US2930914A

US2930914A - Vibration hand tool

Info

Publication number: US2930914A
Application number: US662101A
Authority: US
Inventors: Alben C Johnson
Original assignee: General Dynamics Corp
Current assignee: General Dynamics Corp
Priority date: 1957-05-28
Filing date: 1957-05-28
Publication date: 1960-03-29
Anticipated expiration: 1977-03-29

Description

March 29, 1960 A. c. JOHNSON VIBRATION HAND TOOL Filed May 28, 1957 FIG. 2

INVENTOR. ALBEN C. JOHNSON aww ATTORNEY United States PatentO VIBRATION HAND TOOL Alben C. Johnson, Ontario, Calif., assignor to General Dynamics Corporation, San Diego, Calif., a corporation of Delaware Application May 28, 1957, Serial No. 662,101

7 Claims. (Cl. 310-27) This invention relates to vibration hand tools and more particularly to a vibration tool that will not vibrate until it is in actual contact with the object to be effected thereby.

l-Ieretofore, vibrating tools have been used as test instruments in the field of vibration analysis of structures and mechanisms. Through their use over a wide range of vibrating frequencies it is possible to test reliability of electronic circuits and components and to isolate the frequencies wherein malfunctioning of the equipment occurs. This is done by placing a vibrating armature in contact with the part under test While the part is in operating condition and observing the performance of the part over the selected range of frequencies. However, scoring and damage to parts has occurred when a freely vibrating armature is brought into contact with a part, often rendering an otherwise acceptable part unsatisfactory.

The vibration hand tool comprising the present invention is operable over a wide selection of frequencies and is so constructed that the armature is not vibrated until it is placed in contact with the test part, thereby eliminating possible damage to the part while testing. Upon contact the armature is automatically actuated and upon disengagement from the part, the vibration of the armature is stopped, permitting the operator to concentrate on the testing process Without concerning himself with the actuation of the test instrument. In one embodiment an energizing switch remains open except when the armature is urged inwardly by contact with the test part, at which time the switch is closed causing the armature to vibrate. In another embodiment the armae ture bar is held-in place by action of a polarized magnetic field in a path, a part of which is formed by the armature bar. When the armature contacts the test part it moves the armature bar, creating an air gap in the magnetic path and diminishing the effectiveness of the polarized field. When this is done an alternating magnetic field assists and opposes the polarized field at a variable selective frequency to cause the armature to vibrate at the desired frequency. Removal of the armature from contact with the test part closes the air gap in the polarized magnetic field, rendering the field strong enough to maintain the armature in fixed position.

It is therefore an object of the present invention to provide for an improved vibration hand tool.

Another object is to provide a vibration hand tool which will vibrate a test part selectively over a wide range of frequencies.

Another object is to provide a vibration hand tool which will not operate unless in contact with the object to be actuated thereby.

Another object is the provision of a vibration hand tool which is automatically actuated upon contact with the part to be vibrated thereby and automatically deactivated upon removal therefrom.

Another object is the provision of a vibration hand it tool having both an alternating magnetic field and a polarized magnetic field.

Another object is the provision of a vibration hand tool having two magnetic fields wherein one field alternately assists and opposes the other field to cause the vibrating action.

Another object is the provision of a vibration hand tool wherein contact of its armature with a part to be vibrated selectively opens or closes a gap between two components of said tool to cause vibrating action.

Other objects and features of the present invention will be readily apparent to those skilled in the art from the following specification and appended drawings wherein is illustrated a preferred form of the invention, and in which:

Figure 1 is a side view of one embodiment with parts broken away to better show its construction; and

Figure 2 is a side view of another embodiment broken away in part.

A C-shaped support 11 of soft iron or other material having low resistance to magnetic flux is shown in Figure 1. On the horizontal bottom leg 12 is positioned a permanent magnet 13 although a DC. electromagnet may be used if desired. Mounted on magnet 13 is a coil wrapped laminated core 14. The coil 16 is connected to terminals 17 to which a selected frequency source may be attached. On the vertical arm 18 of support 11 is an armature bar 19 mounted in such manner that its outer end 21 is free to move up and down in an oscillatory motion. A spring 22 extending downward from the top horizontal leg 23 urges the armature bar 19 against the top of laminated core 14. At the outer end of bottom leg 12 is mounted a suitable guide 24 in which an armature 26 is slidably positioned. Spring means 27 interengages the top of guide 24 with the armature 26 and urges the armature in contact with the outer end 21 of armature bar 19. Spring means 27 acts in opposition to the action of spring '22. Stop member 28 limits the upward movement of armature bar 19.

In operation coil 16 is energized from a desired frequency source (not shown). The permanent magnet 13 exerts a strong sealing pull and the armature bar 19 is pulled down tightly so that no chattering or vibration occurs. When the armature 26 is pressed against the part to be vibrated, it pushes the armature bar 19 away from core 14, making an air gap therebetween. This produces an air gap in the magnetic circuit path of the permanent magnet 13 and thereby lessens its pull on the armature bar 19. The alternating magnetic field produced by the A.C. coil 16 assists and opposes the polarized magnetic field to cause oscillations of the armature bar 19. The armature bar drives the armature 26 against the part and releases it each cycle of the A.C. applied to the coil 16. When the armature is removed from the part the air gap is closed and the armature bar 19 remains pressed against the core 14. As soon as the armature is pressed against another part, the tool is again automatically actuated and commences to vibrate the part.

In Figure 2 a permanent magnet 31 is mounted to the horizontal top member 32 of a C-shaped in cross section support 33 of soft iron or other material of low magnetic resistance. A core 34 of similar material extends from the magnet 31 downwardly into the opening between the inturned flanges 36 on the lower ends of legs 37. This forms a continuous path of low resistance to the resultant magnetic flux except for the air gaps between core 34 and flanges 36. Within these air gaps and around core 34 is a voice or driver coil 38 consisting of a plurality of turns of current conducting wire. Due to the shape of the magnetic structure, most of the flux set up thereby is forced to cross the air gaps and thus cross the wires of the driver coil 38. A connecting plate 39 connects armature rod 41 for movement with the driver coil 38. Suitable resilient fiexures 42 interconnect the plate 39 Patented Mar. 29, 1960,

3 t and armature rod 41 to an armature mounting base 43 in such manner as to give the rod lateral support and permit the rod to oscillatein its axial direction. One end of driver coil 38 is fastened to terminal 44. The other end is connected to one contact 46 of a normally open switch 47. The other contact 48 is connected to the armature rod 41 in such manner as to engage contact 46 only when the rod has been urged inwardly upon contact with a part to be vibrated. Contact 43 is connected to terminal 49 to complete the circuit. An energy source, not shown, is connected to terminals 44, 49 to cause vibration of the armature rod 41 when the switch 47 is closed by'armature contact with the part to be vibrated. Contact 43 is resilient and will maintain contact with contact 45 throughout the oscillatory motion of the armature rod.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation of a predetermined frequency assistin and opposing said polarized field, said armature actuating said tool in accordance with said frequency. p

2; A vibration hand tool comprising an electroma netic actuating means adapted to be connected to an external energy source, mechanical means connected to said actuating means and adapted to be actuated thereby, an control means con ected to said mechanical means for causing actuation of said actuating means when said mechanical means is in a predetermined position, said actuating means comprising a polarized magnetic field and an alternating magnetic field assisting and opposing said polarized field at a predetermined frequency, said mechanical means being actuated by said actuating means in response to said frequency.

-3. A vibration hand tool comprising a magnetic path having a gap therein, a driver coil within said gap, an armature connected to said driver coil for movement therewith, and means for connecting said coil to an external energy source of predetermined frequency in response to movement of said armature by engagement with a part to be vibrated thereby.

4. A vibration hand tool as in claim 3, said means comprising a normally open electrical switch closed by inward movement of said armature when contacting said part, said switch remaining closed during armature movement while said armature is in contact with said part.

5. A vibration hand tool comprising means for producing a poiarized magnetic field and an alternating magnetic field, an armature bar normally positioned by said polarizedmagnetic field to form part of a magnetic path therefor, means for moving said bar from said normal position when said means is contacting an external part to thus form an air gap in said magnetic path and thus lessen the relative strength of said polarized field, said alternating magnetic field alternately assisting and opposing said polarized field of lessened strength to thereby cause said means to vibrate against said part.

6. A vibration hand tool comprising an armature bar forming part of a polarized magnetic path, the magnetic field of said path retaining said bar in a predetermined position, means responsive to an external force for moving said bar from said position to create an air gap in said path to thus weaken its magnetic field, means for producing an alternating magnetic field alternating at a preselected frequency, said bar when removed from said position responding to said alternating field with a vibration motion, said bar vibrating said first-named means.

7. A vibration hand tool comprising a magnetic field,

an electromagnetic coil in said field adapted to oscillatetherein in accordance with an external energy source of predetermined frequency to be connected therewith,.

means connected to said coil for oscillating therewith, a normally open switch connected between said coil and said energy source, said means operable to close said switch upon contact of said means with a part to be actuated thereby, and maintain said switch in closed position until said means is removed from contact with said part.

References Cited in the file of this patent UNITED STATES PATENTS 149,797 Siemens Apr. 14, 1874 307,884 Van Depoele Nov. 11, 1884 557,159 Skinner Mar. 31, 1896 2,480,451 De LaTorre Aug. 30, 1949