JPS63281716A - Cutting method for sheet metal - Google Patents

Abstract

PURPOSE:To fatigue a prescribed cutting part on a work and cut a blank without making any burr by moving a vibratory die holding a prescribed blanking part on the work between both sides and vibrating the prescribed blanking part by the reciprocating motion of the vibratory die. CONSTITUTION:The work 2 is held and fixed by a chuck 1. The vibratory dies 3, 4 are moved along the direction at right angles with the surface of the work 2 and a pressure greater than the yield point load of the work 2 and smaller than the breaking load is given to the prescribed cutting part 26 between the chuck 1 and the vibratory dies 3, 4. The vibratory dies 3, 4 holding the prescribed blanking part 2a are reciprocated at the same time by vibratory means 5, 6 to vibrate the prescribed blanking part 2a along the direction at right angles with the surface of the work 2. Backward bends are given alternately and repeatedly by this vibration to the prescribed cutting part 26 to cause fatigue failure and cut the prescribed blanking part 2a out of the work 2.

Description

Detailed Description of the Invention [Objective of the Invention] [Industrial Application Field] The present invention is a method for cutting blanks such as various metal panels for vehicle body construction from sheet metal workpieces to which a coating film is applied after cutting. The present invention relates to a method for cutting sheet metal, which is carried out when obtaining a sheet metal.

(Prior Art) The various metal panels that make up the body of an automobile are obtained by cutting sheet metal workpieces using a press machine.The cut metal panels, or blanks, are then treated with corrosion-resistant A coating film is applied to obtain the desired effect.

Conventionally, cutting of the blank is carried out by applying a shearing force greater than the cutting strength of the workpiece to the workpiece using upper and lower cutting dies provided in the press machine.

A cross section of the blank A obtained by such a conventional cutting method is shown in FIG.

In this figure, the sagging part indicated by the symbol B is formed by the lowering of the upper cutting die that moves vertically, the range indicated by C is the sheared surface area cut by the shearing action of the upper and lower cutting die, and the range indicated by D is the upper and lower cutting. A broken region is cut by the breaking action of the mold, E is a hole formed by continuing to the lower end of the broken region and extending downward, and F is a contact scratch on the lower cutting mold.

Further, G in FIG. 7 is a coating film applied to the blank A, which is baked at a temperature of about 110° when the blank A is various panels for constructing the body of an automobile.

(Problem to be solved by the invention) As mentioned above, the blank A is removed from the workpiece by the perforation action.
According to the conventional method of cutting, there was a problem in that burrs E were inevitably generated on the cut surface as shown in FIG.

If such a burr E is present on the blank A, the coating IG tends to adhere to this portion, and the thickness of the adhesion becomes extremely small, or it becomes as if there is no adhesion at all. especially,
When the coating IIG is baked, the coating film G on the Paris 5 portion is further removed.

For this reason, the corrosion resistance in the burr E part is significantly inferior, so rust easily occurs in the burr E part and progresses in a short period of time. There was a high risk of injury when handling the product by hand.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sheet metal cutting method that can cut a blank without producing burrs.

[Structure of the Invention] (Means for Solving the Problems) Therefore, in order to achieve the above object, the present invention provides a vibration method that clamps and fixes the workpiece with a chuck, and then clamps the blank portion of the workpiece from both sides. The mold is moved along a direction perpendicular to the surface of the workpiece, and a pressure greater than or equal to the yield point load and less than the breakage point load is applied to the workpiece, and from this state, the above-mentioned vibrations sandwiching the blank portion are applied. By simultaneously reciprocating the mold and photographing the blank area along a direction perpendicular to the surface of the workpiece,
The method is characterized by cutting the blank.

[Effect]

According to the method of the present invention, first, a workpiece is clamped and fixed to a chuck. Next, a vibrating mold that clamps the blank portion of the workpiece from both sides is moved along a direction perpendicular to the surface of the workpiece to apply pressure to the workpiece that is greater than its yield point load and less than its breaking point load. . From this state, the vibrating molds sandwiching the blank portion are simultaneously reciprocated. In addition, the time when the vibration mold pinches the blank area is as follows:
It may be done at the time when the above pressure is applied to the workpiece, or it may be done afterwards. Due to the vibration-type reciprocating motion as described above, the blank portion is vibrated along a direction perpendicular to the surface of the workpiece. Due to this vibration, the part of the workpiece to be cut between the chuck and the vibrating die is alternately bent in opposite directions and plastically deformed as the vibrating die repeats the reciprocating movement. A slight inward groove is formed, and the metal fatigue of the section to be cut progresses as the blank section vibrates, so that the section to be cut eventually suffers fatigue failure.

This allows the blank to be cut from the workpiece, and
The formation of the grooves prevents burrs from forming on the cut surface of the blank.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 5.

In FIG. 1 showing the cutting device 18IS, 1 is a chuck, which is formed of, for example, a fixed lower die 1a and an upper die 1b that is vertically movable. This chuck 1 has upper and lower molds 1a.
, 1b, a workpiece 2, which is obtained as a blank of, for example, various metal panels constituting the body of an automobile, is clamped and fixed. In addition, 3.4 in FIG. 1 is provided, for example, in an upper and lower pair, and a blank portion 2a of the workpiece 2 is provided.
It is a vibrating type that clamps the blank from both sides, and the tip surfaces of these match the shape of the blank. And each shooting type 3゜4
are movable up and down, and are connected to excitation means 5 and 6 such as hydraulic vibrators, respectively, and are simultaneously reciprocated along the direction perpendicular to the surface of the workpiece 2 by the excitation means 5 and 6. It is set up like this.

Next, a case will be described in which a cutting device having such a configuration is used to cut a blank from a workpiece 2 that is intermittently fed into the cutting device at a predetermined pitch.

First, the work 2 is placed on the lower mold 1a of the chuck 1, and then the upper mold 1b is lowered to clamp and fix the work 2 on the chuck 1.

Next, the vibrating mold 3.4 that clamps the blank portion 2a of the work 2 from both sides is moved along the direction perpendicular to the surface of the work 2, and the chuck 1 and the imaging mold 3.4 on the work 2 are moved. Apply a pressure equal to or higher than the yield point load of the workpiece 2 (indicated by give. Such a load is indicated by Y in FIG. From this state, the vibrating molds 3 and 4 sandwiching the blank portion 2a are simultaneously reciprocated by the vibrating means 5. In this embodiment, the timing at which the vibrating die 3.4 pinches the blank section 2a is when the pressure Y is applied to the section to be cut 2b of the workpiece 2, and starting from this point, @the moving dies 3, 4
The reciprocating motion of the photographing mold 3 is started, but the reciprocation is not limited to this, and after the pressure Y is applied to the portion 2b of the workpiece 2 to be cut, the photographing mold 3.
4 may sandwich the blank portion 2a.

Due to the reciprocating motion of the vibrating die 3.4 as described above, the blank portion 2a is vibrated along a direction perpendicular to the surface of the workpiece 2. This vibration occurs when the workpiece 2 has a thickness of 0.5 to 1.2 mm, for example.
100 to 100 per second when the initial stress is approximately 1.1 times the yield point load.
It is given about 0 times and continuously for about 15 seconds. Moreover, in the case of this embodiment, in order to further shorten the time required for cutting, the amplitude is gradually increased as shown in FIG. control the movement.

Due to this vibration, the moving direction of the vibrating molds 3 and 4 is changed to, for example, the third direction.
When it is pointing downward as shown by the solid line arrow in the figure, the portion to be cut 2b is bent and plastically deformed in the moving direction of the vibrating die 3.4 as shown by the solid line in FIG. At the same time, when the moving direction of the vibrating die 3.4 is upward as shown by the two-dot chain line arrow in FIG. is bent and plastically deformed in the direction of movement. In other words, such reversal of the bending direction is alternately repeated while being accompanied by plastic deformation in the section to be cut 2b. It goes without saying that the above-mentioned plastic deformation accompanying the reversal of bending is performed under a pressure greater than or equal to the yield point load and less than the breaking point load.

By repeating the above bending in opposite directions alternately, slight grooves 7 directed toward the inside of the work 2 are formed on both sides of the portion 2b to be cut of the work 2, as shown in FIG. Ru. Then, as the vibration of the blank section 2a continues after the groove 7 is formed, metal fatigue of the cut section 2b progresses. As a result, the planned cutting portion 2b finally causes low-cycle fatigue failure so as to connect the grooves 7 on both sides thereof. Thereby, the blank portion 2a can be cut from the workpiece 2.

According to such a cutting method using fatigue fracture, as described above, the inwardly directed grooves 7 are formed on both sides of the section to be cut 2b, so that no burrs occur on the cut surface of the blank.

The cross section of the blank 8 without flash thus obtained is shown in FIG. It was confirmed that the thickness Q of the coating film 9 adhered to the edge portion 8a of No. 8 was 4 to 5 μm. With a film thickness of this level, it is possible to prevent the occurrence of rust at the edge portion 8a over a long period of use.

Furthermore, the present invention can also be carried out when a blank is obtained from a workpiece with a galvanized layer 10 provided on both sides in advance, as shown in FIG. and galvanized layer 10 can be brought closer together. Therefore, the sacrificial corrosion effect of the galvanized layer 10 can be more effectively exerted, so that the blank 8
Corrosion resistance can be further improved.

In carrying out the method of the present invention, the amplitude of the portion 2b to be cut by the vibrating die 3.4 may be constant.

[Effects of the Invention] According to the present invention, the gist of which is the structure described in the claims above, a pressure greater than the yield point load of the workpiece and less than the breaking point load is applied to the part of the workpiece to be cut by vibration. Since the blank is cut by alternately and repeatedly bending the blank in opposite directions to cause fatigue failure in the portion to be cut, the blank can be cut without causing any burrs.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, in which FIG. 1 is a schematic sectional view of the main parts of the cutting device, FIG. 2 is a diagram showing the vibration characteristics of the part to be cut, and FIG. FIG. 4 is a cross-sectional view for explaining the cutting state of each portion to be cut, and FIG. 5 is a cross-sectional view showing the end of the blank to which the coating film is applied. FIG. 6 is a sectional view showing the end of another blank with a coating applied thereto. FIG. 7 is a cross-sectional view showing the edge of a blank obtained by a conventional method with a coating applied thereto. 1... Chuck, 2... Workpiece, 2a... Blank planned section, 2b... Cutting planned section, 3.4... Photography type. Applicant's agent Patent attorney Takehiko Suzue Figure 5 1! 6 Figure 117 @

Claims (1)

[Claims] After clamping and fixing the workpiece with a chuck, a vibrating mold that clamps the blank portion of the workpiece from both sides is moved along a direction perpendicular to the surface of the workpiece, and the workpiece is subjected to a load equal to or higher than its yield point. By applying a pressure smaller than the breaking point load, and from this state, simultaneously reciprocating the vibrating molds sandwiching the blank portion to vibrate the blank portion along a direction perpendicular to the surface of the workpiece. , a sheet metal cutting method characterized by cutting the above-mentioned blank.