JPH0911035A - Band saw machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a clamped phenomenon of a band saw blade by arranging a feed controlling means feeding the band saw by the predetermined quantity in the reverse direction to the cutting feeding direction when a time counted result by means of a timer means reaches the predetermined time. SOLUTION: When a time counted result by means of a timer reaches a cutting continuing time T0 in a RAM, a direction controlling valve 22 is driven, pressure oil from a hydraulic pump 23 is fed to a lower side port in a hydraulic cylinder 5, a saw frame 4 is lifted for a time t0 , and then, the direction controlling valve 22 is returned to the original cutting condition position again so as to lower the saw frame 4. If pressure data P reaches P0 again while the saw frame 4 is lowered again, the saw frame 4 is lifted for time t0 after a lapse of time T0 by the same way. These actions are repeated, and the saw frame 4 is lifted to the initial position when the saw frame 4 reaches the lower end and cutting is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band saw machine, and more particularly to a band saw machine capable of preventing a band saw blade from being caught by a work material.

[0002]

2. Description of the Related Art In the process of cutting a work material with a band saw, by forming a cutting groove in the work material with a band saw blade, internal stress of the work material is released and the cutting groove is narrowed. There is a case in which the cut portion protrudes and the band saw blade is sandwiched, making it impossible to continue the cutting operation or damaging the band saw blade.

Various proposals have hitherto been made in order to prevent such a phenomenon that the band saw blade is caught by the work material.
In Japanese Patent Laid-Open No. 4-25317, in a band saw machine that feeds cutting by lowering a saw frame that supports a band saw blade, when cutting feed is performed by lowering the saw frame,
The load on the traveling drive motor for the band saw blade is detected, and when the load reaches the set value, the saw frame is temporarily raised and then lowered again to scrape the cutting groove narrowed due to deformation. I'm trying to open it. Also, the actual Kaihei 5-37
In No. 148, the load of the traveling drive motor for the band saw blade is also detected, and when the load reaches the set value, the interval between the pair of saw wheels around which the band saw blade is wound on the saw frame is increased. Thus, the tension of the band saw blade is increased to prevent the band saw blade from stopping traveling due to pinching.

In Japanese Patent Laid-Open No. 5-50328, when the band saw blade reaches a position that can be set arbitrarily, the band saw blade is retracted by a set amount, and then the cutting feed is restarted to restart the cutting work. The narrowed portion of the cutting groove due to deformation is cut open.

[0005]

Among the conventional proposals as described above, the occurrence of the pinching phenomenon is detected by detecting the load of the traveling drive motor for the band saw blade, and some measures are taken at that time. According to the proposal of the person, it is difficult to surely prevent the trapping phenomenon. That is, since the load on the traveling drive motor for the band saw blade suddenly increases due to the pinching phenomenon, detection of such a load tends to be too late. Therefore, the pinching phenomenon cannot be prevented unless the set value of the load for starting the operation of raising the saw frame or increasing the tension of the band saw blade is extremely strict. However, the load of the drive motor is usually detected by detecting the current flowing through the motor, but this also changes due to other factors such as fluctuations in the power supply voltage. Is difficult and practically problematic.

On the other hand, the latter proposal of retracting the band saw blade at the time when the cutting position reaches the set position is such that after the cutting position at which the pinching phenomenon occurs in the cutting work of the H-shaped steel or the like, the web portion is cut to some extent or more. By utilizing the fact that it is limited to a substantially constant section until the cutting of the web part is completed, if the cutting position for retracting the band saw blade can be set accurately, the pinching phenomenon can be prevented beforehand. It will be possible. However, there is a problem in this position setting regardless of whether the method of manually moving the dog for the limit switch is adopted or the method of automatically calculating by inputting the size of the work material. That is,
In the method of manually moving the dog, it is necessary to change the setting each time the work material is changed, and it is not possible to support full automation, and it is difficult to always perform accurate position setting. In addition, although the method of automatically calculating the retracted position of the band saw blade by inputting the size of the work material can be fully automated, the size of the work material is the nominal size, especially the large size. In H-section steel, etc., there is a certain amount of difference between the nominal size and the actual size, so it cannot always be said that accurate position setting can be performed.

The present invention has been made in view of the above circumstances, and can be applied to full automation, and even if there is a difference between the nominal size and the actual size of the work material, the pinching phenomenon can be prevented. Moreover, the purpose is to provide a band saw machine that can be surely prevented.

[0008]

In order to achieve the above object, the band saw machine of the present invention has a back component force detecting means for detecting a cutting back component force of a band saw blade and a detection result of the back component force in advance. Judgment means that generates an output when the output exceeds the set standard, time measurement means that measures the time from the time when the output of the judgment means occurs, and the time measurement result by the time measurement means reaches the preset time At this point, the feeding means is provided to feed the band saw blade in a direction opposite to the cutting feed direction by a predetermined amount and then feed the cutting feed again.

In order to achieve the same object, according to the present invention, after the generation of the judgment output by the judgment means, the control means gives the feed to the band saw blade in the direction opposite to the cutting feed direction. It may be the time when the cutting feed amount from the time when the determination output is generated by the determination means reaches a preset amount, regardless of the time measurement result.

Here, as the judging means of the present invention, a reference value is set in advance, the value is compared with the cutting back force, and the output is output when the cutting back force exceeds the reference value. In addition to the means for generating, it is also possible to employ means for obtaining the amount of change in the cutting back force from the beginning of cutting every moment and generating an output when the amount of change exceeds a specified value.

The cutting back force referred to in the present invention may be the cutting back force itself or a physical quantity proportional to the cutting back force and substantially representing the cutting back force. Alternatively, for example, the pressure of a hydraulic cylinder that feeds the band saw blade by cutting may be used. As a method of detecting the cutting back force itself, a method of detecting a force applied to the back portion of the saw blade in a saw guide that guides the band saw blade on both sides of the workpiece can be used.

[0012]

For example, in the cutting work of H-section steel, the pinching phenomenon occurs as described above when the cutting position of the band saw blade is between B and C shown in FIG. 5, that is, the band saw blade cuts the web portion. It is already known that the cutting is limited to the time after cutting the cut to a certain extent and ending the cutting of the web portion. On the other hand, the cutting back force acting on the band saw blade changes in proportion to the length mainly involved in the cutting of the band saw blade, that is, the cutting length. In the cutting work of H-section steel, the cutting back force is until the band saw blade arrives at the position indicated by A in FIG.
In the state where only both flanges are being cut, a substantially constant value is maintained, which increases from the time when the cutting of the web portion is started upon reaching A, and when the cutting of the web portion shown in C is completed, the original value is restored. Returns to a certain value.

The present invention provides the above-described relationship between the actual cutting position of the band saw blade with respect to the work material and the occurrence position of the pinching phenomenon, and the phenomenon that the cutting back force changes depending on the cutting position with respect to the work material. By using this, the cutting position relative to the work material is recognized from the magnitude of the cutting back force without setting or calculating the cutting position for retracting the band saw blade to prevent the pinching phenomenon. Accordingly, by automatically retracting the band saw blade, the band saw blade is operated adaptively to the actual size of the work material, and the pinching phenomenon is surely prevented.

That is, by detecting the change in the detection result by the back force detecting means, it is detected that the band saw blade has passed through A in FIG. 5, that is, the cutting of the web portion has been started, and from that point on, the set time is set. When, or when the cutting feed amount from that time has reached the set amount, the band saw blade is retracted by a predetermined amount (feed in the direction opposite to the cutting feed direction is given) to move backward. It is possible to reliably prevent the occurrence of the pinching phenomenon without performing the position setting and the like.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, in which a schematic configuration diagram of a mechanism and a hydraulic circuit diagram of a main part are shown together.

Main column 2 fixed upright on bed 1.
The saw frame 4 slidably supported along the sub column 3 is moved up and down by driving the hydraulic cylinder 5. A pair of left and right saw wheels 6, 7 is rotatably supported on the saw frame 4, and a loop-shaped band saw blade S is wound around the saw wheels 6, 7. The band saw blade S is guided in the vertical direction by two saw blade guides 8 and 9 in the vicinity of the left and right of the work material W. One of the saw wheels 6 and 7 is rotated by a motor (not shown), which drives the band saw blade S to travel.

On the bed 1, a vise mechanism 10 for holding and fixing the work material W, and a known fixed size for feeding the work material W to the vise mechanism 10 by an arbitrary set amount. A mechanism (not shown) is provided, and the work material W is fed by the sizing mechanism in an amount corresponding to the cutting length, and then clamped and fixed by the vise mechanism 10 in the saw frame 4 Is cut by falling. Such a series of cutting operations is performed based on a control signal from the control unit 30 described later.

The hydraulic cylinder 5 for raising and lowering the saw frame 4 is arranged so as to support the weight of the saw frame 4 by a piston rod 5a protruding from the upper end thereof, and the lower port of this hydraulic cylinder 5 is a pilot. It is connected to the discharge port of the hydraulic pump 23 via the operation check valve 21 and the direction control valve 22, and the upper port is returned to the hydraulic tank T.

The directional control valve 22 is a 4-port 3-position switching valve and has a so-called ABR connection type center structure in which the A port, the B port and the R port are connected to each other. The A port of the directional control valve 22 is connected to the primary side of the pilot operated check valve 21, the B port is connected to the pilot pressure input port of the pilot operated check valve 21, and the P port is connected to the hydraulic pump 23. Further, the R port is connected to the P port of the directional control valve 24.

The directional control valve 24 is a 4-port 2-position switching valve whose A port is returned to the hydraulic tank T through an orifice 25 and whose B port is a back pressure valve 26.
And is returned to the hydraulic tank T via the flow control valve 27.

In the construction of the hydraulic circuit as described above, when the saw frame 4 is raised, the P of the directional control valve 22 is set.
This is performed by supplying pressure oil from the port to the lower port of the hydraulic cylinder 5 via the A port via the check valve 21.

Further, the saw frame 4 is lowered by its own weight. In this case, the pressure oil from the hydraulic pump 23 is fed through the P port and the B port of the directional control valve 22 to the pilot pressure of the check valve 21. To open the oil passage.
As a result, the lower port of the hydraulic cylinder 5 is connected to the check valve 2
1. Connected to the P port of the direction control valve 24 via the direction control valve 22. When the saw frame is lowered during cutting, the P port and the B port of the directional control valve 24 are connected in this state,
The pressure oil from the lower port of the hydraulic cylinder 5 is guided to the flow control valve 27 via the back pressure valve 26. In this state, the pressure oil from the lower port of the hydraulic cylinder 5 is applied with a constant back pressure by the back pressure valve 26 to reduce the pressure, and then passes through the flow control valve 27 under the low pressure. Then, it is returned to the hydraulic tank T. In this cutting state, when the cutting back force of the band saw blade S changes, the pressure in the hydraulic cylinder 5 changes, and the pressure acting on the primary side of the back pressure valve 26 via the lower port changes. The secondary pressure of the back pressure valve 26, that is, the inlet pressure of the flow rate control valve 27 changes, and the cutting speed is controlled according to the cutting back force. Specifically, when the cutting back force of the band saw blade S increases, the inlet pressure of the flow control valve 27 decreases, the flow rate of oil passing therethrough decreases, and the descending speed of the saw frame 4 slows down. When the back force is small, the inlet pressure of the flow rate control valve 27 increases, the flow rate increases, and the descending speed of the saw frame 4 increases. In addition, at the time of rapid descending other than during cutting, P of the directional control valve 24 is maintained in this state.
With the port and the A port connected, the pressure oil from the lower port of the hydraulic cylinder 5 is returned to the hydraulic tank T through the orifice 25 at a constant speed. The above is known.

The feature of the embodiment of the present invention is that the pressure of the hydraulic cylinder 5 at the time of cutting acts in the above hydraulic circuit, for example, as shown in the figure, the hydraulic cylinder at the time of cutting. 5, a pressure sensor 28 is arranged between the directional control valves 22 and 24 through which the pressure oil from the lower port of 5 passes, and the pressure detection output by the pressure sensor 28 is incorporated in the control unit 30 described below. Rarely, the saw frame 4 is appropriately moved up and down during cutting according to the detection result.

FIG. 2 is a block diagram showing the configuration of the electrical control system of the embodiment of the present invention. The output of the pressure sensor 28 that detects the pressure of the hydraulic cylinder 5 during cutting is AD
After being digitized by the converter 31, it is taken into the control unit 30. The control unit 30 includes a CPU 30a and a ROM 3
0b, a RAM 30c, a keyboard 30d, an input / output control unit 30e, and a computer, and a sequencer 30f connected to the computer, and the directional control valves 22 and 24 in the hydraulic circuit described above, or a saw wheel drive motor or the like. A control signal is supplied to each of the actuators via the sequencer 30f under the control of the CPU 30a.

FIG. 3 is a flow chart showing the main part of the routine executed during automatic operation in the program written in the ROM 30b. The operation of the embodiment of the present invention will be described below with reference to this figure.

After the cutting length of the work material W is set, the automatic operation is started with the work material W being clamped and fixed by the vise mechanism 10. Before the issuance of the automatic operation start, the cutting operation is performed. Pressure value P, which is the reference value for feeding backward
₀ , the cutting duration time T ₀ from when the actually measured pressure value reaches the reference pressure value P ₀ until the cutting is actually retracted,
And the retreat continuation time t ₀ from retreating the notch to re-advancing is set by the keyboard 30d.
These set values P ₀ , T ₀ and t ₀ are RA
It is stored in M30c.

When the automatic operation is started, the hydraulic cylinder
The lower port of the da 5 is connected to the flow control valve 27 via the back pressure valve 26.
Drive each directional control valve 22 and 24 to communicate with
While lowering the saw frame 4 to cut the work material W,
The pressure data P from the pressure sensor 28 is taken every moment.
The pressure data P is the reference pressure value P in the RAM 30c. ₀
And the measured pressure data P is compared with the reference pressure value P.₀Reached
At the time, the clock built into the computer of the control unit 30
Start the timer according to. And that timer
The time measurement result T by is the cut duration time T in the RAM 30c.
₀At the time when the pressure is reached, the directional control valve 22 is driven to
The pressure oil from the pump 23 is supplied to the lower port of the hydraulic cylinder 5.
Salary, time t₀Only after raising the saw frame 4 again
Return the directional control valve 22 to the original cutting position, and
Move down M4. When the saw frame 4 descends again
The pressure data P again₀When you reach
Time T₀After the lapse of₀Only risen
Let This operation is repeated until the saw frame 4
When the saw reaches the descending end and finishes cutting,
Raise to the initial position.

FIG. 4 shows the saw frame 4 during the above cutting operation.
5 is a time chart illustrating the relationship between the position of the pressure sensor and the pressure of the hydraulic cylinder 5 by the pressure sensor 28. Since the cutting length of the band saw blade S is constant when the band saw blade S is cutting both flange portions of the H-shaped steel as the work material W, the pressure data P maintains a substantially constant value, From the time when the band saw blade S reaches the position A shown in FIG.
The cutting length increases and the cutting back force increases, and the value of the pressure data P decreases accordingly. When the time T ₀ elapses from the time when the pressure data P decreases to the reference pressure value P ₀ , the saw frame 4 moves up the time t ₀ . This time T
₀ is a value equal to the time from when the pressure data P decreases and reaches the reference pressure value P ₀ to when the band saw blade S reaches the position B illustrated in FIG. 5, or a slightly shorter time. Set to. As a result, the band saw blade S is placed at a position where a pinching phenomenon may occur when cutting the H-section steel.
Immediately before the arrival of, the band saw blade S moves up by a predetermined distance.

Although the cutting back force becomes almost 0 by the rise of the band saw blade S, when the band saw blade S starts to descend again after the time t ₀ , the band saw blade S enters the cutting groove already formed by cutting. Then, the deformed portion (the protruding portion into the cutting groove) due to the rearrangement of the internal stress of the work material W is cut. In this state, since the cutting resistance is small, the cutting back force also becomes a minute value, the pressure of the hydraulic cylinder 5 rises, and the descending speed of the saw frame 4 also increases. When the band saw blade S eventually reaches the uncut portion, the cutting back force starts to rapidly increase. When the pressure data P decreases to P ₀ again due to the increase in the back force, the band saw blade S moves up again for the time t ₀ after the time T ₀ has elapsed from that point. By such repetition, even if the work portion is projected into the cutting groove due to the release of the internal stress of the work material W due to the cutting, the band saw blade S is appropriately raised by a predetermined distance from the groove, and then the By cutting the protruding portion and then starting to cut the uncut portion again, the cutting of the work material W can be completed without the band saw blade S being sandwiched.

As shown in FIG. 3, while the automatic operation continues, after one cutting operation is completed, the operation for the next cutting, that is, the work material W by the vise mechanism 10 is performed.
Is released, the sizing mechanism feeds the work W by a sizing mechanism, the vice mechanism 10 holds and clamps the work W after sizing, and the above cutting operation is repeated.

Here, in the above embodiment, the pressure sensor for capturing the change in the pressure of the hydraulic cylinder 5 due to the change in the cutting back force is provided in the oil passage on the primary side of the back pressure valve 26. It may be provided on the secondary side of the back pressure valve 26, and basically, it may be provided at any place in the oil passage where the change of the cutting back force can be captured.

Further, in the above embodiment, the fact that the cutting back force has changed was identified by comparing the pressure data P from the pressure sensor 28 with the preset reference pressure value P _0. Without setting the pressure value P ₀ , the momentary change of the pressure data P during cutting is obtained, for example, by calculating the difference between the data before and after the sampling of the data P, and the difference is set in advance. It is also possible to identify that the cutting back force has changed when the amount exceeds the cutting amount.

Further, instead of the pressure sensor 26, a pressure gauge with a contact is provided at an appropriate place, a contact signal is generated when the pressure of the hydraulic cylinder 5 is reduced to a set value, and a time is elapsed from the generation of the contact signal. The saw frame 4 may be raised when T ₀ has elapsed.

In the hydraulic circuit for raising and lowering the saw frame 4, if the back pressure valve 26 of the differential pressure amplification type proposed in Japanese Patent Publication No. 56-21531 is used,
After the change of the cutting back force acting on the band saw blade 8 is sensitively reflected on the descending speed of the saw frame 4, highly sensitive cutting control can be performed, and after being amplified by this differential pressure amplification type back pressure valve. If the cutting back force of the band saw blade S is detected from the pressure of 1, the change in the cutting back force can be more reliably captured.

Furthermore, as a method of detecting the cutting back force,
In addition to the method of detecting the pressure of the hydraulic cylinder as in the above embodiment, the same effect can be obtained by using the method of detecting the force applied to the back portion of the band saw blade in the saw guides 8 and 9.

Further, in the above-mentioned embodiment, the time T from the time when the cutting back force increases beyond a certain standard.
_{Although the} saw frame 4 is turned upward when ₀ has passed, the present invention is not limited to this, and the set distance from the time when it is determined that the cutting back force has increased beyond the reference. It is also possible to raise the saw frame 4 when only cutting feed is performed. In this case, it is necessary to know the incision position or the incision amount, which is achieved by fixing one end of the wire 41 to the saw frame 4 as shown in the front view of FIG. The other end of the wire is wound around the shaft of the pulse generator 42 through a pulley or the like, and an elastic force is constantly applied to the wire 41 by a spring or the like in a direction to be wound around the shaft of the pulse generator 42 under a constant tension. By adding the signal, it is possible to detect and know the pulse signal generated according to the moving amount of the saw frame 4 every moment. Then, the pulse signal is taken into the control unit 30, and as shown in the time chart of FIG. 7, the saw based on the output pulse number of the pulse generator 42 from the time when it is determined that the cutting back force has increased beyond the reference. When the descending amount of the frame 4 reaches a preset Δ _F , the saw frame 4 is turned up. Even with such a configuration, it is possible to achieve the same effect as that of the previous example. The amount of increase may be the constant time t ₀ as in the above example, but may be the constant distance Δ _B as shown in FIG. 7.

The method for detecting the incision position or the infeed amount at every moment is not limited to the above-mentioned example, and it goes without saying that any known technique can be adopted, for example, the hydraulic cylinder 5 is a cylinder with an encoder. Yes.

[0038]

As described above, according to the present invention,
The cutting position of the band saw blade with respect to the work material is recognized based on the change in the cutting back force of the band saw blade, and the cutting direction of the band saw blade is opposite to the cutting direction based on the recognition result and the time measurement result or the cutting feed amount. Since the timing for applying (retracting) the direction feed is determined, there is a difference between the nominal size of the work material and the actual size without setting the cutting position to retract the band saw blade as in the conventional case. It is possible to reliably prevent the occurrence of the trapping phenomenon, and it is also possible to easily cope with full automation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention in which a schematic configuration diagram of a mechanism and a hydraulic circuit diagram of main parts are shown together.

FIG. 2 is a block diagram showing a configuration of an electric control system according to the embodiment of the present invention.

FIG. 3 is a flowchart showing a main part of a routine executed during automatic operation among the programs written in the ROM 30b.

FIG. 4 is a time chart illustrating the relationship between the position of the saw frame 4 and the secondary pressure of the hydraulic cylinder 5 by the pressure sensor 28 during the cutting operation according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a cutting position of a band saw blade in which a pinching phenomenon occurs when cutting an H-shaped steel.

FIG. 6 is a front view of another embodiment of the present invention.

FIG. 7 is a time chart illustrating the relationship between the position of the saw frame 4 and the secondary pressure of the hydraulic cylinder 5 by the pressure sensor 28 during the cutting operation according to another embodiment of the present invention.

[Explanation of symbols]

 1 Bed 2 Main Column 3 Sub Column 4 Saw Frame 5 Hydraulic Cylinder 8, 9 Saw Guide 10 Vise Mechanism 21 Pilot Operated Check Valve 22 Directional Control Valve 23 Hydraulic Pump 24 Directional Control Valve 26 Back Pressure Valve 27 Flow Control Valve 28 Pressure Sensor 30 Control unit 31 A-D converter S Band saw blade 41 Wire 42 Pulse generator

Claims (5)

[Claims] 1. A back component force detecting means for detecting a cutting back force component of a band saw blade in a band saw machine for cutting a work material by cutting feed the work material while driving the band saw blade. And a judgment means for generating an output when the back force exceeds a preset standard, a time measuring means for measuring the time from the time when the output of the judgment means is generated, and a timing result by the time measuring means. When a predetermined time is reached, the band saw blade is provided with a feed control means for feeding the band saw blade a feed in a direction opposite to the feed direction by a predetermined amount and then feeding the feed again. . 2. A back component force detecting means for detecting a cutting back force component of a band saw blade in a band saw machine for cutting a work material by cutting feed the work material while driving the band saw blade. And a judgment means for generating an output when the back force increases beyond a preset standard, and a time when the cutting feed amount from the generation time of the judgment means reaches a preset amount. A band saw machine comprising feed control means for feeding a feed in a direction opposite to the feed direction to the band saw blade by a predetermined amount and then feeding the feed again. 3. The determination means is means for comparing the detected value of the back force component with a preset reference value and generating an output when the back force force exceeds the reference value. The band saw machine according to claim 1 or 2. 4. The determination means according to claim 1, wherein the determination means is a means for generating an output when the amount of increase in the back force at regular time intervals exceeds a preset amount. The band saw machine described. 5. The band saw machine according to claim 1, 2, 3 or 4, wherein the back force detecting means is a pressure detecting means for a cylinder that feeds the band saw blade by cutting.