JPH0453645B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a horizontal band saw machine, and more particularly to a horizontal band saw machine that can reduce cutting noise caused by a band saw blade.

<Prior Art> Generally, when cutting H-beam steel, hollow mouth cross-sectional material, etc. using a bandsaw machine, the cutting noise generated increases or decreases depending on the location to be cut. For example, when cutting H-beam steel, cutting noise increases due to chattering noise and the like in the flange portion, which has a shorter cutting length than the web portion.

Conventionally, as a countermeasure against this problem, a method has been adopted to reduce the occurrence of chatter by pressing a chatter presser roller 2 or the like against the back surface of the band saw blade 1, as shown in FIG. After the band saw blade 1 passes through the web part, the chatter presser roller 2 is ineffective, and in the case of a hollow-mouth cross-sectional material, chatter is most likely to occur in the central part, but the above-mentioned conventional method had no effect at all.

<Object of the Invention> An object of the present invention is to provide a horizontal bandsaw machine that can automatically detect chatter when cutting at a location where chatter is likely to occur as described above, and reduce cutting noise.

<Structure of the Invention> The present invention is characterized by detecting changes in the cutting length by changes in the hydraulic pressure acting on the lifting hydraulic cylinder of the saw frame. It is configured to automatically reduce the running speed of the blade.

<Example> Examples of the present invention will be described below based on the drawings.

FIG. 2 is a front view of the embodiment of the present invention.

A drive wheel 15 and a driven wheel 16 are disposed within a saw frame 14 that is slidably supported on main and sub columns 12 and 13 on a base 11.
A band saw blade 17 is suspended between these two wheels. The drive wheel 15 is driven by a motor 20 via a transmission 18 and a reduction gear 19.

The transmission 18 is constituted by a belt-type continuously variable transmission operated by hydraulic pressure, and when hydraulic oil is supplied to the speed increase port _P1 or the deceleration port _P2 , the drive wheel 1 is shifted by displacing the pulley 18a.
5 can be increased or decreased.

The saw frame 14 is raised and lowered by a hydraulic cylinder 21 attached to the base 11. An outline of the elevation control will be explained based on the hydraulic circuit diagrams shown in FIGS. 2 and 3. Hydraulic cylinder 2
One piston rod 21a is attached to the saw frame 14 and supports its weight. The saw frame 14 is raised by forcing the hydraulic oil into the hydraulic cylinder 21 through the check valve 23 by the hydraulic pump 22, and the saw frame 14 is lowered by:
The hydraulic oil in the hydraulic cylinder 21 is guided to the back pressure valve 25 via the directional control valve 24, and a predetermined back pressure is applied by the back pressure valve 25 to lower the pressure, and the flow rate adjustment valve 2 is operated at a low pressure.
This is done by draining the oil to the oil drain passage 27 through the oil drain passage 27. The descending speed is controlled by using the pressure of the hydraulic cylinder 21 due to a change in cutting resistance, that is, the effect of changing the pressure on the secondary side of the back pressure valve 25 due to a change in the pressure on the primary side of the back pressure valve 25, which passes through the flow control valve 26. A method is used to adjust the amount of oil discharged. In other words, the pressure inside the hydraulic cylinder 21 corresponds to the effective gravity of the saw frame, that is, the weight of the saw frame 14 minus the cutting resistance (cutting back force) of the band saw blade 17. By detecting the pressure change inside the cylinder 21, when the pressure inside the hydraulic cylinder 21 is high, the amount of oil discharged is increased and the descending speed is accelerated, and when the pressure inside the hydraulic cylinder 21 is low, the amount of oil discharged is decreased and the descending speed is slowed down. band saw blade 1
The cutting speed is controlled so that the load of No. 7 is approximately constant.

In this hydraulic circuit, a pressure gauge with contacts 28 whose contacts are activated when a predetermined pressure value is reached is installed at an appropriate location in the oil drainage system of the hydraulic cylinder 21, for example, at a stage before (or after) the back pressure valve 25. It is provided. A contact signal from the contact pressure gauge 28 is used to control the supply of hydraulic oil to the transmission 18 described above. That is, as shown in FIG. 4, which shows the hydraulic oil supply circuit of the transmission 18, the speed increase port _P1 and the deceleration port _P2 are connected to a hydraulic pressure source via a direction control valve 29, and each solenoid of this direction control valve 29 a and b are excited according to the state of the contact signal of the pressure gauge 28 with contacts. When the pressure of the pressure gauge with contacts 28 is below the set value, solenoid a is energized and hydraulic oil is supplied to speed increase port _P1 , and when it exceeds the set value, solenoid b is energized and hydraulic oil is supplied to deceleration port _P2 . configured to be supplied. In addition, the pulley 1 of the transmission 18
The left and right displacement ends of 8a are detected by limit switches (not shown) set at appropriate positions, and when the pulley 18a reaches each displacement end due to the excitation of solenoid a or b, the excitation is stopped and direction control is performed. Valve 29 becomes blocked.

Next, we will discuss the effect. Before starting the cutting operation,
The contact operating pressure of the contact pressure gauge 28 and each displacement end of the pulley 18a of the transmission 18 are set. The setting of the contact operating pressure is, for example, when cutting H-beam steel.
Due to the pressure change when the cutting point reaches the web part,
Set solenoid a to be energized. Further, each displacement end of the pulley 18a is set so that, for example, when speeding up, a normal band saw blade traveling speed is obtained, and when decelerating, a speed several tens of percent slower than the normal band saw blade running speed is obtained.

When cutting H-beam steel with the above settings, during the cutting of the flange section at the beginning of cutting, the pressure acting on the hydraulic cylinder 18 is large because the cutting length is short and the cutting resistance is small, and the contact of the pressure gauge 28 with contacts Since the signal is in a state that excites the solenoid b, the band saw blade 17 is run at a low speed. When the cutting point eventually reaches the web part, the cutting length becomes longer and the cutting resistance increases, and the pressure acting on the hydraulic cylinder 18 decreases, and the contact signal of the contact pressure gauge 28 becomes a state that excites the solenoid a, and the band saw The blade 17 is run at high speed. When the cutting progresses further and the flange portion is cut again, the solenoid b is energized and the band saw blade 17 is driven at a low speed.

FIG. 5 shows experimental results using the above embodiment of the present invention and the conventional example of constant speed running. FIG. 5 is a graph showing the measurement results of cutting noise during cutting of each part of A to G of the 500 mm wide H section steel shown in FIG. 6. As is clear from this graph, in the example of the present invention, the noise during cutting of the flange portion is significantly lower than in the conventional example. In particular, in cutting E of the flange part after cutting the web part, in the conventional example, the chatter press roller could not be activated and a large noise was generated, but in the example of the present invention, the noise could be reduced by about 16 dB.

Further, FIG. 7 is a graph showing the measurement results of cutting noise during cutting of each part A to E of the 300 mm hollow-mouth shaped steel shown in FIG. 8. In this case as well, when cutting the center portion C, in the conventional example, the chatter presser roller could not be activated and a large noise was generated, but in the example of the present invention, this was able to be reduced by approximately 13 dB.

In the above two experiments, the running speed of the band saw blade 17 was a constant speed of 60 m/min in the conventional example;
In the embodiment of the present invention, the speed was set at 60 m/min during high speed running and 40 m/min during constant speed running. In this experiment,
It has been confirmed that the amount of cutting and bending, etc. is the same as that of the conventional example, and no other problems occur.

In the above embodiments, a hydraulically operated belt-type continuously variable transmission was used as the transmission.
Of course, other transmission devices such as an inverter system may be used, and instead of binary control of high speed and low speed, stepwise or stepless control may be used. Further, the force acting on the hydraulic cylinder 21 corresponds to the effective gravity of the saw frame described above, so it may be measured elsewhere.

<Effects of the Invention> As explained above, according to the present invention, when cutting a material such as H-beam steel whose cutting length changes significantly as cutting progresses, it is possible to cut a part with a short cutting length where chatter is likely to occur. This is detected by detecting the force acting on the cylinder for lifting and lowering the saw frame, and the traveling speed of the band saw blade is automatically reduced, reducing the occurrence of chatter and significantly reducing cutting noise. Not only that, but it also has a great effect on improving cutting efficiency and extending the life of the saw blade.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing conventional measures against chatter occurrence.
FIG. 2 is a front view of the embodiment of the present invention, FIG. 3 is a hydraulic circuit diagram for controlling the elevation of the saw frame 14, FIG. 4 is a hydraulic oil supply circuit diagram to the transmission 18, and FIGS. 5 and 7. 6 is a graph showing measurement results of cutting noise according to an embodiment of the present invention and a conventional example, and FIG. 6 and FIG. 8 are explanatory diagrams of FIG. 5 and FIG. 7, respectively. 14... Saw frame, 15... Drive wheel,
17... band saw blade, 18... transmission, 21... hydraulic cylinder, 25... back pressure valve, 28... pressure gauge with contact, 29... directional control valve.

Claims (1)

[Claims] 1. In a band saw machine in which the weight of a saw frame on which a band saw blade is suspended is supported by a hydraulic cylinder, and the descending speed of the saw frame is controlled by adjusting the amount of oil discharged from the hydraulic cylinder, the effective effectiveness of the saw frame is means for detecting gravity (a value obtained by subtracting the cutting back force of the band saw blade from the weight of the saw frame), and means for changing the traveling speed of the band saw blade according to the detected value, and the detected value is A horizontal band saw machine, characterized in that the traveling speed of the band saw blade is automatically reduced when the cutting length exceeds a predetermined value, thereby reducing noise caused by chatter that occurs when the cutting length is short.