JP3551714B2 - Correction method of irregular cross section - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for correcting a deformed cross section, and more particularly to a method for correcting a deformed cross section used as a lead frame material for a power transistor.
[0002]
[Prior art]
In a strip material used for a lead frame material for a semiconductor, a straightening process is often included in a manufacturing process in order to improve a shape and make internal stress uniform.
[0003]
As a general method of straightening the strip, as shown in FIG. 3, the strip 14 is clamped by the clamp portions 11a and 11b provided with a predetermined interval, and the longitudinal direction of the strip 14 (in FIG. There is a method of pulling in the left-right direction). When straightening the continuous strip 14 by this method, the strip 14 is pulled in the longitudinal direction, then the strip 14 is fed in a fixed amount in one direction, then clamped again, and the tension is repeated.
[0004]
As shown in FIG. 4, a method of arranging the small-diameter rolls 12 in a staggered manner, inserting the strip 14 between the small-diameter rolls 12, and repeatedly bending the strip 14 to perform straightening, FIG. As shown in (1), there is a method in which a strip material 14 is meanderingly wound around a bridging roll 13 composed of a plurality of roll groups, and a straightening is performed by applying tension to the strip material 14, or a method in which both are combined.
[0005]
FIG. 2 shows a cross-sectional view of the modified cross section. FIG. 2A is a cross-sectional view of the deformed cross-section before the correction is performed, and FIG. 2B is a cross-sectional view of the deformed cross-section where a local warp is caused by the correction.
[0006]
As shown in FIG. 2 (a), when a deformed cross section 4 having a convex portion 4a and thin plate portions 4b, 4b as shown in FIG. 2A is used, and this deformed cross section 4 is to be corrected, the method shown in FIGS. When the straightening is performed, bending stress is applied to the irregularly shaped cross-section strip 4 in which the convex portion 4a and the thin plate portions 4b, 4b have different curvatures, so that the thin plate portions 4b, 4b become convex portions as shown in FIG. Deformation that warps to the 4a side occurs.
[0007]
For this reason, as a method of correcting the deformed cross-section strip 4, a method of intermittently performing linear tension as shown in FIG. 2 is often used.
[0008]
[Problems to be solved by the invention]
However, in the method of intermittently performing the linear tension, the tension and the feeding of the irregularly shaped cross section 4 must be alternately repeated, and there is a problem that the processing efficiency is low.
[0009]
In order to improve the processing efficiency, a method of increasing the distance between the clamps holding the deformed cross-section strip 4 is considered. However, the deformed cross-section strip 4 before the correction shown in FIG. In the case where there is no distortion in the width direction (in the horizontal direction in the drawing), but in the case where there is distortion in the width direction (not shown), a local portion as shown in FIG. Warpage occurs. In the step subsequent to the step of correcting the irregularly shaped cross-section strip 4, press working or the like is performed, so that the local warpage hinders press working or the like.
[0010]
Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a method for correcting a deformed cross-section strip that is continuous and free from local deformation.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for correcting an irregularly shaped strip having a convex cross-sectional shape, wherein at least two endless track belt-type drawers are linearly provided at intervals. A method of inserting a continuous deformed cross-section strip into each drawing device and applying a tensile force for correction by giving a speed difference to a feed speed of each drawing device, wherein the deformed cross section of the drawing device is The method is characterized in that the endless track strip on the side of the convex portion of the strip is softer than the endless track strip on the side of the irregularly shaped strip plane .
[0012]
According to a second aspect of the present invention, the drawing device on the downstream side in the traveling direction of the irregularly shaped cross section is fixed to a base via a load cell, and each feed speed of the drawing device is controlled based on a measured value of the load cell. A method for correcting a deformed cross-section strip according to item 1.
[0013]
According to a third aspect of the present invention, there is provided the method of correcting a deformed cross- section strip according to the second aspect, wherein the feed speed of each of the drawing devices is increased while keeping the tensile force at the time of correction constant based on the measured value of the load cell .
[0014]
According to the above configuration, in the method for correcting a deformed cross-sectional strip having a convex cross-sectional shape, at least two or more endless track type drawing devices are linearly provided at intervals and continuously connected to each drawing device. In order to insert the deformed cross section, and to apply a pulling force for correction by giving a speed difference to the feeding speed of each drawing device, a continuous, and deformed cross section without local deformation is applied. It is a correction method.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0016]
FIG. 1 is a schematic view of a straightening device for straightening a deformed cross-section strip according to the present invention.
[0017]
As shown in FIG. 1, the straightening device 10 includes a feeder 1 for supplying a deformed cross-section strip 4, a winding machine 3 for winding the deformed cross-section strip 4, and at least two units for performing tension correction. The above (two in the figure) endless track belt (commonly referred to as a caterpillar) type drawing device 2 is constituted.
[0018]
As shown in FIG. 2A, the irregularly shaped section 4 has a convex portion 4a and thin plate portions 4b, 4b.
[0019]
At least two or more endless track type drawers 2 (2a, 2b in the figure) are provided linearly with an interval, and each endless track type drawer 2 is provided with a drum 9a, 9b. An endless track strip 9c is stretched between the endless track strips 9c, and the upper and lower two endless track strips 5 are arranged in parallel in a plane, and a pair of drafts are disposed between the endless track strips 5 and 5 of each step. It is composed of devices 6 and 6. The rolling-down device 6 has a roll head 6a provided with a plurality (six in the figure) of small-diameter rolls 6b.
[0020]
Here, the gap between the endless track strips 5 of each step is about the thickness of the thin plate portion 4b of the deformed section strip 4, and the gap between the pair of pressing-down devices 6, 6 is the projection of the deformed section strip 4. It is about the thickness of the portion 4a. The drums 9a and 9b of the endless track zones 5 and 5 of each stage are connected by shafts (not shown), and the drum 9b (or 9a) of the upper endless track zone 5 and each of the lower endless tracks 5 and 5 are connected. The drum 9b (or 9a) of the belt 5 is configured to rotate in the opposite direction at the same rotation speed by a gear or the like (not shown).
[0021]
The endless track belt type drawing-out device 2b on the downstream side in the traveling direction (pass line direction) of the irregularly shaped section 4 is fixed on the base 8 fixed to the foundation (ground), the left end of which is fixed to the base 8, and the pass line It is slidably supported in the direction of the pass line via a load cell 7 for monitoring the tensile force in the direction. The endless track type extractor 2b, be to slidably supported in the pass line direction on base over scan 2, it takes the tensile load to the load cell 7, by extension, control of the tensile force is possible. The load cell 7 may have its right end fixed to the base 8 in order to monitor the compression force in the pass line direction.
[0022]
The space between the endless track type drawing devices 2a and 2b does not need to be large, and may be the minimum necessary space that does not cause inconvenience in maintenance.
[0023]
The endless track band member 9c is not particularly limited, and includes, for example, a rubber belt or a block-shaped member joined in a rosary.
[0024]
The material of the crawler belt material 9c is not particularly limited. For example, when a rubber belt is used as the crawler belt material 9c, if the rubber to be used is too soft, the rubber is deformed by pressure bonding, and It is desirable to use hard rubber as much as possible because local warpage occurs in the thin plate portions 4b, 4b, and it is particularly preferable to use a hard rubber of the endless track strip 9c of each of the endless track strips 5 in the upper stage (on the side of the convex section with the irregular cross section). However, it is preferable that the hardness is lower than the hardness of the endless track band member 9c of each endless track band 5 at the lower stage (side of the irregularly shaped cross section plane).
[0025]
Next, the method for correcting a deformed cross-section strip according to the present invention will be described.
[0026]
First, the deformed cross-section strip 4 supplied from the feeder 1 is inserted into the endless track type drawer 2a.
[0027]
Each of the thin plate portions 4b, 4b of the irregularly shaped cross-section strip 4 inserted into the endless track strip type drawing device 2a is inserted between the drums 9a, 9a of the opposing endless track strips 5, and each of the endless track strips 9c. Receive crimp.
[0028]
Next, the deformed cross-section strip 4 that has been pressed is held between the opposed drums 9b, 9b of each endless track belt 5 in a state where the convex section 4a of the cross-section strip 4 is held between the opposing pressing-down devices 6. , And are pressed again by the endless track strips 9c.
[0029]
The crimping force at this time varies depending on the cross-sectional area of the deformed cross-section strip 4, the width of the convex portion 4a, the material of the endless track strip 9c, and the like.
[0030]
Thereafter, the deformed cross-section strip 4 inserted through the endless track type drawer 2a is inserted into the endless track type drawer 2b, and is subjected to crimping in the same manner as in the endless track type drawer 2a.
[0031]
Here, there is a difference between the feed speeds of the endless track type drawing devices 2a and 2b, and the feeding speed of the endless track type drawing device 2b is higher. Assuming that the feed speed of the endless track type drawer 2a is Va and the feed speed of the endless track type drawer 2b is Vb, the irregularly shaped cross section 4 is located between the endless track type drawers 2a and 2b in the direction of the pass line. Side at the speed of Vb-Va, and the reaction force is pulled toward the upstream side in the pass line direction at the speed of Vb-Va. That is, the tensile force at the speed of Vb-Va in the longitudinal direction of the deformed cross-section line 4 is defined as a tensile force for correcting the deformed cross-section line 4.
[0032]
Thereafter, the irregularly shaped strip 4 inserted through the endless track type drawer 2b is wound up by the winder 3.
[0033]
Since the pressure-bonding force F is given by the formula of sectional area of deformed cross section × tensile force per unit area / (coefficient of friction × 2), for example, when a rubber belt is used as the endless track strip 9c, the rubber belt and the deformed cross section are used. When the friction coefficient between the deformed cross-section strips 4 is about 0.5, the cross-sectional area of the deformed cross-section strips 4 is 50 mm ² , and the tensile force per unit area is 30 kgf / mm ² , the crimping force F is It will be about 1,500 kgf.
[0034]
In other words, the crimping force F is determined by three parameters of the cross-sectional area of the deformed cross-section strip 4, the tensile force per unit area, and the friction coefficient.
[0035]
If the material of the modified cross-section strip 4 is changed, the surface quality of the modified cross-section strip 4 may be affected depending on the material of the endless track strip 9c. It is conceivable to insert paper or flannel between them. In this case, since the coefficient of friction between the endless track strip 9c and the deformed section strip 4 becomes small, a larger pressing force F is required.
[0036]
The pulling force per unit area depends on the pulling force in the direction of the pass line of the profiled cross section 4 between the endless track type drawing devices 2a and 2b. Here, the load cell 7 provided below the endless track type drawer 2b measures the pulling speed in the pass line direction of the irregularly shaped strip 4 between the endless track type drawers 2a and 2b. From this measured value, the tensile force at the time of correction is calculated.
[0037]
From this, it is possible to increase or decrease the pulling force by appropriately controlling the feed speed of each of the endless track type drawing devices 2a and 2b. Conversely, by continuously increasing the feed speed of each of the endless track type drawing devices 2a and 2b while keeping the tension force at the time of correction using the load cell 7 constant, continuous correction with a constant tension force is always performed. It can be done faster.
[0038]
Further, in the endless track type drawers 2a and 2b, the hardness of the endless track strip 9c of each of the upper endless track strips 5 is made softer than the hardness of the endless track strip 9c of each of the lower endless track strips 5. By performing the pressure bonding, the deformation of the endless track strip 9c of each of the upper endless track strips 5 is increased, and the deformation of the endless track strip 9c of each of the lower endless track strips 5 is increased. Local bending of the thin plate portions 4b, 4b can be further prevented. As a result, the workability in the pressing process, etc., which is the next process of the straightening process, is improved.
[0039]
FIG. 1 shows a case where the deformed section 4 is corrected by using two endless track type drawing devices 2a and 2b. When the section of the section 4 is large, it is necessary to obtain a larger tensile force. In addition, it is necessary to increase the crimping force.
[0040]
Here, when performing correction using two endless track belt type drawing devices, it is necessary to increase the length of the endless track belt per unit, which causes problems in terms of maintenance, There is a possibility that the surface pressure of the deformed cross section increases, the endless track band is deformed, and local thinning of the thin plate section of the deformed cross section occurs.
[0041]
Therefore, by using three or more endless track type drawing devices, the crimping force per one endless track type drawing device can be reduced, and the length per one endless track type belt device is also reduced. Thus, the endless track belt can be driven at a higher speed, and the correction can be performed at a higher speed than in the case where the correction is performed using two endless track type drawing devices.
[0042]
【The invention's effect】
In short, according to the present invention, the following excellent effects are exhibited.
[0043]
(1) Since the deformed section is corrected using at least two or more endless track type drawing devices, the deformed section can be corrected continuously.
[0044]
(2) Even a deformed cross section having a distortion in the width direction can be corrected, and a good deformed cross section without local deformation can be obtained by this correction.
[Brief description of the drawings]
FIG. 1 is a schematic view of a straightening device for straightening a deformed cross-section strip according to the present invention.
FIG. 2 is a cross-sectional view of a profiled strip.
FIG. 3 is a view showing a conventional method for correcting a strip material and a deformed cross-section strip.
FIG. 4 is a view showing a conventional method of straightening a strip.
FIG. 5 is a view showing a conventional method of straightening a strip.
[Explanation of symbols]
2 Endless track type drawer (drawer)
4 Irregular cross section 4a Convex part 9a Endless track strip

Claims (3)

In the method for correcting a deformed cross-section having a convex cross-sectional shape, at least two endless track belt-type drawers are linearly provided with a space therebetween, and the continuous deformed cross-section is inserted through each of the drawers. In addition, a method of imparting a tensile force for correction by giving a speed difference to the feed speed of each drawing device, wherein the hardness of the endless track band material on the convex side of the irregular cross section of the drawing device. A method for correcting a deformed cross-section strip, which is softer than the endless track strip material on the side of the deformed cross-section strip plane . The draw-out device on the downstream side in the traveling direction of the modified cross-section strip is fixed to a base via a load cell, and each feed speed of the draw-out device is controlled based on a measured value of the load cell . Straightening method. 3. The method for correcting a deformed cross section according to claim 2, wherein the feed speed of each of the drawing devices is increased while maintaining a constant tensile force at the time of correction based on the measured value of the load cell .

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