Distortions around weld areas on sheet-aluminum tanks and other structures are removed with a portable electromagnetic hammer. The hammer incorporates a coil that generates a controlled high-energy pulsed magnetic field over localized areas on the metal surface

Schwinghamer, R. J.

English

NASA Technical Reports Server

3ulged Tank Wall 
Weld 
November 1965
	 Brief 65-10342 
SA TECHBRIEF 1:P,L 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Electromagnetic Hammer Removes Weld Distortions from Aluminum Tanks 
The problem: To remove distortions (bulges) 
around the weld areas on sheet-aluminum tanks and 
other structures. Time-consuming hammer and die 
operations which have been commonly used for this 
purpose are not generally reliable and tend to damage 
the surface finish of the material. 
The solution: A portable electromagnetic hammer 
incorporating a coil that generates a controlled high-
energy pulsed magnetic field over localized areas on 
the metal surface. The magnetic field applies a fairly 
uniform force over an area corresponding to that of 
the face of the coil and thereby removes distortions 
(by bending or stretching of the metal) without the use 
of a die. 
How it's done: The electromagnetic hammer in-
cludes five essential parts: a power source, capacitors
for storing electric energy, transmission lines, a heavy-
duty switching device (e.g., an ignitron), and a magnet 
coil consisting of a spirally wound insulated heavy 
conductor. The coil is mounted in a holder which is 
used to position the coil with respect to the work 
surface. The holder may also incorporate means for 
clamping it to the work surface and a pneumatic 
damping cylinder to absorb the recoil energy from the 
hammering operation. 
The metal to be reshaped comprises part of the total 
magnetic system. When the electrical energy stored in 
the capacitor bank is switched into the magnet coil, 
the changing discharge current causes a changing mag-
netic field in the coil which induces surface currents in 
the workpiece. The magnetic field associated with the 
workpiece currents reacts with the magnetic field in 
the coil to produce the distortion-corrective forces. 
(continued overteal) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19650000340 2020-03-11T17:25:05+00:00Z
The magnet coil is placed over the workpiece to cor-
reét the distortion over one small area at a time. It is 
repositioned and pulsed as necessary until the distor-
tions are removed from the entire sUrface of the work-
piece. 
Notes: 
1. The special feature of this invention is the design 
of the magnet coil and mounting. 
2. The electrical conductivity of the material being 
processed determines the effectiveness of electrical 
energy conversion to magnetic forces. The electro-
magnetic hammer cannot be used directly on non-
conductive materials. 
3. The coils can be made small and light and con-
nected to a remote power supply by means of long 
transmission lines to provide an assembly-line tool 
for removing distortions from sheet-metal com-
ponents.
4. The electromagnetic hammer should be advanta-
geous in metalworking operations requiring the 
controlled application of a load on a small area of 
workpiece at any one time. 
5. Inquiries concerning this invention may be directed 
to:
Technology .Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama, 35812 
Reference: B65-10342 
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about ob-
taining rights for its commercial use may be made to 
NASA, Code AGP, Washington, D.C., 20546. 
Source: R. J. Schwinghamer 
(M-FS-287)
Pi 
B65-10342	 Category 05


Electromagnetic hammer removes weld distortions from aluminum tanks

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