JP3415080B2 - Bending machine and its operation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending machine such as a press brake and a method of operating the same, and more particularly to a bending machine capable of detecting an angle while bending.

[0002]

2. Description of the Related Art Conventionally, in a bending machine such as a press brake, in-line bending is used for controlling a bending angle during processing and determining whether the bending angle of a processed plate material is good or bad. Angles are being measured. In a bending machine, an angle measuring device for measuring a bending angle in-line is generally installed in the vicinity of an upper mold and inserted into and removed from a bending portion of a plate material by a measuring device inserting / removing mechanism. In addition to this, some of the upper molds that have a built-in angle measuring device have been proposed. As the one using the above-mentioned measuring instrument inserting / removing mechanism, a parallel link-shaped corner contact tool is inserted into a bent portion of a plate material, and this corner contact tool is brought into contact with a corner formation surface of the plate material to form a link coupling. There is one that measures the displacement of the linear position of the section by a rotary encoder to detect the bending angle (Japanese Patent No. 2630720 etc.). According to this, it is difficult to be influenced by the posture of the plate material, and the measurement can be performed regardless of the influence of the thickness variation of the plate material and the dimensions of both surfaces forming the concave corners of the plate material.

However, since the linear position displacement of the corner contactor is converted into the rotation of the encoder, the measurement accuracy is limited by a minute error generated in the motion conversion section, and it is difficult to further improve the measurement accuracy. Further, since the measuring device insertion / removal mechanism is required, the entire device for measurement becomes large, and therefore it is difficult to install a plurality of angle measuring devices and measure angles at a plurality of positions apart in the bending line direction of the plate material. . Such measurement at a plurality of points is desirable for ensuring accuracy as in bending. If the above angle measuring device can be built in the upper mold, it will be easier to install at multiple locations, but since the rotary encoder is a three-dimensional shape with both vertical and horizontal dimensions and a certain depth, the press brake It is difficult to embed it in flat parts such as upper molds. The upper mold of the press brake has a thickness of, for example, about several millimeters, and an angle measuring instrument that can be built in such a flat press mold without affecting the strength of the press mold is still a practical example. Almost never.

As an example of a proposal in which an angle measuring device is built in the upper die of the press brake, two scanning elements having different widths are inserted into the concave corners of the plate material, and both ends of each are brought into contact with both sides of the concave corners. It has been proposed to convert the bending angle from the difference in the depth of penetration of these scanning elements into the concave portion. Each scanning element is in the form of a disc or rod. The difference in penetration depth is detected by an optical sensor such as a PSD (positional response detector). However, the optical sensor is vulnerable to heat, and the measurement accuracy may be deteriorated due to heat generated by bending. In addition, the upper mold needs to have a split structure only for the built-in angle measuring device, which complicates the structure of the upper mold and lowers the strength of the upper mold. It is necessary to increase the size.

Further, in the bending process of a plate material, there is a phenomenon called springback, that is, a phenomenon in which the bending angle returns to a slight extent due to the elasticity of the plate material, so that accurate detection cannot be performed or time is required for detection. There is a problem to take. For example, in order to detect the bending angle after springback, it is necessary to loosen the bending load once. At this time, the posture of the plate material may change, and it is possible to flexibly respond to such a posture change. It is one of the challenges. Therefore, it is necessary to improve the bending machine with the built-in angle measuring device and to develop an effective operation method.

In addition to the above, as an angle measuring device installed in a bending machine, an angle measuring device applying image processing is used. A semiconductor laser irradiates slit light onto an object to be measured, and an image of the bending portion is measured by a CCD camera. There are those that capture and determine the bending angle. However, the accuracy of measurement is greatly affected by fluctuations in ambient brightness, and the structure is complicated and expensive.

An object of the present invention is to provide a bending machine which can compactly incorporate an angle measuring device in a mold and can perform accurate angle measurement while performing bending. Another object of the present invention is to make it possible to perform angle measurement with high accuracy without being affected by signal attenuation, and to perform angle measurement with a simple configuration without the influence of temperature changes. That is. Still another object of the present invention is to facilitate the incorporation of the angle measuring instrument in the mold by dividing the mold. Still another object of the present invention is to provide a method for operating a bending machine, which uses an angle measuring device built in the upper die and can perform a bending process with high accuracy corresponding to springback.

[0008]

The bending machine of the present invention comprises:
In a bending machine that presses by sandwiching a plate material between a male mold and a female mold that extend in a straight line, an angle measuring device that measures the bending angle of the plate material bent by these male and female molds is installed in the male mold, and the angle measurement is performed. The device is characterized by having an inductive linear position detector. According to this structure, since the angle measuring device is incorporated in the male mold, the angle can be detected while bending. Further, the angle measuring device enters the bending portion of the plate material as it is moved up and down for bending the male mold, and a dedicated mechanism for driving the angle measuring device forward and backward for measurement is not required. The angle measuring device has an inductive linear position detector, but the inductive linear position detector is
A compact and highly accurate one has been put into practical use, and by using such a thing as an angle measuring device, accurate angle detection can be performed. Further, it can be easily incorporated into a male die which is a small and flat press die such as a press brake. As the inductive type linear position detector, various types such as a differential transformer and a phase shift type can be used.

Specifically, the angle measuring device is, for example,
A corner contact tool that makes contact with both sides of a bent concave part of a plate material to cause a linear position displacement according to the opening angle between the corner forming surfaces, and the linear position displacement of this corner contact device is measured. And an inductive linear position detector. The linear position detector detects the displacement of the linear position by changing the electrical phase angle, and cancels the temperature characteristics of the coil for detecting the linear position by the outputs of the plurality of coils or impedance means. It is preferable to have a compensation function. If the position is detected by the change of the phase angle, the position can be detected without being affected by the signal attenuation, and the position can be detected with high accuracy. Further, assuming that the linear position detector has a function of compensating for the temperature characteristic of the coil for detecting the linear position by canceling it with the outputs of the plurality of coils or impedance means, the position where the influence of the temperature change is eliminated The detection can be easily performed. Therefore, the measurement can be performed without being affected by the heat generated by the bending process, and the correction according to the operation time is unnecessary. Specifically, such a linear position detector includes, for example, a plurality of coils excited by in-phase AC signals, a magnetic response member that changes the linear position to change the inductance of the coils, and an arithmetic circuit. Can be configured as having In this case, the arithmetic circuit combines the output voltages of the plurality of coils to generate a plurality of AC output signals, and from the correlation of the amplitude values in the plurality of AC output signals, the phase corresponding to the displacement of the linear position. It is supposed to detect a corner.

The male mold is formed of a plurality of divided molds arranged in the mold width direction, and the mold width can be changed by changing the number of divided molds arranged . Further , a housing recess is provided in a side end surface between the split molds of any of the split molds, and the angle measuring device is housed in the housing recess . Specifically, either
In the split mold, there is a housing recess on the side end surface between the split molds.
Then, the angle measuring device is housed in the housing recess. The corner
Degree measuring instrument contacts both sides of the bent corner of the plate
The linear position displacement according to the opening angle between the corner formation surfaces.
The resulting corner contact and the linear displacement of this corner contact
With an inductive linear position detector for measuring
It The above-mentioned corner contact tool enters into the concave corner of the plate and
Contact parts that come into contact with the corner forming surface of the
Linear position in the up-down direction, which is the direction of entry into the reentrant corner
It has a linear displacement component that produces a displacement. Contact parts above
Is configured as a parallel link mechanism consisting of four links.
These links have two support pins that are vertically separated,
The two connecting pins that are separated from each other on the left and right are sequentially connected. Upper side
The support pin of the
Side guide allows free movement within the specified range only in the vertical direction
Be guided. Lower support pin away from linear displacement parts
The guides on the lower side allow the specified
Guided movably in the play area. The lower support pin is
It becomes the support pin on the quasi position side, and the support pin on the upper side
It becomes a support pin. The left and right connecting pins are freely movable.
The upper and lower guides are side edges of adjacent split dies.
Formed as a pair of opposing guide grooves formed on the surface
It The upper and lower support pins project to both sides from the link
The protruding parts move to the upper and lower guides respectively.
It shall be fitted at the location . As this, a recess on split surfaces of the split mold arranged in the mold width direction, when accommodating a goniometer, the division for the mold width changes, available internal goniometer, goniometer It becomes easy to incorporate into the mold. Further, since the accommodating concave portion of the angle measuring device is arranged on the side end surface between the split molds, the angle measuring device can be installed at a plurality of positions in the mold width direction of the upper mold, and therefore, at a plurality of positions along the bending part. It is also possible to easily detect the bending angle and ensure the accuracy of the bending process. The split molds on both sides with the angle measuring device interposed between them are arranged so that, for example, the positions of use are simultaneously changed to the arranged state and the non-selected state.

A bending machine operating method according to the present invention is a method for operating the bending machine having any one of the above-described configurations according to the present invention, wherein the bending machine operates on an ascending / descending position and an upper die of a male upper die. Load, and the bending angle of the plate, and after this bending process, the bending angle of the plate after springback is measured with the upper die returned to a certain degree or the upper die is loosened. A method to obtain the next correction value for the adjustable part that controls the bending angle in the bending machine from the interrelationship between the lifting position of the upper mold, the load acting on the upper mold, the bending angle of the plate material, and the bending angle after springback. is there.
It should be noted that the lift position of the upper die can be known by time as long as the speed curve of the lift operation is determined, and thus may be indirectly indicated by time. Also in the case of the operating method according to each of the other aspects of the present invention, the vertical position of the upper die may be indicated by time. In the bending process of the plate material, a predetermined relationship is generated among the lifting position of the upper die, the load acting on the upper die, and the bending angle of the plate material, and the springback amount is also affected by these relationships. Therefore, during the bending process, the lifting position of the upper die, the load acting on the upper die, and the bending angle of the plate material are measured, and the bending angle after springback is measured, and from the mutual relationship of these measured values, By obtaining the next correction value of the adjustable portion that affects the bending angle in the bending machine, the next bending process can be performed with high accuracy.
The bending angle after springback can be measured after bending, by measuring the upper mold to some extent in the returned state or the upper mold's pressure-relaxed state to measure the actual springback angle. , The angle measuring device built into the upper die can easily and accurately detect. This operation method of the bending machine may be adopted, for example, only at the time of trial bending, and thereafter, the operation may be performed by correcting with the next correction value obtained at the time of trial bending.

In this method of operating a bending machine, a pattern table in which a plurality of patterns are categorized as to the interrelationship between the vertical position of the upper die in the bending process, the load acting on the upper die, and the bending angle of the plate material, and the above-mentioned patterns. For each time, prepare the correction value conversion data that gives the next correction value of the adjustable portion corresponding to the bending angle after springback,
The lifting position of the upper die measured in the bending process, the load acting on the upper die, and the bending angle of the plate material are compared with the pattern table to select the corresponding pattern, and the bending after the springback after the bending process is performed. The angle may be converted with the correction value conversion data of the selected pattern to obtain the next correction value of the adjustable portion. The relationship curve between the bending angle after springback and the adjustment amount of the adjustable part for bending angle control is the mutual relationship between the vertical position of the upper die that occurs during the bending process, the load that acts on the upper die, and the bending angle of the plate material. Studies have shown that they can be classified into multiple patterns depending on the relationship, and that each pattern has a common tendency. For example,
Even if the plate thickness, material, etc. of the plate material change, patterning can be performed only by the relationship of the above-mentioned measured values. Therefore, prepare the above-mentioned pattern table and correction value conversion data for each pattern in advance, select the pattern with each measurement value obtained in the bending process, and then convert with the correction value conversion data of the selected pattern By obtaining the next correction value of the part, high-accuracy bending can be performed easily and quickly without requiring complicated calculation. In order to obtain the next correction value from the correction value conversion data etc. according to the bending angle after springback, the bending angle may be handled as it is, or the error between the bending angle after springback and the target angle may be handled. good.

In the running direction of the bending machine of the present invention,
When the type of bending machine is such that the bottom height of the lower die which is a female die is variable, and the upper die is lowered until the plate material is pressed against the bottom surface of the lower die to perform bending, The adjustable part is the bottom height of the lower mold. The next correction value obtained from the correction value conversion data is the bottom surface height correction value.

In the running direction of the bending machine of the present invention,
When the type of the bending machine is such that the bending angle is determined by adjusting the amount of penetration of the male upper mold into the lower mold, the adjustable portion is the upper mold. The next correction value obtained from the correction value conversion data is a correction value for the target value of the overstroke that lowers the upper die further than the up-and-down position of the upper die that is the target angle of the plate material bending angle.

In the case of operating the bending machine of the type in which the bottom height of the lower mold is variable, the vertical position of the upper mold generated in the bending process, the load acting on the upper mold, and the bending angle of the plate material are The relation patterns may be classified according to the upper die stroke from the load dip point to the target angle and the upper die stroke from the target angle to the lowest point. According to the research results, by classifying the patterns by the strokes before and after the load dip point, the patterning according to the common tendency can be further performed.

A bending machine according to another aspect of the present invention is the bending machine according to any one of the above-mentioned configurations of the present invention, which has an adjustable portion for controlling a bending angle, and is provided with the following learning control means. It is a thing. This learning control means
Correspondence to the bending angle after springback for each pattern and the pattern table that classifies the mutual relationship among the lifting position of the upper mold in the bending process, the load acting on the upper mold, and the bending angle of the plate material into multiple patterns Correction value conversion data for giving the next correction value of the adjustable portion, means for measuring the lifting position of the upper die, the load acting on the upper die, and the bending angle of the plate material during the bending process, and the upper die after bending The means for measuring the bending angle of the plate material after spring back in a certain degree of return, the upper and lower positions of the upper mold obtained in the bending process, the load acting on the upper mold, and the value of the bending angle of the plate material, the pattern Select the relevant pattern in the table,
According to the correction value conversion data, the selected pattern is provided with a correction value generating means for generating a next correction value of the adjustable portion corresponding to the bending angle after the springback. By providing the learning control means having this structure, the operating method for obtaining the patterned next correction value of the present invention can be implemented.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a bending machine equipped with an angle measuring device, and FIG. 2 is a side view thereof. This bending machine is a press brake, in which a linear lower die 2 which is a female die is mounted on a bed 1, and an upper die 4 which is a male die is attached to a lower end of a ram 3. The ram 3 is installed on both sides of the bed 1 so as to be vertically movable by guides 5, and is vertically moved by a ram lifting drive device 6. The ram lifting drive device 6 is composed of an electric motor, a hydraulic cylinder, or the like, and is capable of controlling the lifting position at an arbitrary position. Lower mold 2 and upper mold 4
Is divided into a plurality of divided dies 2A and 4A in the die width direction, and the die width can be changed by selecting the number of arrangements of the divided dies 2A and 4A. This mold width change is divided mold 2
Split type selection mechanism (not shown) between the use position (the illustrated position) used for machining A and 4A and the retracted position.
It is done by moving in. An angle measuring device 9 is provided on a part or all of the divided dies 4A of the upper die 4.

The bed 1 has a plate support 7 provided in front of and behind the lower mold 2.
And a gauge 8 is installed. The plate material W to be folded is placed on the plate material support 7 and inserted into the lower mold 2 until it hits the gauge 8, and the lower mold 2 and the male upper mold 2 are lowered by lowering the upper mold 4 by the ram 3. The sheet material W is sandwiched by 4 and bent into a V shape.

In this embodiment, the lower mold 2 is for a three-point bend, and has a rectangular lower mold groove 2a as shown in FIG. Further, the lower mold 2 has a variable bottom portion 2aa.
The groove depth is variable by adjusting the vertical position of the variable bottom portion 2aa. The position of the variable bottom portion 2aa is adjusted by the bottom surface height adjusting mechanism 29. The bottom surface height adjusting mechanism 29 is composed of a taper member 29a that is in contact with the inclined bottom surface of the variable bottom portion 2aa and can move back and forth, a feed screw mechanism 29b that moves the taper member 29a back and forth, and a motor 29c for driving the same. . The upper die 4 has a V-shaped cross-section with an acute-angled tip 4a, and its tip edge 4aa is
It has an obtuse V-shaped section or an arcuate curved section. The thickness of the upper die 4 is sufficiently smaller than the groove width of the lower die 2. When such a lower die 2 for three-point bend is used, the plate material W is bent by lowering the upper die 4 until the plate material W reaches the groove bottom of the lower die 2. Plate material W
The bending angle of is substantially determined by the groove width and groove depth of the lower mold 2,
Bending load, that is, pressing force for lowering the upper mold 4,
The cross-sectional shape of the front edge 4aa of the upper die 4 which has an arc shape or an obtuse angle shape is determined by a factor.

The lower mold 2 is for a three-point bend as shown in FIG. 7, as well as for an air bend as shown in FIG.
You may use the thing for bottoming as shown in FIG.
In the case of the lower die 2 for air bending and bottoming, the lower die grooves 2b and 2c, which are the die surfaces, are both V-groove-shaped, but the contact point between the lower die 2 and the plate W is for air bending. Is the opening edge 4ba of the lower die groove 2b, and the bottom edge portion 4ca of the lower die groove 4c for bottoming. The bending angle of the plate material W is
Both the air bend and the bottoming are determined by the groove width of the lower die groove 2b, the angle formed by both side surfaces of the groove, the cross-sectional shape of the tip edge 4aa of the upper die 2, and the amount of protrusion of the upper die 2 into the lower die.

FIG. 3 shows one split mold 4A of the upper mold 4. The split mold 4A has an engaging portion 10 for engaging with the split mold selection mechanism at the upper portion, and a recess 11 for accommodating the angle measuring device is provided on a side end surface which is a surface adjacent to each other. The accommodating recess 11 is formed in a vertically extending groove shape, and the angle measuring device 9 is installed in the accommodating recess 11 as shown in FIG.

The angle measuring device 9 is composed of a corner contacting device 12 and an inductive linear position detector 13, and is housed in the lower part and the upper part of the angle measuring device housing recess 11, respectively. The corner contact tool 12 contacts the corner forming surfaces a, a on both sides forming the bent concave corners of the plate material W to be measured, and sets the opening angle α between the corner forming surfaces a, a. A corresponding linear position displacement is generated in the Y direction. The linear position detector 13 measures displacement of the linear position of the corner contact tool 12.

The corner contact tool 12 is a contact part 14 that enters the concave corner of the plate W and contacts the corner forming surfaces a on both sides.
And a linear displacement component 15 that causes a linear position displacement in the approach direction (vertical direction) Y to the concave portion with the displacement of the contact component 14. The linear position detector 13 includes a winding portion 16 and
The magnetically responsive member 17 has a rod-shaped magnetically responsive member 17 that can move back and forth in the winding portion 16 in a linear direction.
Is fixed to the linear displacement component 15 of the corner contact tool 12.

The contact part 14 includes four links 14a-1.
4d is configured as a parallel link mechanism, and these links 14a to 14d are two support pins 1 separated vertically.
8 and 19 and two connecting pins 20 and 20 that are separated from each other on the left and right sides are sequentially connected. The upper support pin 18 is provided on the linear displacement component 15, and is guided by the guide 21 so as to be movable only in the vertical direction within a predetermined range (a range of the guide length). The lower support pin 19 is provided apart from the linear displacement component 15, and is guided by the guide 22 so as to be movable only in the vertical direction within a predetermined play range (a range of the guide length). The lower support pin 19 serves as a reference position side support pin, and the upper support pin 18 serves as a displacement side support pin. The left and right connecting pins 20, 20 are freely movable. The guides 21 and 22 are divided molds 4 on both sides adjacent to each other.
The support pins 18 and 19 are formed as a pair of guide grooves facing each other formed on the side end surfaces of the A and 4A.
-14d from both sides, and the protruding portion is the guide 2
It fits movably to 1 and 22. Guide 2 on the reference position side
2 is set so that the play range is relatively small. Note that the guide 22 on the reference side may be a guide that causes the support pin 19 to move laterally, as shown in a modified example in FIG. 4B. In FIG. 5, the linear displacement component 15 is installed in the split mold 4A so as to be movable only in the vertical direction, and is urged downward by the return elastic body 25. The return elastic body 25 is composed of a compression coil spring, and is provided on the outer periphery of the shaft portion 15 a protruding from the linear displacement component 15. These return elastic body 25 and linear displacement component 1
A part of 5 is accommodated in the lower deep groove portion 11 a provided in the angle measuring instrument accommodation recess 11. Magnetic response member 1
7 is fixed to the linear displacement component 15 so as to project upward at a position where its axis is orthogonal to the upper and lower support pins 18 and 19. The terminal group 16a of the winding part 16 is provided on the winding part 16 and is led out from the wiring hole 23 provided in the split mold 4A.

Considering the constituent parts of the angle measuring device 9, the split mold 4A has a winding part 16 of the linear position detector 13 installed and a contact supporting a corner contact tool 12 so as to move back and forth. It becomes a tool guide member.

The induction type linear position detector 13 is a device for detecting the displacement of the linear position by using the principle of electromagnetic induction, and includes a general differential transformer and an electric device that correlates with the linear position to be detected. A phase shift type linear position detector that outputs an AC signal having a specific phase angle is also included.
In this example, the inductive linear position detector 13 having the following configuration is used.

As shown in FIG. 10, the linear position detector 13 has only a primary coil as a coil. The example of the figure shows an example in which two AC output signals each having an amplitude exhibiting a sine and cosine function characteristic are provided so that the amplitude change can be obtained in the full range from 0 degree to 360 degrees in electrical angle. . FIG. 10 (A) shows an example of the physical arrangement relationship between the winding portion 16 and the magnetically responsive member 17 in this linear position detector by a schematic external view, and FIG. 10 (B) is a schematic cross-sectional view in the axial direction of the coil, FIG. 3C is a diagram showing an example of an electric circuit of the winding unit 16. The position detection device shown in FIG. 10 detects a linear position of a detection target, and for example, the winding portion 16 is relatively fixed,
The magnetic response member 17 is relatively linearly displaced according to the displacement of the detection target. The magnetic response member 17 is a member made of a material that magnetically changes the characteristics of the coil, and is made of a magnetic material or a good conductor. The magnetically responsive member 17 may be made of a magnetic material or a good conductive material only partially, but in this example, the magnetically responsive member 17 is entirely made of a magnetic material or a good conductive material, and is a thin pin-shaped member such as a wire. It is said that. Winding part 1
Reference numeral 6 denotes an in-phase AC signal sin generated from the AC source 50.
A plurality of coils Lα, LA, L excited by ωt
B, LC, LD, and Lβ are sequentially arranged along the displacement direction of the detection target. By changing the relative position of the magnetically responsive member 17 with respect to the winding portion 16, the inductance of each coil Lα, LA, LB, LC, LD, Lβ changes according to the position, and the end 17a of the magnetically responsive member 17 changes. Is 1
During the displacement of one coil from one end to the other, the voltage across the coil gradually increases or decreases.

In this example, the number of coils is 6,
The range corresponding to the four middle coils LA, LB, LC and LD is the effective detection range. When the length of one coil is K, the effective detection range is 4K which is four times as long. Coils Lα and Lβ provided one each before and after the effective detection range
Is an auxiliary coil. The auxiliary coils Lα and Lβ are provided so that the cosine function characteristics can be faithfully obtained, and when accuracy is not pursued so much,
It can be omitted. Each coil Lα, LA, LB, LC, L
D and Lβ do not have to be physically separated separate coils, but terminals may be provided in the middle of a series of coils and individual coils may be provided between the terminals. Analog arithmetic circuit 4
0 and 41 are resistor circuit groups RS1 and RS2 and an operational amplifier O
P1 and OP2 are included, and terminals 43 and 4 are included.
Each coil L through 4, 45, 46, 47, 48, 49
Terminal voltage Vα of α, LA, LB, LC, LD, Lβ,
By extracting VA, VB, VC, VD, and Vβ, and adding and / or subtracting them, depending on the detection target position (position of the end 71a of the magnetic response member 17 into the winding portion 16). A plurality of AC output signals sin θ sin ωt and cos θ sin ωt, each of which has an amplitude according to a predetermined periodic function characteristic, are generated. These AC output signals sin θ sin ωt and cos θ sin ωt are input to the phase detection circuit 42, and their amplitude functions sin θ and co
By detecting the phase angle component θ of sθ, the detection target position can be detected absolutely. The number and arrangement of the coils in the winding portion 16 are not limited to the illustrated example, but can be variously changed. The outputs from the terminals 43 to 49 may be digitally processed. The inductive linear position detector 13 of the example in the figure is small and can perform highly accurate angle detection. Therefore, by using this in the angle measuring device 9, the angle measuring device 9 is compact in the upper die 4 of the bending machine. The simple structure enables accurate bending.

The operation of the linear position detector 13 will be specifically described. The self-inductance of each coil increases as the degree of approach or penetration of the magnetically responsive member 17 to each coil increases, and while the end of this member is displaced from one end of one coil to the other end of the coil. The voltage gradually increases. Multiple coils Lα, LA, LB, LC, LD, L
Since β is sequentially arranged along the displacement direction of the detection target, as the position of the magnetically responsive member with respect to these coils is relatively displaced according to the displacement of the detection target,
As illustrated in FIG. 11A, gradually increasing changes in the voltages Vα, VA, VB, VC, VD, and Vβ across the coils occur in sequence. In FIG. 11A, in the section where the output voltage of a certain coil is inclined, the end of the magnetically responsive member 17 is displaced from one end of the coil to the other end. Typically, the gradual change curve of the voltage across the coil, which occurs during the displacement of one end of the magnetically responsive member 17 from one end to the other of the coil, is in the range of 90 degrees in the sine or cosine function. It can be compared to a change in function value. Therefore, the output voltage V of each coil
By appropriately combining and adding and / or subtracting α, VA, VB, VC, VD, and Vβ, two AC output signals sin θ sin ωt having amplitudes showing sine and cosine function characteristics according to the detection target position, respectively.
And cos θ sin ωt can be generated.

That is, in the analog arithmetic circuit 40, the output voltages VA, VB, V of the coils LA, LB, LC, LD are set.
By calculating C and VD as in the following equation (1),
An AC output signal having an amplitude curve with a sine function characteristic as shown in FIG. 1 (B) can be obtained, which can be equivalently expressed as “sin θ sin ωt”. (VA-VB) + (VD-VC) ... Formula (1)

In the analog operation circuit 41, the output voltage Vα of the coils Lα, LA, LB, LC, LD, Lβ,
By calculating VA, VB, VC, VD, and Vβ as in the following equation (2), it is possible to obtain an AC output signal having an amplitude curve with a cosine function characteristic as shown in FIG. 11B. The amplitude curve of the cosine function characteristic shown in FIG. 11B is actually a minus cosine function characteristic, that is, “one cos θ sin ωt”, but since it shows a deviation of 90 degrees from the sine function characteristic, the cosine function characteristic is shown. It corresponds to the characteristic. Therefore, this is referred to as an AC output signal having a cosine function characteristic, and is equivalently referred to as "cos
θ sin ωt ”. (VA-Vα) + (VB-VC) + (VB-VD) ... Equation (2) Instead of the operation of Equation (2), the operation of Equation (2 ') below may be performed. (VA-Vα) + (VB-VC) -VD ... Formula (2 ')

It should be noted that the AC output signal "1-cos θ sin ωt" having the minus cosine function characteristic obtained by the equation (2) is electrically phase-inverted by 180 degrees to actually obtain c
A signal represented by osθsinωt may be generated and used as an AC output signal having a cosine function characteristic. However, in the subsequent phase detection circuit (amplitude / phase conversion circuit) 42, for example, an AC output signal having a cosine function characteristic is converted into “one cos θs”.
In the case of using in the subtraction operation in the form of “in ωt”, an AC output signal “one cos θ” having a negative cosine function characteristic is used.
It may be used as it is. Note that the formula (2)
If the following formula (2 ″) is calculated instead of
The AC output signal “cos θsi” of the cosine function characteristic is actually
nωt ”can be generated. (Vα-VA) + (VC-VB) + (VD-Vβ) ... Formula (2 ")

The phase angle e in the sine and cosine functions, which are the amplitude components of each AC output signal, corresponds to the position to be detected, and the phase angle θ in the range of 90 degrees corresponds to the length K of one coil. It corresponds. Therefore, the effective detection range having a length of 4K corresponds to the range of the phase angle θ from 0 degree to 360 degrees. Therefore, by detecting this phase angle θ, the detection target position in the range of the length of 4K can be detected absolutely.

Here, the compensation of the temperature characteristic will be described. The impedance of each coil changes according to the temperature,
The output voltages Vα, VA, VB, VC, VD and Vβ also change. For example, each voltage increases or decreases in one direction as shown by a broken line with respect to a solid curve in FIG. However, the AC output signals sin θ sin ωt and c of the sine and cosine function characteristics obtained by adding and subtracting these
In os θ sin ωt, the amplitude changes in both the positive and negative directions appear as shown by the broken line with respect to the solid curve in FIG. If this is shown using the amplitude coefficient A, Asi
n.theta.sin .omega.t and A cos .theta.sin .omega.t, and the amplitude coefficient A changes depending on the ambient environment temperature, and this change appears in the two AC output signals in the same manner. As is apparent from this, the amplitude coefficient A indicating the temperature characteristic does not affect the phase angle θ in each sine and cosine function. Therefore, in this embodiment, the temperature characteristic is automatically compensated, and accurate position detection can be expected.

By measuring the phase components θ of the amplitude functions sin θ and cos θ in the AC output signals sin θ sin ωt and cos θ sin ωt having the sine and cosine function characteristics by the phase detection circuit (or amplitude phase conversion means) 42, the detection target position is absolute. Can be detected. The phase detection circuit 22 may be configured using the technique disclosed in Japanese Patent Laid-Open No. 9-126809, for example. Alternatively, a known R-D converter used for processing the resolver output may be used as the phase detection circuit 42.

As shown in FIG. 11B, the AC output signal sin θ sin ω having the sine and cosine function characteristics.
The amplitude characteristic at t and cos θ sin ωt is the angle e
Assuming that the correspondence relationship between the detection target position x and the detection target position x has linearity, true sine and cosine function characteristics are not shown. However, in the phase detection circuit 42, the AC output signals sin θ sin ωt and cos θ sin ωt are apparently used.
The phase detection processing is performed by assuming that each has the amplitude characteristics of the sine and cosine functions. As a result, the detected phase angle θ does not show linearity with respect to the detection target position x. However, in position detection,
The non-linearity between the detection output data (detected phase angle θ) and the actual detection target position is not a very important problem. That is, it suffices if the position can be detected with a predetermined repeatability. If necessary, the output data of the phase detection circuit 42 is converted by using an appropriate data conversion table so that accurate linearity is provided between the detected output data and the actual detection target position. Can be done easily. Therefore, the AC output signal sin θ having the amplitude characteristics of the sine and cosine functions referred to in this specification.
sin ωt and cos θ sin ωt do not have to show true sine and cosine function characteristics, but may actually have a triangular wave shape, as shown in FIG. ,
It suffices if it shows such a tendency. That is, any periodic function similar to a trigonometric function such as sine may be used. In the example of FIG. 11 (B), changing the viewpoint, assuming that the scale of the axle is θ and that the scale is a required non-linear scale, if the scale of the axle is assumed to be x. Even if it looks like a triangular wave, it can be said that it is a sine function or a cosine function with respect to θ.

The change range of the phase components e of the amplitude functions sine and cose in the AC output signals sin θ sin ωt and cos θ sin ωt having the sine and cosine function characteristics is not limited to the change in the full range from 0 degree to 360 degrees as in the above embodiment. Alternatively, the change may be within a limited angle range narrower than that. In that case, the configuration of the coil can be simplified. Since the effective detection range may be narrow when the purpose is to detect a minute displacement, in such a case, the detectable phase range may be an appropriate range of less than 360 degrees. In addition, there are various cases in which the detectable phase range may be an appropriate range of less than 360 degrees depending on the purpose of detection, and thus the invention can be appropriately applied to such a case.
Hereinafter, those modifications will be described.

FIG. 12 shows an example in which a phase change in the range of 0 to 180 degrees can be generated. In this case, the winding unit 16 is composed of two coils LA and LB corresponding to the effective detection range and auxiliary coils Lα and Lβ provided one before and one behind the coils LA and LB. Analog arithmetic circuit 5
3, the inter-terminal voltage Vα, VA, VB, Vβ of each coil
AC output signal si indicating the amplitude curve of the sine function characteristic by inputting
The AC output signal cos θsin ωt showing the amplitude curve of the cosine function characteristic is generated by generating nθ sin ωt and integrating it as in the following equation (4). VA-VB equation (3) (VA-Vα) ten (VB-Vβ) equation (4)

FIG. 13 shows an example in which a phase change in the range of 0 to 90 degrees can be generated. In this case, the winding unit 16 includes one coil LA corresponding to the effective detection range and one auxiliary coil Lα before and after the coil LA,
And Lβ. In the analog operation circuit 54, the inter-terminal voltages Vα, VA, Vβ of each coil are input,
For example, the AC output signal sin θ sin showing the amplitude curve of the sine function characteristic is calculated by the following equation (5).
An AC output signal cos showing an amplitude curve of a cosine function characteristic is generated by generating ωt and calculating it as in the following equation (6).
θ sin ωt is generated. VA-Vβ equation (5) VA-Vα equation (6)

In each of the above examples, the auxiliary coils Lα and Lβ are provided before and after the effective detection range, but these auxiliary coils Lα and Lβ can be omitted. 14
Is an example thereof, and shows an example in which a phase change in the range of 0 to 180 degrees can be generated.

In this case, by subtracting the voltages VA and VB between both ends of the coils LA and LB by the subtraction circuit 25, an AC output signal sin θ sin ωt having a sine function characteristic can be generated as the subtraction result “VA-VB”. it can.
Further, the voltages VA and VB between both ends of the coils LA and LB are added by the addition circuit 56, and the constant voltage VN generated by the constant voltage generation circuit 57 is subtracted by the subtraction circuit 58 from the addition result VA + VB. "VA + VB-V
N ”as the AC output signal cos θ of the cosine function characteristic
sinωt can be generated. Here, the constant voltage VN generated from the constant voltage generation circuit 57 is the coil LA, L.
Similar to the temperature characteristic change of B, the temperature characteristic is changed. Therefore, the constant voltage generation circuit 57 may be configured by using a dummy coil having the same characteristics as the coil LA or LB, and may be excited by the same excitation AC signal.

As another example of the linear position detector 13, only one coil may be provided corresponding to the effective detection range. In that case, the phase change width of the effective detection range corresponding to the coil length K of one coil is less than 90 degrees.
FIG. 15 shows an example of this, in which one coil LA is provided and a resistance element RI is connected in series to this coil LA. As a result, when the amplitude component of the voltage VA between the terminals of the coil LA changes gradually according to the displacement of the magnetic response member 17, the voltage drop V between the terminals of the resistance element RI accordingly.
The amplitude component of R changes gradually. The voltage VR across the terminals of the resistance element RI is converted into an AC output signal sin θ sin having a sine function characteristic
If it is regarded as ωt and the terminal voltage VA of the coil LA is regarded as an AC output signal cos θsin ωt having a cosine function characteristic, a certain 90 at which the sine function and the cosine function cross each other.
It is possible to correspond to a characteristic in an angular range with a width of less than degrees. Therefore, by inputting these AC output signals to the phase detection circuit 42, it is possible to perform absolute detection of the phase angle θ in the corresponding angular range of width less than 90 degrees.

FIG. 16 is a modification of FIG. 15, in which a dummy coil LN is provided instead of the resistance element RI.
The dummy coil LN is connected in series with the detection coil LA that is affected by the displacement of the magnetic response member 17, but is not affected by the displacement of the magnetic response member 17. The arithmetic circuit 59 calculates these voltages VA and VN according to a predetermined arithmetic expression, and for example, an arithmetic output of “VA + VN”, an AC output signal sin θs having a sine function characteristic.
inωt is generated, and an AC output signal cos θsinωt having a cosine function characteristic is generated by the calculation “VA−VN”.

FIG. 17 shows an example in which primary and secondary windings are used in the inductive linear position detector 13. This linear position detector linearly displaces a winding portion 16 including a primary winding excited by one-phase AC and a plurality of secondary windings arranged at different positions in the linear displacement direction, and a magnetic response member portion 26. A plurality of repetitions are provided at a predetermined pitch along the direction, and the induction output AC signal amplitude-modulated according to the detection target linear position has different amplitude function characteristics according to the displacement of each secondary winding. Magnetic response member 1 induced in each secondary winding
7 and 7. The amplitude function of each induction output AC signal induced in each secondary winding changes periodically with the repetition pitch of the magnetic response member portion 26 as one cycle. An example of this type of linear position detector 13 is disclosed in Japanese Patent Laid-Open No. 10-153402.

The magnetically responsive member 17 has a pin-shaped core portion 17a.
And a magnetically responsive member portion 26 repeatedly arranged around the core portion 17a at the predetermined pitch. The magnetic response member portion 26 is a magnetic body or a good conductor, and may be a magnet. The core 17a may be made of any material.
In short, the magnetically responsive member 17 may have different magnetic response characteristics exerted on the winding portion 16 between the location where the magnetically responsive member portion 26 exists and the location where it does not. The winding unit 16 includes primary windings PW1 to PW5 that are excited by a one-phase AC signal and a plurality of secondary windings SW1 to SW4 that are arranged at different positions in the linear displacement direction Y. The number of primary windings PW1 to PW5 may be one or an appropriate plural number, and the arrangement thereof may also be appropriate.

According to this linear position detector 13, the position corresponding to the winding portion 16 of the magnetic response member portion 26 of the magnetic response member 17 changes according to the change of the linear position to be detected, so that the primary winding The magnetic coupling between the lines PW1 to PW5 and each of the secondary windings SW1 to SW4 is changed according to the detection target linear position, whereby the induction output AC signal amplitude-modulated according to the detection target linear position is changed to 2 each. Next winding SW1 ~
It is induced in each of the secondary windings SW1 to SW4 with an amplitude function characteristic which varies depending on the displacement of the arrangement of SW4. Each secondary winding SW
Since the primary windings PW1 to PW5 are commonly excited by the one-phase alternating current signals, the respective induction output AC signals induced in 1 to SW4 have the same electrical phase, and their amplitude functions are magnetic. The amount of displacement corresponding to one pitch p of the repeated pitch of the response member portion 26 is cyclically changed as one cycle.

The four secondary windings SW1 to SW4 are arranged at predetermined intervals within a range of one pitch p of the repeating pitch of the magnetic response member portion 26, and each of the secondary windings SW1 to SW4.
The amplitude function of the inductive output AC signal generated at 4 is set so as to exhibit a desired characteristic. For example, in the case of configuring as a resolver type position detecting device, each secondary winding SW1 ...
The amplitude function of the induction output AC signal generated at SW4 is set so as to correspond to a sine function, a cosine function, a minus sine function, and a minus cosine function, respectively.
For example, as shown in the same figure, a range of 1 pitch p is divided into four, and they are arranged at respective divided positions shifted by p / 4. Thus, the amplitude function of the induction output AC signal generated in each of the secondary windings SW1 to SW4 can be set so as to correspond to the sine function, cosine function, minus sine function, and minus cosine function, respectively.

FIG. 18 is a circuit diagram of the winding portion 16. A common excitation AC signal (indicated by sin ωt for convenience of explanation) is applied to the primary windings PW1 to PW5. This primary winding P
In response to the excitation of W1 to PW5, an AC signal having an amplitude value corresponding to the corresponding position of the magnetic response member portion 26 of the magnetic response member 17 to the winding portion 16 is induced in each of the secondary windings SW1 to SW4. Each induction voltage level is the detection target linear position x
Corresponding to, the two-phase function characteristics sin θ and cos θ and the antiphase function characteristics −sin θ and −cos θ are shown. That is, each 2
The induction output signals of the next windings SW1 to SW4 are amplitude-modulated with the two-phase function characteristics sin θ, cos θ and the opposite phase function characteristics −sin θ, −cos θ corresponding to the detection target linear position x. It is output in each state. Note that θ is proportional to x,
For example, the relationship is θ = 2π (x / p). For convenience of explanation, coefficients according to other conditions such as the number of turns of the winding are omitted, and the output signal of the secondary winding SW1 is represented by “sin θ · sin ωt” with the sine phase as the secondary winding SW1 and the secondary winding SW2 is cosine. As a phase, its output signal is indicated by “cos θ · sin ωt”. In addition, the output signal of the secondary winding SW3 is shown as "-sin θ ・ sin ωt" with the minus sine phase, and 2
The output signal of the next winding SW4 is shown as "-cos .theta.sin .omega.t" with the minus cosine phase. The first output AC signal (2 with the amplitude function of the sine function is obtained by differentially combining the inductive outputs of the sine phase and the minus sine phase.
sin θ · sin ωt) is obtained. Further, the second output AC signal (2cos θ · sin ωt) having the amplitude function of the cosine function is obtained by differentially combining the induced outputs of the cosine phase and the minus cosine phase. For simplification of expression, the coefficient “2” is omitted, and in the following, the first
The output AC signal of is represented by “sin θ · sin ωt”
The output AC signal of is represented by “cos θ · sin ωt”.

Thus, the first output AC signal A = sin θ · sin ωt having the first function value sin θ corresponding to the detection target linear position y as the amplitude value and the same detection target linear position y
The second function value cos θ corresponding to
Output AC signal B = cos θ · sin ωt is output.
According to such a winding configuration, similar to that obtained in a conventionally known resolver which is a rotary position detecting device,
It can be understood that two output AC signals (sine output and cosine output) that are in-phase AC and have a two-phase amplitude function can be obtained in the linear position detection device. Therefore, two-phase output AC signals (A = sin θ · sin ωt and B = cos θ ·
sin ωt) can be used in the same way as the output of a conventionally known resolver. In addition, as described above, the configuration in which the four secondary windings SW1 to SW4 are arranged at a predetermined interval within the range of one pitch p of the repeating pitch of the magnetic response member portion 26 is Since it can be accommodated in a relatively small size that substantially corresponds to the range of one pitch of the magnetic response member portion 26, it is useful for downsizing the overall configuration of the linear position detecting device.

As described above, according to the inductive linear position detecting device 13 having the above-described structure, the output type AC signal (A = sin θ · sin) of the same phase as that of the rotary resolver (A = sin θ · sin) ωt and B = cos θ · sin ωt) can be output from the secondary windings SW1 to SW4 of the winding unit 16. Therefore, by applying an appropriate digital phase detection circuit, the sine function sin θ and the cosine function
It is possible to detect the phase value θ of cos θ by digital phase detection and obtain the position detection data of the linear position x based on this.

For example, FIG. 19 shows an example in which a known RD (resolver-digital) converter is applied. The resolver-type two-phase output AC signals A = sin θ · sin ωt and B = cos θ · sin ωt output from the secondary windings SW1 to SW4 of the winding unit 16 are analog multipliers 6 respectively.
It is input to 0,61. The sequential phase generation circuit 62 generates digital data of the phase angle φ, and the sine / cosine generation circuit 63 generates an analog signal of the sine value sin φ and the cosine value cos φ corresponding to the phase angle φ. Subtractor 6
In 4, the difference between the output signals of the multipliers 60 and 61 is obtained, and the output of the subtracter 64 controls the phase generating operation of the phase generating circuit 62 in sequence. When the output of the subtractor 64 becomes 0, digital data of the phase angle θ is obtained.

Although the impedance of the primary and secondary windings of the winding section 16 changes due to temperature changes and the like, an error occurs in the electrical AC phase ωt in the secondary output AC signal. At, the phase error of sin ωt is automatically canceled.

FIG. 20 shows another example of the phase detection circuit applied to the inductive linear position detection device 13 described above. This example is shown in the above-mentioned publication (Japanese Patent Laid-Open No. 10-153402), and a description thereof will be omitted.

Next, an example of the control system of this bending machine will be described with reference to FIG. The bending machine control device 70 is means for controlling a bending operation in the bending machine, and has a numerical control function and the like. The bending machine control device 70 uses bending control while measuring the bending angle with the angle measuring instrument 9, and the output of the circuit section 35 of the angle measuring instrument 9 is controlled by the bending value control means 36. Input to the device 70.

The measurement value correcting means 36 is the linear position detector 1
It has a processing function of converting the measured value of the linear position obtained by the circuit section 35 of No. 3 into angle data, and when converting into the angle data, correction is performed based on the characteristics of the corner contact tool 12. That is, in the corner contact tool 12, the upper and lower support pins 18 and 19 are both vertically movable, and the relationship between the measured value of the linear position detector 13 and the angle value is not a proportional relationship but a predetermined characteristic. Since a curve is drawn, correction is performed according to this characteristic curve. The bending angle obtained by the measurement value control means 36 is displayed on the display means 39 of the bending machine control device 70.

The operation method of this bending machine and the outline of the operation for measuring the bending angle of the plate material will be described with reference to FIG. First,
The ram 3 is lowered to start bending (R1). Plate material W
Moves the upper mold 4 into the lower mold 2, thereby
Can be bent between two. When the lower die 2 is for a three-point bend as shown in FIG. 7, the lower die 2 is lowered to the lowest point at which the upper die 2 is movable. That is, the bent plate material W is the lower mold 2
The upper mold 2 is lowered and bent until it comes into contact with the bottom surface of the ram 3, and the ram 3 is turned upward (R2). When the lower die 2 is for air bend as shown in FIG. 8, the lower die 2 is moved up to a predetermined overstroke amount (overstroke target value) below the height of the upper die 2 which is the target value of the bending angle. Type 2
After falling, the ram 3 is turned up. During this time, bending is performed while measuring the bending angle of the plate material W with the angle measuring device 9. When the bending angle of the plate material W after springback is measured, the ram 3 is depressurized by the ram lifting drive means 6 before the upper die 2 is turned upward (R3).
The bending angle of the bent portion of the plate material W after the springback actually occurs due to the release of the pressure is measured by the angle measuring device 9 (R4). After this measurement, the ram 3 is raised and returned (R5).

The angle measurement by the angle measuring device 9 is performed as shown in FIG. As shown in (A) of the figure, since the linear displacement component 15 is urged downward by the elastic body 25 for returning until the corner contact tool 12 formed of a parallel link enters the bending part, The upper support pin 18 attached to the displacement component 15 and the linear displacement component 15 below the support pin 18
The lower support pins 19 provided apart from are both pressed against the lower ends of the groove-shaped guides 21 and 22 provided on the upper mold 4. Therefore, the corner contact tool 12 has a flat parallel link.

When the upper die 4 enters the lower die 2 and the bending progresses to a certain degree, the angle measuring device 9 and the upper die 4 together with the plate material W
In the corner contact tool 12 formed of parallel links, the side edges of the lower two links 14c and 14d incline along the surfaces on both sides of the concave corner of the plate W, respectively. Therefore, the corner contact tool 12 is deformed so that the lateral width of the parallel link is narrowed against the elastic restoring force of the restoring elastic body 25, and the upper side support of the corner contact tool 25 is accompanied by this deformation. The linear displacement component 15 to which the pin 18 is fixed rises. At this time, since the lower support pin 19 is vertically movable within the guide 22, the lower support pin 19 also rises as the bending angle deepens. Therefore, the linear displacement component 15
It does not have a proportional relationship with the bending angle of the plate material W, but rises upward by an amount having a predetermined relationship curve.

The rise of the linear displacement component 15 is detected by the linear position detector 13 as the elevation of the rod-shaped magnetic response member 17, and the detected value of the linear position displacement is measured by the measurement value correcting means 36 (FIG. 21). Converted to bending angle.
In this way, the bending angle is measured.

A control system for performing learning control in the case of a bending machine with a three-point bend will be described with reference to FIGS. The bending machine control device 70 includes a bending control means 71 and a learning control means 72. The bending control means 71 is means for controlling the entire bending machine, and is constituted by a computer-based numerical control device (not shown) and a programmable controller for controlling according to a machining program (not shown). It has a means 73 and a lower die height control means 74. The ram lifting / lowering control unit 73 causes the ram 3 to perform a predetermined lifting / lowering operation according to the target angle of the bending angle.
It is a means for giving a drive command to the ram lifting drive device 6. The ram elevating / lowering control means 73 displays the detected value of the ram position detection means 37 for detecting the stroke position of the ram 3, the bending load detected by the bending load detection means 38, and the measured value of the bending angle of the angle measuring device 9. Ascending and descending control is performed while monitoring. The bending load detecting means 38 is composed of a pressure detecting means or a load cell provided on a ram cylinder which is the ram lifting / lowering driving means 6. In the case of a load cell, it is provided on the upper die 4 or the ram 3. The lower die height control means 74 is means for controlling the height of the variable bottom 2aa of the lower die 2 according to the target angle of the bending angle, and gives a height adjustment command to the lower die height adjusting means 29. The lower mold height control unit 74 has a correction unit 75, and has a function of correcting the lower mold bottom surface height corresponding to the target angle θ _M according to a correction value given from the outside.

The learning control means 72 is a means for generating a correction value from various measured values in the bending process and giving the correction value to the bending control means 71. The learning control means 72 gives the correction portion 75 the next correction value of the lower die bottom surface height. There is. The learning control means 72 is means for performing the processing shown in the flowchart of FIG. 25 to generate the next correction value, and as shown in FIG. 24, the pattern table 76, the bending process measuring means 77, and the product bending angle measuring means 78. , And a correction value generating means 79. Pattern table 76
Is set so that the mutual relationship among the vertical position of the upper die 4 generated in the bending process, the load acting on the upper die 4, and the bending angle of the plate material W is classified into a plurality of patterns, and the pattern number can be selected from the mutual relations. It is a storage means. During the bending process, the measuring means 77 moves the lifting position of the upper mold 4 and the upper mold 4 during the bending process.
Is a means for measuring the load acting on the plate and the bending angle of the plate material W, and has a load dip point detecting means 80 and a ram cylinder motion detecting means 81. The correction value generation unit 79 includes a pattern detection unit 82 and a correction value generation unit 83. In the correction value generation unit 83, correction value conversion data that gives the next correction value θh of the lower die bottom surface height corresponding to the product bending angle (bending angle after springback) for each pattern set by the pattern detection unit 82 84 are stored. The correction value conversion data 84 may be a relational expression or a table. The product bending angle detection means 78 has an angle detection part 85 for taking in the angle after springback at a predetermined timing, and a ram cylinder control means 86.

An operation method of the bending machine for performing learning control by the learning control means 72 will be described. First, a command value and a measured value of each part in one bending process will be described with reference to FIG. The stroke position (Ps) of the ram 3 descends from the lift standby position to the lower die bottom surface height position (lowermost point), and returns to the lift standby position. The lower die bottom surface height position is a height position at which the upper die 4 presses the plate material W against the lower die 2. The ram 3 descends at a high speed up to a predetermined height approaching the lower die 2 at a high speed in the descending process, as shown by RS1 to RS4 as speed command examples of each process of the ram cylinder which is the ram lifting drive device 6, and then becomes a low speed there. Switch and continue descending,
After stopping the pressurization for a predetermined time at the lowest point, it rises at a low speed, switches to a high speed, and rises to the lift standby position. In this process, the ram cylinder is designed to reduce the pressure to a certain value (cushion pressure) when shifting from the lowest point to the raising operation. The bending angle detection angle θs is such that the ram 3 descends and the upper mold 4 moves the plate material W on the lower mold 2.
When the ram 3 comes into contact with the ram 3, it starts to bend and shows a value of 180 degrees or less, and the ram 3 gradually decreases in angle until it reaches the lowest point. When the ram 3 reduces the pressure at the lowest point or slightly increases, the detection angle θs returns slightly due to the springback of the plate material W. After that, until the upper mold 4 comes off the lower mold 2, the pressing force of the corner contact tool 12 against the plate material W in the angle measuring device 4 weakens, so the detected angle θs gradually becomes the original value of 180 degrees. Return. The load WD (load of the ram cylinder) W _D of the bending load detecting means 38 is generated when the upper die 4 comes into contact with the plate material W when the ram 3 descends,
As the bending progresses, when the yield state is reached, the load value once suddenly decreases. The time when this decrease starts is called the load dip point W _DD point. After the load is reduced, the upper die 4 is pressed against the bottom surface of the lower die 2 to increase the detection load W _D again, and thereafter, the ram 3 is elevated and the upper die 4 is moved to the lower die 2.
The detected load W _D gradually decreases and returns to zero until the load is released from.

As shown in the flow chart of FIG. 25, in the learning control, the load dip point detecting means 80 is provided during the descending process of the ram 3.
The detected load W _D is monitored by and the load dip point W _DD is detected (step S1). The load dip point and the lowest point are monitored until the lowest point of the ram cylinder 3 is detected (S1, S4), during which the stroke amount of the ram cylinder from the load dip point to the target angle θ _M. Alternatively, the time (measurement amount A) is detected (S2), and the stroke amount or time (measurement amount B) of the ram cylinder from the target angle θ _M to the lowest point is detected (S3). In the detection of the load dip point, whether the load dip point is detected or not is monitored in the overtime detection step (S7), and in the case of overtime, a measurement error signal is output. When the ram 3 reaches the lowest point, the springback amount (measured amount C) is detected when the ram 3 is raised (S5). The detection of the springback amount is obtained as the difference between the detection angle (product bending angle) θ ₂ after the springback obtained by the angle detection unit 85 and the detection angle θ ₁ when the product is pressed against the lower mold 2. In FIG. 24, the means for calculating the springback amount is not shown. The pattern detection unit 82 in FIG. 24 selects the corresponding pattern in the pattern table 76 from the measured amounts A to C thus measured, and outputs the recognition code (pattern number) of the selected pattern to the correction value generation unit. Tell 83.

Here, the pattern selection will be specifically described. The pattern table 76 is created in advance, that is, offline or the like, before performing learning control. This creation is made based on the measurement results in the past bending work, experimental values, simulation results, and the like. The pattern table 76 is, specifically, a pattern number sheet (S1 to Sn) serving as an individual table for each stroke amount or time (measurement amount A) of the ram cylinder from the load dip point W _DD to the target angle θ _M. Is provided as a sheet group in which is set. On one pattern number sheet, the target angle θ
Stroke amount or time of the ram cylinder from _M to the lowest point (measured amount B) and springback amount (measured amount C)
The pattern numbers (1, 2, ...) Determined by the relationship with are recorded. The pattern detection unit 82 of FIG. 24 first selects a corresponding pattern number sheet from the measurement amount A, and from the selected pattern number sheet, the pattern numbers (1, 2, ...) Determined by the relationship between the measurement amount B and the measurement amount C. …) Is selected.

The correction value generation unit 83 uses the correction value conversion data 8
4, the relationship curve between the bending angle error (θ _D ) and the next correction value θh is set for each pattern. Angle detector 8
The detected angle (product bending angle) θ ₂ after the springback obtained in 5 is compared with the target angle (θ _M ), and the bending angle error (θ _D ) is calculated by the correction value generating unit 83 in the relational curve of the corresponding pattern. Is converted into the correction value θh next time. The next-time correction value θh thus generated is used for the bending control means 41.
It is input to the correction unit 45 in the lower die height control means 44. At the time of the next bending process, the bending process is performed by controlling the lower die height with respect to the target value of the bending angle to the height corrected by the next correction value θh. The next correction value θh may be used as it is for correction, or may be used as a correction with a statistically processed value together with the results of the next correction value θh in a plurality of bending processes and appropriate measurement results. good. In this way, the learning control in the 3-point bend is performed. In addition,
The correction by this learning control is performed, for example, when the target value of the bending angle, the plate thickness, the material, etc. are changed, and when the machining under the same conditions is repeated, the machining is performed without using the learning control function. .

A control system for performing learning control in the case of an air bend bending machine will be described with reference to FIGS.
The bending machine control device 70 includes bending control means 71A and learning control means 72A. The bending control means 71A is shown in FIG.
As in the case of Example 3, it is composed of a computer-based numerical control device and a programmable controller that control according to a machining program. The bending control means 71A has a ram lifting / lowering control means 73A, but does not have the lower mold height control means 74 in the example of FIG. 23.
It has a correction unit 75A. Ram lifting control means 73A
Is for performing the lifting control while monitoring the stroke position of the ram position detecting means 37, the bending load of the bending load detecting means 38, and the measured value of the bending angle of the angle measuring device 9. The correction unit 75A has a function of correcting the overstroke target value corresponding to the target angle according to a correction value given from the outside.

As shown in FIG. 28, the learning control means 72A includes a pattern table 76A, a load dip point detection means 80A, a pattern detection portion 82A, an angle detection portion 78A after spring back, a correction value generation portion 83A, and an NC device. It has an output control unit 86A. The pattern detection unit 82A and the correction generation unit 83A form a correction value generation unit 79A. In order to measure the angle after springback, the output control unit 86A to the NC device once again raises the ram 3 by a predetermined height from the overstroke target value, and after descending, shifts to the ascending return. It has a function to perform the operation (retry), and the part having this function and the angle detection unit 85A,
The product bending angle measuring means 78A is configured. The NC device is a device part that performs numerical control in the bending machine means 73A. The pattern table 76A is created offline, for example, before performing learning control. This creation, the measurement results in the past bending,
It is created based on experimental values and simulation results. Specifically, the pattern table 76A classifies the patterns by the stroke amount of the ram cylinder from the load dip point W _DD to the target angle θ _M (this amount is substituted by time in this example). Is. In the correction value generation unit 83A, as the correction value conversion data 84A, a relationship curve of the error θ _D between the product bending angle θ ₂ and the target angle θ _M and the next correction value Pa of the overstroke target value Pso is provided for each pattern. Has been set. The functions of the other parts will be described together with the description of the following operation method.

Learning control by this learning control means 72A
A method of operating the bending machine for performing the above will be described. First, with FIG.
Both, the operation and measured value of each part in one bending process
Etc. will be explained. Ram 3 is a song at the ram stroke position Ps
As shown by the line, from the rising standby position such as top dead center,
After reaching the stroke target value Pso, the plate material W
In order to detect the bending angle after springback,
After ascending, descending again, it ascends to the ascending standby position.
The bending angle detection angle θs is as follows.
When it touched the plate material W on the lower mold 2, the bending started and 18
The value is 0 degrees or less, and the ram 3 is the overstroke target value.
The angle becomes smaller and smaller until Pso is reached. That
After that, when the ram 3 rises, the upper mold 4 is released from the lower mold 2.
Then, in the angle measuring device 4, the corner contact tool 12 is attached to the plate material W.
Since the pressing force will be weakened, the detected angle θs is
First, it returns to the original 180 degree value. Springback relationship
Will be described later. Bending load detection means 38 inspection
Output load (ram cylinder load) W_DAt the descent of ram 3
It occurs when the upper die 4 contacts the plate material W, and the bending progresses.
When the yield value is reached, the load value
Fall to. When this decrease starts, the load dip point W
_DDCall. After the load is reduced, upper die 4 is the overstroke
Standard P_SODetected load W while reaching_DIs plastic
It temporarily rises again due to the nature of sexual processing, but
Detection until the ram 3 rises and the upper mold 4 comes off the lower mold 2.
Load W _DGradually decreases and returns to zero.

The load dip point detection means 80A of the learning control means 72A in FIG. 28 monitors the detected load W _D and detects the load dip point W _DD . Pattern detection unit 82A
Monitors the detection signal of the load dip point detecting means 80A, the detection angle θs of the angle measuring device 9 and the time, and after detecting the load dip point W _DD , until the detection angle θs reaches the target angle θ _M. The time Δt of is detected. This time Δt indirectly indicates the stroke of the ram 3 until the target angle θ _M is reached after the load dip point is detected. Pattern detection unit 82A
Is the time Δt (ram stroke) detected in this way
Is compared with the pattern table 76A to select a bending characteristic pattern. The pattern detection unit 82A further outputs the next overstroke target value Pso in accordance with the detected time Δt (ram stroke). The product bending angle measuring means 78 monitors the detection angle θs and the detection load W _D , and detects the bending angle of the plate material W when the spring back of the plate material W occurs after the bending process. Specifically, when the ram 3 reaches the overstroke target value Pso, the ram 3 once rises and then falls again under the control of the output control unit 86A. That is, the retry operation is performed. Angle detector 85A, when the signal of the start of the retry operation is input from the output control section 86A, monitors the load detection W _D, the detection angle θs of the angle measuring instrument 9 upon a rise of load detected W _D, product The bending angle is detected as θ ₂ . That is, when the upper die 4 is pressed against the plate material W again in the retry operation, the detected load W _D is generated. The measurement timing is obtained by using the rise of the detected load W _D. The reason why the angle is detected by the re-pressing by the retry operation is to improve the detection accuracy by setting the corner contact tool 12 of the angle measuring device 9 against the plate material W with certainty. The product bending angle θ ₂ detected in this way is compared with the target angle θ _M, and the error θ _D is converted into the correction value Pa of the overstroke target value by the correction value generation unit 83A and output. The correction value generation unit 83A selects a relational curve corresponding to the pattern detected by the pattern detection unit 82A, and converts the error θ _D into the correction value Pa according to the relational curve. The next correction value Pa output from the correction value generation unit 83A is calculated by the correction unit 75A.
And the correction unit 75A corrects the overstroke target value Pso output from the pattern detection unit 82A by the next correction value Pa. The overstroke of the ram 3 in the next bending process is controlled by the overstroke target value Pso-Pa corrected in this way. In this way, learning control can be performed.

[0070]

According to the bending machine of the present invention, an angle measuring device for measuring a bending angle of a plate material is incorporated in a male mold, and the angle measuring device has an inductive linear position detector.
Made built compactly goniometer the mold, Ru can better angular measurement accuracy while bending. Male type is mold width
It is made up of multiple split molds lined up in
The angle measuring device is accommodated by providing a housing recess on the side end surface between the split molds.
The mold is divided for the purpose of incorporating the angle measuring device.
There is no need, and the angle measuring device can be easily installed in the mold.
It When the angle measuring device detects by a change in electrical phase angle, the temperature characteristic of the coil has a function of offsetting and compensating with the outputs of the plurality of coils or impedance means, no problem of signal attenuation, can do more accurate angle measurement, also with a simple configuration, Ru can do angle measurement in which the influence of temperature change. The method of operating a bending machine of this invention, using the angle measuring instrument built into the upper die,
Bending can be performed with high precision corresponding to spring back. In particular, a pattern table that classifies the mutual relationship among the upper mold up-and-down position that occurs during the bending process, the load that acts on the upper mold, and the bending angle of the plate material, and the next correction corresponding to the bending angle after springback for each pattern When preparing the correction value conversion data that gives a value, regardless of the plate thickness, material, etc., only by giving the target angle of the bending angle, appropriate correction can be performed by learning control and good accuracy corresponding to springback is achieved. Bending can be done quickly with simple control.

[Brief description of drawings]

FIG. 1 is a front view of a bending machine according to an embodiment of the present invention.

FIG. 2 is a side view of the bending machine.

3A to 3C are a cross-sectional view, a front view, and a side view of a split mold in an upper mold of the bending machine, respectively.

FIG. 4A is a side view showing an enlarged tip of the same split type, and FIG. 4B is a side view of a modification thereof.

FIG. 5A is a cutaway front view showing an angle measuring device built into the bending machine together with an upper die, and FIG. 5B is a side view thereof.

FIG. 6 is an operation explanatory view of the angle measuring device.

FIG. 7 is a side view showing a relationship between a lower die and an upper die of the bending machine.

FIG. 8 is a side view showing a relationship between a modification of the lower mold and the upper mold of the bending machine.

FIG. 9 is a side view showing the relationship between another modification of the lower mold and the upper mold of the same bending machine.

10A to 10C are an external perspective view showing a linear position detector of the same angle measuring device, a cross-sectional view taken along the coil axial direction, and an electric circuit diagram related to the coil.

FIG. 11 is an explanatory diagram of a detection operation of the linear position detector.

FIG. 12 is an electric circuit diagram related to a coil unit, showing a modification of the linear position detector.

FIG. 13 is an electric circuit diagram relating to a coil unit, showing another modification of the linear position detector.

FIG. 14 shows still another modified example of the linear position detector,
It is an electric circuit diagram relevant to a coil part.

FIG. 15 shows still another modification of the linear position detector,
It is an electric circuit diagram relevant to a coil part.

FIG. 16 shows another modification of the linear position detector,
It is an electric circuit diagram relevant to a coil part.

FIG. 17 is a cutaway perspective view showing still another modified example of the linear position detector.

FIG. 18 is an electric circuit diagram of the linear position detector.

FIG. 19 is a block diagram showing an example of a measurement circuit of the linear position detector.

FIG. 20 is a block diagram showing another example of the measurement circuit of the linear position detector.

FIG. 21 is a block diagram showing an example of a control system of the bending machine.

FIG. 22 is a flowchart showing a method of operating the bending machine in the control system.

FIG. 23 is a block diagram showing another example of the control system of the bending machine.

FIG. 24 is a block diagram of learning control means of the control system.

FIG. 25 is a flow chart of learning control in the control system.

FIG. 26 is a graph showing a relationship between various signals when performing learning control in the control system.

FIG. 27 is a block diagram showing still another example of the control system of the bending machine.

FIG. 28 is a block diagram of learning control means of the control system.

FIG. 29 is a graph showing a relationship between various signals when performing learning control in the control system.

[Explanation of symbols]

1 ... bed 2 ... Lower mold 3 ... Ram 4-upper mold 4A ... Split type 6 ... Ram lifting drive 9 ... Angle measuring device 11 ... Angle measuring device housing groove 12 ... Corner contact tool 13 ... Inductive linear position detector 14 ... Contact parts 14a-14d ... Link 15 ... Linear displacement parts 16 ... Winding part 17 ... Magnetically responsive member 18, 19 ... Support pins 20 ... Connecting pin 21, 22 ... Guide 25 ... Elastic body for return 26 ... Magnetically responsive member section 29 ... Lower mold height adjustment mechanism 36 ... Measured value correcting means 37 ... Ram position detecting means 38 ... Bending load detecting means 40, 41 ... Analog arithmetic circuit 42 ... Phase detection circuit 50 ... AC power supply 70 ... Bending machine control device 71, 71A ... Bending control means 72, 72A ... Learning control means 73, 73A ... Ram lifting control means 74 ... Lower mold height control means 75, 75A ... Correction unit 76,76A ... Pattern table 77 ... Measuring means during bending process 78, 78A ... Product bending angle measuring means 79 ... Correction value generation means 80, 80A ... Load dip point detection means 82, 82A ... Pattern detection unit 83, 83A ... Correction value generator 84, 84A ... Correction value conversion data 85,85A ... Angle detector W ... Plate

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-142769 (JP, A) JP-A-9-295060 (JP, A) JP-A1-210124 (JP, A) JP-A-5- 322551 (JP, A) Actually open 4-22121 (JP, U) Actually open 57-135917 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 5/24 G01B 7 / 00,7 / 30 G01B 21/22 B21D 5/02

Claims (8)

(57) [Claims] 1. A bending machine for pressing a plate material sandwiched between a male mold and a female mold extending in a straight line, and an angle measuring device for measuring a bending angle of the plate material bent by these male and female molds is provided in the male mold. Assembled, the male mold includes a plurality of molds arranged in the mold width direction.
It is formed as a split type, and the type is changed by changing the number of arrays of the split type.
It is possible to change the width,
The side end faces between the split molds each have a housing recess, and the housing recess
The angle measuring device is housed in the
Between the corner formation surfaces by contacting both sides of the bent concave corner
Corner contact tool that produces linear displacement according to the opening angle
And an inductive type that measures the linear displacement of this corner contact tool.
With the linear position detector of
The tool enters the concave corner of the plate and contacts the corner forming surfaces on both sides.
Contact part to touch, and the concave corner part due to the displacement of this contact part
The linear position displacement that causes the vertical position
It has a line displacement part, and the contact part consists of four links.
It is configured as a parallel link mechanism consisting of
Two support pins separated vertically, and two support pins separated left and right
Connected in sequence with connecting pins, the upper support pin is the straight line
It is provided on the displacement part, and the upper and lower parts are guided by the upper guide.
Direction of the lower support pin.
The guide is located below the linear displacement
Guides freely in a predetermined play range only vertically
, The lower support pin becomes the reference position side support pin,
The upper support pin becomes the displacement side support pin, and the left and right connection
The pins are freely movable, and the upper and lower guides are
Opposing pair formed on the side end faces of the split dies on both sides in contact
Are formed as guide grooves for the upper and lower support pins.
From the link, project on both sides, and the projecting part
A bending machine characterized in that the guides are movably fitted to each other . 2. A pre-Symbol linear position detector is for detecting the displacement of the linear position by the change in electrical phase angle, a temperature characteristic of a coil for detecting the linear position, a plurality of coils or impedance The bending machine according to claim 1, which has a function of offsetting and compensating with the output of the means. 3. A method of operating a bending machine according to claim 1 , wherein in a bending process, a vertical position of a male upper die, a load acting on the upper die, and a bending of a plate material. The angle is measured, and after this bending process, the bending angle after the springback of the plate material is measured in the state where the upper die is returned to a certain degree or the upper die is loosened under pressure, and these measured upper and lower positions of the upper die, A method for operating a bending machine, which obtains the next correction value for the adjustable part that controls the bending angle in the bending machine from the interrelationship between the load acting on the upper die, the bending angle of the plate material, and the bending angle after springback. 4. The method for operating a bending machine according to claim 3, wherein the mutual relationship among the lifting position of the upper die, the load acting on the upper die, and the bending angle of the plate material in the bending process is classified into a plurality of patterns. Prepared pattern table and correction value conversion data which gives the next correction value of the adjustable portion corresponding to the bending angle after springback for each pattern, and the upper die measured in the bending process. The vertical position, the load acting on the upper mold, and the bending angle of the plate material are compared with the previous pattern table to select the corresponding pattern, and the bending angle after the springback after the bending process is the correction value of the selected pattern. A method of operating a bending machine that uses conversion data to obtain the next correction value for the adjustable part. 5. The method for operating a bending machine according to claim 4 , wherein in the bending machine, a bottom height of a lower die which is a female die is variable, and a plate material is pressed against a bottom surface of the lower die. The upper mold is lowered until it is bent, and the adjustable portion is the bottom height of the lower mold, and the next correction value obtained from the correction value conversion data is the correction value of the bottom height. How to operate a bending machine. 6. The method of operating a bending machine according to claim 4 , wherein the bending machine determines a bending angle by adjusting the amount of penetration of a male upper mold into a lower mold, and The adjustable portion is the upper mold, and the next correction value obtained from the correction value conversion data is a correction for the target value of the overstroke for lowering the upper mold further than the lifting position of the upper mold that is the target angle of the plate bending angle. How to operate the bending machine, which is the value. 7. The pattern of the relationship between the lifting position of the upper die generated in the bending process, the load acting on the upper die, and the bending angle of the plate material is the upper die stroke from the load dip point to the target angle and the target angle. The method for operating a bending machine according to claim 5 , wherein classification is performed according to the stroke of the upper die up to the lowest point. 8. The bending machine according to claim 1 , wherein the bending machine has an adjustable portion for controlling a bending angle, learning control means is provided, and the learning control means is provided in the bending process. A pattern table in which the mutual relationship among the upper and lower positions of the upper die, the load acting on the upper die, and the bending angle of the plate material is classified into a plurality of patterns, and the pattern table that corresponds to the bending angle after springback for each pattern. Correction value conversion data that gives the next correction value of the adjustment part, a means for measuring the lifting position of the upper die, the load that acts on the upper die, and the bending angle of the plate material during the bending process, and a certain amount of the upper die after bending. Means for measuring the bending angle of the plate material after springback in the returned state or the pressure release state of the upper mold, the lifting position of the upper mold obtained in the bending process, the load acting on the upper mold, and the bending angle of the plate material. A correction value generation unit that selects a corresponding pattern in the pattern table according to the value and generates the next correction value of the adjustable portion corresponding to the bending angle after springback according to the correction value conversion data based on the selected pattern. Bending machine equipped with and.