JP3573395B2 - Hemming device and hemming method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hemming method using a hemming device for sequentially bending a continuous peripheral edge of a metal plate.
[0002]
[Prior art]
As a hemming device applied to the connection between the peripheral portions of an outer panel and an inner panel constituting a door of an automobile, a roller type using a robot arm is disclosed in Japanese Patent Publication No. 5-34101. This roller-type hemming device has a configuration in which a roller 5 is rotatably supported by a roller hem unit 4 attached to the distal end of a robot arm 3 as shown in FIG. 5, for example. As shown in the drawing, the continuous bent portion 2 of the work 1 is sequentially bent.
[0003]
5 shows, for example, an outer panel 1a and an inner panel 1b of an automobile door. The peripheral edge of the outer panel 1a positioned on the lower die 6 is bent upward at a substantially right angle in advance, and the peripheral edge of the inner panel 1b is placed along the peripheral edge. The bent peripheral portion of the outer panel 1a is the bent portion 2 to be hemmed by the roller 5.
[0004]
First, the roller 5 is pressed against the upper end of a part of the bent portion 2 by the robot arm 3 as shown in FIG. 6A, and the roller 5 is bent by the roller 5 as shown in FIG. The portion 2 is pre-hemmed (preliminary bending) to an angle of approximately 45 °, and the roller 5 is rotated laterally along the bent portion 2 to sequentially rotate the bent portion 2 by approximately 45 °. And the entire length of the bent portion 2 is pre-hemmed. Next, as shown in FIG. 6 (C), the roller 5 is pressed against a part of the pre-hemmed bent portion 2 from directly above, and as shown in FIG. 6 (D). 2 is bent to the upper surface of the peripheral edge of the inner panel (final bending). The roller 5 is rotated in the lateral direction along the bent portion 2 as it is, and the entire length of the bent portion 2 is subjected to the main hemming.
[0005]
Although not shown, the bent portion may be bent by a press using a vertically arranged mold.
[0006]
[Problems to be solved by the invention]
In the above-mentioned press method, the equipment becomes large, and it is necessary to prepare many types of dies for each type of work. Therefore, the manufacturing cost increases, and the time required for changing the dies increases the productivity. There are problems such as worsening. Therefore, it is not suitable for high-mix low-volume production.
[0007]
On the other hand, in the case of the roller-type hemming device, since the roller is directly pressed against the bent portion of the work, which is a metal plate, and is bent, the pressing force required at the time of pre-hemming or the main hemming becomes large. Therefore, a robot having a high load-bearing capacity is required, and as a result, the equipment cost of the entire hemming device becomes excessive.
[0008]
In addition, since the robot arm may be bent by the high pressure applied to the rollers during the hemming process, the teaching performed before the hemming process requires high-precision teaching in consideration of the bending amount of the robot arm. It is difficult to perform precision teaching with high reliability. In the actual teaching, the teaching is corrected as many as ten or more times using the actual work after the first teaching. However, this requires a large amount of adjustment man-hour and time, and it is difficult to improve the work efficiency.
[0009]
In addition, the shape of the continuous bent portion of the workpiece in the length direction is various such as a substantially straight line or a curved line, and the substantially straight portion and the curved portion of the bent portion are added by the way of contact of the roller or the roller. Since the applied pressure is different, if the entire length of the bent portion is hemmed with one type of roller, it becomes difficult to perform particularly favorable processing of the curved portion. Therefore, the curved portion of the bent portion is roughly hemmed with a roller, and then manually corrected by hitting with a hammer later. Automation becomes difficult.
[0010]
In addition, the presence of the curved portion makes it difficult to bend the continuous bent portion of the work with a uniform pressing force using a roller over the entire length. The thickness of the portion (corresponding to the thickness d in FIG. 6D) may be non-uniform.
[0011]
In addition, multiple types of rollers with different diameters can be exchanged and mounted on the robot arm, and the heaviness of the bent part of the work is processed with a large diameter roller and the curved part with a small diameter roller. However, there is a problem that the equipment cost is increased due to a plurality of types of rollers and the workability is reduced due to roller replacement.
[0012]
An object of the present invention is to provide a hemming method capable of hemming a work with high accuracy and high work efficiency without increasing equipment costs.
[0013]
[Means for Solving the Problems]
According to the method of the present invention, a hem blade is mounted on a robot arm via a vibration source, and a continuous bent portion of the workpiece is pressed and bent by a hem blade driven by the vibration source, and the hem blade is bent as it is. The bent part to be bent is continuously bent by laterally moving along the part to be processed. With such a method , a dedicated mold is not required, so that the type of work can be easily changed as compared with the press method.
[0014]
In this case, the hem blade is preferably supported by the robot arm via an elastic member so as to be elastically displaceable in a lateral movement direction along the bent portion of the work. Further, the hem blade may be supported on the robot arm via an elastic member so as to be elastically displaceable in the vibration direction of the hem blade.
[0015]
Here, an air cylinder or the like is used as an elastic source for vibrating the hem blade with respect to the robot arm. The hem blade vibrates in the axial direction and presses and bends the bent part of the work, but by specifying the frequency and amplitude of the hem blade vibration at this time, high quality processing of the hemming processing can be achieved. It becomes possible. The elastic member holding the hem blade elastically displaceable is a spring or the like, and the elastic member holding the hem blade elastically displaceable in the vibration direction of the hem blade suppresses the transmission of the vibration of the hem blade to the robot arm. Further, the elastic member for holding the hem blade in the elastic displacement processing in the lateral movement direction of the hem blade makes the hem blade laterally displaceable with respect to the robot arm.
[0016]
It is preferable that a weight that suppresses resonance of the robot arm due to vibration of the hem blade be detachably attached to at least one of the hem blade and its vibration source. By selecting the weight of the weight and the mounting position, the resonance of the robot arm due to the vibration of the hem blade is effectively suppressed, and the hemming processing accuracy is improved.
[0017]
The work surface of the hem blade that presses the bent portion of the work may be a curved surface having a radius of curvature that decreases from the center to both ends of the work surface. Such selective switching of the machined surface having a different radius of curvature of the hem blade is automatically performed by a reaction force from the work generated corresponding to the shape of the substantially straight portion or the curved portion of the bent portion of the work. Is This selective switching facilitates uniform hemming of the substantially straight portion and the curved portion of the bent portion, and allows one type of hem blade to be used for the work.
[0018]
In addition, the method of the present invention mounts a hem blade via a vibration source on a robot arm that moves laterally along a continuous bent portion of a workpiece, and attaches the hem blade to the workpiece using an elastic member. Support to be elastically displaceable in the horizontal direction along the part,
Pressing and bending the continuous bent part of the work with the hem blade in the vibration direction while applying vibration, and moving the hem blade laterally along the bent part as it is, continuously bending the bent part Bending,
When the hem blade is moved laterally by the robot arm, the lateral movement speed of the hem blade is made slower than that of the robot arm due to the load caused by the contact resistance between the hem blade and the bent portion, and the advance occurs when the amount of delay becomes a predetermined value. Locks the lateral movement speed of the robot arm and waits for the following hem blade to catch up with the elastic force of the elastic member, and when the hem blade catches up to the predetermined amount with the robot arm, advances the robot arm again at the original lateral movement speed. It is characterized by making it.
[0019]
That is, when the hem blade is pressed against the bent portion of the workpiece while being vibrated and moved laterally by the robot arm, if the bent portion is sufficiently bent to a proper position, the bent portion is The load applied to the hem blade from the part is small, the hem blade moves laterally with a small amount of delay to the robot arm, and if the amount of bending of the bent part is insufficient, the load applied to the hem blade increases, The amount of delay of the hem blade from the arm increases. Therefore, when the amount of delay of the hem blade from the robot arm reaches a predetermined value, the lateral movement speed of the robot arm is reduced (including stoppage), and the hem blade waits for the hem blade to catch up. Since the bent portion is laterally moved while being processed to a regular bending amount, the bent portion can be processed with high quality at a uniform thickness.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment will be described with reference to FIGS. Note that the same or corresponding parts are denoted by the same reference symbols throughout all the drawings including FIGS. 5 and 6 to avoid duplicate description.
[0021]
1A and 1B are a partial side view and a front view, respectively, of a hemming device. A hem blade unit 7 and a vibration source 9 for vibrating the hem blade unit 7 are attached to the tip of a robot arm 3. Assuming that the length direction of the bent portion 2 of the workpiece 1 installed at the fixed position is the X-axis direction, and the vibration direction of the hem blade unit 7, which is a direction orthogonal to the X-axis direction, is the Z-axis direction, The hem blade unit 7 and the vibration source 9 are installed at the distal end of 3 via a Z-axis free mechanism 11 and an X-axis free mechanism 12.
[0022]
The Z-axis free mechanism 11 includes a Z-axis slide 13 that can be displaced in the Z-axis direction, and a Z-axis elastic member 14 that elastically holds the Z-axis slide 13 at the tip of the robot arm 3 so as to be displaceable in the Z-axis direction. The Z-axis elastic member 14 is, for example, a pair of urethane springs installed above and below the Z-axis slide 13, and holds the Z-axis slide 13 from above and below at a midpoint position in FIG. 1A with an elastic load of about 100 kg, for example. .
[0023]
The hem blade unit 7 and the vibration source 9 are installed on the front side of the Z-axis slide 13 via the X-axis free mechanism 12. The X-axis free mechanism 12 includes a rail 15 installed on the front surface of the Z-axis slide 13 in the X-axis direction, an X-axis slide 16 supported on the rail 15 so as to be displaceable in the X-axis direction, and an X-axis slide 16. It has an X-axis elastic member 17 that keeps elastic pressure in the axial direction. The X-axis elastic member 17 is, for example, a pair of compression springs that resiliently press the opposite ends of the X-axis slide 16, and is installed between both end surfaces of the X-axis slide 16 and brackets 18 projecting from both front ends of the Z-axis slide 13. . The X-axis elastic member 17 holds the X-axis slide 16 at the midpoint of FIG. 1B with an elastic load of, for example, about 30 kg from the left and right.
[0024]
The hem blade unit 7 is installed at the lower part of the front of the X-axis slide 16, and the vibration source 9 is installed at the upper part of the front. The hem blade unit 7 supports the tool 8 ′ extending in the Z-axis direction, the hem blade 8 fixed to the tip of the tool 8 ′, and the tool 8 ′ at the lower front part of the X-axis slide 16 so as to be able to vibrate in the Z-axis direction. The guide 21 is provided. The proximal end of the tool 8 ′ and the vibration source 9 are connected via a stroke adjustment bracket 22. The vibration source 9 applies a vibration of a specific frequency and amplitude to the tool 8 'in the Z-axis direction. Although an air cylinder is shown in FIG. 1, an electric motor, a hydraulic motor, or the like may be used. The weight 23 is attached to the hem blade unit 7 and the weight 24 is detachably attached to the vibration source 9 for reasons to be described later.
[0025]
The hemming of the workpiece 1 by the hemming device in FIG. 1 is performed in the manner shown in FIGS. 2A to 2H while maintaining the state in which the hem blade 8 is vibrated in the Z-axis direction by the vibration source 9. When the work 1 is an outer panel and an inner panel of an automobile door, the hem blade 8 is vibrated at a frequency of about 10 Hz and an amplitude of several mm to be pressed against the bent portion 2 of the work 1, and the hammer caused by the vibration energy of the hem blade 8. The bent portion 2 is sequentially bent by the ring effect and the pressing force.
[0026]
For example, when the vibration source 9 is an air cylinder, the air cylinder is turned on / off by a solenoid valve at a frequency of about 10 Hz, and the amplitude is set to about 2 mm by the stroke adjustment bracket 22, and as shown in FIG. Then, the hem blade 8 is pressed obliquely against a part of the upper end of the bent portion 2 bent in the Z-axis direction of the work 1 and is moved forward as shown in FIG. Then, the bent portion 2 is pushed and bent while being vibrated by the vibrating hem blade 8, and as shown in FIG. 2 (C), when the hem blade 8 advances by a predetermined amount and preheming is performed, The blade 8 moves laterally in the X-axis direction, which is the length direction of the bent portion 2, while vibrating, and prehem processing is performed over the entire length of the bent portion 2.
[0027]
When the hem blade 8 makes a full turn around the bent part 2 and completes the preheming of the entire length of the bent part 2, as shown in FIG. 2 (D), the hem blade 8 is prehemed. Then, as shown in FIG. 2 (E), it is moved right above the to-be-folded portion 2 and is lowered while vibrating as it is to press the pre-hem-formed to-be-folded portion 2 to form a book. Hemming is started. The main hemming is performed in the process of FIGS. 2F and 2G. When the main hemming of a part of the bent portion 2 is completed, the hem blade 8 oscillates in the X-axis direction while vibrating. The main hemming process is performed by moving the entire length of the bent portion 2. When the hem processing is completed, the hem blade 8 separates from the bent part 2 as shown in FIG. The procedure of hemming by moving the hem blade 8 in the X-axis direction will be described later with reference to FIGS.
[0028]
The hemming of the bent portion 2 by the vibrating hem blade 8 is performed reliably and with low energy by the hammering effect of the vibrating hem blade 8 bending while bending the bent portion 2. Therefore, it is not necessary to press the hem blade 8 on the bent portion 2 with a high pressing force by the robot arm 3, and it is possible to reduce the equipment cost by applying a small load-bearing robot to the robot arm 3. . Further, since the hem blade 8 may be pressed by the robot arm 3 against the bent portion 2 with a small pressing force, the bending of the robot arm 3 at the time of the hemming process hardly occurs, and the teaching performed before the hemming process is performed by the robot. This can be performed easily and quickly without considering the bending of the arm 3. Actually, high-precision machining is possible even if the teaching is performed only at the skipped points of the bent portion.
[0029]
When the vibrating hem blade 8 is pressed against the bent portion 2 of the work 1, the vibration energy is transmitted to the robot arm 3 via the X-axis free mechanism 12 and the Z-axis free mechanism 11. Most of the vibration energy is absorbed by the elastic member 14 of the Z-axis free mechanism 11, and the vibration of the robot arm 3 is suppressed. Furthermore, the vibration of the hem blade 8 is accompanied by the vibration of the hem blade unit 7 and the vibration source 9, and the vibration of the respective components may cause the robot arm 3 to resonate and suffer mechanical damage. By adjusting the weight of the weight 23 of the hem blade unit 7 and the weight 24 of the vibration source 9, the weight can be suppressed without any problem. For example, when the hem blade 8 is vibrated at a frequency of 10 Hz and the amplitude is 2 mm, the weight 23 of the hem blade unit 7 is adjusted to 15 kg and the weight 24 of the vibration source 9 is adjusted to 45 kg. The robot arm 3 hardly resonates due to the vibration of the hem blade 8. By executing such a resonance suppression measure by adjusting the weight balance, it becomes possible to set an appropriate vibration frequency of the hem blade 8 in a wider band.
[0030]
Next, the operation of hemming in the X-axis direction of the bent portion 2 by the hem blade 8 will be described with reference to FIG. After bending the hem blade 8 vibrated by the robot arm 3 to a regular angle while pressing the hem blade 8 against a part of the bent portion 2, the hem blade 8 is laterally moved in the X-axis direction along the bent portion 2. When the bent portion 2 is sequentially bent to a regular angle, a load is applied to the hem blade 8 in the anti-X-axis direction due to contact resistance with the bent portion 2. Here, the hem blade 8 is attached to the robot arm 3 via the X-axis free mechanism 12 so as to be displaceable in the X-axis direction and the anti-X-axis direction. The blade 8 can be displaced in the anti-X-axis direction, and by utilizing this, the hem blade 8 is laterally moved with respect to the robot arm 3 as shown in FIGS.
[0031]
First, as shown in FIG. 3 (A), when the hem blade 8 and the centers S ₁ and S ₂ of the robot arm 3 coincide with each other, the hem blade 8 is laterally moved in the X-axis direction by the robot arm 3 to be bent. The part 2 is hemmed in order. In this processing, the lateral movement of the hem blade 8 in the X-axis direction is gradually delayed from the robot arm 3 due to the load applied to the hem blade 8 in the anti-X-axis direction. Figure 3 when the center S ₂ of heme blade 8 from the center S ₁ of the robot arm 3 as shown in (B) is delayed by a predetermined distance L, which is detected by an optical sensor (not shown) such as a robot arm 3 Is slowed, for example, stopped. Then, only the hem blade 8 continues the lateral movement in the X-axis direction due to the elastic force (about 30 kg) in the X-axis direction by the elastic member 17 of the X-axis free mechanism 12, and as shown in FIG. When the center S ₂ approaches the center S ₁ of the stopped robot arm 3 and the two centers S ₁ and S ₂ match as shown in FIG. 3D, the robot arm 3 is again laterally moved at the original speed. Let While the robot arm 3 stops and the hem blade 8 catches up, the hem blade 8 bends the bent portion 2 sequentially in the X-axis direction while vibrating. The above-described intermittent lateral movement and stop of the robot arm 3 are repeated, and hemming is performed by the hem blade 8 over the entire length of the bent portion 2.
[0032]
As shown in FIG. 3, in the case of the hemming process performed by repeating the operation of delaying and catching up the hem blade 8 with respect to the robot arm 3 moving laterally, a portion directly processed by the hem blade 8 of the bent portion 2 to be processed. It is possible to perform the processing continuously while checking the processing precision of each place one by one, and it becomes easy to make the processing precision uniform and high precision. In fact, when the bent portion 2 is processed in the manner shown in FIG. 3, uniform control of the vibration energy applied to each portion of the bent portion 2 for processing becomes easy, and the total length of the bent portion 2 is reduced. Eventually, it becomes easy to make the thickness (corresponding to the thickness d in FIG. 3D) over the entire length when this hemming is performed.
[0033]
When the hem blade 8 is delayed from the robot arm 3 by a predetermined distance L as shown in FIG. 3B, the robot arm 3 is stopped, but the lateral movement speed is delayed to wait for the hem blade 8 to catch up. Is also good. Further, when the delay distance L of the hem blade 8 becomes too large, a countermeasure may be taken as occurrence of an abnormality.
[0034]
Next, the shape of the hem blade 8 and its usage will be described with reference to FIG. 4. The hem blade 8 presses and bends the bent portion 2 of the work 1 from the center to both ends from the center. To a curved surface having a smaller radius of curvature. Working surface central portion curved n ₁ radius of curvature maximum of N corresponds to the outer peripheral surface of the roller of largest diameter used in the roller hemming apparatus, substantially in FIG target bending process portion 2 shown in (A) The curvature is set so as to be suitable for the hemming of the linear portion 2a. Further, both end portions curved n ₂ curvature radius smallest of the processing surface N is roller corresponds to the outer peripheral surface of the minimum diameter of the roller used for hemming apparatus, FIG. 4 (A) to be folded shown in music processing unit 2 Is set so as to be suitable for hemming of the curved portion 2b.
[0035]
When processing the generally straight portion 2a of the bending process portion 2, 4 against substantially vertically heme blade 8 as shown in (B) in a substantially linear portion 2a, mainly the central portion curved n ₁ of the working surface N If the substantially straight portion 2a is hemmed, proper processing can be performed. Also, if when it comes to hemming to be bending process portion 2 of the curved portion 2b in the central portion curved n ₁ of the working surface N, a large central portion curved n ₁ radius of curvature or protruding portion from the curved portion 2b And proper processing may be difficult.
[0036]
Therefore, in the present invention, when the hem blade 8 moves to the curved portion 2b, the hem blade 8 is inclined in the X-axis direction as shown in FIG. the curved portion 2b so as to hemming in parts curved n _2. The inclination of the hem blade 8 is automatically performed by using a reaction force ((1)) in the direction opposite to the X-axis which the hem blade 8 receives from the work 1. That is, when the hem blade 8 reaches the curved portion 2b, the reaction force (1) acting on the hem blade 8 from the work 1 increases more than before, but at this time, the hem blade 8 Since the hem blade 8 is supported so as to be elastically displaceable in the axial direction, the hem blade 8 is inclined as shown in the figure against the elastic force of the X-axis elastic member 17. At this time, the magnitude of the reaction force in the counter X-axis direction that the hem blade 8 receives is determined according to the shape of the curved portion of the work 1, so that the hem blade 8 is set to an appropriate angle in accordance with the curvature of the curved portion 2 b. can be inclined, thereby, the end curved surface n ₂ of the processing surface n is properly in contact with the curved portion 2b, it is possible to properly hemmed curved portion 2b. Such an effect is achieved by selectively using the hem blade 8 with the processing surface N having the different radius of curvature of the hem blade 8 as described above, by using either the substantially linear portion 2a or the curved portion 2b of the bent portion 2 of the work 1. However, hemming can be favorably performed with the same hem blade 8. Therefore, the labor for preparing and replacing a variety of hem blades can be omitted, the efficiency of hemming work can be easily improved, and the number of components including the hem blade can be reduced, thereby reducing equipment costs.
[0041]
【The invention's effect】
According to the hemming method of the present invention, when the hemming blade is laterally moved by the robot arm to hemming the bent portion of the workpiece in order, the hemming blade repeats the operation of catching up with the robot arm a little later to be folded. Since hemming is performed on the curved part in order, by detecting the amount of delay of the hem blade with respect to the robot arm, processing can be performed while observing the processing accuracy of the bent part currently processed by the hem blade. It is possible to proceed, and strict teaching is not required, and the hemming process can be made uniform and highly accurate.
[Brief description of the drawings]
FIG. 1 (A) is a side view showing an embodiment of the hemming device of the present invention, and FIG. 1 (B) is a front view thereof.
2 (A) to 2 (H) are cross-sectional views in each processing step showing a hemming processing operation by the hemming device of FIG. 1;
3 (A) to 3 (D) are front views in respective processing steps showing an outline of a hemming processing operation at the time of lateral movement of a hem blade by the hemming device of FIG. 1;
4 (A) is a plan view of a bent portion of a work, and FIGS. 4 (B) and 4 (C) show a state of hemming of the hem blade at two locations in FIG. 4 (A). It is a front view.
FIG. 5 is a side view of a conventional roller-type hemming device.
6 (A) to 6 (D) are cross-sectional views in each processing step showing a hemming processing operation by the hemming device of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Work 2 Bending part 3 Robot arm 8 Hem blade N Working surface 9 Vibration source 14 Elastic member 17 Elastic member 23 Weight 24 Weight

Claims (1)

A hem blade is attached to the robot arm that moves laterally along the continuous bent part of the work via a vibration source, and this hem blade is elastically elasticized in the lateral direction along the bent part of the work with an elastic member. Displaceably supported,
Pressing and bending the continuous bent part of the work with the hem blade in the vibration direction while applying vibration, and moving the hem blade laterally along the bent part as it is, continuously bending the bent part Bending,
When the hem blade is moved laterally by the robot arm, the lateral movement speed of the hem blade is made slower than that of the robot arm due to the load caused by the contact resistance between the hem blade and the bent portion, and the advance occurs when the amount of delay becomes a predetermined value. Suppress the lateral movement speed of the robot arm and wait for the following hem blade to catch up with the elastic force of the elastic member, and when the hem blade catches up to the robot arm to a predetermined amount, advance the robot arm again at the original lateral movement speed. A hemming method, characterized in that:

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