JPH0542413A - Lowering speed control device for saw frame in band saw machine - Google Patents

Abstract

PURPOSE:To lower a super large saw frame with good balance and to drastically reduce sliding resistance at a guide part by constituting so that a pressure of a predetermined size in the direction to lift the saw frame is applied to each of auxiliary cylinders on both sides of a main cylinder. CONSTITUTION:Auxiliary cylinders 4 and 5 are provided on both sides of a main cylinder 3 between them, and a predetermined pressure in the direction to lift a saw frame 2 is applied to them. Due to this, when the saw frame 2 is lowered, back pressure is applied to its oil drain passage, respectively, the heavy saw frame 2 can be lowered with a good balance and its unbalanced load can be eliminated. As a result, sliding resistance between a guide column (a main column 6 and an auxiliary column 7) for guiding the saw frame 2 and a guide (main guide part 21 and an auxiliary guide part 22) can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a descending speed control device for a saw frame in a horizontal band saw machine, and more specifically, in comparison with the amount of change in cutting resistance due to a change in cutting length of a workpiece, the saw The present invention relates to a saw frame descending speed control device suitable for an ultra-large band saw machine having a significantly large frame weight.

[0002]

2. Description of the Related Art In a horizontal band saw machine, generally, the weight of a saw frame having a band saw blade is supported by a hydraulic cylinder, and the amount of oil discharged from the hydraulic cylinder is adjusted by a back pressure valve, a flow control valve, etc. It is common to control the cutting down speed of the frame. FIG. 3 is an explanatory view of a descending speed control system of a saw frame of a conventional band saw machine, and the outline thereof will be described below with reference to this figure.

The weight of the saw frame 32 having the band saw blade 31 is supported by the hydraulic cylinder 33, and the lifting of the saw frame 32 pumps oil from the oil tank 35 into the hydraulic cylinder 33 through the hydraulic pump 34 and the check valve 36. The saw frame 32 is lowered by cutting the hydraulic cylinder 33.
This oil is guided to the back pressure valve 38 via the directional control valve 37, the back pressure valve 38 applies a constant back pressure to reduce the pressure, and the oil is discharged to the oil tank 35 through the flow rate control valve 39 at a low pressure. ing. The lowering speed is controlled by controlling the pressure in the hydraulic cylinder 33 due to the change in cutting resistance, that is, the back pressure valve 3
A method of adjusting the amount of drainage oil passing through the flow rate control valve 39 by using the action of changing the primary side pressure of 8 and the changing action of the secondary side pressure of the back pressure valve 38, that is, the pressure at the inlet of the flow rate control valve 39 accordingly. Is done by.

That is, since the pressure of the hydraulic cylinder 33 corresponds to the weight of the saw frame 32 minus the back force of the saw blade, that is, the cutting resistance, a change in the cutting resistance is detected as a pressure change in the hydraulic cylinder 33. Then, when the pressure in the hydraulic cylinder 33 is high, the amount of drained oil is increased to increase the descending speed, and when the pressure is low, the amount of drained oil is decreased to decrease the descending speed, thereby making the saw blade load almost constant. It is something that you try to control.

[0005]

By the way, in a band saw machine for cutting a shaped steel such as an H-shaped steel, in recent years, a machine has become extremely large in size as the shaped steel becomes extremely large. The following problems occur when it becomes a super-large machine. First, in the cutting down speed control of the saw frame, the value of the change of the back force force applied to the saw blade due to the change of the cutting resistance, that is, the value of the change of the substantial weight of the saw frame is compared with the total weight of the saw frame. Since it becomes a small value, the controllability is extremely lowered.

That is, the control method as described above is effective in a machine in which the self-weight of the saw frame is not so large as compared with the change of the cutting resistance, but the band saw machine becomes extremely large and the self-weight of the saw frame is increased. If the cutting resistance changes significantly, the responsiveness to the cutting resistance changes decreases,
There are drawbacks such as damage to the saw blade, or the cutting speed of the band saw blade is extremely reduced to impair productivity.

For example, in a material having a large cross-section change such as H-section steel, the cutting resistance changes from 0 to 100 Kg,
Assuming that the weight of the saw frame 32 is 3000 kg, the force acting on the piston of the hydraulic cylinder 33 is 30
It varies between 00 Kg and 2900 Kg. Now, assuming that the pressure receiving area of the hydraulic cylinder 33 is 100 cm ² , the primary pressure P ₁ of the back pressure valve 38 is 30 Kg / cm ² to 29 K.
It varies between g / cm ^2, the variation [Delta] P ₁ (= 1Kg
/ Cm ² ) is only 3.3% of the maximum value of P ₁ .

Here, a constant differential pressure type using a spring is used as the back pressure valve 38. If the spring pressure is set to 29 Kg / cm ² , the secondary pressure P ₂ is 1 to 0 Kg / cm. It becomes very low at ^2, and the drainage speed, that is, the descending speed of the band saw blade is extremely reduced, and the hydraulic control becomes unstable. If the spring pressure is set to 25 Kg / cm ² , the secondary pressure is 5 to 4 K.
g / cm ² (ΔP ₂ = 1 Kg / cm ² ), which is a value that does not change much, and the responsivity to changes in cutting resistance is too small to achieve the original purpose.

Secondly, as the size of the machine increases, the uneven load on the saw frame due to the deviation of the supporting position of the hydraulic cylinder increases, so that the sliding between the guide column and the guide for guiding the lowering of the saw frame. There is also a problem that the resistance becomes a large value and the pressure in the hydraulic cylinder is fluctuated to adversely affect the descending speed control. In order to solve the above-mentioned first problem,
The applicant has already used, as a back pressure valve in this type of control, a spool in which the working area of the secondary pressure is smaller than the working area of the primary pressure, and the spring is oriented in the same direction as the working direction of the secondary pressure. Using an improved back pressure valve that exerts pressing force, the pressure change of the hydraulic cylinder corresponding to the change of cutting resistance is amplified, and the amount of oil discharged from the hydraulic cylinder is controlled based on this pressure change after amplification. A saw frame descending speed control device has been proposed (Japanese Patent Publication No. 56-2153).
No. 1). However, even if the differential pressure amplification type back pressure valve based on this proposal is used, its amplification factor is limited, so that it cannot sufficiently function as a super-large machine.

The present invention has been made in view of the above points, and solves the above-mentioned first and second problems in a super-large band saw machine used for cutting a super-large H-section steel. It is an object of the present invention to provide a saw frame lowering speed control device that can be used.

[0011]

In order to achieve such an object, in a saw frame descending speed control device in a band saw machine according to the present invention, as shown in FIGS. 1 and 2 corresponding to an embodiment, a band saw blade is provided. In the device for supporting the weight of the saw frame 2 provided with 1 by the hydraulic cylinder (main cylinder) 3 and controlling the cutting downward speed of the saw frame 3 by adjusting the amount of oil discharged from the hydraulic cylinder 3, Separate hydraulic cylinders (sub-cylinders) 4 and 5 are provided on both sides of the cylinder 3 and a predetermined amount of pressure for raising the saw frame 2 is applied to the hydraulic cylinders 4 and 5 on both sides. Hydraulic circuit means (hydraulic pump P, pressure reducing valves BV1 and BV2 with relief) are provided.

[0012]

[Operation] In addition to the hydraulic cylinder 3 (main cylinder) used for adjusting the amount of drained oil, the saw frame 2 has two hydraulic cylinders (sub-cylinders) 4 and 5 provided on both sides thereof, for a total of 3 Since it is supported by the hydraulic cylinder of No. 1, the weight shared by the main cylinder 3 is reduced, and as a result, the weight of the saw frame to be lowered by the main cylinder 3 is apparently reduced. Can solve the problem.

Further, the auxiliary cylinders 4 and 5 are provided on both sides of the main cylinder 3 with the main cylinder 3 interposed therebetween, and a predetermined pressure for raising the saw frame 2 is applied to the auxiliary cylinders 4 and 5, so that when the saw frame 2 descends, its drain oil is drained. Since back pressure is applied to each of the paths, the heavy saw frame can be lowered in a well-balanced manner to remove the unbalanced load. As a result, it is possible to reduce the sliding resistance between the guide columns (main column 6 and sub column 7) for guiding the saw frame and the guides (main guide portion 21 and sub guide portion 22). The second problem can be solved.

[0014]

EXAMPLE FIG. 1 is a front view showing an example of an ultra-large horizontal band saw machine to which the present invention is applied. A table 11 is arranged on the base 10, and a vise device 12 for sandwiching the material W to be cut is provided on the table 11. A main column 6 and a sub column 7 are planted in the base 10 near the left and right ends thereof.
A saw frame 2 is slidably guided in its guide portions 21 and 22 along.

The saw frame 2 has a pair of left and right saw wheels 2
3 and 24 are supported, and the saw wheels 23 and 24
The band saw blade 1 is wound around in between, and is driven by a motor (not shown). The main cylinder 3 is fixed upright on the base 10 close to the inside of the main column 6, and the tip of the piston rod of the main cylinder 3 is fixed to the guide portion 21. A first sub-cylinder 4 is provided near the outside of the main column 6, and the tip of the piston rod of the first sub-cylinder 4 is similarly fixed to the guide portion 21. Further, a second sub cylinder 5 is provided near the outside of the sub column 7, and the tip of the piston rod of the second sub cylinder 5 is fixed to the guide portion 22.

With the structure described above, the saw frame 2 is supported by its own weight by a total of three hydraulic cylinders including the main cylinder 3, the first and second sub-cylinders 4 and 5, and the saw frame 2 has the following hydraulic circuit. By the action, the main column 6 and the sub column 7
It is configured to move up and down along. FIG. 2 is a main part hydraulic circuit diagram showing only the portion related to the vertical movement of the saw frame of the embodiment of the present invention.

The lower port of the main cylinder 3 is connected to the discharge port of the hydraulic pump P via the pilot operated check valve PCV1 and the solenoid valve SV1, and the upper port is also connected to the oil tank T. The solenoid valve SV1 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 port A of the solenoid valve SV1 is connected to the primary side of the pilot operated check valve PCV1, the port P is connected to the hydraulic pump P, and the port R is connected to the port P of the solenoid valve SV2.

The solenoid valve SV2 is a 4-port 2-position switching valve, the A port of which is connected to the oil tank T through the orifice TV, and the B port of which is connected through the back pressure valve AV1 and the flow control valve FCV1. It is connected to the tank T. The lower ports of the first and second sub-cylinders 4 and 5 are connected to the discharge port of the hydraulic pump P via the first and second pressure reducing valves BV1 and BV2, respectively, and these upper ports are Each is connected to an oil tank T. Therefore, this first and second
The sub-cylinders 4 and 5 are always operated with hydraulic pressure in the direction in which the saw frame 2 is lifted when the apparatus is driven.

In the above circuit configuration, when raising the saw frame 2, pressure oil is supplied from the P port of the solenoid valve SV1 to the lower port of the main cylinder 3 via the A port. Further, the saw frame 2 is lowered by its own weight. At this time, the solenoid valve SV1
Is switched and the pressure of the pump P is changed from the P port to the B port as pilot pressure as a pilot operated check valve PCV1.
The hydraulic oil in the lower port of the main cylinder 3 is guided from the A port of the solenoid valve SV1 to R
It goes toward the P port of the solenoid valve SV2 through the port. At the time of rapid descent other than during cutting, the solenoid valve SV2 is set in such a state that the P port and the A port communicate with each other, and the pressure oil from the lower port of the main cylinder 3 passes through the orifice TV and the oil tank at a constant speed. Return to T.

On the other hand, when the cutting depth for cutting is lowered, the solenoid valve SV2 is set so that the P port and the B port communicate with each other. In this state, the pressure oil from the lower port of the main cylinder 3 is guided from the A port of the solenoid valve SV1 to the R port of the solenoid valve SV2 to the P port of the solenoid valve SV2, and further through the B port of the solenoid valve SV2 to the back pressure valve AV1. And returns to the oil tank T via the flow control valve FCV1.

At any descent, the pressure oil in the first and second sub-cylinders 4 and 5 is back pressure because the pressure setting of the pressure reducing valves BV1 and BV2 with relief is less than the weight of the saw frame. The oil is relieved while returning to the oil tank T. When the saw frame 2 is moved up and down as described above, the saw frame 2 is supported by its own weight not only by the main cylinder 3 but also by the sub-cylinders 4 and 5 on both sides thereof, so that the weight applied to the main cylinder 3 is reduced by the saw. Frame 2
It is the weight obtained by subtracting the shared amount of the sub cylinders 4 and 5 from the actual weight of. Further, the existence of the left and right sub cylinders 4 and 5 also contributes to the elimination of the eccentric load of the saw frame 2, and the sliding resistance between the left and right guide portions 21 and 22 of the main column 6 and the sub column 7 is reduced. To do.

Now, when the saw frame 2 is lowered for cutting, the primary pressure of the back pressure valve AV1 changes by an amount corresponding to the increase or decrease in the cutting resistance of the workpiece W acting on the band saw blade 1. By that amount, the secondary side pressure of the back pressure valve AV1, that is, the inlet pressure of the flow rate control valve FCV1 changes. Similar to the control method described above, when the cutting resistance is large, the inlet pressure of the flow rate control valve FCV1 decreases, the flow rate decreases, the descending speed of the saw frame 2 becomes slow, and when the cutting resistance is small, As the inlet pressure of the flow rate control valve FCV1 rises, the flow rate increases and the saw frame 2 descends faster.

At this time, the weight acting on the main cylinder 3 is reduced by the amount shared by the left and right sub-cylinders 4 and 5 as described above, so that the controllability is greatly improved as compared with the conventional control method. To improve. That is, the weight of the saw frame 3 is set to 3000 kg as described above, and the first and second
By adjusting the relief pressure reducing valves BV1 and BV2, the total shared weight of the left and right sub-cylinders 4 and 5 is 2000.
If set to Kg, the main cylinder 3 will have 1000K
Only g will work. This means that the weight of the saw frame 2 is not excessively large with respect to the amount of change in the cutting resistance, and the sliding resistance between the main column 6 and the sub column 7 and the guide portions 21 and 22 is reduced. Together with this, the control sensitivity is greatly improved.

Here, as the back pressure valve AV1, the Japanese Patent Publication Sho 56
-If the differential pressure amplification type proposed in No. 21531 is used, even in an extremely large band saw machine, a change in cutting resistance acting on the band saw blade 1 is sharply fed back to the descending speed of the saw frame 2 to enable highly sensitive cutting control. It can be performed. In the above embodiment, a pressure reducing valve with a relief is provided in each oil discharge passage of each of the first and second sub cylinders 4 and 5, and the back pressure is separately applied when the saw frame 2 is lowered. However, one common pressure reducing valve with relief may be provided to the first and second sub-cylinders 4 and 5 to provide the same back pressure. However, when the saw frame 2 has a large eccentric load, in order to eliminate it and lower the balance in a well-balanced manner, different back pressures should be applied to the sub cylinders by separate pressure reducing valves with relief as in the present embodiment. Is desirable.

[0025]

As described above, according to the present invention, the sub cylinders are provided on both sides of the main cylinder for controlling the descending speed of the saw frame by the flow rate control, and the sub cylinders are provided in the respective sub cylinders. Since it is configured to apply a predetermined amount of pressure in the direction to lift the saw frame, by adjusting the back pressure of the sub cylinders on both sides as appropriate, the super-large saw frame can be used for the main column and sub column. It is possible to reduce the sliding resistance in the guide portion significantly by eliminating the unbalanced load on these columns by well descending along with.

At the same time, the load acting on the main cylinder provided with the back pressure valve for controlling the saw frame lowering speed in the oil discharge passage is:
As a result of being reduced by the amount shared by the sub cylinders on both sides, the ratio of the amount of fluctuation of the working load to the main cylinder due to changes in cutting resistance to the total working load is large, and the saw frame is very large and heavy. Even if the secondary pressure fluctuation of the back pressure valve becomes large, the descending speed of the saw frame is controlled in response to the change in the cutting resistance, in addition to the above-described effect of reducing the sliding resistance. Highly sensitive cut control is possible. This effect is achieved as a back pressure valve for the main cylinder in Japanese Patent Publication No. 56-21.
By using the differential pressure amplification type proposed in No. 531, it becomes even more remarkable, and it becomes possible to control even an ultra-large machine with the same sensitivity as a medium / small machine.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a super-large horizontal band saw machine to which an embodiment of the present invention is applied.

FIG. 2 is a main part hydraulic circuit diagram showing only a portion related to vertical movement of the saw frame according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a descending speed control method for a saw frame of a conventional band saw machine.

[Explanation of symbols]

 1 ...- Band saw blade 2 ... Saw frame 21,22 ...- Guide part 23,24 ...- Saw wheel 3 ... Main cylinder 4 ... First sub-cylinder 5・ ・ ・ Second sub cylinder 6 ・ ・ ・ Main column 7 ・ ・ ・ ・ Sub column 10 ・ ・ ・ ・ Base 11 ・ ・ ・ ・ Table 12 ・ ・ ・ ・ ・ ・ Vise device W ・ ・ ・ ・ ・ ・ Cutting Material P ... Hydraulic pump SV1, SV2 ... Solenoid valve PCV1 ... Pilot operated check valve AV1 ... Back pressure valve FCV1 ... Flow rate control valve BV1, BV2 ... Relief Pressure reducing valve with

Claims (1)

[Claims] 1. A device for supporting the weight of a saw frame provided with a band saw blade with a hydraulic cylinder and controlling the cutting down speed of the saw frame by adjusting the amount of oil drained from the hydraulic cylinder, wherein the hydraulic cylinder is Separate hydraulic cylinders are provided on both sides of the hydraulic cylinder, and hydraulic circuit means for applying a predetermined amount of pressure to the hydraulic cylinders on both sides to lift the saw frame is provided. Saw frame descending speed controller for band saw machine.