JPS6222264Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is an apparatus for hot bending metal strips, which eliminates the guide rollers that are provided in the vicinity of the bending position in conventional apparatuses, and which enables accurate and smooth bending. This invention relates to a hot bending device that enables processing.

Conventionally, a strip to be bent is passed through a narrow annular heating device such as a high-frequency inductor, and the front end of the strip is gripped by a rotatable bending arm having an effective length depending on the bending radius. A hot bending method has been used in which the strip is propelled to continuously generate a bending moment in the heated portion of the strip to sequentially cause plastic deformation.

This method is an excellent method, but a guide roller is installed close to the heating device to support the reaction force that constitutes the bending moment, guide the strip, and keep the bending radius constant. It was essential to do so.

However, as the bending progresses, in addition to the bending moment required for bending, there is often an unsteady state in the support due to distortion of the strip, heating conditions, mechanical errors, misalignment, etc. When a reaction force is generated and the reaction force increases, it may distort the bending mechanism, disturb the bending radius, dent the strip, or cause rebound deformation when the strain energy is released after bending. caused an accident that damaged the clamp or destroyed the bending device itself.
Various improvements were made.

For example, the method disclosed in Japanese Patent Application Laid-Open No. 46-2804 makes the distance between the center of rotation of the bending arm and the heating area and therefore the guide roller variable. By increasing the degree of freedom in this way, the unsteady reaction force generated in the relevant part can be reduced to virtually zero, making smooth operation possible. Since the rollers themselves remained in place, the following notable drawbacks remained.

(1) When the strip is a pipe, when the rear end of the pipe approaches the guide roller at the final stage of bending, the lever that creates the bending moment becomes shorter, and the reaction force of the guide roller increases in inverse proportion to this. It may become large and cause flattening or denting of the pipe.

(2) In addition, an extra amount of pushing distance for the strip material is required for the guide rollers, etc.

(3) Impurities may enter the heating section via the guide roller and cause thermal brittle cracks.

On the other hand, if the guide rollers are removed, the unsupported section of the strip will naturally become larger, and the amount of elastic deformation will increase significantly.
Since the relative relationship between the strip and the heating device changes greatly,
The strip to be bent tries to be bent in a direction perpendicular to the line connecting the centers of rotation of the bending arms at the heated part, forcing the strip to undergo unreasonable deformation, while also applying undue force to the bending device itself. give.
Additionally, the distribution of the bending moment itself would change as the strip deformed, but the technology at the time was unable to find a way to overcome this, so it was impossible to eliminate the guide rollers. It was hot.

Therefore, the first thing we need to do is to develop technology that ensures that even if bending conditions fluctuate widely, the necessary operations are carried out under control, and that the bending radius is accurately controlled to avoid unreasonable bending. I realized that the first thing to do was to figure it out.

For this reason, the method disclosed in Japanese Patent Application Laid-Open No. 123072/1980 attempts to control the bending radius based on the following equation.

Bending radius = ds/dθ = ds/dt (beam feed rate)/dθ/dt (rotational angular velocity of clamp section)...(1) This method not only maintains the bending radius accurately, but also prevents errors in the bending radius. However, since the guide roller is left in place, the defects caused by this remain unresolved.

Next, in the method disclosed in JP-A No. 51-140862, the heating device is advanced relative to the strip by a minute amount in advance to compensate for the effects of elastic strain etc. occurring on the strip. Since we were able to maintain a good relative relationship between the heating device and the strip on average throughout the entire bending operation, even if the heating device was not moved during the bending operation, the bending operation could generally be performed properly and the strain energy was transferred to the bent tube. It is possible to perform rational and accurate bending without excessively accumulating and therefore preventing the bending from rebounding and distorting the shape after the bending is completed. In addition, the above invention enables good bending operation by selecting the heated part, and is easy to control, but it does not eliminate the guide roller, so this problem remains built-in. It was hot.

On the other hand, the method disclosed in JP-A-51-12369 is to provide an arm at the rear end of the strip with approximately the same length as the bending arm at the front end, and to pull this arm and the bending arm mutually. Through bending work,
A substantially constant bending moment can be applied to the strip. This mechanism did not have a guide roller near the bending position, had a long unsupported section, and had considerable elastic strain on the strip. This effect can be compensated for by relative movement along the bending arm, and the strip can be propelled substantially perpendicular to the line connecting the center of rotation of the bending arm and the heating section, thereby ensuring a comfortable and accurate We were able to maintain a consistent bending radius.

In this invention, by providing an arm at the rear, the bending radius can be controlled relatively easily by omitting the guide roller, and the structure is excellent in terms of mechanics. However, it requires two arms at the front and rear, and requires precision There were problems such as the need for a mechanism.

To summarize the research results of JP-A-51-12369 for each of the above proposals, if the guide roller is omitted,
Naturally, as the support section becomes longer, the elastic strain of the strip increases, and as the bending progresses, it is unavoidable that the relative positional relationship between the strip and the heating device changes greatly, but even in such a case, This can be said to suggest that it is possible to perform bending while maintaining a sufficiently accurate bending radius, going beyond the conventional technical knowledge of hot bending (which inevitably affects the bending radius).

The present invention was developed based on the above-mentioned results, with the purpose of providing a single bending arm type bending device that can easily perform accurate bending even when the guide roller is omitted. The structure consists of an annular heating device such as a high-frequency inductor that can heat a metal strip to be bent at high temperature in a narrow width, and the strip that is freely rotatable around a fixed point and inserted through the heating device. a bending arm capable of fixing a clamp that firmly grips the front end of the material to be bent at a position of an arm length corresponding to the bending radius; and a propulsion device that propels the strip along a guide surface in the direction of the heating device. In a hot bending device that continuously bends the gripped strip by heating and propelling it, a line connecting the center of rotation of the bending arm and the center of the heating position during the bending operation. , a device for positioning the heating device at a position perpendicular to the axis of the strip or a truncated line thereof at that position, or a device for positioning the heating device in the immediate vicinity; and a clamp for firmly gripping the rear end of the strip or its vicinity. ,
Where the clamp is firmly fixed and has a length that allows it to be propelled in contact with the guide surface and to be able to withstand the couple and shearing force that occur during bending work and be smoothly propelled in a certain direction. It is characterized by comprising a clamp base.

Next, an embodiment of the present invention will be described with reference to the drawings.

In Figs. 1 and 2, 1 is a metal strip to be bent, 1a is an already bent part of the strip 1, and 2 is rotatable around a fixed shaft 3. A bending arm 5 has a length corresponding to the bending radius of the metal strip 1 to be bent and is equipped with a clamp 4 for gripping and fixing the tip or an appropriate point in the middle of the strip 1; Regarding the axis of material 1,
Here, two
two guide frames 6, 6a guide the strip 1 toward a heating device to be described later, and two guide surfaces arranged perpendicular to the bending plane; 7 refers to both the guide surfaces 6,
6a, and is movable only in the direction of movement, and its effective length is necessary to support the couple and shear force acting on the rear end of the strip 1. In the illustrated example, the diameter of the strip is approximately three times the outer diameter of the strip.

8 is a clamp fixed on the clamp base 7 and grips and fixes the vicinity of the rear end of the portion of the metal strip 1 to be bent; 9 is an annular heating device made of a high-frequency inductor; The position where the line connecting one point on the strip 1 is perpendicular to the axis of the strip 1 or its cutting line (hereinafter referred to as the "appropriate position")
) or in the immediate vicinity thereof, and is equipped with a moving device necessary for moving the heating device and a device for cooling the heated portion immediately after heating.

In the hot bending apparatus according to the present invention configured as described above, the metal strip 1 is passed through the heating device 9, and the front end of the part to be bent is clamped with the clamp 4.
In addition, the vicinity of the rear ends of the strips 1 are gripped and fixed by clamps 8, respectively, and a propulsion device (not shown) using hydraulic pressure, screws, chains, etc. is used to substantially control the thrust force P of the strips 1. While propelling the clamp base 7 so as to act on the axis of the material 1, the heating device 9 heats the strip 1 in a narrow width at a high temperature. The strip material 1 is bent by continuously plastically deforming it in the heated region while applying the following properties.

Here, the reason why the length of the clamp base 7 is set to be about three times or more the outer diameter of the strip material 1 is that if the length of the clamp base 7 is made longer, it will act on the guide surfaces 6, 6a during bending. This is because the reaction force of the bending moment of the metal strip 1 becomes smaller.

What should be noted in the above device of the present invention is that the distance between the guide surfaces 6 and 6a is adjusted to the clamp base 7.
The width of the clamp base 7 is made to be approximately the same as the width of the surfaces 6, 6a, so that the clamp base 7 is closely fitted into the surfaces 6, 6a, so that it will not be distorted even if a strong moment is applied to the clamp base 7 during bending, and The clamp base 7 is formed so that it can move forward smoothly while receiving a reaction force. Therefore, in the device of the present invention, the length of the clamp base 7 is made as long as possible within a practically allowable range to prevent the base 7 from becoming twisted, and at the same time, to prevent the clamp base 7 from becoming twisted.
In order to improve the sliding on the guide surfaces 6, 6a and prevent wear, the guide surfaces 6, 6a are hardened, and the sliding surface of the clamp base 7 is made of gun metal, oil-impregnated alloy, or the second Roller 71 as shown
It is preferable to use

In the above device, when the thrust for bending is applied, the strip 1 is elastically deformed, but since the rear part is fixed in a constant direction by the clamp 8, the axis hardly changes and the strip 1 deforms slightly. The arm moves forward, and the distance from the arm rotation center 3 remains substantially constant. On the other hand, since the proper position of the heating device moves slightly, at the beginning of bending, the heating device 9 is moved to the corresponding position and heating is started to perform bending. During bending, the proper position changes slightly as the elastic deformation of the strip 1 changes, so if necessary, the heating device 9 can be positioned at the proper position by program control or the like.
While paying attention to the distance between the heating part of the strip 1 and the arm rotation axis 3, which corresponds to the bending radius, if the distance changes, perform the necessary operations based on the principle shown in equation (1). Continue bending while maintaining the bend radius accurately.

Therefore, when performing bending where the bending angle exceeds 90 degrees and extends to 180 degrees, the position of the heating device 9 is moved forward by a considerable amount to reduce the deviation in the bending radius caused by the deflection of the bent portion 1a. In some cases, it may be possible to prevent

3 and 4 are a front view (longitudinal side of the metal strip) of an example of a hot bending device in which the two guide surfaces 6, 6a are constructed using a single I-beam type member, and FIG. This is a cross section taken along the line A-A in the figure, and as shown in FIG.
The front and back surfaces of the part that corresponds to the blade on one side of the member 62 serve as the guide surfaces 6, 6a of the metal strip 1, and the cross section of the sliding surface of the clamp base 7 corresponds to the member 6.
The clamp base 7 is formed to match the cross-sectional shape of the portion having the guide surfaces 6, 6a of
A clamp 8 integrated with the clamp 8 is opened and closed by a hinge 81 shown in dotted lines, and a hydraulic cylinder 74 provided at the bottom of the clamp base 7 opens and closes the clamp 8. .

The clamp base 7 shown in FIGS. 3 and 4 has a considerable self-weight and the weight of the metal strip 1 is added to it, so in order to support and guide it, guide surfaces 6 and 6a are provided on the guide frame 5. Parallel rails 61 are provided, and rollers 75 are provided on the lower surface of the clamp base 7, and the rollers 75 are placed on the rails 61 and supported by the guide frame 5. Further, as a propulsion device for applying thrust P to the clamp base 7, two hydraulic cylinders 10 are arranged vertically symmetrically with respect to the axis of the strip 1, and their piston rods 11 are connected to the back surface of the clamp base 7. When bending the strip 1, the thrust force P generated by the operation of the hydraulic cylinder 10 is configured to substantially act on the axis of the strip 1.

The arrangement of the clamp 4, bending arm 2, shaft 3, etc. in this device may be the same as in the device shown in the figure; (not shown) can reduce the weight of the device.

As described above, the present invention eliminates all the disadvantages of using a conventional guide roller as an essential component in a device for hot bending metal strips using a single bending arm. This method is extremely useful industrially because it does not create undue force on the device and the strip to be bent, and the device can be simplified and lightened, and accurate bending is possible.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a hot bending device in which the guide surfaces of the clamp base are formed on the inside and outside of the bending metal strip, Fig. 2 is a plan view of the other side of the clamp base, and Fig. 3 is a plan view of the bending of the metal strip. FIG. 4 is a front view of a device in which two guide surfaces are formed on the outside. FIG. 4 is a sectional view taken along the line A--A in FIG. 3. DESCRIPTION OF SYMBOLS 1...Metal strip, 1a...Bent part of metal strip, 2...Bending arm, 3...Shaft, 4...Clamp, 5...Guiding frame, 6, 6a...Guiding surface, 7
... Clamp base, 71 ... Roller, 8 ... Clamp, 9 ... Heating device, 10 ... Hydraulic cylinder.

Claims (1)

[Scope of utility model registration request] An annular heating device such as a high-frequency inductor that can heat a metal strip to be bent at high temperature in a narrow width, and a front end of the strip to be bent that is freely rotatable around a fixed point and inserted through the heating device. a bending arm capable of fixing a clamp that firmly grips the part at a position of an arm length corresponding to the bending radius; and a propulsion device that propels the strip along the guide surface in the direction of the heating device. In a hot bending device that continuously bends the strip by heating and propelling it, during the bending operation, the line connecting the center of rotation of the bending arm and the center of the heating position is A device for positioning the heating device at a position perpendicular to the axis of the strip or a tangential line thereof, or a clamp for firmly gripping the rear end of the strip or its vicinity; A clamp base that is firmly fixed and has a length that allows it to be propelled in contact with the guide surface, and to be able to withstand the couple and shear forces that occur during bending work and smoothly propel it in a certain direction. A hot bending device characterized by comprising: