US 3593001 A
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Description (OCR text may contain errors)
United States Patent  Inventors William G. Simpson;
Bllly K. Devin, both of Huntsville, All. [21 Appl. No. 889,437  Filed Dec.3l,1969 [4S] Patented July 13, 1971  Assignee The United States of America as represented by the Adminbtrntor of the National Aeronautics and Space Administration  STUD-BONDING GUN 9Clnims,7 Drawing Figs.
 U.S.C1 219/243, 156/66, 156/320, 219/221  Int-Cl H051! H00  Field 0! Search 219/243, 221, 228, 230, 237, 245, 240;156/66, 306, 320, 502
 Reierences Cited UNITED STATES PATENTS 2,681,685 6/1954 Arkless 219/227 2,942,096 6/1960 Jones... 219/98 3,281,576 10/1966 Cooper et a1 219/421 32 ts. :27. N i 60 i b i 34 6 "11;" :1
l l :..:1 .1 1 l 74 N s :zzzj 3,005,421 10/1961 Lea.
OTHER REFERENCES IBM TECHNICAL DISCLOSURE Epoxy Curing Tool," Vol.9 No. 10, March 1967 ABSTRACT: A tool for mounting and removing studs having an adhesive coated head portion and a stem extending therefrom. The tool includes an outer housing with attached handle and a stud-receiving means mounted in the housing. The stud-receiving means includes a heater for softening the adhesive on the stud, a locking device for releasably holding the stud in the tool and ejection means for ejecting the stud toward a mounting surface when the locking means is released by closing a trigger switch. Electrical contact elements mounted in the housing are actuated when pressed against the mounting surface. The contact elements are connected in series with the trigger switch to prevent release of the locking means unless the contact elements are properly actuated. This assures proper positioning of the tool with respect to the mounting surface. A heat-sensing device is provided for monitoring the temperature of the stud head portion.
PATENTED JUL 1 319m SHEET 1 BF 2 III! Fig. 6
INVEN TOR Biliy K. Davis William G. Simpson BY (,0?
M C ATTOHNF Y5 STUD-BONDING GUN ORIGIN OF THE INVENTION The invention described herein was made by employees of the United States Government and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION The invention is a tool for bonding studs of various types to a surface. More particularly it is a tool which makes it possible to mount and/or remove a stud from a surface without altering or defacing the mounting surface.
The time is rapidly approaching when men will be either fabricating or modifying various structures in the zero gravity environment of space. To accomplish this a number of new tools have or will be developed; some useful only in space, but many also useful in a terrestrial environment where gravity forces are present. The present invention falls in this latter group since it will be useful here on earth even though designed specifically for zero gravity operation. Some features of a space tool might be altered somewhat if it were going to be used only on earth. For example, the handle of the tool described herein has been made very large and roomy so as to easily accommodate the gloved hand of an astronaut. Also the handle has been designed so that no rotational torque will be generated "Zen a stud is ejected from the gun. The first experimental prototype built had a simple pistol grip, which made the tool cheaper to construct and adequate for use on earth where the user is firmly anchored because, due to gravity, he has weight. A space-rated tool however, requires an improved handle. This brief discussion is not an attempt to attach particular significance to the tool handle, but is intended only to point out that tools for space may have expensive special requirements not present in tools for terrestrial use. Actually, handle design is one of the more simple and straightforward features to be considered in designing a tool for an astronaut.
It can be appreciated that in most construction operations various types of studs can be put to good use in mounting arrangements and in making connections. For example, space station equipment such as TV cameras, workshop-type tools, lights, and wiring harnesses associated with such equipment, could be stud mounted. Studs will facilitate extra-vehicular activity when used to fasten mooring lines or attachment rings to the outer surface of the space station. Equipment and supplies can be positioned outside the vehicle and lashed down to one or more studs. Telescopes, solar cell panels and antennas could be fastened to the outer surface of a space station with studs. The listing could go on to include almost anything which required mounting or attaching.
For down-to-earth applications the tool could be used to apply studs to aircraft and other vehicles for mounting added equipment. This could be simpler than drilling and/or tapping holes in the mounting surface. In public buildings, particularly those having walls of marble or other expensive coverings, removable studs could be used for hanging pictures or signs so that subsequent changes will not result in the wall being defaced. Methods of mounting studs heretofore have usually included an actual insertion of the stud into the wall. In instances where the stud was applied to a wall or workpiece by adhesives. the wall or workpiece was heated. Heating the workpiece is often difficult and sometimes prohibited if the workpiece is heat sensitive.
SUMMARY OF THE IN VENTION The object of the invention is to provide a tool for mounting and removing adhesively bonded studs from a surface. The tool includes a housing having a handle attached thereto, and a stud-receiving means mounted within the housing for holding and ejecting a stud from the tool. The stud-receiving means includes a heater having a heating element positioned such that heat will reach a coating of thermoplastic adhesive on the head portion of a stud inserted in the stud-receiving means. The stud-receiving means also includes a locking device for releasably holding the stem portion of a stud in the stud-receiving means. The locking device is actuated to release the stud by a trigger and trigger switch positioned in the handle. A spring and piston arrangement included in the stud-receiving means bears against the stem of the stud and ejects the stud with considerable force when the locking device has been released. A plurality of electrical contact means are mounted in the housing around the periphery of the heater. Each contact means includes a plungerlike device which when depressed by contact with the mounting surface actuates a control switch. Each control switch is in turn connected in series with the trigger switch that releases the locking device holding the stud. Thus, the locking device cannot be released unless the tool is properly positioned with respect to the mounting surface. When the stud is ejected against a cold surface the adhesive thereon is spread evenly upon impact because of the ejection force and rapid cooling of the adhesive occurs to form a quick bond between the surface and the stud. A heat-sensing device is included in the tool to monitor the temperature of the head portion of the stud. An adjustable temperature control is also provided so that various heats can be applied to the head of the stud and thus permit the use of different adhesives.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a pictorial view of the stud-bonding gun;
FIG. 2 is a cross-sectional side view, partially broken away, of the stud-bonding gun;
FIG. 3 is a cross-sectional view of the stud-receiving means removed from the tool and includes the heater, locking device and stud ejection means;
FIG. 4 is a view of the heat-sensing means removed from the stud-receiving means;
FIG. 5 is an enlarged view of the sensing end of the thermocouple probe;
FIG. 6 is a cross-sectional view of the electrical contact means mounted in the housing around the heater;
FIG. 7 is a view taken along lines 7-7 of FIG. 2 that illustrates the temperature-indicating gage, the temperature regulating device and an on-off switch.
DETAILED DESCRIPTION OF THE INVENTION FIG. I is a pictorial view of the stud-bonding gun consisting of an outer housing It) having a forward or front cylindrical casing 12 and an enlarged rear casing M to which a handle 16 is secured by bolts 18 or other suitable means. A trigger i7 is mounted in the handle along with a trigger switch 19 (see FIG. 2), electronics package 20 and power cord 21. Casing 12 has an inner housing or casing 22 mounted therein that is concentric to casing l2. Casings 22 and 12 form an annular chamber 24 in which three equally spaced electrical contact devices 26, 28 and 30 are mounted. The function of the electrical contact devices will be described in more detail hereinafter. Annular chamber 24 is closed by a closure member 32 which has openings formed therein to accommodate the electrical contact devices.
Centrally mounted within housing I0 is a studreceiving means indicated generally in FIG. 2 by numeral 34. The studreceiving means includes a relatively large disc-shaped housing 36 attached to a smaller cylindrical housing 38. Housing 36 is designed to receive the head portion 40 (FIG. 3) of a stud 42 which has a layer 43 of thermoplastic adhesive applied thereto. As can be seen from FIG. 3, stem 44 of the stud is hollow and is positioned within cylindrical housing 38. A heating device for softening the adhesive is mounted in housing 36 and consists of a plate 41 having an inwardly tapering surface that conforms to the shape of the head portion of the stud. Resistance heating elements 43 are encased in a ceramic material which abuts plate 41 so as to facilitate heat transfer therebetween and to the head portion of the stud. A source of electrical current is connected to heating element 43 by means of externally threaded electrical connector pins 46 and 48. Plate 4l and ceramic material are insulated from housing 36 by a suitable mounting adhesive 50 and an insulator block 52 which is secured in position by a plate 54 closing one side of housing 36. The elements just described all have a central opening therein that forms an opening 56 through which the stem portion 44 of the stud can pass. The output of the heating device is high enough to accomplish rapid heating of the stud to a temperature required by the adhesive coating.
Housing 38 which accommodates the stem portion of the stud is composed of a forward section 58 and a slightly larger rear section 60. Where the two sections meet a shoulder 62 is formed which functions as a stop for a piston 64 slidably mounted in housing 38. Piston 64 has a skirtlike portion 66 having a diameter substantially equal to that of cylinder section 58 and an outwardly extending flange 68 having a diameter substantially equal to that of cylinder section 60. Flange 68 abuts shoulder 62 when the piston has been biased to a forward position by spring 70 housed in section 60 of cylinder 38. A hollow cylindrical plug 72 closes end 60 of cylinder 38.
A locking device 74 mounted on section 58 of cylinder 38 engages a groove 82 in stem 44 of the stud to hold the stud in a cocked position and retain piston 66 in a rearwardly or cocked position wherein spring 70 is compressed between flange portion 68 of the piston and one end of cylindrical plug 72. The locking device is a solenoid-actuated mechanism that is released when electrical current is passed through the solenoid via connections 76 and 78 (see FIG. 2) and plunger 80 is withdrawn from groove 82 in the stud. As is readily apparent, withdrawal of plunger 80 releases the stud so that it will be ejected from the stud-receiving means by the forward motion of piston 66 due to spring 70 expanding.
A heat-sensing device, like for example a thermocouple probe 84 (see FIG. 4), is centrally mounted in the stud-receiving means and adapted to enter the hollow stem of the stud. The probe is composed of a long slender tube 86 having two wires 88 and 90 (see FIG. composed of dissimilar metals, one of iron and one of constantan, extending the length thereof and embedded in an insulation material 92 filling tube 86. The ends of wires 88 and 90 are welded together at one end of tube 86 and this weld is surrounded by a heat-conduo tive packing 94 which also forms a closure for one end oftube 86. The other end of tube 86 is closed by means of a base member 96 mounted thereon. A guide member 98 is mounted intermediate the ends of tube 86. The tip ofthe probe containing the welded wires is positioned near the stud head portion for sensing the temperatures thereof.
Base member 96 is slidably mounted in a bore 99 formed in cylindrical plug 72 and guide member 98 is slidably mounted in a bore I00 formed in piston 64. Bore 100 is closed by a plug 102 threaded into piston 64. A spring I04 mounted between guide member 98 and plug 102 biases probe 84 to a forward position. In the forward position end surface 106 of base 96 is spaced away from a microswitch I08 mounted in cylindrical member 72. Insertion of the stud into the stud-receiving means results in probe 84 being moved to the rear so that surface 106 of base 96 comes into contact with contact [I0 of microswitch I08. Microswitch 108 is connected into a circuit with heating element 42 so that the heater cannot be activated unless the stud has been fully inserted into the stud-receiving means. Electrical leads I12 and 114, extensions of wires 88 and 90, are connected to a suitable temperature readout device discussed hereafter.
As mentioned above, proper positioning of the tool is assured by means of electrical contact devices 26, 28 and mounted in housing 12 in a spaced relation about the periphery of disc-shaped housing 36 surrounding the studhealing device. Each electrical contact means, as shown in FIG. 6. consists of a tubular housing l 16 having another tubular housing 118 mounted in one end thereof. Housing [16 has a bore 120 formed therein in which a pistonlike member I22 is slidably mounted. A plunger I24 is slidably mounted in member I22 and guided in its movement through bore 120 by means of a guide member 126 intermediate the ends thereof. A spring 128 mounted on plunger 124 between guide 126 and the end of piston I22 normally maintains plunger I24 in the position shown in FIG. 6. Plunger 124 has an end portion 130 which extends outwardly to a position in front of housing 10 as shown in FIG. I. When plunger end portion 130 is pushed to the rear against the action of spring 128 it tends to push piston 122 to the rear to actuate microswitch 132 mounted in casing 118. Each of the three spaced electrical contact devices includes a microswitch and all three of these microswitches are connected in series with trigger l6 and the solenoid of locking device 74 shown in FIG. 4. This is so that the stud cannot be released from the stud-receiving means until the stud-bonding gun has been properly positioned with respect to a surface on which it is to be mounted.
FIG. 7 is a view taken along lines 7-7 of FIG. 2 illustrating a plate 134 which forms a closure for housing 10. Plate 134 also provides a mounting surface for a temperature-indicating instrument I36 connected (not shown) to the heat-sensing probe. The instrument could be any galvanometer or potentiometer-type instrument adapted for use with a thermocouple probe and capable of reading out temperature. An adjustable temperature control mechanism I38, a potentiometer or other suitable device. is mounted in plate 134 and also connected to the heater (not shown) for controlling the amount of heat applied to the stud head portion. Immediately below mechanism I38 is an on-off switch 140, also connected to the heater by circuitry not shown herein, that the user of the tool actuates to turn the heater on or off.
The operation of the tool will now be discussed, assuming that the tool is in the grasp of a user and that the power cord has been connected to a suitable source of power and the user has a supply of studs available to him with adhesive on the head portions thereof. A stud is inserted into the stud-receiving means so that the head portion abuts the tapering surface of plate 40 of the heating device. In this position groove 82 in the stem of the stud will be engaged by plunger 80 of locking device 74 and the stud will be held in the tool. Inserting the stud will also move piston 64 to the rear compressing spring 70. The user will turn the gun on with onoff switch to start the heating and then position the tool with respect to the surface on which a stud is to be mounted. When the tool has been properly positioned the plunger 130 in each of the electrical contact devices will be depressed to actuate the microswitch in each contact device, so as to activate the circuit containing the trigger switch. As was discussed above, no current can flow to the trigger until all three of the microswitches in the electrical contact devices have been closed. When, as indicated by the temperature readout device 136, the head portion of the stud has been heated to a point wherein the adhesive applied thereto is ready for use, the user will depress trigger 17 to close trigger switch I9 and thereby apply power to locking device 74 to retract plunger 80 from groove 82 in the stem of the stud. When the stud is released piston 64 will be driven forward by spring 70 to eject the stud from the stud-bonding tool. The stud will strike the surface on which it is to be mounted with considerable force and this results in an even spreading of the adhesive over both of the surfaces to be joined. The mounting surface is cold and there results a rapid transfer of heat away from the stud that cools the adhesive and makes a quick bond between the stud and the mounting surface.
This completes the detailed description of the invention. While a preferred embodiment has been described there will be many variations which can be made to the invention. The exact circuitry employed in the device has not been described in detail herein because such circuitry could vary considerably depending upon how sophisticated the tool was to be constructed. For example, it may well be for some applications that a very precise temperature control would be required and therefore a more complicated temperature adjustment mechanism 138 made up of several components might be required. The same would hold true for the temperature-indicating mechanism 136 and for all of the other components used in the tool. Thus, the circuitry would vary with the selection of components. In any event the actual circuit design for connecting the various components of the tool would be well within the skill ofa competent electronics technician.
What we claim is:
l. A tool for mounting a stud having a hollow stem and a head portion with a coating of thermoplastic adhesive applied thereto to a mounting surface by bonding the adhesive-coated head portion of the stud to the mounting surface, said tool comprising:
an outer housing adapted to be held in a person's hand;
a stud-receiving means mounted in said outer housing for holding the stud, said stud-receiving means including a heater means for heating the head of the stud to soften the adhesive and an ejection means for directing the heated head portion of the stud against the mounting surface, whereby the heated thermoplastic adhesive will adhere to the mounting surface and form a permanent bond when the thermoplastic adhesive cools and solidifies; and
electrical control means mounted in said tool for controlling said heater means and said ejection means, said electrical control means comprising contact means mounted in said outer housing and actuated by contact with the mounting surface, said contact means operating to effectively inactivate said electrical control means unless the contact means are in engagement with the mounting surface.
2. The tool recited in claim 1 wherein said stud-receiving means includes:
a disclike housing mounted in said outer housing so as to surround and abut a stud positioned in said stud-receiving means. said disclike housing having said heater means mounted therein for applying heat to the stud so as to soften the thermoplastic adhesive on the stud; and
a cylindrical housing mounted to said disclike housing for receiving the stern of the stud and housing said ejection means.
3. The tool recited in claim 2 wherein:
said cylindrical housing has a reduced inside diameter at a point intermediate the ends thereof and an inwardly projecting shoulder at that intermediate point, whereby two bores of different diameter are formed in said cylindrical housing, that end of said cylindrical housing having the reduced inside diameter being connected to said disclike housing;
a cylindrical member having an internal bore substantially smaller than either of those in said cylindrical housing fixedly mounted in the other end of said cylindrical housing and forming a substantial closure therefor;
a pistonlike member slidably mounted in said cylindrical housing for engagement with the stern of a stud held therein, said pistonlike member having an annular flange formed on one end thereof that abuts the inwardly pro jecting shoulder in said cylindrical housing at one extreme of its travel; and 7 spring means positioned between said pistonlikc member and said cylindrical member that exerts a force tending to bias said pistonlike member toward said inwardly projecting shoulder. whereby an ejecting force will be applied to a stud held in said stud-receiving means.
4. The tool recited in claim 3 which further includes:
locking means mounted on said cylindrical housing for releasable engagement with the stem of said stud to lock said pistonlike member in a cocked position wherein said spring means i compressed.
5 The tool recited in claim 4 wherein said stud-receiving means further includes a rod-shaped heat-sensing element centrally mounted in said cylindrical housing and slidably mounted through said pistonlilte member, said heat-sensing element having one end thereof extending into the hollow stem of said stud to a position ad acent the head portion thereof for sensing the temperature of the head portion.
6. The tool recited in claim 5 wherein:
a base member is mounted on the other end of said rodshaped heat-sensing element and positioned for slidable movement in said cylindrical member;
a switch means mounted in said cylindrical member that is contacted by said base member when the rod-shaped heat-sensing element is moved rearwardly in response to a stud being inserted in said stud-receiving means.
7. The tool recited in claim 6 which further includes:
a large handle connected to said outer housing for facilitating use of the tool; and
a hand-operated trigger switch mounted in said handle.
8. The tool recited in claim 7 which further includes a temperature gage for reading out the temperature of the stud head portion.
9. The tool recited in claim 8 which further includes an adjustable temperature control means for controlling the amount of heat applied to the stud head portion.