Dimple-forming tool for projection welding

A tool is provided for forming a dimple on the edge of a metal sheet to facilitate projection welding of the sheet to an adjacent metal sheet. A reversible drill motor has a housing and chuck. A mounting bracket clamps onto the housing and a base is attached to the mounting bracket. A frame is attached to the base and has spaced apart arms. A first dimple forming die is mounted on one of the arms and a second dimple forming die is slidably mounted on the other of the arms. A driveshaft has a threaded end engaged in a threaded aperture of the second dimple forming die and a drive end captured in the chuck. Rotation of the driveshaft in one direction advances the second dimple forming die toward the first dimple forming to form a dimple in a sheet edge interposed between the dies.

FIELD OF THE INVENTION

The present invention relates to a tool for forming a dimple on the edge of a sheet metal panel, thereby forming a projection for a subsequent projection welding operation.

BACKGROUND OF THE INVENTION

It is well known in the manufacture as well as the repair of sheet metal articles to attach sheet metal panels together via a projection weld. In projection welding, a dimple is formed on one metal sheet and then a second sheet is abutted against the dimple of the first sheet. Electrodes are applied to the metal panels adjacent the location of the dimple and electric current is conducted between the panels to form an electric resistance weld.

The presence of the projection serves to concentrate the point of contact between the two metal panels so that an effective weld is formed.

In the manufacturing environment, the dimple is readily formed on the one metal sheet by including a dimple-forming feature in the metal stamping dies that are used to form the sheet.

The present invention relates to a handheld tool for readily forming dimples on the edge of a sheet metal panel and is particularly useful in vehicle body repair facilities, and in the broader construction and repair industries, where a series of dimples need to be formed on the edge of a metal panel in readiness for making a projection electric resistance weld between a pair of panels.

SUMMARY OF THE INVENTION

A tool forms a dimple on the edge of a sheet metal sheet to facilitate projection welding of the sheet to an adjacent metal sheet. The tool includes a reversible drill motor having a housing and adjustable rotating chuck, a mounting bracket for clamping onto the housing of the drill motor and a base attached to the mounting bracket. A frame is attached to the base and has spaced apart arms. A first dimple forming die is mounted on one of the arms and a second dimple forming die is slidably mounted on the other of the arms and has a threaded aperture therein. A driveshaft has a threaded end engaged in the threaded aperture of the second dimple forming die and a drive end captured in the adjustable chuck of the drill motor so that rotation of the driveshaft in one direction advances the second dimple forming die toward the first dimple forming die to form a dimple in a sheet edge interposed between the dies. Reversing the direction of rotation of the driveshaft in the other direction will withdraw the second dimple forming die away from the first dimple forming die.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following description of certain embodiments is exemplary in nature and is not intended to limit the invention, its application, or uses.

Referring toFIG. 1, a dimple-forming tool generally indicated at10is mounted upon a reversible electric drill motor12. Referring toFIGS. 1 and 2, it is seen that the tool10includes a mounting bracket14having an aperture16that fits over a cylindrical housing portion18of the electric drill12.

With regard to the following description,FIG. 2shows the component parts of the tool exploded for clarity, andFIGS. 3 and 4show the tool fully assembled but with parts broken away in section.

As seen inFIG. 2, the mounting bracket14has a slit22that intersects with the aperture16. A screw24is installed through threaded apertures in the mounting bracket14to reach across the slit22and, when tightened, causes the mounting bracket14to be tightly secured on the housing portion18of the drill12.

A tool base26is attached to the mounting bracket14by screws28and30. The tool base26is generally rectangular in shape but has a central slot36defining spaced-apart legs38and40. A U-shaped frame44includes a lower end that is captured within the slot36of the tool base26between the spaced-apart legs38and40. A bolt48extends through an aperture50in the leg38and a threaded aperture52in the leg40so that tightening of the bolt48will clamp the U-shaped frame44to the tool base26.

The U-shaped frame44has a left arm58and a right arm60spaced apart from one another by a slot62. The left arm58has a bore68that is aligned with a bore70provided in the right arm60. The left arm58has a female dimple die72mounted within the bore68. The dimple die72has threads74by which the dimple die72can be threaded into corresponding threads78provided within the bore68. The dimple die72has a die face82with a die cavity84.

A male dimple die or punch88is movably mounted within the bore70of right arm60by a cylindrical die housing90. The die housing90has a cylindrical outer surface92that fits within the bore70of the right arm60. The die housing90has a central rectangular bore94that will receive the male dimple die88. The male dimple die88has a transverse elongated slot98that aligns with apertures100and102provided in the die housing90. The right arm60of the U-shaped frame44has apertures106and108. The male dimple die88is inserted into the die housing90and the die housing90is in turn inserted into the bore70of the right arm60. A retaining pin or bolt112is installed through the aligned apertures106and108of the right hand arm60, and through the aligned apertures100and102of the die housing90and through the elongated slot98of the male dimple die88. Accordingly, the dimple die88is slidably retained within the right arm60and permitted to advance and withdraw relative to the fixed female dimple die72, as defined by the length of the elongated slot98. Dimple die88has an elongated projection110at the leading edge thereof.

A retaining block114is attached to the right arm60by screws116,118,120, and122. The retaining block114has a bore128that aligns with the bore70of the right arm60and the mounting aperture16of the mounting bracket14.

A driveshaft134has a threaded end136that is engaged within a threaded bore140of the male dimple die88. The driveshaft134also has a hex-shaped end142that is gripped within an adjustable chuck assembly148of the electric drill12.

An adjustable edge guide block150is captured within the slot62between the arms58and60of the U-shaped frame44. As best seen inFIG. 2, the guide block150has retaining arms152and154that ride on the left arm58. An elongated slot160is provided in the left arm58to receive a retaining bolt162. Retaining bolt162has threads164that are received within a threaded bore168of the adjustable guide block150. When the bolt162is loosened, the guide block150can be adjusted vertically up and down toward and away from the axis of the dimple forming dies72and88and the driveshaft134to an extent defined by the lengthwise elongation of the elongated slot160. When the bolt162is tightened, the guide block150will be held in place against vertical up and down movement. By adjusting the guide block up and down, the dimple184can be formed at a precise location on the edge of the panel180.

Referring now toFIG. 3, it is seen that the male dimple die88is withdrawn rightwardly away from the female dimple die72. A sheet metal panel180has an edge182that is resting upon the guide block150.

Referring toFIG. 4, the electric drill12has been energized to rotate the driveshaft134and thereby drive the male dimple die88leftwardly so that its projection110has displaced sheet metal into the corresponding cavity84of the female dimple die72. In this way, a dimple184is formed on the sheet metal panel180in order to enable the subsequent making of a projection bond between the sheet metal panel180and another sheet metal panel, not shown.

Reversing the drill12will withdraw the movable dimple die88rightwardly so that the sheet metal panel180can be removed from the tool. Or alternatively, the tool can be moved away from the sheet metal panel180.

In view of the foregoing, it will be appreciated that a dimple for projection welding can be readily formed on the edge of a sheet metal panel, and in particular, the tool hereof is particularly suited for use in a body repair shop in the automotive industry.

The description of the invention is merely exemplary in nature and, thus, variations thereof are intended to be within the scope of the invention.