JPH0115464Y2 - - Google Patents

Description

[Detailed description of the invention] "Technical field" The present invention relates to a cutter that cuts metal pipes, reinforcing bars, etc. using hydraulic pressure, and in particular, a hydraulically operated cutter that is characterized by a valve mechanism installed inside. Regarding the improvement of

"Prior Art and its Problems" Various types of cutters using hydraulic power that are convenient to carry and easy to handle have been developed for cutting reinforcing bars, metal pipes, etc. at construction sites and the like. For example, a pump mechanism is installed in the casing body of a cutter equipped with an oil tank to pump oil from the oil tank into a cylinder, and the pressurized oil from this pump mechanism moves against a piston head that is slidably disposed inside the cylinder. By sliding the piston rod forward and moving the piston rod connected to the piston head in a straight line, the cutting blade attached to the tip of the piston rod cuts the object to be cut, such as reinforcing bars or metal pipes, and then feeds it under pressure into the cylinder. In order to release the released pressure oil to the outside of the cylinder and move the piston head and piston rod back again, a valve mechanism has been proposed.

However, in this conventional hydraulically operated cutter, the valve mechanism must be installed internally in a position concentric with the piston head, so although the cylinder space for housing the valve mechanism has been reduced, this valve mechanism requires a This requires a guide bar that projects in the axial direction, and the valve body is attached to the guide bar and inserted into the piston rod, making the structure of the valve mechanism itself complicated. Furthermore, in order to be able to handle large-diameter objects to be cut, it is necessary to increase the stroke of the piston rod, and for this purpose the guide bar must be lengthened. However, increasing the length of the guide bar requires high processing accuracy and is difficult to form. Further, in the conventional piston, the guide bar, the inner diameter of the cylinder, the piston rod, and the piston head must all be in concentric positions to function properly. These concentricities also require high precision. Therefore, more advanced molding technology is required to satisfy all of these conditions.

``Purpose of the invention'' This invention solves the above problems all at once. It has a simple structure, is easy to process, does not require high processing accuracy, and has excellent adhesion to and from the oil release passage. The object of the present invention is to provide a hydraulically operated cutter having a valve mechanism.

``Summary of the invention'' The hydraulically operated cutter of the invention is an improvement over the conventional valve mechanism. That is, the present valve mechanism has an annular valve portion seated around the opening of the oil release passage to close it at the tip thereof, and a columnar sliding valve provided inside the piston rod so as to be slidable in the axial direction;
A float spring is installed inside the columnar slide valve at an axial center position facing the oil release passageway and maintains the columnar slide valve in its unseated state when pressure oil is released. It is characterized in that the pressure oil in the cylinder is also applied to the columnar sliding valve while the annular valve body is seated in the oil release passage.

``Embodiments of the invention'' Examples of the hydraulically operated cutter according to the invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a motor, and a casing body 3 is directly connected to the motor 1 and attached to the motor shaft 2.
It is attached to the casing body 3 while being inserted therein. A cylinder 4 is connected to the casing body 3, and an oil tank 5 for storing oil is formed within the cylinder body 3. Further, the casing body 3 is provided with a pump mechanism for pumping oil from the oil tank 5 into the cylinder 4. The pump mechanism 6 includes a cam portion 7 formed on the motor shaft 2.
, a piston 9 that reciprocates via a needle bearing 8 by this cam portion 7, and this piston 9.
is connected to the oil passage 11 via a spring 10.
It consists of an on-off valve 12 disposed inside. The oil passage 11 and the oil passage 14 are formed in communication with the cylinder 4, and the on-off valve 12 normally blocks communication between the oil passage 11 and the oil passage 14 by the elastic force of the spring 13. .

A piston head 15 is disposed inside the cylinder 4 so as to be slidable in the axial direction.
A piston rod 16 is connected to the piston rod 5 in the axial direction. In the figure, the piston rod 16 moves forward in the right direction and moves backward in the left direction. The piston rod 16 is preferably formed at the axial center of the piston head 15, but it is also permissible to form it eccentrically with respect to the axial center of the piston head 15. At the center of the cylinder 4, there is an oil release passage 17 that communicates between the inside of the cylinder 4a and the oil tank 5 outside the cylinder.
is provided. This oil release passage 17 is
It is located at or near the axis of the cylinder 4. Further, an insertion hole 19 is formed in the axis of the piston rod 16 for inserting the valve mechanism 18 from the inner wall side of the cylinder 4. A cylindrical guide portion 20 is fitted into the insertion hole 19 and fixed to the piston head 15 with a fixing screw. Therefore, the guide portion 20 moves together with the piston rod 16. This guide portion 20 includes a cylinder 4
An oil passage 21 is bored through which the insertion hole 19 communicates with the insertion hole 19. This oil passage 21 functions to introduce the pressure oil in the cylinder 4a into the insertion hole 19 and cause it to be applied to the valve mechanism 18.

The valve mechanism 18 opens and closes the opening of the oil release passage 17, and includes a slide valve 22 shaped like a column. The columnar sliding valve 22 is inserted into the insertion hole 19 and is slidable in the axial direction while slidingly contacting the inner surface of the guide portion 20 . An annular valve part 22a is connected to the tip of the columnar sliding valve 22 and is seated apart from the valve seat of the oil release passage 17. They are now seated around a group of people. Therefore, with respect to the oil release passage 17, the columnar sliding valve 22
Even if a slight displacement occurs in the seating position of the driver, the annular valve portion 22a can reliably close the opening of the oil release passage 17 when the driver is seated. The length of the columnar sliding valve 22 can be changed as appropriate depending on the stroke of the piston rod 16.

A stiff spring 2 is attached to the outer periphery of the columnar sliding valve 22.
3 is wrapped. This hard spring 23
The piston rod 16 functions to separate the columnar sliding valve 22 from the valve seat of the oil release passage 17 when the piston rod 16 comes to the most advanced position, and one end of the columnar sliding valve 22 is connected to the annular valve of the columnar sliding valve 22. It is locked to a flange-shaped stopper 24 formed at the end opposite to the portion 22a. Further, a mounting hole 25 is formed in the axis of the columnar sliding valve 22 on the side where the annular valve portion 22a is formed. This mounting hole 25 is connected to the oil release passage 17.
A float spring 26 is mounted in the mounting hole 25 to maintain the columnar sliding valve 22 in a seated state relative to the valve seat of the oil release passage 17 when oil is released.

Also, the piston head 15 and the jaw-shaped casing 2
A spring 28 is interposed between it and 7. This spring 28 is connected to the piston head 15.
The force is applied in the direction of retracting (leftward in the figure). In addition, 29 is a cutting blade attached to the tip of the piston rod 16, 30 is the object to be cut by this cutting blade 29, and 31 is the inside of the cylinder 4a.
It is an air bag that adjusts the change in volume.

Next, the operation of the hydraulically operated cutter having the above configuration will be explained.

As shown in FIG. 1, the piston head 15 is
When the motor 1 is driven with the motor 1 positioned at the rearward end within the cylinder 4, the cam portion 7 rotates in synchronization with the rotation of the motor shaft 2, and the piston 9 reciprocates via the needle bearing 8. The reciprocating movement of the piston 9 forces the oil in the oil tank 5 toward the oil passage 14. The pressure oil generated by the pump mechanism 6 is applied to the on-off valve 12 against the elastic force of the spring 13.
4a inside the cylinder through the oil passage 14.
will be pumped to. The pressure oil forced into the cylinder 4a acts on the flange surface of the piston head 15,
The piston head 15 is moved in the forward direction against the elastic force of the spring 28. As a result, the piston rod 16 also moves forward, and the piston rod 16
The cutting blade 29 at the tip cuts the object 30.
The pressure oil in the cylinder 4a also fills the insertion hole 19 through the oil passage 21 formed in the guide portion 20, and presses the columnar sliding valve 22 in the seating direction. Therefore, the columnar sliding valve 22 has an annular valve portion 22a.
is seated on the valve seat of the oil release passage 17 from around its opening to reliably close the passage 17.

While the piston head 15 is moving forward, the annular valve portion 22a of the columnar sliding valve 22 remains seated on the valve seat of the oil release passage 17 against the elastic force of the float spring 26, and the oil release passage 17
is maintained in a closed state by this columnar sliding valve 22. At this time, since the annular valve portion 22a is seated so as to surround the opening of the oil release passage 17, even if the seating position of the columnar sliding valve 22 with respect to the oil release passage 17 is slightly misaligned, oil leakage will be prevented. No good occlusion is maintained. In addition, guide part 2
0 is fixed to the piston head 15, so it goes without saying that it moves along the columnar sliding valve 22 together with the piston head 15.

The guide portion 20 that has slid forward together with the piston head 15 has its inner tip connected to the stiff spring 2.
3, this tight spring 23 is compressed. When the piston head 15 reaches its most advanced position, the elastic force of the kick spring 23 becomes greater than the pressing force of the pressure oil in the seating direction of the columnar sliding valve 22, causing the annular valve of the columnar sliding valve 22 to Part 2
2a is momentarily separated from the valve seat of the oil release passage 17. As a result, the oil release passage 17 is opened, and the oil passage 14, the oil passage 21, and the inside of the cylinder 4a are opened.
and the oil release passage 17 communicate with each other, and the pressure oil is supplied to the oil tank 5.
The pressure difference on both sides of the flange surface of the piston head 15 is eliminated, and the piston head 15
The movement in the forward direction is stopped, and the cutting operation of the object 30 by the cutting blade 29 is completed.

When the piston head 15 stops, the spring 28, which has been compressed by the piston head 15, pushes the piston head 15 back in the backward direction (to the left in the figure) by its elastic force. During this time, the columnar sliding valve 22 is moved by the float spring 26.
The annular valve portion 22a is kept separated from the valve seat of the oil release passage 17. Therefore, the oil release passage 17 remains open and the piston head 15 slides quickly in the backward direction along the columnar slide valve 22 via the guide section 20. Then, the insertion hole 19 for the piston rod 16
The bottom part of the columnar sliding valve 22 collides with the head surface of the columnar sliding valve 22 to move the columnar sliding valve 22 in the seating direction, whereby the annular valve part 22a is seated on the valve seat of the oil release passage 17. , the oil release passage 17 is hermetically closed. At this time, the backward movement of the piston head 15 is stopped, and one step of the cutting operation is completed.

In this way, the present valve mechanism 18 opens and closes the oil release passage 17 using the columnar sliding valve 22 that slides within the piston rod 16 in accordance with the movement of the piston head 15.
Therefore, the structure of the valve mechanism 18 can be simplified. Further, since the oil release passage 17 is moved into and out of the valve seat by the annular valve portion 22a so as to surround the oil release passage 17,
Even if there is a deviation in the seating position of the columnar sliding valve 22 with respect to the oil release passage 17, the pillar-shaped sliding valve 22 is seated satisfactorily. Therefore, high processing accuracy is not required. Further, the columnar sliding valve 22 for the oil release passage 17 is reliably held in its seated state by the action of pressure oil from the oil passage 21 until the piston rod 16 reaches its most forward position, and when the oil is released, the columnar sliding valve 22 is held in place by the float spring 26. Since the unseated state is maintained, the unseated and unseated state can be smoothly performed without any hindrance. Furthermore, piston rod 1 with a large stroke
6 as well, by changing the length dimension of the columnar sliding valve 22, high precision can be achieved and machining becomes easy.

"Effects of the Invention" As explained above, according to the present invention, since the oil release passage is opened and closed by the columnar sliding valve, the structure can be simplified and the processing is easy. Furthermore, since the annular valve body is seated so as to surround the opening of the oil release passage, even if the columnar slide valve is misaligned when seated, it can be reliably seated. Therefore, high machining accuracy is not required for the valve mechanism. Furthermore, when the annular valve body is seated, pressure oil is applied to the columnar sliding valve to maintain its seated state, and when it is unseated, that is, when the oil is released, the float spring maintains the unseated state of the annular valve body. The oil release passage can be opened and closed accurately at all times.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a hydraulically operated cutter according to the present invention. 4...Cylinder, 6...Pump mechanism, 11,1
4, 21...Oil passage, 15...Piston head,
16... Piston rod, 17... Oil release passage, 18... Valve mechanism, 19... Insertion hole, 20...
Guide part, 22... Column sliding valve, 22a... Annular valve part, 23... Kick spring, 25... Mounting hole, 26... Float spring.

Claims (1)

[Scope of claim for utility model registration] A casing body of a cutter equipped with an oil tank, a cylinder connected to this casing body, a piston head slidably disposed within this cylinder, and a piston head connected to this piston head. a piston rod with a cutting blade attached to its tip; a pump mechanism that pumps oil in the oil tank into the cylinder to move the piston head and piston rod forward in the axial direction; an oil release passageway for releasing oil to the outside of the cylinder; a valve mechanism that opens and closes the opening of this oil release passageway in accordance with the movement of the piston head and piston rod; and a mechanism for unblocking the oil release passageway of this valve mechanism at the most advanced position of the piston rod. In a hydraulically actuated cutter equipped with a spring and in which the piston rod is located concentrically or eccentrically with respect to the axis of the piston head, the valve mechanism seats around and closes off the opening of the oil release passage at the tip. A columnar slide valve having an annular valve portion and provided axially slidably inside the piston rod; It is equipped with a float spring that maintains the unseated state of the columnar sliding valve when released, and further communicates the inside of the piston rod with the inside of the cylinder, and when the annular valve body is seated in the oil release passage, pressurized oil in the cylinder is transferred to the columnar slide. A hydraulically operated cutter that is characterized by its effect on the valve train.