JP2805276B2 - Portable steel bar cutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable steel bar cutter, and more particularly, to a portable steel bar cutter capable of manually retracting a cutting blade in an emergency or emergency.

[0002]

2. Description of the Related Art There is known a portable steel bar cutter for cutting a bar-shaped material such as a reinforcing bar by operating a hydraulic operating mechanism (see, for example, Japanese Utility Model Publication No. 1-156464). In general,
This type of portable steel bar cutter is called a hydraulically operated rebar cutter or simply a rebar cutter. The hydraulic operating mechanism of such a steel bar cutter includes a piston rod equipped with a cutting blade, and a hydraulically operated cylinder device for reciprocating the piston rod. The hydraulic operating mechanism further includes a pump mechanism for supplying hydraulic oil to the hydraulic chamber of the cylinder device for supplying hydraulic oil to the cylinder device, and an electric motor for driving the pump mechanism. A pump mechanism generally includes a plurality of pump elements radially arranged around a rotation axis of an electric motor, and each pump element reciprocates by rotation of an output shaft (eccentric shaft) of the electric motor, and operates in an oil tank. The oil is pumped into the hydraulic chamber of the cylinder device. Due to the pressure increase in the hydraulic chamber, the piston of the cylinder device advances while compressing the return spring, and the piston rod extends. When the piston moves to the most advanced position (stroke end), the automatic release valve mechanism in the hydraulic chamber operates, and the release passage is automatically opened. Thus, the hydraulic oil in the hydraulic chamber returns to the suction side of the pump mechanism via the release passage, and the piston retreats to the initial position due to the extension of the return spring, and pulls the piston rod into the cylinder device.

[0003]

However, in such a portable steel bar cutter, when the steel bar cutter is operated under certain conditions, the piston rod cannot completely cut the steel bar such as a reinforcing bar, and the steel bar is not cut. As a result, the extension may be prevented halfway, and the piston may stop before reaching the most advanced position. For example, when the power of the electric motor is insufficient (insufficient voltage), the cutting blade cannot completely cut the bar, and as a result, the cutting blade is prevented from moving forward by the bar and stands still. Such an unexpected situation can occur even in a portable steel bar cutter which has reached the end of its life due to aging. In the event of such an emergency or emergency, the operator must retract the cutting blade and release the steel bar from the cutting blade to quickly restore the intended function of the portable steel bar cutter. However, in the conventional hydraulically operated steel bar cutter, an operator has to disassemble the cylinder device manually in order to retract the piston rod into the cylinder device and retract the cutting blade. However, disassembly of the cylinder device not only requires complicated and difficult operations but also involves outflow or drainage of hydraulic oil and re-injection of new hydraulic oil.

[0004] The present invention has been made in view of such a point, and an object thereof is to retreat a cutting blade easily and quickly by manual operation in an emergency or emergency without disassembling a cylinder device. It is to provide a portable steel bar cutter that can.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a portable steel bar cutter having the following structure. That is, the portable steel bar cutter includes a driving device, a hydraulic pump device connected to the driving device, and a hydraulic cylinder device supplied with hydraulic oil by the pump device. The hydraulic cylinder device includes a piston rod carrying a cutting blade, a piston connected to the piston rod, biasing means for biasing the piston to an initial position, and first and second pistons respectively defined on both sides of the piston. A hydraulic chamber, and an automatic release valve for releasing hydraulic oil in the first hydraulic chamber when the piston advances to a predetermined position, wherein the pump device pressurizes the first hydraulic chamber to advance the piston from the initial position. The oil is supplied, and the automatic release valve recirculates the pressure oil in the first hydraulic chamber to the suction side of the pump device when the piston advances to a predetermined position. In the steel bar cutter having such a basic configuration, the steel bar cutter of the present invention includes a pressure oil release passage that connects the first hydraulic chamber and the suction area of the pump device, and a manual oil pressure passage that is interposed in the pressure oil release passage. An on-off valve. The manually operated on-off valve has a head provided with a recess capable of receiving the operating means, and the head slightly protrudes from the outer surface of the casing of the hydraulic cylinder device.

According to the above configuration of the present invention, the pressure oil release passage and the manually operated on-off valve constitute an emergency or emergency hydraulic release means. When the cutting blade is prevented from advancing and the piston rod stops without advancing to a predetermined position (stroke end), the on-off valve is manually opened to open the first valve.
The pressure oil in the hydraulic chamber is forcibly released, and the piston and the piston rod are retracted by the urging means, whereby the function of the portable steel bar cutter can be quickly restored. Therefore, it is possible to avoid complicated and difficult work relating to disassembly of the cylinder device, outflow or drainage of hydraulic oil, or reinjection of hydraulic oil. Furthermore, since the opening / closing valve has a head provided with a concave portion capable of receiving the operating means, it can be easily operated by a driver or a coin in an emergency or emergency. In addition, since the head only slightly protrudes from the outer surface of the casing of the hydraulic cylinder device, opening / closing operation of the opening / closing valve due to erroneous operation can be avoided, and the space around the steel bar cutter can be effectively used. In addition, portable steel bar cutters are generally used at construction sites where maintenance and management are relatively difficult to perform.However, according to the on-off valve having the above structure, damage to the operation lever and the like can be avoided, and cement and mud can be removed. When adhered to the concave portion of the head and the concave portion is filled with cement or the like, the concave portion can be easily cleaned and the intended function of the on-off valve can be easily restored.

[0007] In a preferred aspect of the present invention, the pressure oil release passage connects the first hydraulic chamber and the second hydraulic chamber so that they can communicate with each other. In another embodiment of the present invention, the pressure oil release passage connects the first hydraulic chamber and an oil tank of the pump device so as to be able to communicate with each other.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a steel bar cutter according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of a steel bar cutter according to the present invention. The steel bar cutter 1 shown in FIG. 1 is mainly configured as a portable rebar cutter for cutting rebar. The steel bar cutter 1 includes a portable handle 2 and
An electric motor 3 supported by the portable handle 2, a pump unit 4 connected to the electric motor 3, a hydraulic cylinder unit 5 constituting a hydraulic operating mechanism together with the pump unit 4, and a jaw extending forward from the hydraulic cylinder unit 5. And the mold head 6. Portable handle 2 that the operator grips with fingers
Has a trigger switch 7 for manually controlling the operation of the electric motor 3 and a rechargeable battery 8 constituting a power source of the electric motor 3. The electric motor 3 includes an output shaft 30 extending into the pump unit 4. The output shaft 30 drives a hydraulic pump unit 4 a in the pump unit 4, and the pump unit 4 a pressurizes the hydraulic cylinder unit 5. Feed oil. The hydraulic cylinder unit 5 includes a hydraulically operated piston
A cylinder mechanism is provided, and is configured to extend the piston rod 9 fixed to the piston 51 by hydraulic pressure.

A movable blade 10 is fixed to the distal end of the piston rod 9, and a fixed blade 11 is mounted on the front end of the jaw-type head 6 so as to face the movable blade 10.
0 and the fixed blade 11 are aligned on the axis of the piston rod 9. In the jaw-shaped head portion 6, the difference between the hydraulic oil supply / discharge amount of the hydraulic chamber 53 in which the piston rod 9 is disposed and the hydraulic oil supply / discharge amount of the hydraulic chamber 52 to which the pressurized oil is supplied via the oil passage 47 is provided. Oil storage mechanism 65 that adjusts the
Is provided. The oil storage mechanism 65 includes an oil storage chamber 66 that communicates with the hydraulic chamber 53 via an oil passage (not shown), and an oil storage chamber 66.
, A bag-shaped elastic film material 67 facing the air-conditioner, an air chamber 68 formed in the film material 67 and opened to the atmosphere, and a film material holder 69 provided with a vent. FIG. 2 is a partially enlarged sectional view of the hydraulically operated piston / cylinder mechanism shown in FIG. As shown in FIG. 2, the output shaft 30 of the electric motor 3 extending into the pump section 4 has a cam shaft 31 at a front end portion. The center axis of the cam shaft 31 is the rotation axis X of the output shaft 30.
Slightly eccentric with respect to -X. On the outer periphery of the cam shaft 31, a needle bearing 32 is disposed concentrically with the cam shaft 31.

[0010] A housing 40 of the pump section 4 is connected to the electric motor 3, and an oil tank 42 for storing hydraulic oil is formed in the pump housing 40. Above the oil tank 42, a supply port 48 penetrating the housing 40 is formed, and a plug 49 is screwed into the supply port 48. The pump section 4 is composed of a plurality of pump units 4a radially arranged around the rotation axis XX of the output shaft 30 (only one pump unit 4a is shown in FIG. 2). , Pump piston 4 of each pump unit 4a
1 is in sliding contact with the outer peripheral surface of the needle bearing 32. The pump piston 41 is always moved upward in the figure by the spring 44, that is, the needle bearing 32.
Is being biased toward. Oil passage 4 communicating with oil tank 42
3 is arranged adjacent to the lower end of the pump piston 41,
In addition, an opening / closing valve 45 that controls opening / closing of a flow path between the pump unit 4 and the hydraulic cylinder unit 5, that is, an oil passage 47, is disposed below the pump piston 41. The on-off valve 45 is urged upward by the spring 46, that is, toward the pump piston 41, and always closes the oil passage 47. The hydraulic cylinder unit 5 includes a cylinder case 50 and a piston 51 reciprocally arranged in the cylinder case.
A hydraulic chamber 52 defined on both sides of the piston 51,
53.

The hydraulic chamber 52 communicates with the oil passage 47 and can communicate with the release oil passage 54 when the automatic release valve device 55 is opened. The automatic release valve device 55 is opened when the piston 51 advances a predetermined distance and reaches the stroke end, and connects the hydraulic chamber 52 and the release oil passage 54. As a result, the operating oil in the hydraulic chamber 52 returns to the oil tank 42 via the release oil passage 54. In the hydraulic chamber 53, a return spring 57 for urging the piston 51 rearward and a piston rod 9 extending forward from the piston 51 are arranged. Return spring 5
7 is a position where the piston 51 is most retracted (FIG. 2).
(The position shown in the figure). Also, the piston rod 9
Passes through the hydraulic chamber 53, penetrates the cylinder connecting portion 60 of the jaw-type head portion 6 that defines the front end of the hydraulic chamber 53, and the movable blade 10 (FIG. 1) is attached to the front end. . The cylinder case 50 is provided with a bypass oil passage 56 for fluid communication between the hydraulic chamber 53 and the oil tank 42.
The front end of the bypass oil passage 56 has a groove 5 opening into the hydraulic chamber 53.
The groove 58 extends in the circumferential direction of the cylinder case 50 and communicates with the hydraulic chamber 53. Hydraulic oil discharged from the hydraulic chamber 53 when the piston 51 moves forward is supplied to the bypass oil passage 5
6, the oil returns to the oil tank 42, and the hydraulic oil in the oil tank 42
When the piston 51 retreats, it flows into the hydraulic chamber 53 via the bypass oil passage 56.

FIG. 3 is a partially enlarged sectional view showing a different section of the hydraulically operated piston-cylinder mechanism, and FIG.
FIG. 4 is an enlarged sectional view of a forced release oil passage and a manual release valve shown in FIG. 3. As shown in FIG. 3, a forced release oil passage 110 extending parallel to the bypass oil passage 56 is formed in the cylinder case 50, and a front end of the forced release oil passage 110 is
It opens in the groove 58 and communicates with the hydraulic chamber 53 through the groove 58. The rear end of the forced release oil passage 110 is connected to the hydraulic chamber 52 via a normally closed manual release valve 100. As shown in FIG. 4, the rear end of the oil passage 110 is
To the manual release valve 100 through the oil passage 11
0 and the manual release valve 100 constitute an emergency or emergency hydraulic release means. The manual release valve 100 includes a head 101 that can be operated from outside the machine.
Grooves or recesses that can accept tools such as screwdrivers or operating means such as the periphery of coins (hereinafter referred to as tool engagement grooves)
Is provided. The head 101 only slightly protrudes from the outer surface of the cylinder case 50 to prevent the manual release valve 100 from being opened or closed due to an erroneous operation, and to prevent the surrounding area of the steel bar cutter 1 from being occupied by the manual release valve 100. ing.

An O-ring 102 is fitted in a circumferential groove of the head 101. Screw part 10 screwed with cylinder case 50
3 extends downward from the lower end of the head 101 and
3, the valve element 104 hangs down. The lower end of the valve body 104 is seated on the port 105 opening to the hydraulic chamber 52, and closes the port 105. Reduced diameter passage 111 of oil passage 110
Is opened to the side of the valve chamber 106 that accommodates the valve body 103, and communicates with the hydraulic chamber 52 by opening the port 105. The port 105 is opened by a tool or the like.
By rotating 1 and raising the valve body 104, it can be executed manually or manually. Next, the operation of the steel bar cutter 1 will be described. By pulling the trigger switch 7 (FIG. 1) of the portable handle 2 with a finger, the steel bar cutter 1 starts. The electric motor 3 is operated, and the output shaft 30 and the cam shaft 31 are rotated. The needle bearing 32 located on the outer circumference of the camshaft 31 rolls around the rotation axis X, and reciprocates the pump piston 41 (FIG. 2) that slides on the outer circumference of the needle bearing 32. Since each pump piston 41 is reciprocated at a phase shifted by a predetermined angle, for example, 45 degrees, the suction step and the discharge step of each pump piston 41 occur at mutually shifted timings. The working oil is supplied to the hydraulic chamber 52 of the hydraulic cylinder device 5 efficiently at a predetermined pressure, for example, a pressure of 250 kg / cm ² , at a uniform flow rate.

As the pressure in the hydraulic chamber 52 increases, the piston 51
Is moved forward (leftward in FIG. 2) while resisting the elastic force of the return spring 57. Thereby, the piston rod 9 and the movable blade 10 move forward, and the movable blade 10
The reinforcing bar is cut in cooperation with the fixed blade 11. As shown in FIG. 3, the automatic release valve device 55 has an annular stopper 5 at its front end.
The valve body 55a includes a valve body 55a, a kick spring 55c engaged with the stopper 55b, and a compression spring 55g disposed in a hollow portion of the valve body 55a. Valve 5
An annular valve seat 55d arranged at the rear end of 5a is seated on the rear end wall of the hydraulic chamber 52, and closes the release oil passage 54. The valve element 55a is in sliding contact with a substantially cylindrical valve guide 55f fixed to the piston 51, and is supported by the piston 51 so as to be relatively displaceable from the piston 51. The valve guide 55f has an oil passage 5
5h is formed, and the hydraulic pressure in the hydraulic chamber 52 acts on the front end surface of the valve body 55a.
5a is pressed by the rear end wall of the hydraulic chamber 52, and the valve seat 55d continues to sit on the rear end wall of the hydraulic chamber 52. FIG. 4 shows a state where the piston 51 has advanced to a certain extent. When the piston 51 advances to the stroke end, the kick spring 55c pushes the stopper 55b forward, and the valve body 5
5a is moved forward. As a result, the valve seat 55d opens, and the hydraulic chamber 52 communicates with the release oil passage 54. Thus, the hydraulic oil in the hydraulic chamber 52 returns to the oil tank 42 through the release oil passage 54, and the return spring 57 moves the piston 51 to the initial position shown in FIG. Piston 5
1, the valve body 55a is retracted, and the valve seat 55d is
The release passage 54 is closed. Note that the structure of the automatic release valve device 55 is the same as that of the present invention filed by the present inventor.
The valve structure is substantially the same as the valve structure disclosed in Japanese Patent No. 464, and further detailed description of the structure and operation of the automatic release valve device 55 is omitted.

Insufficient power of the electric motor 3, exhaustion of the battery 8, excessive shear resistance of the reinforcing steel, or the steel bar cutter 1
The movable blade 10 cannot completely cut the rebar due to the life of the piston rod 9 and the piston rod 9 and the piston 51.
However, as shown in FIG. 4, when it stops halfway, it becomes necessary to forcibly retract the piston rod 9 and the piston 51 to the initial position. When such a situation occurs, the operator engages a driver or the like in the tool engagement groove, and
1 is rotated, and the valve body 104 is raised. This allows
The port 105 is opened, and the hydraulic chamber 52 is
1. It communicates with the hydraulic chamber 53 via the oil passage 110 and the groove 58. The high-pressure hydraulic oil in the hydraulic chamber 52 flows into the hydraulic chamber 53 via the oil passage 110, the reduced-diameter passage 111, and the groove 58.
As a result, the pressure in the hydraulic chamber 52 decreases, and the piston 51 and the piston rod 9 retreat to the initial position shown in FIG. As described above, the steel bar cutter 1 of the present embodiment includes the electric motor 3 as a drive source, the pump unit 4 connected to the electric motor 3,
A hydraulic cylinder section 5 connected to the pump section 4. The hydraulic cylinder section 5 includes a cylinder case 50 and a piston 5.
1 and hydraulic chambers 5 defined on both sides of the piston 51, respectively.
2, 53. The hydraulic oil in the pump section 4 is supplied to the hydraulic chamber 52 through an oil passage 47, and the automatic release valve device 55 and the release oil passage 54 return the hydraulic oil in the hydraulic chamber 52 to the oil tank 42. A return spring 57 for urging the piston 51 rearward and a piston rod 9 extending forward from the piston 51 are disposed in the hydraulic chamber 53. The hydraulic chamber 53 is connected to the oil tank 42 via a bypass oil passage 56.
Is in fluid communication with The hydraulic operating mechanism further includes a forced release oil passage 110 extending parallel to the bypass oil passage 56, and a manual release valve 100 that is opened and closed in an emergency or emergency.
The hydraulic chamber 52 and the hydraulic chamber 53 can be forcibly communicated via 10.

According to such a configuration, when the extension of the piston rod 9 is prevented halfway, the manual release valve 100 is opened by manual operation to allow the high-pressure hydraulic oil in the hydraulic chamber 52 to pass through the hydraulic chamber 53, thereby The piston 51 and the piston rod 9 can be retracted. Further, the head 101 of the manual release valve 100 having the tool engagement groove is
Can be easily operated in emergency or emergency with a driver or coin. Moreover, the head 101 is connected to the cylinder case 50.
Only slightly protrudes from the outer surface of the steel bar, the opening / closing operation of the manual release valve 100 due to erroneous operation can be avoided, and the space around the steel bar cutter 1 can be effectively used.
In addition, since the steel bar cutter 1 is generally used in a construction site where maintenance and management are relatively difficult to perform, the operating lever and the like of the valve mechanism are relatively easily damaged, and moreover, cement and mud are applied to the operating section of the valve mechanism. A situation that sticks and hinders valve operation is likely to occur. However, the head 10 having no operation lever or the like
According to 1, not only can the operating portion be reliably prevented from being damaged, but also when the tool engagement groove is completely filled with cement or the like.
The recess can be quickly cleaned or cleaned, and the intended function of the manual release valve 100 can be quickly restored.

Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and various modifications or changes can be made within the scope of the invention described in the claims. It goes without saying that they are also included in the scope of the present invention. For example, in the above embodiment, the hydraulic chamber 5
2 and 53 are communicable, but a similar forced release oil passage is formed between the hydraulic chamber 52 and the oil tank 42,
A configuration in which the second pressure oil is passed through the oil tank 42 may be adopted.

[0018]

According to the above configuration of the present invention, when the extension of the piston rod is stopped halfway, the hydraulic oil in the first hydraulic chamber is opened by opening the on-off valve manually without disassembling the cylinder device. Can be forcibly released, and the piston and the piston rod can be retracted. Further, the on-off valve can be easily operated in an emergency or emergency by operating means such as a driver or a coin. Further, according to the on-off valve head structure of the present invention, the on-off operation of the on-off valve due to an erroneous operation can be reliably prevented, and the space around the steel bar cutter can be effectively used. In addition, according to the head structure of the on-off valve, not only can the damage to the operation lever and the like be avoided, but when the recess is filled with cement or the like, the recess can be easily cleaned, and the desired function of the on-off valve can be achieved. Can be easily recovered. Thus, according to the present invention, it is possible to provide a portable steel bar cutter that can easily and quickly retreat the cutting blade by manual operation in an emergency or emergency without disassembling the cylinder device.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a steel bar cutter according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view showing a hydraulic operating mechanism of the steel bar cutter shown in FIG.

FIG. 3 is a partially enlarged sectional view showing a hydraulic operating mechanism of a steel bar cutter in a different cross section.

FIG. 4 is an enlarged sectional view of a forced release oil passage and a manual release valve shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel bar cutter 3 Electric motor 4 Pump part 5 Hydraulic cylinder part 9 Piston rod 10 Movable blade 11 Fixed blade 42 Oil tank 51 Piston 52, 53 Hydraulic chamber 54 Release oil path 55 Automatic release valve device 56 Bypass oil path 57 Return spring 100 Manual release Valve 110 forced release oil passage

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B23D 29/00

Claims (2)

(57) [Claims] 1. A drive device, a hydraulic pump device connected to the drive device, and a hydraulic cylinder device supplied with hydraulic oil by the pump device, wherein the hydraulic cylinder device has a piston rod carrying a cutting blade, A piston connected to the piston rod, biasing means for biasing the piston to an initial position, first and second hydraulic chambers respectively defined on both sides of the piston, and when the piston advances to a predetermined position. An automatic release valve for releasing the hydraulic oil in the first hydraulic chamber, wherein the pump device supplies the hydraulic oil to the first hydraulic chamber to advance the piston from the initial position, and the automatic release valve has a piston. A portable steel bar cutter for recirculating pressure oil in a first hydraulic chamber to a suction side of a pump device when advanced to a predetermined position, wherein the first hydraulic chamber and a suction device of the pump device are provided. A pressure oil release passage communicating with the region, and an emergency manually operated on-off valve interposed in the pressure oil release passage, wherein the on-off valve has a head provided with a recess capable of receiving an operation means. A portable steel bar cutter, wherein the head projects slightly from the outer surface of the casing of the hydraulic cylinder device. 2. The portable steel bar cutter according to claim 1, wherein the pressure oil release passage connects the first hydraulic chamber and the second hydraulic chamber so as to be able to communicate with each other.