JPH0459128A - Device for correcting ram position on hydraulic press brake - Google Patents

Abstract

PURPOSE:To make the position of lower limit constant and to improve the accuracy of bending angle of the work by measuring the position of lower limit of the ram, comparing its amount of the change with the lapse of time with the allowable value preliminarily set with computing and correcting the data. CONSTITUTION:The correction of the quantity of change with the lapse of time of the position of lower limit is stored to the memory 133 by lowering the ram for bending, making the ram lower limit switch ON, and digital-converting with the A/D converter of the lower limit position sensor 123 after T1 seconds set at the timer 137. The initial value setting of (XA) ram lower limit position is stored to the sub- memory 141 at the 1st working time by pushing the key of the lower position setting means 139. (XB) On each stroke after setting the initial value, its quantity of changing (XA-XB) is processed with the processing means 143. And the allowable displacement quantity are made preliminarily XC, XD, and set to the displacement quantity setting means 145, the next equations are set with the comparing means 147, and command of elevation or lowering is outputted. XA-XB>=XD is the command to elevate. XA-XB<=XD is the command to lower.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) This invention relates to an improvement of a ram position correction device in a hydraulic press brake.

(Prior art) Conventionally, the ram drive systems of press brakes used for bending long objects include mechanical and hydraulic types, and the ram lowering speed required for bending work can be easily varied. In addition to being advantageous in terms of price, the hydraulic type was used because it allowed further machining while maintaining pressure from the lower limit position.

A typical example of such a hydraulically driven mechanism is a ram positioning mechanism using a fluid bearing, and its operation will be explained with reference to FIG. It should be noted that the hydraulic circuit shown in FIG. 7 is a well-known one, and a detailed explanation will be omitted, limiting the explanation to the main parts involved.

By switching the main valve 205 connected to the cylinder 203 that drives the ram 201, the ram 201 is raised and lowered to bend the workpiece.

The ram 201 is lowered to approach the workpiece at a high speed to improve productivity, and the bending process is performed at a low speed by operating the speed switching valve 207 to prevent the workpiece from bouncing up.

When this speed switching valve 207 is activated, the check valve of the counterbalance valve 209 with pilot check valve opens to perform high-speed machining, and when the ram 201 reaches a certain set height, the speed switching valve 207 closes and the machining speed is reduced to a low speed. The gear will be changed.

While the ram 201 bends the workpiece at a low processing speed, it further processes the workpiece and hits the stopper on the fluid bearing, causing the fluid bearing to narrow the gap. For this reason, a pressure difference is generated between the inside and outside of the fluid bearing, and when a certain set pressure difference is reached, the balance valve 211 is activated, and in order to maintain this pressure difference, the gap in the fluid bearing is kept constant and the ram 201 is stopped.

Therefore, since the ram 201 is not mechanically stopped by a stopper, by rotating the shaft 213, the piston 215 of the cylinder 203 is rotated.
The nut 217 screwed into the piston 215 rotates, allowing the piston 215 to continue lowering.

The above operation will be explained in more detail. Referring also to FIG. 8, when the lower limit handle 219 is turned, the bevel gear 2
21, it is decelerated through a reducer 223, and the rotational speed is transmitted to the shaft 213. The shaft 213 is the bearing 22
5, and the nut 217 engages with a key 227 provided on the shaft 213 so as to be vertically movable. In addition, an orifice 2 is provided at the lower end of the shaft 213.
29 is included. Furthermore, an oil passage 231 is bored in the axial center of the shaft 213, and a male thread 233 provided on the outer periphery of the nut 217 is screwed into an oil thread 235 provided on the inner periphery of the piston 215. piston 2
Move up and down inside 15.

The stroke of the machine is such that the piston 215 is at the rising end;
When the nut 217 is rising, this nut 217
The distance between the washer 237 and the washer 237 is the stroke.

To set the lower limit during pressurization, when the lowering foot pedal device is stepped on in a single inching motion, the ram 201 descends to the lower limit setting position and stops. In other words, the nut 217 is in contact with the surface of the washer 237, and it can be said that the ram 201 is being held back by the stopper in an attempt to continue lowering. At that time, the distance between the shaft 213 and the orifice 229 is narrowed.

As a result, the pressure on the A side shown in FIG. 8 increases, creating a differential pressure with respect to the pressure on the B side. This differential pressure acts on the spool of the counterbalance valve 209 and creates a drain circuit, so oil continues to return from the drain boat of the counterbalance valve 209 to the tank 239 through the orifice 229, and the pressures on the A and B sides are balanced. Ru. Therefore, the lowering end can be further lowered continuously.

As mentioned above, by rotating the shaft 213,
By changing the position of the nut 217, the lower limit setting position of the ram 201 can be changed.

Note that the reference numeral 241 is a hydraulic pump, the reference numeral 243 is a relief valve, and the reference numeral 245 is a pressure gauge provided in the cut-off valve 247. Further, reference numeral 249 is a pressure regulating valve, and reference numeral 251 is a check valve.

(Problem to be Solved by the Invention) By the way, in the conventional hydraulically driven press brake described above, the ram descends while bending the workpiece at low speed, hits the stopper on the hydrodynamic bearing, and the hydrodynamic bearing narrows the gap. However, in hydrodynamic bearings, the gap changes over time due to increases in oil temperature and room temperature fluctuations. For this reason, there was a problem in that the bending angle changed as the lower limit position of the ram changed.

The purpose of this invention is to improve the above-mentioned problems by measuring the ram lower limit position with a sensor, calculating and comparing the amount of change over time with a preset tolerance value, and correcting the ram lower limit position, thereby keeping the ram lower limit position constant. An object of the present invention is to provide a ram position correction device for a hydraulic brake that improves the bending angle accuracy of a workpiece.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a hydraulic press brake that allows an upper mold and a lower mold to cooperate with each other by vertical movement of a arm to bend a workpiece. , a lower limit position sensor that detects the lower limit position of the ram, a setting means that sets the lower limit position of the ram in advance, a displacement amount setting means that sets an allowable displacement amount in advance, and a lower limit position sensor that detects the lower limit position of the ram; arithmetic processing means for calculating the actual lower limit position and the set lower limit position set by the setting means; the actual amount of change calculated by the calculation processing means and the displacement amount set by the displacement amount setting means; A ram position correcting device for a hydraulic press brake was constructed by comprising a comparison means for comparing the two.

(Function) By employing the ram position correction device in the hydraulic press brake of the present invention, a lower limit position sensor for detecting the lower limit position of the ram and a setting means for setting the lower limit position of the ram in advance are provided, and this setting means is provided. The set lower limit position set by the lower limit position and the actual lower limit position detected by the lower limit position sensor are subjected to calculation processing by a calculation processing means.

On the other hand, the comparison means compares the displacement amount set by the displacement amount setting means for setting an allowable displacement amount in advance with the actual change amount calculated by the calculation processing means, and the ram position correction device Provides feedback and corrects position errors.

Therefore, even if the lower limit position of the ram changes over time due to an increase in oil temperature or a change in room temperature, it can be corrected, and the lower limit position of the ram remains constant, improving the bending accuracy of the workpiece.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

Referring to FIG. 6, the hydraulic press brake 1 is composed of a C-shaped frame 3, a lower table 5 is provided on the lower side of the C-shaped frame 3, and a diamond is mounted on the lower table 5. A punch 11 is provided on the upper side of the C-shaped frame 3 and is vertically disposed on a ram 9 facing the diamond. Although not shown, a lower limit position adjustment shaft 15 is provided inside, and in order to adjust the lower limit position adjustment shaft 15, a lower limit handle 19 is provided via a reduction gear 17.

Further, a hydraulic device 21 for operating the cylinder 13 is provided inside the C-shaped frame 3, and a foot pedal device 23 is movably provided on the front side of the machine.

With the above configuration, by operating the foot pedal device 23,
The hydraulic device 21 is operated to move the ram 9 vertically disposed on the cylinder 13 up and down, and the punch 11 and the diamond work together to bend the workpiece.

When changing the lower limit stop position of the punch 11, the lower limit of the ram 9 is set by rotating the lower limit handle 19 and moving the lower limit position adjustment shaft 15.

The hydraulic system 21 will be explained in detail based on the hydraulic circuit diagram shown in FIG. Note that since this hydraulic circuit is a known hydraulic circuit employed in a ram positioning mechanism using a fluid bearing, the description will be limited to the main parts.

Main valve 2 leading to cylinder 13 that drives ram 9
5, the ram 9 moves up and down to bend the workpiece. The ram 9 is lowered at high speed when approaching the workpiece to improve productivity, and at low speed by operating the speed switching valve 27 to prevent the workpiece from bouncing back during bending.

That is, when the speed switching valve 27 operates, the check valve 31 of the counter balance valve 29 with a pilot check valve opens, the unloading valve 33 closes and high-speed machining is performed, and when the ram 9 reaches a certain set height, the speed switching valve 27 opens.
By closing, the machining speed is changed to a low speed. In addition, the reference numeral 35 is a tongue, and the reference numeral 37 is a double hydraulic pump. Reference numeral 39 is a relief valve for keeping the line pressure constant, and reference numeral 41 is a regulator for keeping the line at a predetermined pressure.

Reference numeral 43 is a balance valve, and while the ram 9 bends the workpiece at low speed, it further descends and hits the stopper on the fluid bearing, and the fluid bearing narrows the gap, creating a pressure difference inside and outside the fluid bearing. , the balance valve 43 is activated when a certain set differential pressure is reached. Due to the operation of the balance valve 43, the differential pressure is maintained, so the fluid bearing has a constant gap, and the ram 9
stops. Also, reference numeral 45 is a check valve;
7 is a cut-off valve, 49 is a check valve, 51 is a pressure gauge, 53 is a pressure switch, 55 is a check valve, and 56 is a relief valve.

Next, regarding the cylinder 13 and the ram position correction device which is the main part of this embodiment, FIGS.
This will be explained in detail with reference to the drawings.

As for the structure of the cylinder 13, the cylinder body 59 is fixed to the C-shaped frame 3 (not shown) by bolts 61 or the like, and a piston 63 is provided inside the cylinder body 59 so as to be movable up and down. The lower end (lower side in FIG. 2) of this piston 63 is engaged with the ram 9.

A female thread 65 is provided around the inside of the piston 63, on the inner periphery of the cylindrical portion, and a nut 69 having a male thread 67 that is screwed into the female thread 65 is mounted so as to be vertically movable. nut 69
is engaged via a key 71 provided on the lower limit position adjustment shaft 15 inserted into the shaft center. Note that the reference numeral 73 is an end plate, and the reference numeral 75 is an end cap, each of which is closely fixed to the other to form an oil chamber.

With the above configuration, by rotating the lower limit position adjustment shaft 15, the nut 69 is rotated, and the screwed male and female threads 65 are rotated.
．． 67 causes the nut 69 to move up and down within the piston 63. Therefore, it is possible to freely set the stroke of the cylinder 13.

The lower limit position adjustment shaft 15 has a first oil passage 77 bored in its axial center, and a check valve 79 is provided at the bottom of the first oil passage 77, and the first oil passage 77 communicates with the inside of the piston 63. A second oil passage 81 is provided. In addition, the orifice 83 that opens or narrows the second oil passage 81 is located on the lower limit position adjustment shaft 1.
5, and the washer 8 is fitted on the top surface of the orifice 83.
5 is a provision.

On the other hand, the upper end of the lower limit position adjustment shaft 15 is locked to the reducer 17, and the input shaft 87 of the reducer 17 is connected to the bevel gear device 1.
The input shaft 93 of the bevel gear device 89 is connected to the lower limit handle 19.

With the above configuration, when the lower limit handle 19 is turned, the rotation of the lower limit position adjustment shaft 15 passes through the bevel gear device 89 and the reducer 17.
transmitted to. Note that when the piston 63 is at the rising end and the nut 69 is fully raised, the distance between the nut 69 and the washer 85 is the stroke of the machine.

Regarding the lower limit setting during pressurization, when the foot pedal device 23 is stepped on in a single inching motion, the ram 9 descends to the lower limit setting position and stops.

More specifically, it can be said that the nut 69 is in contact with the surface of the washer 85, and that even if the ram 9 attempts to continue lowering, it is held back by the stopper. then,
The distance between the lower limit position adjustment shaft 15 and the orifice 83 is narrowed, and the pressure in the first oil passage 77 increases, creating a pressure difference with respect to the pressure in the piston 63. This differential pressure causes the above-mentioned hydraulic system 2
Since the oil acts on the spool of the balance valve 43 of No. 1 to create a drain circuit, the oil flows from the first oil path 77 to the second oil path 81.
through the orifice 83 and continue returning to the tank 35 from the drain port of the balance valve 43. As a result, the pressure in the first oil passage 77 and the pressure in the piston 63 are balanced, and the lowering end can be further lowered continuously.

As shown in FIG. 2, the ram position correction device 57, which is a mechanism for detecting the speed switching position of the cylinder 13 described above, has one end of the dog rail 95 locked to the ram 9 (not shown), and the dog rail 95 moves up and down as the ram 9 moves up and down. Move up and down while being guided by the support 97. This dog rail 95 is provided with a dog 99 for setting a lower limit speed change position which engages with an elongated hole 101 and whose attachment position can be adjusted freely. (See Figure 4) On the other hand, a coupling gear box 107 is connected to the output shaft 103 of the reducer 17 connected to the lower limit position adjustment shaft 15 of the cylinder 13 via a coupling shaft 105, and the output side of this coupling gear box 107 and A connecting shaft 109 is provided hanging down.

The connecting shaft 109 is rotatably supported via a bearing 113 mounted on a support member 111, and has a thread 115 cut in a predetermined range. Note that the support member 111 is fixed to the C-shaped frame 3 (not shown). A nut 117 is screwed onto the screw 115, and a lower limit switch 121 is engaged with a bracket 119 provided on the nut 117.

With the above configuration, the lower limit position adjusting shaft 15 of the cylinder 13 is connected to the connecting gear box 107 by the connecting shaft 105, and as the nut 69 that sets the lower limit position of the cylinder 13 goes up and down, the connecting shaft 109 hangs down from the connecting gear box 107. The nut 117 that is screwed into the can be moved up and down by the same amount. A lower limit switch 12 is attached to a bracket 119 provided on the nut 117.
1 is turned ON by the dog 99 that has moved due to the lowering of the ram 9, and a speed change operation is performed.

Furthermore, in addition to the above-mentioned mechanism, a lower limit position sensor 123 (for example, a non-contact displacement sensor, etc.) and a dog 125 are provided for constantly detecting the lower limit position.

That is, the dog 125 is provided in an elongated hole 127 provided in the dog rail 95 described above so that its mounting position can be adjusted. (
(See Figure 4).

Further, the lower limit position sensor 123 is connected to the nut 117 described above.
The bracket 119 is provided at a position facing the dog 125. (See Figures 2 and 3) With the above configuration, the lower limit position sensor 123 moves up and down in synchronization with the nut 69 engaged with the lower limit position adjustment shaft 15, and the dog 125 moves up and down as the ram 9 moves up and down. Since it moves, the lower limit position can be detected.

Next, the means for correcting the amount of change over time in the lower limit position, which is the main part of this embodiment, will be explained in detail.

Referring to FIG. 1, the position control system starts with a lower limit position sensor 123 that detects the lower limit position of the ram 9, passes through a DC amplifier 129, is converted by an A/D converter 131, and stores the lower limit position in a main memory 133. Ru.

Also, an upper limit switch 1 for detecting the upper limit of the ram 9
35 and the timer 137 from the lower limit switch 121.
The fact that the switch has been turned on via the main memory 133 is stored in the main memory 133. Furthermore, setting means 1 for setting the lower limit position of the ram 9 in advance.
39 and stored in the sub memory 141.

Then, the memory values in the main memory 133 and the submemory 141 are subjected to arithmetic processing by the arithmetic processing means 143. That is, the actual lower limit position detected by the lower limit position sensor 123 and the set lower limit position set by the setting means 139 are calculated.

On the other hand, a displacement amount setting means 145 is provided, in which an allowable displacement amount is set in advance, and a comparison means 147 is provided for comparing this displacement amount with the actual displacement amount calculated by the calculation processing means 143. ing. The value compared by this comparison means 147 is transferred to the control device 149 of the lower limit position adjustment shaft 15.
, and command the amount of upward or downward correction. In addition,
Reference numeral 151 is a display.

With the above configuration, the amount of change over time in the lower limit position can be corrected by lowering the ram 9 for bending and lowering the ram lower limit switch 1.
When 21 is turned on, the signal is converted into digital data by the A/D converter of the lower limit position sensor 123 after 11 seconds set in the timer 137, and is stored in the main memory 133. (XA) This measurement is performed for each stroke, and when the upper limit switch 135 is turned on, the main memory 133 is reset and cleared.

The lower limit position initial value setting of the ram 9 is stored in the sub-memory 141 by pressing the key of the lower limit position setting means 139 during the first machining. (XB) After setting the initial value, the amount of change (XA-XB) is calculated for each stroke by the calculation processing means 143.

Further, allowable displacement amounts are set in advance as XC and XD in the displacement amount setting means 145, and when the following formula is established in the comparison means 147, XA-XB>XD... Ascent command XA-XB ≦X
D: Nut 6 that commands the correction amount to the control device 149 of the descending command lower limit position adjustment shaft 15 and sets the lower limit position.
By changing the position of 9, the position error is corrected.

As mentioned above, the lower limit position of the ram 9 is detected by the lower limit position sensor 1.
23, and the amount of change over time is calculated and compared with a preset tolerance value to correct it. Therefore, in the hydrodynamic bearing, even if the gap changes over time due to a rise in temperature or a change in room temperature, the lower limit position of the ram 9 does not change, making it possible to improve the bending angle accuracy during bending.

Note that the present invention is not limited to the embodiments described above, and can be implemented in other embodiments by making appropriate changes. For example, in this embodiment, the correction is performed at a fixed displacement amount, but it may be performed at a time, number of times, etc. Also, the lower limit position sensor (non-contact displacement sensor) is , for example, it may be mounted on a processing table.

〔Effect of the invention〕

As can be understood from the above description of the embodiments, according to the present invention, the lower limit position of the ram is measured by the lower limit position sensor, and the amount of change over time is calculated and compared with a preset tolerance value to correct it. do. Therefore, the lower limit position of the ram is always constant, and it is possible to improve the bending angle accuracy of the workpiece.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram of the ram position correction device which is the main part of this invention, FIG. 2 shows the ram position correction device, and
An enlarged sectional view taken along the line ■-■ in the figure, Figure 3 is the
4 is a partial right side view of FIG. 2, FIG. 5 is an explanatory diagram of a hydraulic circuit, and FIG. 6 is a side view of a hydraulic press brake according to an embodiment of the present invention. FIG. 7 is an explanatory diagram of a hydraulic circuit showing a conventional example, and FIG. 8 is an enlarged sectional view of a portion taken in the direction of the arrow ■ in FIG. 1... Hydraulic press brake 7... Die 11... Punch 57... Ram position correction device 123... Lower limit position sensor 139... Setting means 143... Arithmetic processing means 145... Displacement amount setting means 147... comparison means

Claims (1)

[Claims] A hydraulic press brake is used to bend the workpiece by making the upper die and lower die work together by the vertical movement of the ram, and a lower limit position sensor is installed to detect the lower limit position of the ram, and the lower limit position of the ram is set in advance. a setting means, a displacement setting means for setting an allowable displacement amount in advance, and an arithmetic process for calculating the actual lower limit position detected by the lower limit position sensor and the set lower limit position set by the setting means. A ram in a hydraulic press brake, comprising: a means for comparing an actual amount of change computed by the arithmetic processing means with a displacement amount set by the displacement amount setting means. Position correction device.