JOINT CONSTRUCTION FOR METAL SHEETS

Abstract: A joint construction for metal sheets (1, 2) which is made by joining first and second metal sheets by utilizing plastic working. The first metal sheet (1) is formed with first cut-up pieces (4) to have openings therein. A portion of one end edge of the second metal sheet partly superposed on the first metal sheet is held between the openings and the first cut-up pieces and in this state it is pressed along with the cut-up pieces so that the portion is pressed into the openings. The portion of the second metal sheet (2) pressed into the openings is locked by the peripheral walls of the openings.

Description: This invention relates to a joint construction between metal sheets which is made by utilizing plastic working. As for joining metal sheets together, there have heretofore been proposed various joint constructions, including one using welding, another using rivets, another using crimping or curling technique. For parts which are to be exposed on the outside of an article, however, it is desirable to dispense with a coating operation by using a coated steel sheets; in that case, it is not efficient to employ a joint construction based on welding. The reason is that it would be necessary to coat the joined portions again after welding. On the other hand, in a joint construction using rivets, the use of rivets in addition to metal sheets to be joined is required, involving performing a sequence of troublesome operations for forming a joint construction, such as drilling holes for receiving rivets, inserting rivets in the drilled holes, and crimping the rivets; moreover, special equipment must be used. Also, in a joint construction utilizing plastic deformation as in crimping or curling operation, coating operation can be dispensed with by using coated steel sheets. However, a special mold and equipment are required in forming the joint. From the DE-C-909 446 a joint construction between two metal sheets is known, wherein the first metal sheet is formed with first cut-up pieces to have openings therein, a portion of one end edge of the second metal sheet partly superposed on the first metal sheet is held between said openings and said first cut-up pieces and in this state it is pressed along with the cut-up pieces so that said portion is pressed into said openings, the portion of the second metal sheet pressed into said openings is locked by the peripheral walls of the openings. Although this joint construction allows the use of coated steel sheets, it comprises a lack of reliability of the joint, especially in case of shearing or traverse forces. In this case the free end edge of the first metal sheet tends to yield away from the second metal sheet. Accordingly, an object of the invention is to provide a joint construction for metal sheets, whereby metal sheets to be joined can be easily and reliably joined without requiring special equipment. In a joint construction for metal sheets, a first metal sheet is formed with cut-up pieces to have openings therein. Additionally the second metal sheet is formed with second cut-up pieces to have second openings therein. Those sheets are superposed in such manner that a portion of the end of each metal sheet is held between the openings and cut-up pieces in the respective other metal sheet, and in this state they are pressed along with the cut-up pieces to press the portions into the openings. Thus, the portions of the metal sheets pressed to the openings are locked by the inner peripheral walls of the openings. Thus, a rugged joint construction can be obtained by simply pressing a portion of the metal sheets into the openings in the other metal sheet by using a simple press device. These objects features, aspects and advantages of the present invention disclosed in claims 1 and 2 will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. Fig. 1 is a perspective view of a first metal sheet and a second metal sheet which are used to obtain a joint con­ struction according to one embodiment of the invention; Fig. 2 is a perspective view showing a joint construc­ tion formed by using the first and second metal sheets shown in Fig. 1; and Fig. 3 is a sectional view taken along the line XIII- XIII in Fig. 2. Figs. 1 through 3 are views for explaining one embodiment of the invention. In the joint constructon of this embodiment, a first metal sheet 31 and a second metal sheet 32 shown in Fig. 1 are used. The first metal sheet 31 is formed with first cut-up pieces 31a to have first openings therein, said cut-up pieces being spaced a predetermined distance in the direction of the length of the first metal sheet 31. The second metal sheet 32 is also formed with second cut-up pieces 32a to have second openings therein, said cut­ up pieces being parallel to the end edge 33 of the second me­ tal sheet 32 and being spaced a predetermined distance from each other. However, the second cut-up pieces 32a are direc­ ted downwardly of the second metal sheet 32. In joining the first and second metal sheets 31 and 32, the second metal sheet 32 is partly superposed on the first metal sheet 31 so that the end edge 33 of the second sheet 32 is held between the first cut-up pieces 31a and the main sur­ face of the first metal sheet 31. In this case, on the second metal sheet 32, the end edge 34 of the first sheet 31 is held between the second cut-up pieces 32a and the back of the se­ cond metal sheet 32. Thus, a joint construction shown in Fig. 2 which is a perspective view is obtained by performing a press operation in this assembled state. In the construction shown in Fig. 2, the joint portion shown in sectional view taken along the line XII-XII, i.e., the joint portion of the first cut-up pieces 31a and first opening in the first metal sheet 31 and of the second metal sheet 32, is shown. The joint portion shown in sectional view taken along the line XIII-XIII in Fig. 2 is shown in Fig. 3. As is clear from Fig. 3, there is shown a joint construction which is re­ verse to the one formed on the side associated with the first cut-up pieces 31a. More particularly, the portion 34a of the first metal sheet 31 adjacent its end edge 34 enters the se­ cond openings 35 formed in the second metal sheet 32 and is pressed along with the second cut-up pieces 32a so that it is locked by the peripheral walls 35a of the second openings 35. That is, in the joint construction shown in Fig 2, a joint construction formed by utilizing the second cut-up pie­ ces 32a and second openings 35 formed in the second metal sheet 32 and the portion of the first metal sheet 31 adjacent its end edge 31 has been formed. Thus, even if the joint con­ struction is subjected to an external force which ends to move the first and second metal sheets 31 and 32 away from each other, there is much less danger of them being disloca­ ted; thus, the first and second metal sheets 31 and 32 can be more firmly joined.

Claims: 1. A joint construction between two metal sheets which is made by joining first and second metal sheets, wherein: the first metal sheet is formed with first cut-up pieces to have openings therein, a portion of one end edge of the second metal sheet partly superposed on the first metal sheet is held between said openings and said first cut-up pieces, characterized in that said second metal sheet is formed with second cut-up pieces to have second openings therein, the end edge of said first metal sheet on the side asso­ ciated with the second metal sheet is held between said se­ cond openings and said second cut-up pieces and in this state the sheets are pressed along with the respective openings, whereby the portion of the metal sheets pressed into the openings of the other one and are locked by the peripheral walls of the openings. 2. A method for making a sheet metal joint between an edge of a first piece of sheet metal and a second piece of sheet metal, characterized by the following steps: ( a ) leaving said edges of said pieces of sheet metal as a flat edge initially undisturbed and without any holes, (b) punching a plurality of generally U-shaped slots into (a) said sheet metal pieces for forming a tongue surrounded by its respective U-shaped slot, (c) bending said tongue out of said sheet metal piece sufficiently for forming a gap between said tongue and said sheet metal piece, (d) pushing said initially undisturbed holeless flat edges of said sheet metal pieces into said gaps of the respective other one, (e) pressing said tongues against said sheet metal pieces for plastically deforming a portion of said sheet metal pieces into said U-shaped slots surrounding said tongues, whereby said plastically deformed portion of said sheet metal pieces anchors said first sheet metal piece to said second sheet metal piece and whereby said pressed tongues maintain the anchoring.

Inventors: TOSHIAKI, ENAMI
Applicants: ENAMI SEIKI MFG. CO., LTD.
Application year: 1987
Main classification: F16B5
IPC codes: F16B17, B21D39, F16B5