A rotary valve type hydraulic directional control valve, a hydraulic system and a grid punching device

Abstract

The present invention discloses a rotary valve type hydraulic directional control valve, which comprises a valve core, a valve body sleeved with the valve core in clearance fit, end covers hermetically arranged at both ends of the valve body, and a rotary drive assembly connected to the valve core. It is characterized in that a first oil port group and a second oil port group are arranged on the valve body. The first oil port group and the second oil port group respectively comprise an oil inlet, an oil return port and two working oil ports connected to an actuator. First oil hole groups and second oil hole groups are arranged on the valve core. Two oil holes of the first oil hole group are communicated with the first oil port group to form a first passage for oil inlet and oil return, and two oil holes of the second oil hole group are communicated with the second oil port group to form a second passage for oil inlet and oil return. The first passage and the second passage are alternately conducted. The rotary valve type hydraulic directional control valve has a short response time and meets the use requirements of high-speed operation of hydraulic actuators. The present invention also discloses a hydraulic system and a grid punching device based on the rotary valve type hydraulic directional control valve.

Description

Technical Field

[0001] The present invention relates to the technical field of reversing valves, and particularly to a rotary valve type hydraulic reversing valve, a hydraulic system, and a grid punching device. Background Art

[0002] The hydraulic rotary valve is a type of rotary valve type hydraulic reversing valve, and its working principle is to use the rotation of the valve core relative to the valve body to achieve the opening, closing, and reversing of the passage, and it is commonly used in hydraulic systems with high-speed reversing and high-speed excitation. A common hydraulic rotary valve has a set of oil ports arranged circumferentially on the valve body, including an oil inlet, an oil return port, and working oil ports connected to the actuating element. The oil inlet is connected to the oil inlet pipeline, and the oil return port is connected to the oil return pipeline; corresponding oil holes are provided on the valve core, and the sliding or rotation of the valve core relative to the valve body switches the oil inlet and oil outlet states of different oil cavities in the hydraulic actuating element. In the automatic reversing valve structure, the movement of the valve core is mostly through electromagnetic response.

[0003] The process of using the existing rotary valve type hydraulic reversing valve in the grid punching device is as follows: After one punching is completed, while the cutting tool moves upward and resets, the continuous grid is fed to below the cutting tool, and then the cutting tool moves downward again. The time for the cutting tool to move upward and reset and the time for the cutting tool to remain at the high position need to adapt to the feeding speed of the grid, that is, the time for the cutting tool to move upward and reset and the time for the cutting tool to remain at the high position are not less than the feeding speed of the grid. The electromagnetic response time of the valve core in the hydraulic system of the existing rotary valve type hydraulic reversing valve is long, and the time for the cutting tool to move downward and move upward and reset is similar. Therefore, the time for the cutting tool to move downward and the time for the cutting tool to be at the low punching position are too long, which is not conducive to realizing the high-speed punching of the grid. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects existing in the prior art and provide a rotary valve type hydraulic reversing valve with fast response.

[0005] To achieve the above technical effects, the technical solution of the present invention is: A rotary valve type hydraulic reversing valve, including a valve core, a valve body sleeved with the valve core with a clearance fit, end covers hermetically arranged at both ends of the valve body, and a rotary drive assembly connected to the valve core, characterized in that,

[0006] The valve body is provided with a first oil port group and a second oil port group, and the first oil port group and the second oil port group respectively include an oil inlet, an oil return port, and two working oil ports connected to the actuating element;

[0007] The valve core is provided with a first oil hole group and a second oil hole group. Two oil holes of the first oil hole group are connected to the first oil port group to form a first passage for oil inlet and oil return, and two oil holes of the second oil hole group are connected to the second oil port group to form a second passage for oil inlet and oil return; the first passage and the second passage are alternately conducted.

[0008] Preferably, the spool is a unidirectional rotary spool. The spool rotation angle from the second passage to the first passage is the first rotation angle, and the spool rotation angle from the first passage to the second passage is the second rotation angle, and the first rotation angle is greater than the second rotation angle.

[0009] Preferably, the oil holes are all straight holes, and the center lines of the oil holes intersect with the center line of the spool.

[0010] Preferably, the two oil holes in the first oil hole group are arranged in parallel, and / or the two oil holes in the second oil hole group are arranged in parallel.

[0011] Preferably, the center line of the oil hole and the center line of the spool have an acute angle.

[0012] Preferably, an oil seal is arranged between the first oil hole group and the second oil hole group, and the oil seal is arranged along the circumferential direction of the spool.

[0013] Preferably, the rotary drive assembly is a motor assembly.

[0014] Preferably, the oil inlets of the first oil port group and the second oil port group are respectively arranged on both sides of the spool.

[0015] The second object of the present invention is to provide a hydraulic system, including a hydraulic actuator, characterized in that it further includes the above-mentioned rotary valve type hydraulic directional control valve. The hydraulic actuator includes a first oil chamber and a second oil chamber. The first oil hole group is communicated with the oil inlet pipeline of the first oil chamber and the oil outlet pipeline of the second oil chamber, and the second oil hole group is communicated with the oil outlet pipeline of the first oil chamber and the oil inlet pipeline of the second oil chamber.

[0016] Preferably, the hydraulic actuator is a telescopic hydraulic cylinder, and the piston rod of the telescopic hydraulic cylinder passes through the second oil chamber.

[0017] The third object of the present invention is to provide a grid punching device, characterized in that it includes the above-mentioned hydraulic system and a cutting tool, and the cutting tool is connected to the piston rod of the telescopic hydraulic cylinder.

[0018] The advantages and beneficial effects of the present invention are as follows:

[0019] The rotary valve type hydraulic directional control valve drives the spool to rotate actively by using the rotary drive assembly, and the first passage and the second passage formed by the communication of the oil port group and the oil hole group are alternately conducted. Compared with the electromagnetic directional control valve in the prior art, the response time is shortened, meeting the use requirements of the high-speed operation of the hydraulic actuator. Description of the Drawings

[0020] Figure 1It is a schematic cross-sectional structure diagram of the rotary valve type hydraulic directional control valve in Embodiment 1 along the center line of the valve core;

[0021] Figure 2 It is along Figure 1 The A-A cross-sectional view in;

[0022] Figure 3 It is a schematic partial structure diagram of the valve core and valve body of the rotary valve type hydraulic directional control valve in Embodiment 2;

[0023] Figure 4 It is along Figure 3 The B-B cross-sectional view in;

[0024] Figure 5 It is a schematic partial structure diagram of the valve core and valve body of the rotary valve type hydraulic directional control valve in Embodiment 3;

[0025] Figure 6 It is along Figure 5 The C-C cross-sectional view in;

[0026] Figure 7 It is a schematic partial structure diagram of the valve core and valve body of the rotary valve type hydraulic directional control valve in Embodiment 4;

[0027] Figure 8 It is along Figure 7 The D-D cross-sectional view in;

[0028] Figure 9 It is a schematic structure diagram of the valve core of the rotary valve type hydraulic directional control valve in Embodiment 5;

[0029] Figure 10 It is a schematic structure diagram of the hydraulic system in Embodiment 6;

[0030] Figure 11 It is a schematic structure diagram of the grid punching equipment in Embodiment 7;

[0031] In the figure: 1. Valve core; 2. Valve body; 3. End cover; 4. Rotary drive assembly; 5. First oil port group; 6. Second oil port group; 7. First oil hole group; 8. Second oil hole group; 9. Oil seal; 10. Hydraulic actuator; 101. First oil cavity; 102. Second oil cavity; 103. Piston rod; 11. Cutting tool. Specific embodiments

[0032] The following combines the accompanying drawings and embodiments to further describe the specific embodiments of the present invention. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0033] The rotary valve is one of the known types of reversing valves. The selection range of the rotary drive assembly connected to the valve core is known technology, including but not limited to high-speed motors, motor output and transmission via a rotary transmission mechanism. The rotary drive assembly is located outside the valve body. The rotary drive assembly also includes a transmission shaft, and the transmission shaft passes through the end cover and is connected to the valve core.

[0034] The setting of the oil port group and the oil hole group

[0035] The oil ports in the oil port group and the oil holes in the oil hole group should be set to match each other to form the first passage and the second passage. The first passage and the second passage respectively include an oil inlet passage and an oil return passage. When the valve core rotates a certain angle, the oil inlet passage and the oil return passage of the first passage are formed simultaneously. Then, when the valve core rotates another certain angle, the oil inlet passage and the oil outlet passage of the second passage are formed simultaneously.

[0036] The same oil port group respectively includes an oil inlet port, an oil return port, and two working oil ports connected to the actuator. Taking the connection between the first oil port group and the first oil hole group to form the first passage as an example, the oil inlet port P of the first oil port group is arranged opposite to the working oil port A. The above-mentioned opposite arrangement is based on the oil hole that communicates the oil inlet port P and the working oil port A. Similarly, the working oil hole B is also arranged opposite to the oil outlet port T.

[0037] The oil holes in the first oil hole group can be straight holes or arc-shaped holes. Considering the oil pressure and the structural stability of the valve core, the preferred oil holes are straight holes. Based on the straight-hole-shaped oil holes, the distribution of the four oil ports in the first oil port group depends on the relative positions of the oil holes in the first oil hole group:

[0038] When two oil holes are arranged in parallel and the projections of the oil holes on the cross-section of the valve core coincide (the oil holes may or may not intersect with the center line of the valve core), the center points of the oil inlet port, the oil return port, and the two working oil ports connected to the actuator in the first oil port group (taking the oil port as a perfect circle as an example) are respectively arranged on two generatrices of the cylindrical inner cavity of the valve body;

[0039] When the midpoints of the projections of the center lines of the two oil holes on the cross-section of the valve core intersect or the extension lines of the projections intersect, or the projections of the two oil holes are parallel, the center points of the oil inlet port, the oil return port, and the two working oil ports connected to the actuator in the first oil port group (taking the oil port as a perfect circle as an example) are respectively arranged on four generatrices of the cylindrical inner cavity of the valve body;

[0040] When one end point of the projections of the center lines of the two oil holes on the cross-section of the valve core intersects, the center points of the oil inlet port, the oil return port, and the two working oil ports connected to the actuator in the first oil port group (taking the oil port as a perfect circle as an example) are respectively arranged on three generatrices of the cylindrical inner cavity of the valve body.

[0041] Preferably, the oil inlets in the first oil port group and the second oil port group are separately arranged on both sides of the valve body. Along the axial direction of the cylindrical inner cavity of the valve body, the two oil inlets are arranged opposite to each other or offset. The technical effect of the above structure is that the oil inlets of the first oil port group and the second oil port group are both filled with high-pressure hydraulic oil. When the valve core rotates to the state where both the first passage and the second passage are disconnected, the high-pressure oil extrusion forces on both sides of the valve core cancel each other out, ensuring the normal clearance between the valve core and the valve body, and also contributing to extending the service life of the valve core and the valve body.

[0042] The first rotation angle and the second rotation angle

[0043] Taking the telescopic hydraulic cylinder of the hydraulic actuator as an example, the alternating conduction process of the first passage and the second passage is as follows:

[0044] S1: The first passage is connected, and the piston rod makes an extending or retracting movement;

[0045] S2: The first passage and the second passage are disconnected, and the piston rod maintains the extended end position or the retracted end position of S1;

[0046] S3: The second passage is connected, and the piston rod makes a retracting or extending movement opposite to S1;

[0047] S4: The first passage and the second passage are disconnected, and the piston rod maintains the retracted end position or the extended end position of S3;

[0048] S5: The first passage is connected again.

[0049] Based on the description of the passage conduction process, preferably, the rotation angle of the valve core when switching from the second passage to the first passage is the first rotation angle, and the rotation angle of the valve core when switching from the first passage to the second passage is the second rotation angle. The first rotation angle is greater than the second rotation angle. Based on a certain valve core rotation angular velocity, the holding time of S4 is longer than that of S2. Applying the above to a punching device, using S4 for feeding and minimizing the holding time of S2 (by adjusting the angle difference between the first rotation angle and the second rotation angle) can reduce the time consumed for a single punching.

[0050] Oil seal

[0051] The function of the oil seal is to prevent the high-pressure oil at the oil inlets of the first oil port group and the second oil port group from passing through the clearance between the valve body and the valve core and affecting the oil inlet and outlet of the hydraulic actuator when neither the first passage nor the second passage is connected, or when only the first passage or the second passage is connected alone. The oil seal is a known structure and is usually arranged circumferentially around the valve core and is a closed ring.

[0052] The oil seal can be separately arranged between the first oil hole group and the second oil hole group, or between the two oil holes of the first oil hole group and the second oil hole group, or between the oil hole and the end of the valve core. The oil seal can also be arranged at the above three positions simultaneously.

[0053] The acute angle between the center line of the oil hole and the center line of the spool

[0054] The oil hole is a straight hole. The center line of the oil hole intersects and is perpendicular to the center line of the spool. When the spool rotates 360°, the oil hole and the oil port are connected twice to form the first passage; when the center line of the oil hole intersects the center line of the spool and has an acute angle, when the spool rotates 360°, the oil hole and the oil port are connected once to form the first passage. Based on the same spool rotation angular velocity and reaching the same commutation frequency, for a spool with a straight oil hole, the spool diameter is larger, which is not conducive to spool heat dissipation.

[0055] Hydraulic actuators

[0056] Hydraulic actuators include existing hydraulic motors and hydraulic cylinders. Based on the hydraulic switching valve of the present invention, hydraulic motors and hydraulic cylinders are suitable for high-speed production. Hydraulic cylinders include telescopic type, rotary type, and telescopic rotary integrated type.

[0057] Embodiment 1

[0058] As Figure 1-2 shown, the rotary valve type hydraulic commutation valve in Embodiment 1 includes a spool 1, a valve body 2 sleeved on the spool 1 with a clearance fit, end caps 3 hermetically arranged at both ends of the valve body 2, and a rotary drive assembly 4 connected to the spool 1;

[0059] The valve body 2 is provided with a first oil port group 5 and a second oil port group 6. The first oil port group 5 includes an oil inlet P, an oil return port T, and two working oil ports A and B connected to the actuator. The second oil port group 6 includes an oil inlet P', an oil return port T', and two working oil ports A' and B' connected to the actuator;

[0060] The spool 1 is provided with a first oil hole group 7 and a second oil hole group 8. Two oil holes of the first oil hole group 7 are connected to the first oil port group 5 to form the first passage for oil inlet and return. Two oil holes of the second oil hole group 8 are connected to the second oil port group 6 to form the second passage for oil inlet and return; The first passage and the second passage are alternately conducted.

[0061] The oil holes are all straight holes, and the center line of the oil hole intersects and is perpendicular to the center line of the spool 1.

[0062] Two oil holes of the first oil hole group 7 are arranged in parallel, and two oil holes of the second oil hole group 8 are arranged in parallel; The rotary drive assembly 4 is a motor assembly.

[0063] Figure 2 The dotted line in the spool 1 in

[0064] represents the first oil hole group, and the first oil port group 5 and the second oil port group 6 overlap.

[0065] In Embodiment 1, the valve core rotates counterclockwise. Figure 2 In Figure 2 , the first oil hole group communicates with the first oil port group to form a first passage. The valve core rotates counterclockwise by 90°. The second oil hole group communicates with the second oil port group to form a second passage. Then the valve core rotates counterclockwise by 90°, and the first oil hole group communicates with the first oil port group again to form a first passage.

[0066] Embodiment 2

[0067] As Figure 3-4 shown, Embodiment 2 is based on Embodiment 1. The difference is that the center lines of the oil holes in the first oil hole group 7 and the second oil hole group 8 both have an acute angle with the center line of the valve core 1.

[0068] The valve core in Embodiment 2 rotates 360°, forming a first passage and a second passage once.

[0069] In Embodiment 2, the valve core rotates counterclockwise. Figure 4 In Figure 4 , the first oil hole group 7 communicates with the first oil port group 5 to form a first passage. The valve core rotates counterclockwise by 35°. The second oil hole group 8 communicates with the second oil port group 6 to form a second passage. Then the valve core rotates counterclockwise by 325°, and the first oil hole group 7 communicates with the first oil port group 5 again to form a first passage.

[0070] Embodiment 3

[0071] As Figure 5-6 shown, Embodiment 3 is based on Embodiment 1. The difference is that the four oil ports in the first oil port group 7 are arranged in pairs opposite to each other. The center lines of the two oil holes in the first oil hole group 7 are perpendicular to the center line of the valve core 1 but do not intersect. Similarly, the center lines of the two oil holes in the second oil hole group 8 are also perpendicular to the center line of the valve core 1 but do not intersect. The projections of the center lines of the oil holes in the first oil hole group 7 and the second oil hole group 8 on the cross-section of the valve core 1 intersect.

[0072] In Embodiment 3, the valve core rotates counterclockwise. Figure 6 In Figure 6 , the first oil hole group 7 communicates with the first oil port group 5 to form a first passage. The valve core rotates counterclockwise by 40°. The second oil hole group 8 communicates with the second oil port group 6 to form a second passage. Then the valve core rotates counterclockwise by 320°, and the first oil hole group 7 communicates with the first oil port group 5 again to form a first passage.

[0073] Embodiment 4

[0074] As Figure 7-8 shown, Embodiment 4 is based on Embodiment 1. The difference is that in Embodiment 5, the oil holes in the first oil hole group are arranged in a cross shape, and the center lines of the oil holes intersect with the center line of the valve core. Correspondingly, the center points of the oil ports in the first oil port group that cooperate with the first oil hole group are distributed on the four generatrices of the cylindrical inner cavity of the valve body.

[0075] The oil holes of the second oil hole group in Embodiment 4 are arranged in the same way as those of the first oil hole group.

[0076] In Embodiment 4, the spool rotates counterclockwise. Figure 8 In it, the first oil hole group 7 communicates with the first oil port group 5 to form a first passage. The spool rotates counterclockwise by 30°. The second oil hole group 8 communicates with the second oil port group 6 to form a second passage. Then the spool rotates counterclockwise by 120°, and the first oil hole group 7 communicates with the first oil port group 5 again to form a first passage.

[0077] Embodiment 5

[0078] As Figure 9 shown, Embodiment 5 is based on Embodiment 2. The difference is that on both sides of the orifice of each oil hole along the axial direction of the spool 1, a closed annular oil seal 9 is provided, and the oil seal 9 is arranged circumferentially along the side surface of the spool 1.

[0079] Embodiment 6

[0080] As Figure 10 shown, the hydraulic system of Embodiment 6 includes a hydraulic actuator 10, and also includes the rotary valve type hydraulic directional control valve of Embodiment 2. The hydraulic actuator includes a first oil chamber 101 and a second oil chamber 102. The first oil hole group 7 is communicated with the oil inlet pipeline of the first oil chamber 101 and the oil outlet pipeline of the second oil chamber 102. The second oil hole group 8 is communicated with the oil outlet pipeline of the first oil chamber 101 and the oil inlet pipeline of the second oil chamber 102; the oil inlet port P of the first oil hole group 7 and the second oil hole group 8 is communicated with the oil inlet pipeline connected with an oil pump, and the oil return port T is communicated with the oil return pipeline connected with an oil tank.

[0081] The hydraulic actuator 10 is a telescopic hydraulic cylinder, and the piston rod 103 of the telescopic hydraulic cylinder penetrates through the second oil chamber 102.

[0082] The operation process of the hydraulic system of Embodiment 6 is as follows in a cycle:

[0083] S1: The first oil hole group 7 of the spool 1 communicates with the first oil port group 5, the oil inlet port P intakes oil. Through the working oil port A, the hydraulic oil enters the first oil chamber 101. The piston rod 103 extends downward out of the cylinder body. The piston rod 103 extrudes the hydraulic oil in the second oil chamber 102, and it returns to the oil tank through the working oil port B and the oil return port T.

[0084] S2: The spool 1 rotates counterclockwise. Before the second passage is connected, the first passage is disconnected, and the piston rod maintains the end state of the extending action in S1. The duration of this section is counted as t1.

[0085] S3: The spool 1 continues to rotate counterclockwise, the second oil hole group 8 communicates with the second oil port group 6, the oil inlet P' admits oil, and via the working oil port B', the hydraulic oil enters the second oil chamber 102. The piston rod 103 retracts upward into the cylinder block. The piston rod 103 extrudes the hydraulic oil in the first oil chamber 101, and returns it to the oil sump through the working oil port A' and the oil return port T'.

[0086] S4: The spool 1 rotates counterclockwise. Before the first passage is connected, the second passage is disconnected. The piston rod 104 maintains the end state of the retraction action in S3. The duration of this period is recorded as t2.

[0087] Since the spool 1 needs to rotate counterclockwise by 35° in S2 for the second passage to be fully connected, and the spool 1 needs to rotate counterclockwise by 325° in S4 for the first passage to be fully connected. Based on the constant angular velocity of the spool 1 rotation, t2 is much greater than t1.

[0088] Embodiment 7

[0089] As Figure 11 shown, the grid punching device of Embodiment 7 includes the hydraulic system of Embodiment 6 and a cutter 11. The cutter 11 is connected to the piston rod 103 of the telescopic hydraulic cylinder.

[0090] Since the piston rod maintains the end state of the retraction action in S3 in S4, when applied to a high-speed punching device, the cutter is at a high position and feeds in S4; the piston rod 103 in S1 can drive the cutter 11 to move downward to a low position to complete the cutting; the cutter 11 stays at the low position for a short time in S2; while the piston rod 103 retracts upward into the cylinder block in S3, the cutter 11 moves upward to a high position, and S4 is cycled.

[0091] The hydraulic systems including the hydraulic control valves of Embodiments 1, 3, 4, and 5 can also be substituted for Embodiment 6 and applied to the high-speed punching device. The difference is that during the use of the punching device including the hydraulic control valve of Embodiment 1, the duration of the cutter at the high position and the low position is the same. The rotary valve type hydraulic control valve of Embodiment 1 is used in conjunction with a high-speed motor to achieve the purpose of reducing the response time of the switching valve. While during the use of the punching devices including the hydraulic control valves of Embodiments 3, 4, and 5, t2 is greater than t1 in all cases.

[0092] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A rotary valve type hydraulic directional control valve, comprising a valve core, a valve body sleeved on the valve core with a clearance fit, end covers hermetically arranged at both ends of the valve body, and a rotary drive assembly connected to the valve core, characterized in that, a first oil port group and a second oil port group are arranged on the valve body, and the first oil port group and the second oil port group respectively include an oil inlet, an oil return port, and two working oil ports connected to an actuator; a first oil hole group and a second oil hole group are arranged on the valve core, two oil holes of the first oil hole group are communicated with the first oil port group to form a first passage for oil inlet and oil return, and two oil holes of the second oil hole group are communicated with the second oil port group to form a second passage for oil inlet and oil return; the first passage and the second passage are alternately conducted; the valve core is a one-way rotary valve core, the valve core rotation angle from the second passage to the first passage is a first rotation angle, and the valve core rotation angle from the first passage to the second passage is a second rotation angle, and the first rotation angle is greater than the second rotation angle; the central line of the oil hole intersects the central line of the valve core, and the central line of the oil hole and the central line of the valve core have an acute angle.

2. The rotary valve type hydraulic directional control valve according to claim 1, characterized in that, The two oil holes of the first oil hole group are arranged in parallel, and / or the two oil holes of the second oil hole group are arranged in parallel.

3. The rotary valve type hydraulic directional control valve according to claim 1, wherein An oil seal is arranged between the first oil hole group and the second oil hole group, and the oil seal is arranged along the circumferential direction of the valve core.

4. The rotary valve type hydraulic directional control valve according to claim 1, characterized in that, The rotary drive assembly is a motor assembly.

5. The rotary valve type hydraulic directional control valve according to claim 1, characterized in that, The oil inlets of the first oil port group and the second oil port group are respectively arranged on both sides of the valve core.

6. A hydraulic system, comprising a hydraulic actuator, characterized in that, It further includes the rotary valve type hydraulic directional control valve according to any one of claims 1 to 5, and the hydraulic actuator includes a first oil chamber and a second oil chamber. The first oil hole group is communicated with the oil inlet pipeline of the first oil chamber and the oil outlet pipeline of the second oil chamber, and the second oil hole group is communicated with the oil outlet pipeline of the first oil chamber and the oil inlet pipeline of the second oil chamber.

7. The hydraulic system according to claim 6, characterized in that, The hydraulic actuator is a telescopic hydraulic cylinder, and the piston rod of the telescopic hydraulic cylinder passes through the second oil chamber.

8. A grid punching device, characterized in that, It includes the hydraulic system according to claim 7 and a cutting tool, and the cutting tool is connected to the piston rod of the telescopic hydraulic cylinder.

Images