JP2010071441A - Boost type cylinder apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boost type cylinder apparatus capable of surely swinging a cutting arm of a cutter in two directions which are a closing direction and an opening direction. <P>SOLUTION: When load is applied to a hydraulic cylinder 1 opening/closing the movable cutting arm 76 of the cutter, a booster cylinder 20 is operated to form boost oil, and the boost oil is fed into the hydraulic cylinder 1 to increase the operating pressure of the hydraulic cylinder 1. An outlet side selector valve 30 is provided for selectively switching and feeding the boost oil formed by the boost cylinder 20, to a bottom chamber 4 and a rod chamber 5 of the hydraulic cylinder 1. When load is applied in opening the movable cutting arm 76 by the contraction of the hydraulic cylinder 1, the boost oil is fed into the rod chamber 5 by the switching of the outlet side selector valve 30. When load is applied in closing the movable cutting arm 76 by the expansion of the hydraulic cylinder 1, the boost oil is fed into the bottom chamber 4 by the switching of the outlet side selector valve 30. The movable cutting arm 76 is thereby opened/closed surely. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pressure-increasing cylinder device used for driving a cutting machine for cutting an iron plate, a steel material or the like.

  As a cutting machine that cuts an object to be cut such as an iron plate or a steel frame, the one shown in FIG. 10 is conventionally known. In this cutting machine, a frame 71 is rotatably connected to a bracket 70 attached to an arm tip of a hydraulic excavator, and a fulcrum shaft 73 and a fixed shaft 74 are passed to a pair of side plates 72 provided on the frame 71, The shafts 73 and 74 support the central portion and the rear end portion of the fixed cutting arm 75, and support the movable cutting arm 76 so that it can be opened and closed around the fulcrum shaft 73. The hydraulic cylinder 1 of the pressure-increasing cylinder device X is swung in the closing direction, and cutting objects such as iron plates and steel frames are cut by cutting blades 77 and 78 provided on the cutting arms 75 and 76, respectively.

  As a pressure-increasing cylinder device employed in the cutting machine, the one described in Patent Document 1 has been conventionally known. This pressure-increasing cylinder device has a hydraulic cylinder 1 for opening and closing the movable cutting arm 76 and a booster cylinder that forms pressure-increasing oil. When the load on the hydraulic cylinder 1 increases, the pressure is increased by the booster cylinder. Oil is formed and the pressure-increasing oil is fed into the hydraulic cylinder 1 to increase the operating pressure of the hydraulic cylinder 1.

Japanese Patent Publication No. 7-6524

  By the way, in the pressure-increasing cylinder device described in Patent Document 1, the booster cylinder is operated at the time of a load increase at the time of cutting to swing the movable cutting arm 76 in the closing direction to cut the object to be cut. Since the hydraulic cylinder 1 is of a one-way operation type in which the pressurized oil is fed into the hydraulic cylinder 1, the output when the hydraulic cylinder 1 is contracted is significantly smaller than the output when the hydraulic cylinder 1 is expanded.

  Therefore, when the hydraulic cylinder 1 is extended, the movable cutting arm 76 is swung in the closing direction, and the cutting object is cut by the movable cutting arm 76 and the fixed cutting arm 75, as shown in FIG. If the object to be cut W is not cut, and if it is firmly bitten between the cutting blade 77 of the fixed cutting arm 75 and the cutting blade 78 of the movable cutting arm 76, the movable cutting arm 76 cannot be swung in the opening direction. Occurs.

  In the cutting machine, as described above, one of the pair of cutting arms is fixed, the other is swingable, and the swingable cutting arm is opened and closed by a hydraulic cylinder, Each of the cutting arms is swingably supported, and each of the pair of cutting arms is opened and closed by a hydraulic cylinder of a pressure-increasing cylinder device. This cutting machine also cuts a pair of cutting arms. When the object to be cut is caught between the blades, the pair of cutting arms may not be opened.

  An object of the present invention is to provide a pressure-increasing cylinder device capable of reliably swinging a cutting arm of a cutting machine in two directions: a closing direction and an opening direction.

  In order to solve the above problems, in the present invention, a hydraulic cylinder that relatively opens and closes a pair of cutting arms of a cutting machine, a hydraulic pump for operating the hydraulic cylinder, and a pressure discharged from the hydraulic pump An operation valve that selectively supplies oil to an expansion oil passage that communicates with the bottom chamber of the hydraulic cylinder and a contraction oil passage that communicates with the rod chamber, and pressure increase by pressure oil supplied from the hydraulic pump The piston is reciprocated, and the pressure-increasing oil is formed in the first pressure-increasing chamber by moving the pressure-increasing piston in one direction, and the oil in the second pressure-increasing chamber is formed by moving in the other direction. Booster cylinder for supplying the booster oil to the bottom chamber of the hydraulic cylinder, the first pressurizing chamber for moving the booster piston of the booster cylinder in one direction, and the second pressurizing for moving in the other direction Hydraulic against chamber A switching valve for switching and supplying the pressure oil discharged from the pump, and a direction in which the switching valve is switched to the booster cylinder by being released by the pressure of the pressure oil sent from the hydraulic pump when a load is applied to the hydraulic cylinder A sequence valve for supplying a pilot pressure for switching control of the booster cylinder, and when the boosting piston of the booster cylinder moves to a position slightly before reaching the stroke end, the pilot pressure supplied from the sequence valve is switched. In the pressure-increasing cylinder device that is added to the valve to switch the switching valve, the booster cylinder pressure increasing oil flows into the bottom chamber using the pressure oil supplied from the hydraulic pump to the bottom chamber as a pilot pressure. At the same time, booster cylinder pressure is increased using the pressure oil supplied from the hydraulic pump to the rod chamber as pilot pressure. From the hydraulic pump using the pilot-operated outlet side switching valve that switches to flow into the rod chamber, the pressure oil supplied from the hydraulic pump to the bottom chamber and the pressure oil supplied from the hydraulic pump to the rod chamber as a pilot pressure. A configuration provided with a pilot-operated inlet side switching valve that switches so that the discharged pressure oil flows toward the sequence valve is adopted.

  In the pressure-increasing cylinder device configured as described above, when the operation valve is switched in a direction in which the discharge port of the hydraulic pump communicates with the bottom chamber of the hydraulic cylinder, the pressure oil discharged from the hydraulic pump is supplied to the bottom chamber, and the hydraulic cylinder The cutting arm of the cutting machine swings in the closing direction to cut the object to be cut.

  If the object to be cut is thick or hard and not cut and the load on the hydraulic cylinder increases, the inlet side switching valve switches in the direction in which the hydraulic oil from the hydraulic pump flows to the sequence valve, and the booster cylinder operates. To form a pressurized oil.

  On the other hand, the outlet side switching valve is switched to the direction in which the booster cylinder and the bottom chamber are communicated with each other by the pressure of the pressure oil flowing from the hydraulic pump to the bottom chamber. For this reason, the boosted oil formed by the booster cylinder is sent to the bottom chamber, and the cutting arm of the cutting machine swings in the closing direction by supplying the boosted oil to the bottom chamber, and the cutting object is moved with a strong force. Disconnect.

  Here, since the cutting machine is configured to cut the cutting object by swinging the cutting arm, the cutting object is not cut due to backlash of the opening / closing center of the cutting arm, warping of the cutting arm, twisting, etc. There is a case where a jamming state is generated in which the blade is caught between the cutting blades of the pair of cutting arms and stops moving.

  In this case, the operation valve is switched so that the pressure oil of the hydraulic pump flows into the rod chamber of the hydraulic cylinder, the pressure oil is supplied to the rod chamber, and the hydraulic cylinder is contracted to open the movable cutting arm of the cutting machine. To.

  Here, when the biting object is strong, the cutting arm may not move even if pressure oil is supplied to the rod chamber. At this time, the inlet side switching valve is switched in the direction in which the pressure oil from the hydraulic pump flows to the sequence valve, and the booster cylinder is activated to form pressure-increasing oil.

  On the other hand, the outlet side switching valve is switched in a direction in which the booster cylinder and the rod chamber communicate with each other by the pressure of the pressure oil flowing from the hydraulic pump to the rod chamber. For this reason, the boosted oil formed by the booster cylinder is fed into the rod chamber, the supply of the boosted oil to the rod chamber moves the hydraulic cylinder in the contracting direction, and the cutting arm of the cutting machine swings in the opening direction. To release the bite of the object to be cut.

  As described above, when the object to be cut is bitten, the booster cylinder is activated to form the pressure-increasing oil, and the pressure-increasing oil is fed into the rod chamber of the cylinder, so that the cutting arm of the cutting machine is reliably opened. be able to.

  In general, in a pressure-increasing cylinder device, a relief valve is incorporated for the purpose of preventing leakage of pressurized oil from the connection parts of various oil passages and preventing damage to the oil passages. The pressure of the oil pressure in the oil passage is held at the set pressure.

  At this time, when the set pressure of the relief valve that holds the extension oil passage at the set pressure is equal to the set pressure of the relief valve that holds the contraction oil passage at the set pressure, the difference in area between the side surface of the piston rod chamber and the side of the bottom chamber in the hydraulic cylinder Therefore, there is a case where a difference occurs between the output when the hydraulic cylinder is contracted and the output when the hydraulic cylinder is extended, and the biting of the object to be cut cannot be released.

  Therefore, by making the set pressure of the relief valve that holds the contraction oil passage at the set pressure higher than the set pressure of the relief valve that holds the extension oil passage at the set pressure, the output when the hydraulic cylinder is contracted and the The difference in output can be reduced, and the biting of the object to be cut can be released more reliably.

  Here, since the set pressure of the relief valve can be adjusted by manual operation, the set pressure of the relief valve that holds the contraction oil passage at the set pressure is set to the relief valve that holds the extension oil passage at the set pressure. The operation of adjusting the pressure higher than the pressure may be performed in advance before starting the cutting work, or may be performed when a jamming state occurs.

  As described above, in the present invention, when the hydraulic cylinder that supplies pressure oil discharged from the hydraulic pump to the bottom chamber is extended, if the load is applied to the hydraulic cylinder, the pressure oil flows from the hydraulic pump to the sequence valve. As the inlet side switching valve is switched to the booster cylinder, the booster cylinder is switched to the direction in which the booster oil formed by the booster cylinder flows into the bottom chamber of the hydraulic cylinder. The movable cylinder can be extended and the movable cutting arm of the cutting machine can be reliably swung in the closing direction.

  In addition, when the hydraulic cylinder that supplies pressure oil discharged from the hydraulic pump to the rod chamber contracts, if a load is applied to the hydraulic cylinder, the inlet side switching valve switches in the direction in which the hydraulic oil from the hydraulic pump flows to the sequence valve. Since the booster cylinder is activated and the outlet side switching valve is switched to the direction in which the boosted oil formed by the booster cylinder flows into the rod chamber of the hydraulic cylinder, the hydraulic cylinder can be reliably contracted with a large force. The hydraulic cylinder can be reliably swung in the direction of opening the cutting arm of the cutting machine.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the hydraulic cylinder 1 for opening and closing the movable cutting arm 76 of the cutting machine of FIG. 10 with respect to the fixed cutting arm 75 includes a piston 3 slidably incorporated in the cylinder body 2 and the cylinder body 2. The bottom chamber 4 and the rod chamber 5 are formed inside the piston rod 6, and the piston rod 6 provided in the piston 3 is slidably passed through the rod cover 2a of the cylinder body 2.

  The expansion oil passage 7 communicating with the bottom chamber 4 of the hydraulic cylinder 1 is connected to the A port of the operation valve 8 composed of a 4-port 3-position switching valve, and the contraction oil passage 9 communicating with the rod chamber 5 is an operation valve. 8 B ports are connected.

  The position of the operation valve 8 is switched by a lever operation, and the pressure oil discharged from the hydraulic pump 10 is selectively switched between the expansion oil passage 7 and the contraction oil passage 9 and supplied. Here, when the pressure oil is supplied to the extension oil passage 7, the pressure oil is supplied to the bottom chamber 4, so that the piston 3 moves in a direction in which the volume of the rod chamber 5 decreases, and the hydraulic cylinder 1 is moved. Stretch. On the other hand, when pressure oil is supplied to the contraction oil passage 9, the pressure oil is supplied to the rod chamber 5, so that the piston 3 moves in a direction in which the volume of the bottom chamber 4 decreases, and the hydraulic cylinder 1 contracts. It is supposed to be.

  A pilot operation type first check valve 11 is incorporated in the extension oil passage 7, while a pilot operation type second check valve 12 is incorporated in the contraction oil passage 9. When pressure oil is supplied to the contraction oil passage 9, the first check valve 11 is held in an open state using the pressure oil as a pilot pressure. In the open state, the oil flow from the bottom chamber 4 to the tank T is allowed.

  On the other hand, when pressure oil is supplied to the extension oil passage 7, the second check valve 12 is held in an open state using the pressure oil as a pilot pressure. In the opened state, the oil flow from the rod chamber 5 to the tank T is allowed.

  The hydraulic cylinder 1 is supplied with boosted oil from the booster cylinder 20 when a load is applied to the piston rod 6 during expansion and contraction.

  As shown in FIG. 2, the booster cylinder 20 has a cylinder body 21 and a pressure-increasing piston 22 incorporated therein, and the pressure-increasing piston 22 is integrated with a large-diameter portion 22a and both sides thereof. The first small-diameter portion 22b and the second small-diameter portion 22c provided in the first and second small-diameter portions 22c.

  The cylinder body 21 slides over the large diameter chamber 23 for slidably guiding the large diameter portion 22a, and the first pressure increasing chamber 24a and the second small diameter portion 22c for slidably guiding the first small diameter portion 22b. A second pressure-increasing chamber 24b that is movably guided is formed.

  The large-diameter chamber 23 is partitioned into a first pressurizing chamber 23a and a second pressurizing chamber 23b by incorporating the large-diameter portion 22a, and the first pressurizing chamber 23a and the first pressurizing chamber 24a are increased. A check valve 26a is incorporated which communicates with the first passage 25a formed in the pressure piston 22 and prevents the oil in the first pressure increasing chamber 24a from flowing into the first pressurizing chamber 23a. ing.

  On the other hand, the second pressurizing chamber 23b and the second pressure increasing chamber 24b communicate with each other via a second passage 25b formed in the pressure increasing piston 22, and oil in the second pressure increasing chamber 24b is in the second passage 25b. 2 A check valve 26b for preventing flow into the pressurizing chamber 23b is incorporated.

  The first pressure increasing chamber 24a and the second pressure increasing chamber 24b communicate with each other via a pressure increasing supply passage 27. The pressure increasing supply passage 27 is connected to a P port of an outlet side switching valve 30 including a three-port three-position switching valve. Has been.

  The A port of the outlet side switching valve 30 communicates with the rod chamber 5 of the hydraulic cylinder 1 via a passage 31 connected to the contraction oil passage 9, and the B port of the outlet side switching valve 30 is connected to the extension oil passage 7. It communicates with the bottom chamber 4 of the hydraulic cylinder 1 through a passage 32 connected to the hydraulic cylinder 1.

  The outlet side switching valve 30 uses the pressure oil pressure in the rod chamber 5 as a pilot pressure, and when the pilot pressure is applied, the pressure increasing supply passage 27 is switched so as to communicate with the rod chamber 5. The pressure of the pressure oil is set as a pilot pressure, and when the pilot pressure is applied, the pressure increasing supply passage 27 is switched so as to communicate with the bottom chamber 4.

  A first circumferential groove 28a, a second circumferential groove 28b, and a third circumferential groove 28c are formed on the inner diameter surface of the first pressure increasing chamber 24a at intervals in the sliding direction of the pressure increasing piston 22, while the pressure increasing piston 22 is provided. On the outer diameter surface of the first small-diameter portion 22b, a circumferential groove-like switching passage 29 is formed.

  The switching passage 29 allows the first circumferential groove 28a and the second circumferential groove 28b to communicate with each other when the pressure-increasing piston 22 moves to a position near the limit of the forward movement stroke in which the volume of the first pressurizing chamber 23a is reduced. The second circumferential groove 28b and the third circumferential groove 28c are made to communicate with each other when the pressure-increasing piston 22 moves to a position near the limit position of the reverse stroke in which the volume of the second pressurizing chamber 23b is reduced. It has become.

  The pressure oil pressure-fed to the extension oil passage 7 by driving the hydraulic pump 10 is also sent to the branch passage 7 a that branches from between the operation valve 8 and the first check valve 11. The branch path 7a is connected to a P port of a pilot operated inlet side switching valve 40 comprising a four port three position switching valve.

  On the other hand, the pressure oil pressure-fed from the hydraulic pump 10 to the contracting oil passage 9 by switching the operation valve 8 is also sent to the branch passage 9 a that branches from between the operation valve 8 and the second check valve 12. The branch path 9 a is connected to the T port of the inlet side switching valve 40.

  The AP oil passage 41 connected to the A port of the inlet side switching valve 40 is connected to the P port of the switching valve 50 consisting of a pilot operated 4-port two-position switching valve, and to the B port of the inlet side switching valve 40. The connected BT oil passage 42 is connected to the T port of the switching valve 50.

  The A port of the switching valve 50 communicates with the first pressurizing chamber 23a of the booster cylinder 20 via the first oil supply passage 51, and the B port of the changeover valve 50 and the second pressurizing chamber 23b communicate with the second oil supply passage 52. It communicates through.

  Further, the pilot port of the switching valve 50 and the second circumferential groove 28b formed in the booster cylinder 20 communicate with each other through the pilot passage 53, and when the pilot pressure is applied from the pilot passage 53 to the switching valve 50, the switching valve 50 50 switches to a position where the AP oil passage 41 and the second oil passage 52 and the BT oil passage 42 and the first oil passage 51 communicate with each other.

  A sequence oil passage 54 is connected to the third circumferential groove 28 c formed in the booster cylinder 20, and the sequence oil passage 54 is connected to the AP oil passage 41. A sequence valve 60 is incorporated in the sequence oil passage 54, and the sequence valve 60 opens the sequence oil passage 54 when the pressure oil in the AP oil passage 41 exceeds a set pressure.

  A first communication path 63 and a second communication path 64 are provided between the extension oil path 7 and the contraction oil path 9 from the operation valve 8 to the branch point of the branch paths 7a and 9a. A relief valve 61 for setting an expansion pressure is incorporated in the communication passage 63, while a relief valve 62 for setting a contraction pressure is incorporated in the second communication passage 64.

  The relief valve 61 for setting the extension pressure opens when the pressure oil pressure in the extension oil passage 7 exceeds the set pressure, and causes the pressure oil in the extension oil passage 7 to flow into the contraction oil passage 9. The pressure oil pressure in the extension oil passage 7 is kept below the set pressure.

  On the other hand, the relief valve 62 for setting the contraction pressure is opened when the pressure of the pressure oil in the contraction oil passage 9 exceeds the set pressure, and the pressure oil in the contraction oil passage 9 flows into the extension oil passage 7. Thus, the pressure of the pressure oil in the contracting oil passage 9 is kept below the set pressure. The set pressure of the relief valve 62 for setting the contraction pressure is higher than the set pressure of the relief valve 61 for setting the extension pressure.

  The pressure-increasing cylinder device shown in the embodiment has the above structure. FIG. 1 shows a state in which the hydraulic cylinder 1 is contracted, and the movable cutting arm 76 of the cutting machine shown in FIG. 10 is in an open state.

  When the hydraulic valve 10 is driven by switching the operation valve 8 in the direction in which the pressure oil of the hydraulic pump 10 is sent to the extension oil passage 7 from the state shown in FIG. 1, the pressure oil discharged from the hydraulic pump 10 is as shown in FIG. As indicated by the arrows, the oil is fed into the extension oil passage 7 and supplied to the bottom chamber 4 of the hydraulic cylinder 1. For this reason, the piston 3 moves in the direction in which the volume of the rod chamber 5 decreases, the hydraulic cylinder 1 expands, and the movable cutting arm 76 shown in FIG. 10 swings in the closing direction.

  At this time, since the pressure of the pressure oil sent to the extension oil passage 7 is applied to the second check valve 12 incorporated in the contraction oil passage 9, the second check valve 12 is in an open state. The oil is returned to the tank T from the contraction oil passage 9.

  When the object to be cut W is sandwiched between the cutting blades 77 and 78 of the fixed cutting arm 75 and the movable cutting arm 76 and a load is applied to the piston rod 6 of the hydraulic cylinder 1, the pressure oil in the extension oil passage 7 is obtained. The pressure gradually increases, and the pressure oil is added as pilot pressure to the inlet side switching valve 40. Therefore, the inlet side switching valve 40 has a branch path 7a, an AP oil path 41, and a branch as shown in FIG. The position is switched to a position where the path 9a and the BT oil path 42 communicate with each other.

  Further, since the pressure of the pressure oil in the bottom chamber 4 is applied as a pilot pressure to the outlet side switching valve 30, the outlet side switching valve 30 includes the pressure increasing supply passage 27 and the bottom chamber as shown in FIG. 4 is switched to the position where it communicates.

  For this reason, the pressure oil that has flowed from the extension oil passage 7 into the branch passage 7a flows into the AP oil passage 41 and flows into the first pressurizing chamber 23a, and the oil in the second pressurizing chamber 23b is the second oil supply. The oil flows into the passage 52, the BT oil passage 42, the branch passage 9a, and the contraction oil passage 9 and is returned to the tank T, and the pressure-increasing piston 22 moves backward in the direction in which the volume of the second pressurizing chamber 23b is reduced. For this reason, pressure-increasing oil is formed in the second pressure-increasing chamber 24 b, and the pressure-increasing oil is sent from the pressure-increasing supply passage 27 to the bottom chamber 4.

  Further, since the pressure oil flowing through the AP oil passage 41 flows to the inlet side of the sequence oil passage 54, the sequence valve 60 is in a state of opening the sequence oil passage 54 as shown in FIG.

  When the pressure-increasing piston 22 moves to the vicinity of the limit position of the reverse stroke and the switching passage 29 communicates with the second circumferential groove 28b and the third circumferential groove 28c as shown in FIG. Flows from the third circumferential groove 28 c to the second circumferential groove 28 b and flows into the pilot passage 53, and a pilot pressure is applied to the switching valve 50.

  Therefore, as shown in FIG. 5, the switching valve 50 switches to a position where the AP oil passage 41 and the second oil passage 52 and the BT oil passage 42 and the first oil passage 51 communicate with each other and branches off from the hydraulic pump 10. The pressure oil sent to the path 7a and the AP oil path 41 is sent from the second oil supply path 52 to the second pressurizing chamber 23b. Further, the oil in the first pressurizing chamber 23a flows into the first oil supply passage 51, the BT oil passage 42, the branch passage 9a and the contracting oil passage 9 and is returned to the tank T, and the pressure increasing piston 22 is connected to the first pressurizing chamber. It moves (forward movement) in the direction in which the volume of 23a decreases. For this reason, pressure-increasing oil is formed in the first pressure-increasing chamber 24 a, and the pressure-increasing oil is fed into the bottom chamber 4 from the pressure-increasing supply passage 27.

  When the pressure-increasing piston 22 moves to near the limit position of the forward stroke and the switching passage 29 communicates with the second circumferential groove 28b and the first circumferential groove 28a as shown in FIG. 6, the pilot pressure on the switching valve 50 is increased. Therefore, as shown in FIG. 3, the switching valve 50 is switched to a position where the AP oil passage 41 and the first oil supply passage 51 and the BT oil passage 42 and the second oil supply passage 52 communicate with each other. For this reason, the pressure oil from the hydraulic pump 10 is supplied to the first pressurizing chamber 23a, and the pressure-increasing piston 22 moves (returns) in the direction of reducing the volume of the second pressurizing chamber 23b.

  Thereafter, by repeating the switching operation of the switching valve 50 as described above, the pressure oil from the hydraulic pump 10 is alternately supplied to the first pressurizing chamber 23a and the second pressurizing chamber 23b, and the pressure increasing piston 22 moves forward. And the pressure increasing oil in the first pressure increasing chamber 24a and the second pressure increasing chamber 24b is formed by repeating the return movement. Since the pressure-increasing oil is sequentially supplied to the bottom chamber 4 of the hydraulic cylinder, the operating pressure of the hydraulic cylinder 1 gradually increases, and the object to be cut W moves its movable cutting arm 76 by swinging the movable cutting arm 76 in the closing direction. The cutting blade 78 and the cutting blade 77 of the fixed cutting arm 75 are cut.

  When the object to be cut W is cut, the pilot pressure for the inlet side switching valve 40 and the pilot pressure for the outlet side switching valve 30 are removed, so the inlet side switching valve 40 and the outlet side switching valve 30 are removed. Each is returned to the neutral position as shown in FIG.

  After the return to the neutral position of the inlet side switching valve 40 and the outlet side switching valve 30, as shown in FIG. 7, when the operation valve 8 is switched to a position where the pressure oil of the hydraulic pump 10 is fed into the contracting oil passage 9, The pressure oil discharged from the hydraulic pump 10 is supplied from the contraction oil passage 9 to the rod chamber 5 of the hydraulic cylinder 1, and the piston 3 moves in a direction in which the volume of the bottom chamber 4 is reduced. The oil in the bottom chamber 4 is returned from the extension oil passage 7 to the tank T.

  For this reason, the hydraulic cylinder 1 contracts, and the movable cutting arm 76 shown in FIG. 10 is opened.

  Here, when the cutting object W is cut, the cutting object W is caught between the cutting blade 77 of the fixed cutting arm 75 and the cutting blade 78 of the movable cutting arm 76 as shown in FIG. When the jamming state in which 76 does not move occurs, the hydraulic cylinder 1 cannot be contracted only by the pressure of the pressure oil supplied from the hydraulic pump 10 to the rod chamber 5, and the movable cutting arm 76 may not be released. .

  At this time, due to the pressure of the pressure oil supplied from the contraction oil passage 9 to the rod chamber 5, the outlet side switching valve 30 has a passage 31 communicating with the pressure increase supply passage 27 and the rod chamber 5 as shown in FIG. 8. Switch to the direction of communication. Further, the inlet side switching valve 40 switches to a position where the branch path 9a and the AP oil path 41 and the branch path 7a and the BT oil path 42 communicate with each other by the pressure of the pressure oil supplied from the hydraulic pump 10 to the branch path 9a. .

  Therefore, the pressure oil sent from the hydraulic pump 10 to the branch passage 9a flows into the first pressurizing chamber 23a from the AP oil passage 41 and the first oil supply passage 51, and the pressure-increasing piston 22 is connected to the second pressurizing chamber 23b. The volume is reduced (returned) in the direction of reducing the volume, and pressure increasing oil is formed in the second pressure increasing chamber 24b. The pressure-increasing oil flows from the pressure-increasing supply passage 27 through the passage 31 into the rod chamber 5.

  When the pressure-increasing piston 22 moves to near the limit position of the reverse stroke, and the switching passage 29 communicates with the second circumferential groove 28b and the third circumferential groove 28c, as shown in FIG. Flows from the third circumferential groove 28 c to the second circumferential groove 28 b and flows into the pilot passage 53, and a pilot pressure is applied to the switching valve 50.

  Therefore, as shown in FIG. 9, the switching valve 50 switches to a position where the AP oil passage 41 and the second oil passage 52 and the BT oil passage 42 and the first oil passage 51 communicate with each other. The pressure oil sent to the branch passage 9a and the AP oil passage 41 is sent from the second oil supply passage 52 to the second pressurizing chamber 23b. The oil in the first pressurizing chamber 23a flows to the first oil supply passage 51, the BT oil passage 42, the branch passage 7a, and the extension oil passage 7 and is returned to the tank T, and the pressure increasing piston 22 is connected to the first pressurizing chamber. It moves forward in the direction in which the volume of 23a shrinks. For this reason, pressure-increasing oil is formed in the first pressure-increasing chamber 24 a, and the pressure-increasing oil is fed into the rod chamber 5 from the pressure-increasing supply passage 27.

  When the pressure-increasing piston 22 moves to a position close to the limit position of the forward stroke and the switching passage 29 communicates with the second circumferential groove 28b and the first circumferential groove 28a, the pilot pressure for the switching valve 50 is removed. 50 switches to a position where the AP oil passage 41 and the first oil supply passage 51 and the BT oil passage 42 and the second oil supply passage 52 communicate with each other. For this reason, the pressure oil from the hydraulic pump 10 is supplied to the first pressurizing chamber 23a, and the pressure-increasing piston 22 moves backward in the direction of reducing the volume of the second pressurizing chamber 23b.

  Thereafter, by repeating the switching operation of the switching valve 50 as described above, the pressure oil from the hydraulic pump 10 is alternately supplied to the first pressurizing chamber 23a and the second pressurizing chamber 23b, and the pressure increasing piston 22 moves forward. And the pressure increasing oil in the first pressure increasing chamber 24a and the second pressure increasing chamber 24b is formed by repeating the return movement. Since the pressure increasing oil is sequentially supplied to the rod chamber 5 of the hydraulic cylinder 1, the piston 3 moves in the direction of reducing the volume of the bottom chamber 4, the hydraulic cylinder 1 contracts, and the movable cutting arm 76 is opened. Is done.

  As described above, in the pressure increasing cylinder device shown in the embodiment, when a load is applied to the hydraulic cylinder 1 when the hydraulic cylinder 1 that supplies pressure oil discharged from the hydraulic pump 10 to the bottom chamber 4 is extended, The inlet side switching valve 40 is switched in the direction in which the pressure oil of the hydraulic pump 10 flows to the sequence valve 60 to operate the booster cylinder 20, and the outlet side switching valve 30 hydraulically pressurizes the boosted oil formed by the booster cylinder 20. Since it switches to the direction which flows into the bottom chamber 4 of the cylinder 1, the hydraulic cylinder 1 can be extended reliably and the movable cutting arm 76 of a cutting machine can be reliably rock | fluctuated by the hydraulic cylinder 1 in the closing direction. .

  In addition, when the hydraulic cylinder 1 is supplied with pressure oil discharged from the hydraulic pump 10 to the rod chamber 5, when the load is applied to the hydraulic cylinder 1, the pressure oil in the hydraulic pump 10 flows into the sequence valve 60 in the direction of flow. Since the side switching valve 40 is switched and the booster cylinder 20 is operated, and the outlet side switching valve 30 is switched in the direction in which the boosted oil formed by the booster cylinder 20 flows into the rod chamber 5 of the hydraulic cylinder 1. The cylinder 1 can be reliably contracted, and the hydraulic cylinder 1 can reliably swing the movable cutting arm 76 of the cutting machine in the opening direction.

  Here, in the pressure-increasing cylinder device shown in the embodiment, the hydraulic cylinder 1 is installed by incorporating relief valves 61 and 62 for the purpose of preventing the leakage of pressurized oil from the connecting portions of various oil passages and preventing the oil passages from being damaged. The pressure oil pressure in the extension oil passage 7 and the contraction oil passage 9 is maintained at a set pressure.

  At this time, if the set pressure of the relief valve 61 for setting the extension pressure that holds the extension oil passage 7 at the set pressure and the set pressure of the relief valve 62 for setting the contraction pressure that holds the contraction oil passage 9 at the set pressure are equal, Due to the area difference between the rod chamber side surface and the bottom chamber side surface of the piston 3 in the cylinder 1, there is a difference between the output when the hydraulic cylinder 1 is contracted and the output when it is extended, and the biting of the workpiece W cannot be released. There are cases.

  However, in the embodiment, since the set pressure of the relief valve 62 for setting the contraction pressure is set higher than the set pressure of the relief valve 61 for setting the extension pressure, the output when the hydraulic cylinder 1 is contracted and the output when it is extended Can be reduced. As a result, the biting of the object to be cut W can be more reliably released.

  Since the set pressure of the relief valves 61 and 62 can be adjusted manually, the set pressure of the relief valve 62 that holds the contracting oil passage 9 at the set pressure is held at the set pressure of the extension oil passage 7. The operation of adjusting the pressure higher than the set pressure of the relief valve 61 may be performed in advance before starting the cutting operation, or may be performed when a jamming state occurs.

  In the embodiment, as a cutting machine, the movable cutting arm 76 is opened and closed with respect to the fixed cutting arm 75, and the movable cutting arm 76 that can be opened and closed is swung by the hydraulic cylinder 1 of the pressure increasing cylinder device. However, the cutting machine is not limited to this. For example, it may be a cutting machine in which each of the pair of cutting arms is swingably supported, and each of the pair of cutting arms is swung by a hydraulic cylinder of a pressure increasing cylinder device.

Hydraulic circuit diagram of pressure-increasing cylinder device according to the present invention 1 is an enlarged sectional view of the booster cylinder of FIG. Hydraulic circuit diagram with the hydraulic cylinder extended Hydraulic circuit diagram showing the switching state of the inlet side switching valve and the outlet side switching valve when the hydraulic cylinder is extended Hydraulic circuit diagram showing the switching state of the switching valve Hydraulic circuit diagram of booster cylinder pressure increasing piston moved to near limit of forward stroke Hydraulic circuit diagram with hydraulic cylinder contracted Hydraulic circuit diagram showing the switching state of the inlet side switching valve and the outlet side switching valve in the contraction operation state of the hydraulic cylinder Hydraulic circuit diagram showing the switching state of the switching valve Front view showing a cutting machine Sectional view showing the incomplete cutting state of the object to be cut

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic cylinder 4 Bottom chamber 5 Rod chamber 7 Extension oil path 8 Operation valve 9 Contraction oil path 10 Hydraulic pump 20 Booster cylinder 22 Boosting piston 23a First pressurizing chamber 23b Second pressurizing chamber 24a First pressurizing chamber 24b Second pressure increasing chamber 30 Outlet side switching valve 40 Inlet side switching valve 50 Switching valve 60 Sequence valve 61 Relief valve 62 Relief valve 63 First communication path 64 Second communication path 75 Fixed cutting arm 76 Movable cutting arm

Claims (2)

A hydraulic cylinder that relatively opens and closes a pair of cutting arms of a cutting machine, a hydraulic pump for operating the hydraulic cylinder, and an extension oil that communicates pressure oil discharged from the hydraulic pump to the bottom chamber of the hydraulic cylinder An operation valve that selectively switches between a path and a contracting oil path that communicates with the rod chamber, and a pressure increasing piston is reciprocated by pressure oil supplied from the hydraulic pump, and the pressure increasing piston is moved in one direction. The pressure-increasing oil is formed in the first pressure-increasing chamber by the movement of, the pressure-increasing oil is formed in the second pressure-increasing chamber by the movement in the other direction, and these pressure-increasing oils are supplied to the bottom chamber of the hydraulic cylinder. The pressure oil discharged from the hydraulic pump is switched between the booster cylinder and the first pressurizing chamber that moves the booster piston of the booster cylinder in one direction and the second pressurizing chamber that moves in the other direction. Switch valve to supply A sequence valve that supplies a pilot pressure for switching control in a direction in which the switching valve is switched to the booster cylinder by being released by the pressure of the pressure oil sent from the hydraulic pump when a load is applied to the hydraulic cylinder. Further, when the boosting piston of the booster cylinder moves to a position slightly before reaching the stroke end, a pilot pressure supplied from the sequence valve is added to the switching valve to switch the switching valve. In the cylinder device,
The pressure oil supplied from the hydraulic pump to the bottom chamber is changed to a pilot pressure so that the booster cylinder pressure increasing oil flows into the bottom chamber, and the pressure oil supplied from the hydraulic pump to the rod chamber is changed to the pilot pressure. Pilot operated type outlet side switching valve that switches so that cylinder pressure increasing oil flows into its rod chamber, pilot pressure oil supplied from the hydraulic pump to the bottom chamber, and pressure oil supplied from the hydraulic pump to the rod chamber A pressure-increasing cylinder device comprising a pilot-operated inlet side switching valve that switches pressure oil discharged from a hydraulic pump as pressure to flow toward a sequence valve.   A first communication path and a second communication path are provided to communicate the extension oil path and the contraction oil path, and when the pressure of the pressure oil in the extension oil path exceeds a set pressure in the first communication path. A relief valve for setting the extension pressure that opens and allows the pressure oil in the extension oil passage to flow into the contraction oil passage is incorporated, and the pressure oil pressure in the extension oil passage exceeds the set pressure in the second communication passage. The relief valve for setting the contraction pressure is built in so that the pressure oil in the contraction oil passage flows into the extension oil passage, and the set pressure of the relief pressure setting relief valve is set to the The pressure-increasing cylinder device according to claim 1, wherein the pressure-increasing cylinder device is higher than a set pressure.

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