The invention relates to perforated pieces of metal sheet or strip material used in the construction industry, such as, for example, manufacturing nailing plates, wind brace collars, and beam shoes. More precisely the invention relates to a method for manufacturing such plate or strip pieces, especially manufacturing in connection with forming the holes to be made in the piece, as well as the perforated piece manufactured by such a method.

By perforated piece of sheet metal or strip material used in the construction industry is meant here pieces whose thickness is essentially smaller than the width and which are provided with holes for attachment of the pieces in guestion. An example of such pieces is wind brace collars, which are used in construction technology to support and stiffen various structures, especially roof structures. Another example of such pieces is nailing plates, which can be straight or bent into an angle and are used, for example, as corner joints in roof structures. A third example of such pieces is beam shoes, which are used at joining points of beams .

Nailing plates, which can thus be straight or bent into an angle and possibly reinforced, are manufactured from metal plates, the material thickness of which usually varies between 2.0 and 3.0 mm. Nailing plates are provided with several holes through which the nailing plates can be attached with nails, screws, or other similar devices.

Beam shoes are usually manufactured by bending sheet metal 2.0-3.0 mm thick, and they are provided with several holes for attaching the beam shoes with nails, screws, etc.

Other pieces used in the construction industry that are made at least partly from sheet metal and are provided with holes in the metal area are, among other things, fork plates, bearing plates, concrete bonds, pillar shoes, and rafter slide rails.

One form of wind braces is the wind brace collar, which is usually formed from a long metal strip or piece of sheet metal that can be cut into lengths suitable for various installation sites, which strip is provided with holes along the entire length of the strip. Through these holes, the ends of wind brace collars are attached to the support structure or other attachment points, usually intermediate pieces, such as wind braces. In addition, a break is often formed along the length of the wind brace collar, to which break an adjustment tightening piece is fitted, by means of which the tension of the wind brace collar can be regulated. Attachment of the wind brace collar to an intermediate piece is realized through holes in the wind brace collar, for example as a screw joint.

The width of a wind brace collar strip is typically 25- 80 mm, and its thickness is usually about 2.0-3.0 mm. Wind brace collar strips are usually delivered wound into a coil, in which case the length of the strip is usually 25-50 m, the weight with a strip thickness of 2 mm and a width of 40 mm is about 16-32 kg.

A problem in these known wind brace collars is the difficulty of handling the wind brace collar strip. A wind brace collar strip wound into a coil is heavy for the installer to carry to the installation place, usually the roof structure of a building. In addition, unpacking and straightening a wind brace collar strip is awkward, due to the thickness of the strip. These problems significantly slow down the installation process of a wind collar brace.

According to the level of technology of these pieces presented above, the holes are formed in manufacturing by cutting strip material away from hole places to achieve the holes in the plate or strip portion of the piece . In the solution according to the present invention, the holes are formed in a metal piece including a perforated plate or strip part for use in the construction industry in such a way that the metal or strip material is pressed stronglyat the place of the hole to be formed, advantageously from both sides simultaneously. Due to the effect of this pressing, material from the area of the hole is forced to be transferred to the edge of the hole. If necessary, at the end of formation of the hole in the area, a thin layer of material is cut away to finish the hole, but in many applications, this is not necessarily needed.

With the solution according to the invention, it is possible to strengthen the structure of the piece to be manufactured advantageously, compared to a piece manufactured in the usual way, because in the piece according to the invention, the material previously removed is transferred substantially entirely to the edges of the hole being formed in the plate or strip material. In addition, the material pressed from the area of the hole is strain hardened due to the effect of being transferred by the pressing, which further strengthens the piece according to the invention. In addition, in the solution according to the invention, by shaping the punches or pressing punches, the pressing process can be directed in such a way that most of the material from the area of the hole is pressed to the sides of holes being formed with respect to the most central load direction of the plate or strip materialwhen in use . In this way the strength of the piece to be formed can be improved further in this load direction.

The solution according to the invention makes it possible to achieve, among other things, the strength of usual wind brace collars with a thinner material thickness, in which case material savings and thereby cost savings are achieved in manufacturing. In addition, thinner wind brace collars are easier to handle for the installers and easier to straighten after being taken from a coil for installation. With the solution according to the invention, holes can be produced in the plate or strip material of the pieces in a roller-type method, in which case the plate or strip material is directed by a continuous feed between punches or pressing punching and said pressing tools perform a pressing motion repeatedly to the moving material. In this way, it is possible to speed up the manufacturing process of the pieces and achieve cost savings. For example, in the manufacture of wind brace collars a final product is obtained very guickly in this way, especially in applications in which a thin film of remaining material does not have to be removed, but it can be punctured without problems, for example with the tip of a nail in connection with installation.

Formation of the hole according to the invention can be implemented by pressing the plate or strip material with a punch from both sides of the material, in which case, material transferred by pressing from the area of the hole is transferred substantially evenly to both sides of the plate or strip material, increasing the thickness of the material evenly in the edge areas of the hole with respect to both pressed surfaces. Alternatively, and especially advantageously, for example, in manufacturing nailing plates, in the solution according to the invention, a transfer of material by pressing from the area of the hole can be implemented by pressing a plate of strip material from one side only with a punch or crimp indenter, in which case the opposite side of the material is supported evenly onto a support surface. Then thickening of the material occurs substantially only on the surface being pressed, with the opposite surface being preserved substantially straight. In this way, the installation surface of the product to be manufactured can be kept advantageously sunstantially even, which makes attachment of the piece easier in the installation stage, for example to the surface of a structure to be supported or attached.

The method according to the invention is more precisely characterized by what is presented in the characterizing part of claim 1, and the piece according to the invention is characterized by what is presented in the characterizing part of claim 6.

In the following, the invention will be described as an example with reference to the attached figures, in which :

Figures 1A and IB show schematically two pieces of a usual wind brace collar of different widths, seen from above,

Figures 2A-2D show schematically stages

manufacturing of a wind brace collar according invention, seen from the side,

Figure 3 shows schematically a piece of a wind brace collar manufactured with a method according to the invention at the location of a hole, seen from above, and Figure 4 shows schematically a piece of plate or strip material manufactured by an optional method according to the invention, viewed from above the hole.

In Figures 1A and IB, pieces of two wind brace collars of different widths are shown schematically. From the figures, the structure of the wind collar braces can be seen well, which includes brace material strips 1 and 2, and holes 3 and 4, which are formed at egual intervals in the strip, and are used to attach the wind brace collar in place.

In Figures 2A-2D, the manufacturing method of a wind brace collar according to the invention is shown, in which method, according to Figure 2A, the metal material strip 5 of the wind brace collar starts to be pressed from both sides of the strip by punches or crimp indenters 6 and 6', to form the hole.

By pressing the punches 6, 6' in Figure 2A against each other in the direction of the arrows, the tips of the punches start to force strip material from between the tips of the punches outside the area bounded by the punches, in other words, outside of the area of the hole to be formed.

In the situation of Figure 2B, the pressing caused by the punches 6, 6' in the material strip 5 is stopped. At this time, the tips of the punches 6, 6' have substantially met each other, and the material that was in the area of the hole has been forced to the edge area 7 of the hole, and the material thickness of the strip material in the surrounding area has increased due to the transferred material from the hole area according to the figure. From Figure 2B, it can also be seen how with the aid of shaping the tips of the punches 6, 6', it is possible to achieve a shape of the area of the material that has been transferred from the edge area 7 and thus shape the edge of the hole being formed suitably.

From Figure 2C, it can be seen that it is nearly impossible to achieve a transfer of all material of the material strip 5 from the area of the hole 8 in the edge area 7 by using punches provided with level tips to be used in the manufacturing method according to this invention, because usually a thin film or material layer 9 remains in the area of the hole after the pressing. Removal of the material layer 9 in guestion is performed as a separate finishing work step, in which case the final state shown in Figure 2D is reached, in which the hole 8 formed in the material strip 5 is ready. Removal of the material layer 9 can be performed, for example, by punching with the aid of a punch and a hole cushion.

In the final situation of forming the hole 8 in the material strip 5 according the invention shown in Figure 2D, the material transferred by pressing from the area of the hole has accumulated in the edge area 7 of the hole, where a zone surrounding the hole has thus been formed, where the thickness of the accumulated material is greater than the thickness of the material strip 5, and in which zone the metal material located there has also been strain hardened, as a conseguence of the transfer of material achieved by the pressing in guestion .

The solution according to the invention can also be implemented in such a way that after the pressing by the punches 6, 6' in the manufacturing, the thin material layer 9 remaining after the pressing can be left in the final product, in other words, it does not have to be removed in a separate work stage. In practice, this thin material layer is very thin, for example, about 0.2 mm thick. This is especially advantageous in manufacturing, for example, nailing plates with the solution according to the invention, in which case the thin material layer remaining after the pressing of the hole is punctured without effort by the tip of the nail when the nailing plate is attached, and it thus does not substantially affect the attachment process of the nailing plate, especially when a nailing machine is used.

In the manufacturing according to the invention shown in Figures 2A-2D, pressing the hole is shown as occurring from both sides of the plate or strip material. Alternatively, in the solution according to the invention, the hole can also be produced by pressing the material with a punch from only one side against suitable support cushion, in which case the material transferred by the pressing accumulates substantially only on the surface on the side of the pressing. In this way, the attachment surface of the piece being formed can be kept substantially straight.

In addition, formation of the hole according to the invention can be implemented advantageously in a roller-type method, by feeding the plate or strip material continuously between pressing tools or, alternatively, between pressing tools and support surfaces, and the hole formation is implemented continuously by repeated blows from the pressing tools.

In Figure 3, a piece 10 of a wind brace collar manufactured by the method according to the invention is shown from the point of the hole 11. From the figure, it can be seen that by the pressing, the material transferred from the area of the hole 11 has accumulated in the edge area 12 of the hole substantially uniformly around the hole. The edge area 12 of the hole 11 in the material strip of the wind brace collar 10, being greater in its thickness, strengthens the edges of the hole and thus increases the strength of the wind brace collar manufactured by the method according to the invention, compared to usual wind brace collars, in which the holes are formed by cutting strip material away from the area of the hole. In addition, the material of the edge area 12 of the hole 11 has also been strain hardened due to the effect of the transfer achieved by the pressing, which further improves the strength of the wind brace collar 10 according to the invention. In addition, by shaping the crimp indenters or punches used in the solution according to the invention, the pressing process can be guided in such a way that most of the plate or strip material is pressed in the sides of the hole in the most central load direction of the piece being manufactured. In this way, the strength of the wind brace collar with respect to a tension load can be strengthened even further. An example of this kind of embodiment of a finished hole is shown in Figure 4, in which the material 15 transferred to the edges of the hole pressed from the area of a hole 14 in the piece 13 has been directed in connection with the transfer in the length direction more in the length direction of the piece, which is also advantageously the most central load direction of the piece 13 being manufactured, with respect to the sides of the hole 14.

In the holes 11 and 14 shown in Figures 3 and 4, the thin material layer remaining after the pressing can be left to cover the area of the hole, or alternatively, it can be removed from the area of the hole in a separate finishing work stage.

The applicant has performed tension tests with wind brace collars according to the invention, the results of which are presented in Table 1 below. The material of the wind brace collars in the tests was SSAB Dogal 500 LAD steel, with width of 40 mm. In the first test series, the thickness of the material was 0.75 mm, and in the second test series, the thickness of the material was 0.85 mm. Four test pieces of wind brace collars that were perforated with the method according to the invention were used in the test series, which were substantiallyidentical, as well as an unperforated steel collar as a comparison object. The test pieces of the test series were manufactured manually, so there were differences in similarity and especially in the hole formation and positioning, as can be seen from the results in Table 1, especially for test piece 2 in tension-test series 2.

Table 1

From the results in Table 1, it can be seen that with the solution according to the invention, a tensile strength of about 85% percent is achieved, compared to the unperforated steel material. The corresponding ratio for wind brace collars manufactured in the usual way is about 75%.

In interpreting the results of Table 1, it should be noted that these test pieces were manufactured manually. In series manufacturing by machine, at least a 90% ratio compared to an unperforated material strip can be achieved in wind brace collars manufactured according to the invention.

On the basis of the tests performed, and on the basis of these results, in can be noted, based on the conclusions, that with wind brace collars according to the invention, for example, the tensile strengths of usual wind brace collars of thickness 2 mm can be achieved already with a material thickness of 0.7 mm, when a strip material of a little higher guality is used, whereby significant material savings and thereby cost savings can be achieved in manufacturing wind brace collars . Although the invention has been described in the above explanation of the figures only in connection with manufacturing a wind brace collar, the manufacturing method according to the invention and the products according to the invention can be generalized simply in a way that is obvious to a person skilled in the field also to other joint or support pieces used in the construction industry that form pieces or include a perforated metal plate or strip portions.