System and method for impact welding by magnetic implosion

• US 4,513,188 A
• Filed: 10/20/1981
• Issued: 04/23/1985
• Est. Priority Date: 10/20/1981
• Status: Expired due to Fees

• Current Assignee: Jack Katzenstein
• Original Assignee: Jack Katzenstein
• Inventors: Katzenstein, Jack
• Primary Examiner(s): Envall, Jr., Roy N.
• Assistant Examiner(s): LATEEF, MARVIN M
• Application Number:
  US06/312,964
• Time in Patent Office: 1,281 Days
• Field of Search: 219/7.5, 219/9.5, 219/10.41, 228/107, 72/56
• US Class Current: 219/617
• CPC Class Codes: B23K 20/06 by means of high energy impulses, e.g. magnetic energy

Abstract

A system for impact welding using an electrical coil producing a magnetic field of sufficiently high-intensity to impel a ballistic workpiece into a separate stationary workpiece for producing a weld therein. The pressure on the ballistic workpiece resulting from the magnetic repulsion between the ballistic workpiece and the coil results in the ballistic workpiece being propelled towards the stationary workpiece at sufficient velocity to form a weld. Parameters are provided for varying the voltage and inductance of the capacitor bank for particular driving coil and ballistic workpiece dimensions to obtain matching of the impedances of the capacitor and coil arrangement to the particular ballistic workpiece. The impedance matching maximizes the conversion of electrical energy in the bank to kinetic energy of the workpiece.

Claims

1. A system for impact welding by magnetic implosion comprising:

a ballistic work piece member for implosion to collide at welding velocity with a stationary work piece;

driving coil means disposed around said stationary work piece and said ballistic work piece and connected to a power source such that upon energization of said driving coil means by said power source, said driving coil means will cause said work piece to implode, propelling said ballistic work piece to welding velocity against said stationary work piece, said driving coil means being configured such that it possesses a coupling parameter selected to maximize efficiency of conversion of electrical energy of said power source to kinetic energy of said ballistic work piece, and

an insulator mounted between said ballistic work piece member and said driving coil means to prevent passage of electrical current between said coil means and said ballistic work piece.

2. The invention as set forth in claim 1 wherein said coupling parameter is defined as follows:

##EQU19## wherein L_o is the self-inductance of the driving coil, C is the capacitance of said power source, V_o is the initial charging voltage of the power source, R_o is the radius of the driving coil, and m is the mass of the ballistic work piece.

3. The invention as set forth in claim 2 wherein the efficiency is given as follows:

##EQU20## wherein x_f is equal to Rf divided by R_o, R_f being equal to the final radius of the work piece after implosion, said efficiency being the ratio of final kinetic energy of the work piece to the electrical energy stored in the power source.

4. The invention as set forth in claim 1 further including a power source in the form of a capacitor means connected to said driving coil means.

5. A system for impact welding by magnetic implosion for application to butt welding substantially flat plates comprising:

ballistic work piece members in the form of substantially straight bars disposed around a stationary work piece to be welded;

a power source;

driving coil means disposed adjacent said ballistic work pieces, said driving coil means forming an elongated rectangular coil and being configured to produce a pressure of approximately 2×

10⁶ to 3×

10⁶ psi on said ballistic members so that said ballistic members are propelled at welding velocity into said stationary work piece and to maximize efficiency by maximizing a coefficient of coupling thereof.

6. A system for impact welding by magnetic implosion applicable to pipe welding comprising:

a ballistic work piece in the form of a ring disposed about a work piece to be welded;

driving coil means in the form of a ring disposed upon said ballistic work piece, said driving coil means being connectable to a power source and being configured to maximize efficiency of conversion of electrical energy of said power source of kinetic energy of said ballistic work piece, by appropriate selection of a coupling paremeter of said power source and said driving coil means with said ballistic work piece; and

an insulator mounted between said ballistic work piece member and said driving coil means to prevent passage of electrical current between said coil means and said ballistic work piece.

7. The invention as set forth in claim 6 wherein said coupling parameter is given as follows:

##EQU21## wherein r is the minor radius of the driving coil member, R is the major radius of the driving coil member μ

_o is the permeability of the vacuum, C is the capacitance of the power source, V_o is the initial voltage of said power source, R_o is the initial major radius of the driving coil means, and m is the mass of the ballistic work piece.

8. A system for impact welding by magnetic implosion comprising:

a ballistic work piece member disposed adjacent a stationary work piece member;

driving coil means disposed adjacent ballistic member and a connectable to a power source in the form of capacitance means, said driving coil means being positioned to produce a pressure of approximately 2×

10⁶ to 3×

10⁶ psi on said ballistic member to thrust said ballistic member at welding velocity against said stationary member upon energization of said driving coil means by said capacitance means, said driving coil means having a coefficient of coupling with said capacitance means such that efficiency of energy transfer from said capacitance means to said driving coil means and to the implosion thereof, is maximized.

9. The system of claim 8 wherein said ballistic member prior to being thrust against said stationary member is spaced from said stationary member a distance at least approximately twice the thickness of said ballistic member in order that said ballistic member can be accelerated for a sufficient distance to attain welding velocity prior to colliding with said stationary member.

10. The system of claim 8 wherein said ballistic member is positioned to collide with said stationary member at a chamfered section thereof, the faces of said ballistic member being inclined from the faces of said chamfered section at an angle of approximately 5-8 degrees.

11. The system as set forth in claim 8 further including a mandrel, said mandrel positioned adjacent said stationary work piece member to stop movement of said ballistic work piece member at said stationary work piece member.

12. The system as set forth in claim 8 wherein said driving coil means comprises a solenoid member including capacitor means connected to form a transmission line.

13. A method for maximizing efficiency of impact welding by magnetic implosion comprising the steps of:

(1) providing a ballistic work piece for colliding with a stationary work piece to be welded at welding velocity;

(2) providing a driving coil means disposed adjacent said work piece member and connectable to power source, for actuation therefrom so that said driving coil produces a pressure of approximately 2×

10⁶ to 3×

10⁶ psi on said ballistic member in order to said ballistic work piece to impel the latter at welding velocity to collide with the stationary work piece; and

(3) configuring the driving coil means such that its coefficient of coupling with said power source maximizes efficiency of energy utilization.