US2324853A - Core clamp - Google Patents

Description

CORE CLAMP Eed Dec. 2'?, 194B H. R'. KORTE July 20, 1943.

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H erm am 1Q. Korte by )Va/y ,JMA/M4 His Attorney.

corners being furthermore suitably rounded not only for facilitating the stamping operation but also for the purpose of improving the stress distribution as will be more fully explained hereinafter. After the stamping operation is completed, the edges of the channel sides may be trimmed, if necessary, in order that the edges will lie in a substantially common plane throughout the channel sides. {Ihe two clamping members are placed against the opposite sides of the core structure with the edges of the channel sides against the fiat or longitudinal surface of the laminations, it being understood that the width of the channel of the clamp members is somewhat less than the width of the outer core legs and yokes of the core structure. The two clamp members are forced `together by means of a pair of bolts 35 and 36 which extend through cooperating holes pro-` vided in the yokes of the E laminations of the reactor units Il and I2. The cooperating openings in the clamp members being in substantial registry with the holes or apertures in the yokes are elongated in the direction of the core axis in order to permit adjustment of the non-magnetic gaps in a manner to be presently described. Suitable washers 31 are provided between the head and nut of the bolt and the clamping members. Thus, each of the frame members has a generally ring-like shape with straight sides connected by wholly rounded corners and has a substantially uniform channel shape cross section at all points around its periphery so that the core members may be clamped tightly tgether.

Because of the channel cross sectional shape of the clamp members, they will be Very rigid due to the fact that the channel sides thereof extend edgewise with respect to the core surfaces. So great is their rigidity that only two bolts are required, as shown, for securely clamping together a core structure of the type herein described comprising three separate lamination stacks. By providing rounded corners for the clamp members there is no`such concentration of stress as might cause bending of the clamp members at these points, and as a result, tightening of the bolts at the opposite ends of the assembly will exert sufficient compressive force between the clamp members throughout their length so as to adequately clamp together the laminations of the intermediate transformer unit as well as those of the reactor units.

After the unit has been assembled, the leads of the various windings may be connected to indicating instruments of the testing apparatus (not shown), and the operational characteristics of the device may be adjusted, if necessary,

by slightly varying the spacing of the non-magnetic gaps through the use of any suitable means. It will be readily understood by those skilled in the art that even though a non-magnetic spacer 25 is selected of such a predetermined thickness which should give the required gap spacing, further adjustment of the gap may be necessary depending upon the degree of accuracy required in the finished product. Such adjustment may be accomplished by simply tappin'g the appropriate end of the device with a small mallet, variously comprising the fibrous spacer 24 or25 until the exact desired indication is obtained on the test instruments., By reason of the slightly elongated holes provided in the core clamps, the cores of the two reactance units may be shifted somewhat for effecting the adjustment of the non-magnetic gaps relative to the transformer core. Since the bolts 35 and 36 extend laterally or at right angles with respect to the lamination stacks, there will be no tendency on the part of these bolts to alter'the nonmagnetic gap spacing once it has been adjusted. The contact friction between the edges of the clamp members and the laminations will hold the cores rmly and maintain the gap as adjusted throughout the remainder of the assembly operation.

The transformer device may now be mounted within an enclosing housing 39, as shown in Fig.-

3, which may then be filled with a suitable insulating compound indicated at 40, substantially lling the housing after which the cover 4l may be applied. l

It will be apparent that the clamping arrangement of this invention is extremely simple and of low manufacturing cost, and yet at the same time may be adapted for clamping relatively complicated core structures, such as that shown. The clamping device serves not only for fastening together the laminations of a number of individual core stacks, but because of the great rigidity of the clamp members, it may also be utilized for securing the plurality of core stacks relative to each other in a predetermined spaced relation.

Having described my invention in what I consider to represent a preferred embodiment thereof, I desire to have it 'understood that the specic structure shown is merely illustrative and that the invention may be carried out by other means. y

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A clamp for a stack of magnetic core laminations having outer core legs and yokes comprising a pair of stamped sheet metal frame members, each of said members having a generally rectangularly ring-like shape with straight sides connected by wholly rounded corners and conforming to the contour of the outer legs and yokes, each of said members having substantially uniform channel shaped cross section of less width than that of the legs and yokes at all points around its periphery, the edges of the channel sides being continuous and terminating apparatus having a substantially rectangular laminated magnetic core with outer legs and yokes, a pair of clamping members for said core each comprising a stamped substantially rectangularly ring-like shaped sheet metal frame with straight sides connected by rounded corners and conforming to the contour of the outer legs and yokes, each of said frames having a substantially uniform channel shaped cross section at all points around its periphery, each of said frames around its periphery having a width less than the width of the outer legs and yokes and` contlnuous edges terminating in a common planev so that the channel edges of said frames-will en-` gage said outer legs and yokes of said substantially rectangular core, and means for clamping shaped sheet metal frame with straight sides y connected by wholly rounded corners, said frames including said corners having a substantially uniform channel shaped cross section of less width than that of the legs and yokes at all points around its periphery with continuous edges terminating in a common plane, and clamping means for forcing said frames against opposite surfaces of said core with the channels of said frames facing said core.

HERMAN R. KORTE.

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