JPS5823165B2 - Manufacturing method for a continuous piece of metal that is easy to separate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a continuous body of metal pieces that can be easily separated, and more particularly, to a method for producing a continuous body of metal pieces that can be easily separated.

This method relates to a method for manufacturing a continuous metal piece that can be easily separated by applying the same method twice in the thickness direction in forward and reverse directions.

Examples of easily separable continuous metal pieces include stapler staples (JIS S 6036), stationery cutter blades, and easy-open can lids.

These continuous bodies of metal pieces are usually kept as a continuous body for handling or sealing, and if necessary, the metal pieces are separated and used with a tool such as a stapler or by hand.

Conventionally, stapler staples are made by forming a large number of straight needle-shaped metal pieces (staplers) from wire or the like in advance, and then connecting them in parallel with adhesive to form a metal plate or metal strip. It is manufactured by creating a U-shaped cross section by bender processing, press processing, or roll forming processing.

However, with this method, the process is complicated, and the adhesive inevitably becomes unstable depending on humidity and temperature conditions, and it is expected that one type of adhesive composition will provide suitable adhesive processing workability throughout the year. It is difficult to do so, and it is also difficult to maintain appropriate adhesive strength in the product.

Furthermore, these manufacturing methods and products were also unsatisfactory in terms of productivity and cost.

Conventionally, easy-open can lids have been made by pressing an aluminum alloy or tin plate into a score section (slit, recess) so that the lid can be opened from that section when necessary.

First of all, this method requires a limited number of materials, and requires a very precise press machine.Even if the punch and die are made of ultra-hard material such as tungsten carbide, they must be replaced frequently, and the working conditions are not precise. The problem was that it had to be controlled.

In addition, there is a limit to the depth of the score when scoring with a press, and therefore the thickness of the easy-open can lids is also limited, making it impossible to make easy-open can lids for bale cans and drum cans using conventional methods.

Further, conventionally, break-off type stationery cutters have been used, for example, in a 0.
A steel strip with a thickness of 4 mm or a long rectangular piece of steel with a depth of 0.0
It is manufactured by attaching a large number of scratch grooves of about 3 mm in parallel and at equal intervals, and the material is JIS SK2.
Since the cutter blade is made of hard steel, it is difficult to form the scratch groove deeply, and therefore the cutter blade cannot be made thick and strong.

Further, roll-molded products such as curtain rails, shutter plates, spandrels, metal roofing materials, etc. are generally manufactured by forming long strips using a roll-forming machine and cutting them into predetermined dimensions after forming.

This is because when roll forming, there is a tendency for the product shape to become unstable if there are tension fluctuations between the forming rolls at each stage, and this tendency is noticeable when roll forming material that has been cut into lengths in advance, causing the shape of the end part to be twisted or buckled. This is because the product value may be impaired due to abnormal shapes such as

However, since roll-formed products generally have a complicated cross-sectional shape, problems arise when cutting them with a rotary saw, a precision press, a shear, or the like.

In other words, in the case of a rotary saw, burrs are unavoidable on the cutting surface, and in the case of precision presses and shears, it is necessary to prepare a blade with a complicated shape according to the cross-sectional shape of the roll-formed product. Therefore, there have been problems in that the cost is high, the production efficiency is poor, and the yield is also poor.

In view of the various problems mentioned above, the inventors of the present invention, as a result of various considerations and experiments, decided to apply shear pre-strain to the metal plate with a stroke less than the thickness of the metal plate, or to apply shearing in the opposite direction with a stroke less than the thickness of the metal plate. We have discovered that by applying pre-strain, it is possible to produce a continuous piece of metal that is easy to separate and has various characteristics depending on the intended use in a relatively simple process, and have arrived at the present invention.

An object of the present invention is to provide a method for manufacturing a continuous body of metal pieces that can be easily separated and can be obtained without bonding metal pieces in advance or scoring metal plates in advance.

Another object of the present invention is to provide a method for producing a continuous body of metal pieces that can be easily separated directly from various metal plates by applying shear prestrain twice in the thickness direction of the metal plate in forward and reverse directions.

Still another object of the present invention is to provide a method for producing a continuous body of metal pieces that can be easily separated from a metal plate having a relatively large thickness or a metal plate having a relatively high hardness.

Still another object of the present invention is to provide a method for producing a continuous metal piece that has a narrower score portion, that is, has a larger effective area and is easier to separate even if the length is the same compared to the conventional method.

According to the present invention, the first step is to apply shear prestrain to a metal plate by cold working with a stroke less than the thickness of the metal plate, and then to further prestrain the prestrained metal plate in the opposite direction with a stroke less than the thickness of the metal plate. A second step of applying shear prestrain is provided.

The present invention will be explained in detail below by way of examples and with reference to the accompanying drawings.

FIGS. 1, 2, 3, and 4 are cross-sectional views sequentially showing a conventional shearing process for a thin metal plate.

In the shear, the upper blade 2 and the lower blade 3 are arranged facing each other with a clearance G maintained, and in this case, the lower blade 3 is fixed and only the upper blade 2 moves vertically downward.

The metal plate 1 passed between the two blades is pressed and fixed by the clamp 4 before shearing starts, and in this state, the metal plate 1 is then pinched between the upper blade 2 and the lower blade 3 and subjected to shearing.

Then, as shown in FIG. 3, when the shearing stroke L exceeds a certain value, which is slightly larger than the thickness T of the metal plate 1, the metal plate 1 is separated into two pieces.

At this time, the cut surface of the metal plate 1 varies depending on the mechanical properties of the material and the clearance G between the upper blade 2 and the lower blade 3, but generally it is as shown in Fig. It is composed of a C1 burr.

Therefore, by reducing the clearance G or setting it to zero, and by selecting the stroke L to be equal to or less than the plate thickness T, an easy-separation region 5 with shear prestrain in one direction is created as shown in FIG. Can do things.

Note that this shear prestrain can of course be applied continuously using a slitter.

In the first step only, that is, in the method of applying only unidirectional shear prestrain, if the stroke L is less than 8 of the plate thickness T, an appropriate easy-separation zone will not be formed, and the stroke L will be
If the clearance is set below, the upper limit will generally break as early as the processing stage if the clearance is small, and the same holds true when applying shear prestrain in two directions.

When the easy-separation region 5 is subjected to strong shear strain, the crystal grains are crushed into a fibrous structure as shown in FIG.

Therefore, although the easy-separation region 5 is work-hardened, if a shear stress or a stress close to it is applied in the opposite direction to the applied strain direction, the Bauschinger effect allows easy fracture separation even with a small stress applied manually.

However, it is important to appropriately select the clearance G and stroke L that regulate the amount of shear prestrain, and to maintain appropriate strength when separation is not allowed.

The easy separation region obtained by this unidirectional shear prestrain can be applied to easy-open can lids and the like.

In addition, if the metal plate subjected to the unidirectional shear prestrain is further subjected to shear prestrain in the opposite direction, that is, bidirectional shear prestrain is added, and the workable surface of the metal plate is made almost flat, it becomes a continuous metal piece. Since the shape of the product is improved, products suitable for various uses can be obtained.

This two-way shear prestrain is achieved by placing the metal plate, which has been subjected to one-way shear prestrain using the shear or slitter, between a flat anvil 7 and a punch 6 as shown in FIG. 7, and pressurizing it with an appropriate pressure. It can be easily applied.

Note that this pressurization can also be performed using two rotating rolls.

At this time, a slightly higher plateau-like convex portion may be provided on the anvil 7 in consideration of springback.

Further, this secondary processing can also be performed continuously using a pair of rolls.

In particular, when the primary processing is performed using a slitter, it is extremely useful in terms of production efficiency to perform the secondary processing using rolls.

In addition, in the case of further applying shear prestrain in the opposite direction in the second process to the metal plate that has been subjected to the shear prestrain in the first process, the amount of shear prestrain in the second process, that is, the stroke is as described above. Correct the shear prestrain in the first step,
It is not necessary to limit the stroke to a degree that substantially flattens the product, in other words, to a stroke in the opposite direction corresponding to the shear prestrain of the first step.

Therefore, the stroke in the second step can be freely selected to be larger or smaller than the stroke in the first step, as long as it is less than the plate thickness.

However, in this case, the product shape generally remains uneven at the shear prestrain portion and is not flat.

The shearing stroke in the second step is generally equal to or less than the shearing stroke in the first step in accordance with work hardening and also on the condition that it does not lead to breakage, which is a feature of the present invention.

Next, we will discuss again the case where the metal piece continuum (product) is almost flat, which is considered to be the most versatile.

The reason why it is considered to be the most versatile is that long continuous metal pieces, including staplers, can easily slide in the longitudinal direction in a holder or supply device, and can be piled up or rolled up into a coil. This is because in many cases, the surface of the continuous metal piece is required to be flat from the viewpoint of improving the space factor.

Also in the present invention, the case where the product surface is substantially flat occupies an important part.

In this case, the surface of the product after the second step is visually almost flat, but microscopically, as shown in Figure 7, which is a cross-sectional view, the surface of the shear strained part is not necessarily flat, leaving considerable unevenness. ing.

It has been experimentally confirmed that this unevenness tends to decrease unless the shear stress is relaxed due to a restraining force acting in a direction perpendicular to the shear plane, that is, in a direction parallel to the plate surface in the second step.

Therefore, the changes in the internal structure of the sheared part are observed as follows.

FIG. 6 is a cross-sectional micrograph (100x magnification) of a mild steel plate subjected to the first step of shearing with a stroke of 50 times the plate thickness (0.5+tm).

In the easily separated region subjected to shearing, the crystal grains are elongated and have a fibrous structure.

Even in this state, depending on the degree of processing, if stress is applied to separate from the opposite direction (direction of the arrow), the Bauschinger effect, work hardening, and stress concentration will occur, and even if the stress is in the positive direction, work hardening and stress will occur! The concentration causes brittle fracture mainly in the easy-to-separate region, leading to separation.

Then, the second step of reverse shearing was performed as shown in FIG. 7, and the cross-sectional structure of the mild steel plate according to the present invention is as shown in FIG. 8.

As for the surface of the product after processing, even though the second process is performed with the aim of making it appear flat, some unevenness remains.

This is for the reason mentioned above.

In Fig. 8, the material is completely continuous at the center of the plate thickness, and the thickness of the easy-to-separate region (hereinafter also referred to as the connecting part) is about the same as the original plate thickness.

The thickness of this connecting portion varies depending on the amount of indentation in the first step, the clearance between the processing tools, and the amount of processing in the second step.
West German Patent Publication No. 180 states that the material is continuous with connecting parts at any stage after the completion of the process.
The technical concept is completely different from the so-called counter cut method or the burrless slit method described in No. 6305 and Japanese Patent Application Laid-open No. 52-96477, in which the material is completely cut and separated.

FIG. 9 is a microscopic photograph (200x) of the connecting portion in FIG. 8C.

Further, FIG. 10 is a model diagram of FIG. 9, and is for explaining the structure of FIG. 9.

That is, the metal plate 1 is a part that has not been processed yet, the area 6 is a part where the fibrous structure generated in the first step remains, and the area 5 is a part that has been sheared in two directions. This is the connecting part.

As shown in FIG. 9, the fibrous structure forms a one-cycle wave pattern, which is always a true shear stress even if there is considerable restraining force in the transverse direction on both surfaces of the metal plate 1.

This is thought to be due to material flow occurring in a direction that relaxes the .

In any case, there is no doubt that in this part, the grain boundaries that were observed when unprocessed have completely disappeared, resulting in a brittle structure with an extremely high density of dislocations and vacancies.

Incidentally, when the change in hardness was measured using a microscopic crush tester, the result was as shown in FIG. 11, and the state of work hardening of the connection part was clear.

The above phenomenon was observed in relatively ductile mild steel, but the tendency changes when it comes to hard carbon steel and the like.

In other words, an easy-to-separate region in the first and second steps is formed by a very slight shear prestrain.

Regarding the clearance between tools during shearing in the present invention, it is convenient to set the clearance between 0 and 30, particularly between 0 and 10, of the thickness of the metal plate to be processed.

If the clearance becomes negative, there will be more parts that are vertically pressurized between the tools, and even if the rotational force that the metal plate receives is taken into account, the plastic flow of the material will not work properly and compressive deformation will increase, so the objective of the present invention is achieved. Can not.

On the other hand, if it exceeds 30, the shear true stress will be relaxed as described above, and the width of the groove or connecting portion between the metal pieces will become wider, which is not preferable.

Next, regarding the shearing strokes (shearing strain) in the first step and the second step, these can be respectively expressed as metal plates.

Here, T is the thickness of the metal plate, and 11 and 12 are the thicknesses of the connecting portion after the first step and after the second step, respectively.

Expressing these 11 and 12 as percentages, T, tl,
The present invention is illustrated in FIG. 12, where t2 is expressed in ho, respectively.

Note that FIG. 12 shows an example of a mild steel plate, and the tendency is slightly different for carbon steel, aluminum or its alloys, copper, brass, copper, and other various metals or alloys.

Now, this embodiment is shown as area A in FIG.

In other words, the object of the present invention is achieved when 11 is in the range of 5 to 80%, particularly 15 to 70%, and in the case of lkino 2, that is, when the appropriate shear prestrain for each plate thickness is within this range A. Ru.

In region B where the shear prestrain is large for each plate thickness, cracks occur during the prestrain stage, whether only in the first process or when the second process is added, propagates, and the mild steel plate breaks and separates. Resulting in.

Therefore, region B can be said to be a region of conventional counter cut method or burrless slitting.

In addition, region C is the so-called "burrless slitting method"
is within the range of

Note that all the shearing prestrain processing in the present invention is cold processing.

In addition, Figure 12 shows the relationship between shear prestrain and plate thickness when the product surface is made almost flat by applying reverse shear prestrain with the same stroke as in the first process in the second process. Region B tends to become wider when it is thicker or when the second step prestrain is larger than the first step prestrain.

That is, even if the sum of the shear prestrains in the first step and the second step is relatively small, the metal pieces are cut and separated.

The above-mentioned applications of the present invention include staplers for staplers, easy-open can lids, continuous curtain rails, continuous flat blades such as safety razor blades, name plates for various industrial products, and watch bands. Continuous display boards for calendars, etc., continuous blades for Venetian blinds, continuum of binding straps with each length as a unit, narrow metal hoops continuous in the width direction in integral multiples, and There are continuous leaf springs used in toys, watches, various other household goods, precision machinery, etc.

The present invention not only achieves all of the above objectives, but also has the effect of producing a continuous body of metal pieces that is useful in various industrial technical fields and is easy to separate, and has immeasurable industrial applications. .

[Brief explanation of the drawing]

1, 2, 3, and 4 are cross-sectional views showing the state of conventional thin plate shear processing, and FIG. Figure 6 is a cross-sectional microscopic structure of the mild steel plate after processing as shown in Figure 5, Figure 7 is a cross-sectional view showing the process of applying reverse prestrain to make it almost flat, and Figure 8.
The figure is a cross-sectional microscopic structure of the mild steel plate after processing shown in Fig. 7, Fig. 9 is an enlarged microscopic structure of the joint part shown in Fig. 8, Fig. 10 is a conceptual diagram for explaining the structure of Fig. 9, and Fig. 11 is a graph showing the hardness distribution, and FIG. 12 is a graph showing the relationship between shear prestrain and plate thickness. 1: Metal plate, 2: Upper blade, 3: Lower blade, 4: Clamp, 5:
Easy separation area.

Claims (1)

[Scope of Claims] 1. A first step of applying shear prestrain to a metal plate by cold working with a stroke less than the thickness of the metal plate, and then further subjecting the prestrained metal plate to a stroke less than the thickness of the metal plate. A method for manufacturing a continuous metal piece that is easy to separate, comprising a second step of applying shear prestrain in the opposite direction. 2. The method for producing a continuous metal piece according to claim 1, wherein the shear prestrain in the first step and the shear prestrain in the second step are approximately equal, and the surface of the metal piece continuous body as a product is substantially flat. 3. The manufacturing method according to claim 2, wherein the continuous metal piece is a stapler needle. 4. The manufacturing method according to any one of claims 1 to 2, wherein the continuous metal piece is an easy-open can lid. 5. The manufacturing method according to claim 2, wherein the continuous metal piece is a curtain rail. 6. The manufacturing method according to claim 2, wherein the continuous metal piece is a continuous plate-shaped cutter. 7. The manufacturing method according to claim 2, wherein the continuous metal piece is a continuous display board. 8. The manufacturing method according to claim 2, wherein the continuous metal piece is a continuous plate of a Venetian blind. 9. The manufacturing method according to claim 2, wherein the continuous metal piece is a continuous banding strap. 10. The manufacturing method according to claim 2, wherein the continuous metal piece is a continuous plate spring.