JPS6076228A - Pressing method - Google Patents

Abstract

PURPOSE:To punch precisely a thin metallic material without producing burrs by specifying the clearance between a punch and a die and forming the cutting edges of the punch and die into a circular arcuate edge and a sharp edge respectively. CONSTITUTION:Both of the clearances between a blanking punch 16 and a die 26 and between a square-hole piercing punch 29 and a die 17, are set to >=100% the thickness of a material 30 to be worked. Further, both cutting edges of punch 16 and die 17 are formed into sharp edges, and both cutting edges of die 26 and punch 29 are formed into circular arcuate edges. By this constitution, the material 30 is teared off by the sharp edges while press-holding and constraining it by respective opposite surfaces of a stripper 18, a knockout 27, and the dies 17, 26. In this way, the punching is performed without requiring a troublesome clearance adjustment and producing burrs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a press working method for precisely cutting and punching a thin metal material without causing fringing.

[Technical background of the invention and its problems]

Generally, small metal parts used in electron tubes and the like are mostly formed into a predetermined shape by press working, but the particles generated during press working can have a negative effect on the characteristics of the product. For example, an inner shield provided within a color cathode ray tube is also a type of this type of component. In other words, color cathode ray tubes are required to have stricter pressure resistance characteristics year by year, and this trend is particularly noticeable for large tubes. Here, there is a strong correlation between the amount of dust inside the pipe and the process straight withstand voltage failure rate, and in particular, the extremely small falling metallic objects in the dust further deteriorate the withstand voltage characteristics. . The inner shield has the highest specific gravity among the parts made of metal inside the pipe, both in terms of surface area and cutting length during processing, and it reduces the amount of metal foreign objects (paris) that will fall. There is a need to.

The manufacture of the above inner shield is shown in Figure 1 (α) (4) (
C) (B) The process shown in (ε) is used. That is,
(α) A blank α°C and four square holes (C) punching process from a material (not shown) by press working, ←) first bending and beat forming process, (C) second bending process,
It is manufactured through the third bending step in (d), the U-shaped bending step in (e), and a cleaning (degreasing) step and a blackening treatment step (not shown). Among the above steps, burrs occur in the step of punching blanks and square holes from the material in step 0. Here, due to the necessity of its use, it is necessary to use conventional press machines to punch out blanks and square holes as raw materials. A very thin iron material with a thickness of 0.15m+ is used. For this reason, the clearance between the punch and die for punching is 0 on one side.
．． The b value is set to an extremely small value of 0.01 m or less.

Normally, the press machine used for blank processing for inner shields has a large surface area, so
00 ton to 200 ton class.

Therefore, even if a press machine equivalent to JI81 class or higher is used, the parallelism accuracy between the head and ram of the press machine is 0.1.
! Therefore, as mentioned above, even if the clearance of the cutting die is set to a high precision of about 0.01 m, when this is installed in a press machine, the force will be applied to the clearance of 0.03w1 in some places, and vice versa in some places. The clearance becomes negative and the punch starts to bite the die.

The smaller the clearance, the less likely the occurrence of hollowing, and good results can be obtained by setting the clearance to 0.01 m or less. However, if the clearance is about 0.03 mm or more, the gap becomes large, causing a problem when used as an inner shield.

Therefore, conventionally, the clearance was set to 0.0 as follows.
My limbs were below 1wI+. First, the punch hardens the tool steel (to a hardness of about RC60 to 63).On the other hand, the die heats the tool steel to a relatively soft hardness of about HRC40 to 45. Attach a suitable cutting die to a press machine and test-cut the material for the inner shield to check for holes. As a result, when the clearance is large (b), that is, as mentioned above, due to the parallelism accuracy of the press machine, etc., the clearance becomes larger than about 0.03 m, and the die cut in that part is determined. Hammer the blade into the inside of the p-die. This tapping is possible because the hardness of the die is relatively soft.

Next, the ram of the press machine is lowered and the punched part is removed (sieving). Do this several times
By turning it over, I completed the proper clearance adjustment (0.01m or less) and centering the upper and lower molds, and after confirming that the punching condition was good, I started punching the inner shield.

However, such a press working method has the following problems. In other words, because the clearance between the punch and the die is small, the inner surface of the die is rubbed by the outer edge of the punched blank, and the outer surface of the punch is rubbed by the inner edge of the punched workpiece. , the wear of these parts is large and the life of the mold is shortened. Furthermore, since the die is hammered out for the above-mentioned clearance adjustment, its hardness must be relatively soft (the highest hardness within the range that can be hammered out), and quenching cannot be performed. In addition, the reason why the die cannot be hardened is that the clearance is small, which causes irregularities in the workpiece, such as two pieces of workpiece material, and if some eccentric load is applied to the upper die and the face angle of the punch is distorted, the punch will not be able to harden. A collision with the die occurs. In this case, if both parts are hardened and hardened, they will both be damaged and the work will become impossible. For these reasons, green sea bream cannot be hardened. Moreover, as a result, the cutting edge quickly wore out, causing large burrs to form on the workpiece.◎ When large burrs occur in this way, they fall into the pipe during transportation or during nodding during the assembly process. Put it away. In addition, this gouge scrapes the blackened film on other inner shields, which adheres to the inner shield and is carried into the pipe.

As described above, these adversely affect the voltage resistance characteristics of the cathode ray tube.

In order to completely prevent such problems, in the past, once the mold was installed on the press machine and the clearance check was completed, even if the production at that time was completed, the mold was removed (key to the press machine's convenience). If the seal maintains a good clearance without being removed, or if the inner shield has been punched out, it should be thoroughly controlled (normally controlled within ±0.1 error of the par height), and mold repair (blade sharpening, clearance control) should be carried out. I was dealing with things to do every day. However, these methods cannot sufficiently prevent the occurrence of paris, and improvements have been desired.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a press working method that allows punching into a predetermined shape without causing burrs, without having to perform troublesome rearrangement or the like.

[Summary of the invention]

In the press working method according to the present invention, the clearance between the punch and the die is set to 100 times or more of the thickness of the material to be processed, and the cutting edge of either the punch or the die is formed into an arcuate edge, and the other The cutting edge is a sharp edge, and as the press ram operates, the workpiece is compressed and restrained by the opposing surfaces of the strip, knockout, and die, and the workpiece is torn and separated by the sharp edge. It is something to do.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

FIG. 2 shows the cutting die section of the press machine used in the present invention.

In the figure, (G) is a lower mold shoe that is mounted on a press bed (not shown), and a punch αQ for punching out the outer shape of the blank α9 shown in FIG. 1 is fixedly attached to the upper surface of the shoe. This punch OQ has a die η for punching out the square hole υ shown in FIG. 1, and serves as both the outline punch αQ and the square hole punch die α. α→ is a strip arm which is fitted to the outer periphery of the punch αQ so as to be movable up and down. Also, this strip arm -α→ is supported on the lower shoe aQ by the spring α, and the upper surface of this spring is almost flush with the upper surface of the punch (ld). Figure 3 is a plan view of the left half of this lower die.Also, the angle 90 force for the square hole provided on this punch 16 is as shown in Figure 5. A knockout (A) is fitted into the hole so as to be able to move up and down. The upper end) is positioned so that it is approximately flush with the upper surface of die 0.

Returning to FIG. 2, (c) is an upper shoe which is attached to an isole ram (not shown) and moves up and down with the operation trap of the press ram. 2) is an outline punching die which is attached to the lower surface of the upper die shoe (C), and when lowered, fits into the outer periphery of the outline punch 0Q while maintaining a predetermined clearance. 2) is a knockout, and as shown in FIG. 4, the outer periphery shape is almost similar to the inner periphery shape of the outer shape cutting die). This knockout (B) is installed on the lower surface of the upper mold sleeve (C) via a spring (C) so that it can move up and down, and the lower surface of the knockout (C) is normally moved by the repulsive force of the spring (C). Cutting die (
c) It is positioned so that it slightly protrudes from the lower surface. (
c) is a square hole punch, which is fixedly attached to the lower surface of the upper mold shoe so as to face the square hole punching die αη provided on the lower mold, and is used for ink-out as shown in FIG. ) and protrudes from its underside.

In addition, in FIG. 2, the country is the workpiece material for the inner shield.

Here, the clearance between the outline punch α and the die (C) and the clearance between the square hole punch α and the die are set to be 1005 J or more, which is the thickness of the workpiece (1). In the example, the thickness of the workpiece is 0.15 mm and the above clearances are 0.3 to 0.5 m on one side.
And so. In addition, the external shape punch αQ and the square hole punch die (
The cutting edge of (b) was a sharp edge, and the cutting edge of the outline punching die (c) and square hole punch (a) was an arcuate edge. The radius of this arcuate edge is 1.0m as a result of real numbers.
The condition was good.

With the above configuration, with the wrinkled material (to) positioned on the upper surface of the lower mold's strips 1,000-θ seconds and the outline punch 0-yen, the press ram is operated and the upper mold shoe (c) is lowered. First, the lower surface of the knockout on the upper die side) comes into contact with the upper surface of the workpiece (G), and the workpiece (to) is fully clamped and restrained by the upper surface of the outline punch αQ. Next, the tip of the square hole punch (c) comes into contact with the top surface of the workpiece (to), and the workpiece is clamped and restrained together with the top surface of the knockout (a) located on the lower surface of the square hole punch (c). Then, as the upper mold shoe (c) descends, the workpiece (to) is punched out together with the square hole punching die (b), as shown in FIG. Also, at the same time,
The lower surface of the outline cutting die (c) contacts the upper surface of the workpiece (to), and clamps and restrains the workpiece (to) together with the upper surface of the strip Δ-(le) located on the lower surface. As (c) further descends, the outline punch Q
Together with Q, the workpiece material (to) is punched out to obtain the blank U shown in FIG.

Here, the process of cutting the punched portion will be explained with reference to FIGS. 6 and 7. FIG. 6 shows an enlarged view of the process of punching out the square holes (A). In this case, as mentioned above, the workpiece (G) is first cut between the lower surface of the knockout (B) and the square hole punching die α.
It is clamped and restrained by the upper surface of η (which is also the upper surface of the outline punch αQ). In this state, use a square hole punch (c)
descends and punches out the workpiece (A) while clamping it between its tip and the knockout (1). (4) (B) in the diagram
(C)■) represents the lowered position of the punch (C). As is clear from the illustration, as the punch (A) descends, the workpiece ■ is pushed and bent along the arcuate edge of the punch (A), and is torn off by the sharp edge (17cL) of the die αη. , separated. In this case, the hole shape is formed following the dimensions of the die ση having a sharp edge. On the other hand, the punched blank part is deformed and becomes scrap. Also, at this time, punch (c) and die α
Since the clearance between the die and the force is large, the deformed outer wash part on the scrap side does not come into contact with the inner surface of the die α force during cutting, and this part will not be rubbed and worn.

FIG. 7 shows the outline cutting process. In this case as well, the workpiece (to) is the lower surface of the knockout (goods) and
It is clamped and restrained with the upper surface of the 1-inch αQ outline cutout. In this state, the outline cutting die (c) descends, and the bottom surface and
While pressing the workpiece (G) between the IJ barrel and the top surface of the barrel, punch it out. In the figure, (G), (B), (C), and (B) represent the lowered positions of the outline cutting die. As is clear from the illustration, as the die (to) descends, the workpiece (to) is pushed and bent along the arcuate edge of the die (c), and is torn off by the sharp edge (16G) of the punch αQ. , separated. In this case, the shape of the punched blank follows the dimensions of the punch αd having a sharp edge. On the other hand, the punched workpiece material ■ is deformed and becomes scrap. Also, in this case, punch 00
Since the clearance between the punch and the die (c) is large, the inner side of the torn workpiece (g) does not come into contact with the outer surface of the punch OQ, and this area will not be rubbed and worn.

FIG. 8 shows a conventional punching section, and as shown in the figure, the edges are formed to protrude in the punching direction (downward). FIG. 9 shows a punched portion processed by the method of the present invention.

As is clear from the illustration, although arcuate portions are formed, there are no gaps as in the conventional case.

Further, in the present invention, since the clearance between the punch and the die is set large, there is no need for the troublesome clearance adjustment that involves punching out and shoeing the die, which is required in the conventional method. Moreover, as a result, both the punch and the die can be hardened and have high hardness. It has also become possible to use cemented carbide for these punches and dies. Therefore, machining problems due to such wear and the like do not occur, and high-precision machining can be maintained for a long period of time.

In the above embodiments, the inner shield of a color cathode ray tube was exemplified as the product to be processed, but of course the method is not limited to this manufacturing method, and is generally related to sheet metal press working in general.

It is particularly effective for palli-less processing of thin plates, and is suitable for processing the above-mentioned inner shield cores, electron shields, and inside electron shields. The other cutting edge is a sharp edge, but the cutting edge of the punch or die on the side corresponding to the one that will remain as a pressed product is a sharp edge, and the cutting edge of the punch or die on the side corresponding to the one that will be scrapped is a sharp edge. The blade portion may have an arcuate edge, which can be appropriately selected depending on the shape of the product and the mold structure.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to perform a punching process that does not produce any cracks without requiring troublesome rearranging training, and therefore, when used for processing electron tube parts, etc., the effect is extremely large.

[Brief explanation of the drawing]

Fig. 1 (α) (a) (a) (C) (A) (g) is a diagram showing the manufacturing process of the inner shield, and Fig. 2 shows the main parts of a press machine used in an embodiment of the press processing method according to the present invention. Figures 3 and 4 are plan views of the lower mold and upper mold shown in Figure 2, Figure 5 is a diagram showing the operating state of the portion shown in Figure 2, and Figures 6 and 7 are The figure is a diagram showing the cutting-edge separation process in the present invention, and Figures 8 and 9 are diagrams showing the shapes of the punched parts by the conventional method and the method of the present invention.・Medium square hole, αQ...Outline punch, (6)...Square hole punching die, α→...Stritz-1 (To) (B)...Knockout, ni)...Outline punching die, (I) )... Square hole punch, ■ - Core processing material. CC)

Claims (1)

[Claims] (1) The clearance between the punch and die is set to 100% or more of the thickness of the workpiece material, and the cutting edge of either the punch or the die is made into an arcuate edge, and the cutting edge of the other is made into an arcuate edge. A sharp edge is used, and as the press ram operates, the workpiece is pinched and restrained by the opposing surfaces of the strip Δ-, the knockout, and the die, and the workpiece is torn apart by the sharp edge. Press processing method.