Method for joining a sheet metal part to a component

Abstract

Method for joining a sheet metal part (1) to a component (2), characterized by the following method steps: a. Heating the sheet metal part (1) to a temperature above the recrystallization temperature of the metal sheet, b. Forming the sheet metal part (1) in a forming tool, c. Placing the component (2) in a defined position on the hot sheet metal part (1) before, during or after forming the sheet metal part (1), d. Punching the component (2) into the still hot sheet metal part (1) with a punching device which is designed as part of the forming tool.

Description

[0001] The present invention relates to a method for joining a sheet metal part to a component according to the preamble of claim 1.

[0002] Various methods for fastening a component, such as a connecting component to a sheet metal part, are already known from the prior art, for example from the publications DE 10 2009 012 243 A1, DE 11 2007 001 331 T5, DE 11 2006 001 867 B4, or US 2004 / 0134 573 A1. The component connections produced in this way enable the assembly of another component to the sheet metal part via a connecting component designed, for example, as a nut with an internal thread.

[0003] For example, it is known to connect such a connecting component to the sheet metal part by welding, which requires the use of cost-intensive welding machines due to different coatings of the sheet metal part.

[0004] DE 103 46 906 B3 discloses a method for producing a hardened sheet metal part with an attached connecting component. The sheet metal part, which has a hole, is first heated to a temperature above the recrystallization temperature of the sheet metal material. The unheated connecting component is then fed into the sheet metal part. The sheet metal part is then formed in a forming tool, with the connecting component penetrating the hole in the sheet metal part and being enclosed by the sheet metal part. The sheet metal part, still in the forming tool, is then hardened and shrinks onto the connecting component in a subsequent cooling step.

[0005] The disadvantage of these processes is that the hole into which the connecting component is to be inserted must be made in an additional process before hot forming.

[0006] The object of the present invention is to provide a method for connecting a sheet metal part to a component, which simplifies the manufacturing process and ensures an exact position of the component in the sheet metal part.

[0007] This object is achieved by a method for joining a sheet metal part to a component having the features of claim 1.

[0008] According to the invention, the opening in the sheet metal part is punched into the sheet metal part during the hot forming process with the aid of the component. By punching the opening through the component to be inserted itself, the costs of the manufacturing process are reduced by eliminating the previously additional process step of creating the opening in the sheet metal part. Creating the opening through the component itself during the hot forming process also allows for precise positioning of the component. In addition, a further cost saving in the manufacturing process is achieved by eliminating the otherwise necessary punch for creating the opening in the sheet metal part, and consequently, no costs arise due to wear on the punch.

[0009] The component itself is preferably designed as a punch nut and is used as a cutting punch when punching the openings into the sheet metal part. Using the component itself as a cutting punch eliminates wear-related costs for the cutting punch.

[0010] An embodiment of the invention is described in more detail below with reference to the figure. It shows: Fig. 1 a side sectional view of a sheet metal part with a punched component and punch ejection.

[0011] In the following description of the figures, terms such as top, bottom, left, right, front, back, etc., refer exclusively to the exemplary representation and position of the sheet metal part and component chosen in the respective figures. These terms are not to be understood as limiting; i.e., these references may change due to different working positions or mirror-symmetrical design, etc.

[0012] In the Fig. 1, a sheet metal part is designated overall by reference numeral 1. A component 2, designed here as a self-piercing nut, is inserted into this sheet metal part 1. The component 2 consists of a circumferentially polygonal annular piece 21 protruding from the sheet metal part 1 and a punching area 22, which is designed in particular as a punching ring and is embedded in the sheet metal part 1.

[0013] In order to join the sheet metal part 1 to the component 2, the sheet metal part 1 is first heated to a temperature above the recrystallization temperature of the metal sheet. Before, during or after the forming of the sheet metal part, the component 2, designed here as a self-piercing nut, is then placed in a defined position on the sheet metal part 1 and punched into the still hot sheet metal part 1. The punching of the component 2 into the sheet metal part 1 can be carried out using a punching device (not shown) which is designed as part of a forming tool or as a stand-alone tool which is brought closer to the forming tool for punching the component 2. For example, the use of an industrial robot is conceivable for this purpose, which ensures precise positioning of the component on the sheet metal part.

[0014] During the punching process, the punching area 22 of the component 2 is punched into the sheet metal part 1 to such an extent that it completely penetrates the sheet metal part 1. When the component 2 is designed as a punching nut, the part 3 of the sheet metal part 1 punched out in the center of the punching area 22 of the punching nut, which is designed as a punching ring, will, depending on the design of the forming tool, fall downwards out of the component 2 due to gravity or, for example, be pressed out of the punching opening of the component 2 with the aid of a pin projecting into the punching nut.

[0015] After the component 2 has been punched into the sheet metal part 1, the composite component thus created is shrunk in a cooling step following the hot forming process by shrinking the sheet metal part 1 in the openings in the sheet metal part 1 created during the punching process, ie the opening in the sheet metal part 1 contracts as a result of the cooling to such an extent that the component 2 is securely held in the sheet metal part 1.

[0016] According to a preferred embodiment, the component 2 has a circumferentially polygonal punching area 22, which pierces the sheet metal part 1 when the component 2 is punched. As a result, the component 2 is additionally held in the opening of the sheet metal part 1 with a positive fit and is thus able to withstand even larger torques exerted on the component 2 and to securely hold the component 2 in the sheet metal part.

[0017] By using component 2, designed here as a punch nut, as a cutting punch for cutting out the opening into which component 2 is to be inserted, the otherwise usual reworking of a cutting punch used to cut multiple sheet metal parts is no longer necessary. Furthermore, by simultaneously cutting the sheet metal part and inserting the component into the sheet metal part, a process step in the production of the composite component consisting of sheet metal part 1 and a component 2 is eliminated. Finally, the method according to the invention also eliminates problems that arise when attaching a component, such as a nut, to the sheet metal part by welding. List of reference symbols 1 sheet metal part 2 component Part 3 21 ring piece 22 Punching area

Claims

[1] Method for joining a sheet metal part (1) to a component (2), characterized by the following procedural steps: a. Heating the sheet metal part (1) to a temperature above the recrystallization temperature of the metal sheet, b. Forming the sheet metal part (1) in a forming tool, c. Placing the component (2) in a defined position on the hot sheet metal part (1) before, during or after forming the sheet metal part (1), d. Punching the component (2) into the still hot sheet metal part (1) with a punching device which is designed as part of the forming tool. [2] Method according to claim 1, characterized by that the component (2) is designed as a connecting component. [3] Method according to claim 1 or 2, characterized by that the component (2) is designed as a punching nut and is used as a cutting punch when punching the opening into the sheet metal part (1). [4] Method according to one of claims 1 to 3, characterized by that after punching the opening with the component (2) into the sheet metal part (1), the sheet metal part (1) shrinks onto the component (2) in a cooling step. [5] Method according to one of claims 1 to 4, characterized by that the component (2) has a circumferentially polygonal shaped punching area (22) which pierces the sheet metal part (1) when the component (2) is punched in, and that after the sheet metal part (1) has been shrunk onto the component (2), the component (2) is additionally held in a form-fitting manner in the opening of the sheet metal part (1).

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