Process for producing bundles of laminated sheet metal for magnet cores

A process for producing bundles of laminated sheet metal for magnet cores, wherein laminations are punched free along two longitudinal edges of a sheet metal strip, at least two sheet metal laminations of a magnet core are of a different width extending from one longitudinal edge to the other, and several laminations, which rest against each other, are connected with each other to form the bundle. To simplify the tool control, the two longitudinal edges of a lamination are punched in edge cutting stations, which are separate from each other and are arranged offset in the feed direction of the sheet metal strip. The edge cutting stations for cutting the longitudinal edges have a cutting die and an associated bottom die. The cutting die, together with the bottom die, is displaced for creating different laminate widths.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for producing bundles of laminated sheet metal for magnet cores, wherein laminations are punched free along two longitudinal edges of a sheet metal strip, at least two laminations of a magnet core are of a different width extending from one longitudinal edge to the other longitudinal edge, and several laminations, which rest against each other, are connected with each other to form the bundle.

2. Discussion of Related Art

A process for producing bundles is known from German Patent Reference DE 197 41 364 A1. Bundles made of sheet metal laminations are described there, which are employed in electromagnetic apparatus, for example impeders, transformers, drive mechanisms, and the like.

Individual laminations are stamped out of a sheet metal strip and are stacked on top of each other. Connecting the laminations is performed by a known packing method. With the process described in German Patent Reference DE 197 41 364 A1 it is intended to produce magnet cores of an approximately round cross section. Thus the width of the sheet metal laminations is varied. One or several sheet metal laminations with dimensions of the greatest width are positioned in the area of the center of the round cross section. For producing the geometry of the changing sheet metal laminations, a variable punching station is installed in a follow-on tool, which cuts the longitudinal edges of the sheet metal laminations. The cutting dies of this station can be adjusted, together with the bottom dies, by synchronous drive mechanisms.

A large control and positioning cost outlay is required, in particular in connection with tools in which several sheet metal laminations are punched in a single stroke.

SUMMARY OF THE INVENTION

It is one object of this invention to provide a process of the type mentioned above but in which the production of the variable widths of the sheet metal laminations is possible with a reduced technical cost outlay for the tool and with a high degree of accuracy.

This object is achieved with two longitudinal edges of a lamination punched in edge cutting stations, which are separate from each other and are arranged offset in a feed direction of the sheet metal strip. The edge cutting stations for cutting the longitudinal edges have a cutting die and an associated bottom die, and the cutting die, together with the bottom die, is displaced for creating different lamination widths.

Because there is a separation of the working of the longitudinal edges, the synchronization cost outlay for the exactly aligned displacement of the cutting dies and bottom dies is considerably reduced. It is thus possible to provide a clearly simplified mechanical tool arrangement. In particular, this is also improved because the cutting die is coupled with the bottom die, and they are displaced as a unit.

The fixed association of the cutting die and the bottom die makes alignment of these two parts of the tools unnecessary.

This embodiment of the tools is particularly advantageous when processing several laminations simultaneously in an edge cutting station. In this case the synchronization cost outlay is not at all, or is only slightly, increased.

In one preferred embodiment of this invention, through-holes for the formation of sheet metal pieces are punched out of some of the laminations in a follow-on perforating device between the two edge cutting stations. The sheet metal separation pieces are used for separating the produced bundles.

For continuously providing an exactly fitting alignment of the sheet metal laminations in the various processing stations of the follow-on tool, a follow-on perforating device is provided upstream of the edge cutting stations, in which locator perforations are punched out.

For combining the sheet metal laminations in the packing process, in a stamping unit depressions are punched out of a predetermined number of laminations, which protrude in the form of nipples on the side of the sheet metal piece opposite the side with the depressions.

The nipples of a sheet metal lamination are then pressed into the depressions of the adjoining sheet metal lamination in a manner of a snap fastener. When using sheet metal separation pieces, the nipples of the end lamination are inserted into the through-holes of the sheet metal separation pieces.

For punching the sheet metal laminations completely out of the sheet metal strip, in one variation of this invention the laminations are punched out of the sheet metal strip in the edge cutting stations of downstream-connected transverse stamping presses, wherein the transverse stamping presses each cut a transverse edge connecting the longitudinal edges.

DESCRIPTION OF PREFERRED EMBODIMENTS

The follow-on tool has a base plate10on which several processing stations are installed. A sheet metal strip30is conducted through the processing stations, out of which sheet metal laminations are punched.

A follow-on perforating device11is arranged at the entry into the follow-on tool, which punches locator holes out of the sheet metal strip30. The locator holes are subsequently used for positioning and aligning the sheet metal strip30in the follow-on stations. Thus, position pins engage the locator holes in each cycle of the machine. Following the follow-on perforating device11, the sheet metal strip30reaches an edge cutting station12, where the longitudinal edges of the sheet metal laminations which are on the left in the feed direction are punched out. The edge cutting station12has a lower bottom die support12.5. An upper element is connected with guide columns12.6. The upper element supports five punching dies12.1. The upper element and the bottom die support12.5form a carriage which can be displaced transversely with respect to the feed direction of the sheet metal strip30. The carriage is connected to a motor12.2via a coupling bearing14.4and an adjusting spindle12.3. The carriage can be displaced by the drive mechanism. In this case the bottom die and the punching dies12.1are positioned, fixed with respect to each other, by the guide columns.

A follow-on perforating device13is installed in the follow-on tool following the edge cutting station12. The through-holes for the sheet metal separation pieces are there punched out. Because only one sheet metal separation piece is needed for each magnet core bundle, the hole-punching dies are activated via the packing control by a slide. An edge cutting station14is arranged following the follow-on perforating device13and is embodied substantially identical with respect to the edge cutting station12. It can also be displaced transversely to the feed direction of the sheet metal strip30. But it is employed for cutting the longitudinal edge of the sheet metal lamination which is to the right in the feed direction. To change the width of the sheet metal laminations it is only necessary to displace the carriages in opposite direction to each other.

A stamping unit15is arranged following the edge cutting station14. It stamps depressions into one side of the sheet metal laminations. Thus, nipples are pushed out of the opposite side of the sheet metal lamination. The transverse edges, which connect the longitudinal edges, and therefore the sheet metal lamination L, are punched out in the transverse stamping presses16and18. Braking magazines are arranged underneath the transverse stamping presses16,18. The sheet metal laminations can be pushed into these with the punching dies of the transverse stamping presses16,18. The required counterforce for pushing the sheet metal laminations with nipples into the depressions of the previous sheet metal laminations (packing) is generated by a braking effect in the braking magazines. As soon as the required number of sheet metal laminations is stacked on top of each other, the sheet metal separation pieces are employed. Because these do not have nipples, no connection with the lamination underneath them occurs. Thus, the sheet metal separation piece forms the first sheet metal lamination of the next magnet core bundle. The two transverse stamping presses are spatially separated from each other by an empty follow-on device17.

Continuous monitoring takes place in a feed detection unit20for controlling the feeding of the follow-on tools.

The piece remaining of the sheet metal strip30is cut into individual pieces by a cutting device19at the end of the follow-on tool.