METHOD AND DEVICE FOR INSPECTING AND/OR CONTROLLING THERMALLY PRODUCED MECHANICAL JOINTS

• US 3,648,009 A
• Filed: 05/05/1970
• Issued: 03/07/1972
• Est. Priority Date: 05/06/1969
• Status: Expired due to Term

• Current Assignee: Karl Heinz Steigerwald
• Original Assignee: Karl Heinz Steigerwald
• Inventors: Steigerwald, Karl Heinz
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): Peterson, Gale R.
• Application Number:
  US05/034,775
• Time in Patent Office: 672 Days
• Field of Search: 219/109,124,125,121EB,110,131R 318/638 73/340 324/62
• US Class Current: 219/121.14
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/034 Observing the temperature of the workpiece
• CPC Class Codes: B23K 26/0342 Observing magnetic fields related to the workpiece
• CPC Class Codes: G01K 1/146 arrangements for moving thermometers to or from a measuring position
• CPC Class Codes: G01N 25/72 Investigating presence of flaws

Abstract

The invention is concerned with a method and apparatus for effecting a thermal joint between two materials while sensing the condition of the joint during the joining process. The described example utilizes an electron beam as the heating means, there being sensing elements located in the region of the joint being made. The elements are sensitive to temperature or sonic or electric signals, and their outputs are processed to show the state of the joint, or to control the means making the joint. The sensing elements may be fixed to the workpieces or move with the electron beam along the path of the joint.

Claims

1. A method of monitoring the state of mechanical joints produced by joining two workpieces by a thermal joining process such as welding which comprises sensing, at the workpieces, during the joining process, values existing in the workpieces and dependent on changes of state occurrIng in the area where the joining takes place, said sensing taking place at predetermined sensing locations remote from said joining area, and utilizing said sensed values as a measure of the state of the joint produced.

2. A method as recited in claim 1, in which said values are sensed at a plurality of predetermined sensing locations which are spaced from each other and are remote from said joining area.

3. A method as claimed in claim 2 as applied to the production of a joint along a seam, including the steps of moving a thermal tool relative to said workpiece along said seam, and sensing the values of a particular quantity of state at sensing locations arranged on both sides of said seam and spaced therefrom.

4. A method as recited in claim 3, including the step of moving said sensing locations together with said tool.

5. A method as recited in claim 3, including the step of fixedly locating said sensing locations with respect to said workpiece.

6. A method as recited in claim 4, comprising the step of effecting movement of said sensing locations by successively taking sensing signals from different sensing locations which are stationary with respect to said workpiece.

7. A method as recited in claim 1, comprising the steps of producing an image of the area where said joint is to be made, said image corresponding with the distribution of at least one sensed variable quantity of state in said workpiece, said distribution being represented by the intensity distribution of said image.

8. A method as recited in claim 7, including the step of transposing said sensed variable quantity of state into visible light, the distribution of said quantity being represented by the light intensity distribution of said image.

9. A method as recited in claim 1, applied to repeated production of like joints in like workpieces, including the steps of performing a number of preliminary tests to determine an optimum distribution of a quantity of state corresponding to optimum processing by applying predetermined different working conditions, sensing and recording the associated distribution as to time and space of said quantity of state, examining to destruction the joints obtained;

thereafter applying, in the actual production of said joints, those working conditions which correspond to said optimum processing, sensing the distribution of said quantity of state occurring during said actual production, and discarding any joint obtained in which the deviation between the sensed and optimum distributions of said quantity of state is outside a predetermined tolerance range.

10. A method as recited in claim 9, including selecting the number of preliminary tests in accordance with a desired degree of security of the joint.

11. A method as recited in claim 1, including deriving a signal from at least one distribution of a sensed quantity of state, and utilizing said signal for controlling an operation of said thermal jointing process.

12. A method as recited in claim 3, including sensing the magnitudes of quantity of state at sensing locations which are disposed in front of said tool in the direction of the movement of said tool.

13. A method as recited in claim 1, comprising utilizing the temperature at predetermined parts of said workpiece as the quantity of state which reflects the changes of the state of the joint produced.

14. A method as recited in claim 1, comprising the step of feeding input signals into at least one input location of said workpiece to be connected during said jointing process, said input signals being of a kind capable of propagation within the workpiece material, and sensing a quantity of state which is dependent on said input signals and on the jointing condition prevailing in said jointing area.

15. A method as recited in claim 14, wherein said input signals are pressure signals, and wherein said quantity of state is a pressure signal which is sensed at at least one sensing location of said workpiece, said sensing location being spaced from said input location.

16. A method as recited in claim 15, wherein said pressure signals are ultrasonic signals.

17. A method as recited in claim 16, including the step of measuring the propagation time of said signals between said input location and said sensing location.

18. A method as recited in claim 16, wherein a reflection of said signals is sensed in the area of said joint being produced.

19. A method as recited in claim 16, comprising the steps of synchronously feeding sonic signals into at least two input locations, and sensing the resultant acoustic interference pattern at at least one location.

20. A method as recited in claim 14, utilizing magnetic signals as said input signals, and sensing a magnetic signal as said quantity of state at at least one sensing location.

21. A method as recited in claim 20, comprising the steps of utilizing an alternating magnetic field as said input signal, and sensing a magnetic flux change to evaluate said quantity of state.

22. A method as recited in claim 21, including sensing said magnetic flux density, and supplying the alternating magnetic field to the area of the joint being produced.

23. A method as recited in claim 14, applied to the production of a joint between two workpieces along a seam, including the steps of moving an electron beam thermal tool along said seam relative to said workpieces, and moving said signal input location along together with said tool.

24. A device for making a thermal joint between a pair of meltable workpiece materials, comprising a source of heat, means for producing relative movement between said workpieces and said heat source so that heat is progressively applied along the line of the joint to be made, a plurality of sensing elements arranged on said workpieces in a predetermined pattern relative to said line, said sensing elements being remote from said line and being responsive to values existing in the workpieces and dependent on changes of state occurring during the joining process in the area where the joining takes place, and means for evaluating signals received from said sensing elements.

25. A device as recited in claim 24, comprising sensing elements provided on both sides of said workpiece if a joint extends partly or totally between the two sides of said workpiece.

26. A device as recited in claim 24, wherein in the production of a joint along a seam, sensing elements are provided on both sides of said seam and remote therefrom.

27. A device as recited in claim 24, comprising a support, sensing elements arranged in a predetermined pattern on said support, and means for connecting said support with said workpieces, the arrangement being such that the sensing elements become effective at predetermined sensing locations on the workpieces upon interconnection of said support with said workpieces.

28. A device as recited in claim 24, comprising a support, said sensing elements being carried on said support, means for moving said support relative to said workpieces together with said thermal tool, said sensing elements becoming effective as measuring elements at;

predetermined surface areas along predetermined paths of said movement.

29. A device as recited in claim 28, wherein said means for moving said support provides yielding engagement between said workpieces and said sensing elements.

30. A device as recited in claim 24, comprising a programmer adapted to supply, synchronously with the progress of said jointing action, a program of desired values with respect to the signals obtained from said sensing elements during the jointing action.

31. A device as recited in claim 30, comprising a comparator adapted to compare the program values with the sensed signals, and to produce corresponding differential signals therefrom.

32. A device as recited in claim 24, comprising control means controlled by said signals of said sensing elements, and adapted to modify parameters of said jointing process in such a manner that said sEnsed signals remain within a predetermined range of values.

33. A device as recited in claim 24, comprising an imaging system, means causing said imaging system to respond to temperature differentials produced during the joining process in the region of the workpieces to be joined, said sensing elements being arranged on the image surface of said imaging system and separated from said workpieces.

34. A device as recited in claim 24, wherein said sensing elements are temperature sensors.

35. A device as recited in claim 24, wherein said sensing elements respond to the magnetic permeability of said workpieces.

36. A device as recited in claim 24, comprising a signal transmitter coupled to at least one predetermined input location of a workpiece to be joined, said signed transmitter supplying a signal which is capable of being propagated within said workpiece and responsive to said changes of state and which is receivable by said sensing elements.

37. A device as recited in claim 36, comprising means for moving said signal transmitter relative to said workpiece together with said thermal tool producing said joint.

38. A device as recited in claim 36, comprising means for coupling said signal transmitter to one of said workpieces, wherein at least one sensing element is arranged on the other of said workpieces so that the proportion of the signal supplied by said signal transmitter which is received by said sensing element, is dependent on the condition of said joint.

39. A device as recited in claim 36, wherein said signal transmitter is an alternating pressure transmitter.

40. A device as recited in claim 38, comprising two synchronously operated alternating pressure signal transmitters coupled to said one workpiece at a predetermined distance apart in the direction of said joint.

41. A device as recited in claim 40, wherein two sensing elements are located on the other of said workpieces at a predetermined distance apart.

42. A device as recited in claim 24, for the production of joints between electrically conductive workpieces, comprising at least one signal generator producing an alternating magnetic field, and at least one sensing element capable of responding to alternating magnetic flux, the density of which responds to said changes of state, said generator being located to produce said field in an area including the location where said thermal tool produces said joint.

43. A device as recited in claim 42, comprising means for moving at least one sensing element so that said sensing element senses during its movement different portions of said magnetic field.