil in the cylinder 10 does not leak. What has been done is the same as before.

In the present invention, an orifice bottom plate 24 having a small through hole 23 is fixed to the lower opening end of the first ram 20. If the diameter of the orifice bottom plate 24 is set so that the oil in the cylinder 10 flows into the first ram 20 or the oil in the first ram 20 flows out into the cylinder 10 to have a predetermined resistance value. However, in this embodiment, the diameter of the small through hole 23 is gradually increased toward the upper surface side with a small diameter on the lower surface side of the orifice bottom plate 24, and when the oil in the cylinder 10 flows into the inside of the first ram 20, the resistance is large. Conversely, when the oil in the first ram 20 flows into the cylinder 10, the resistance is reduced.

That is, since oil is a viscous fluid, it is known that when passing through a portion where the flow path is sharply narrowed, a larger pressure loss is caused than when passing through a portion where the diameter is gradually reduced. In this embodiment, this property of oil is used, and a difference is made depending on the direction of oil passage.

It is also known that a large pressure loss accompanies the presence of burrs at the time of machining at the inlet of the narrowed flow path of the oil. Therefore, in the illustrated embodiment, a small through hole 23 is formed on the lower surface side of the orifice bottom plate 24. The surface is arranged so as to be perpendicular to the orifice bottom plate 24, and the corner between the conical surface 23a and the right-angled portion of the small through-hole 23, whose diameter gradually increases toward the upper surface side, is formed as a chamfered surface 23b. Depending on the direction in which the oil passes, there is a great difference in the difficulty of the flow.

The reason why the shape of the small through hole 23 is modified in the illustrated example is that when the oil in the first ram 20 flows into the cylinder 10 with excessive resistance, the first ram 20 and the second ram If no load is applied to the second ram 30, the first ram 20 may be lowered before the first ram 20 to which no load is directly applied. However, the resistance of the orifice bottom plate 24 is large, and as another factor, when the “scratch” between the first ram 20 and the second ram 30 is added, the first ram 20
This is to prevent both the first and second rams 30 from descending from the beginning.

Although the present application has been described as a two-stage type, it is needless to say that the present invention can be applied to a multi-stage type having three or more stages.
In the present application, the small through hole 23 is provided in the orifice bottom plate 24, but the small through hole 23 may be provided on the peripheral surface of the first ram 20.

In the drawing, reference numeral 40 denotes an air vent valve, and 41 denotes an air vent conduit.

[0028]

As described above, the present invention can provide a multi-stage ram lift in which the ascending and descending order can always be predicted. Incidentally, the weight W is moved from the state (A) of FIG. 6 to an intermediate position between the positions (B) and (C) (a position where the first ram 20 is raised to the rising end and the second ram 30 is in the middle of the lifting). If it is assumed that the weight W is raised and the weight W is transferred to another conveyor at the raised position, both rams 20 and 30 are moved.
First, the first ram 20 and the second ram 30 are integrated, and the first ram 20 is raised to the rising end, and then only the second ram 30 is raised. It is possible to provide a multi-stage ram-type lift that can be used most efficiently for interlocking with other equipment, because it always takes a predetermined time to raise W.

Also, in the present invention, assuming that the second ram 30 is stopped suddenly when ascending and descending, a large surge pressure builds up in the first ram 20 and this surge pressure is applied to the conventional orifice bottom plate 2.
If there is no 4, there is an effect on the hydraulic piping and the like. Therefore, the piping and the like must be prepared in advance to be strong against this type of surge pressure. When the oil suddenly stops, the oil passes through the small small through-holes 23 to exhibit a buffering action, thereby reducing the influence of piping and the like.
Since the orifice bottom plate 24 exhibits a shock-absorbing action against an impact at the time of a sudden stop, it is possible to provide a safe multi-stage ram-type lift that does not cause the heavy object W to fall.

[Brief description of the drawings]

FIG. 1 is a partially sectional front view showing an embodiment of a multi-stage ram lift of the present invention.

FIG. 2 is a sectional view of an orifice bottom plate used in the present invention.

FIG. 3 is a hydraulic circuit diagram.

FIG. 4 is a schematic view of the multi-stage ram lift of the present invention.

FIG. 5 is a front view illustrating an operation sequence.

FIG. 6 is a front view for explaining another operation sequence.

[Explanation of symbols]

 Reference Signs List 11 upper opening 12 first metal 20 first ram 21 upper opening 22 second metal 23 small through hole 24 orifice bottom plate 30 second ram

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B66F 7/18 B66F 3/28 F15B 15/14 325 F15B 15/16

Claims (1)

(57) [Scope of request for utility model registration] The first ram (20) is housed in a cylinder (10) having an upper opening (11) and a first metal (12) fixed inside the upper opening (11). One ram (20) is formed in a cylindrical shape and has an upper opening (2
A second metal (22) is fixed inside 1), and an orifice bottom plate (24) having a small through hole (23) at the lower open end is fixed. ) Is a multi-stage ram lift.