US2736219A

US2736219A - Bolt tensioner and wrench

Info

Publication number: US2736219A
Authority: US
Publication date: 1956-02-28
Anticipated expiration: 1973-02-28

Description

Feb. 28, 1956 M 2,736,219

Filed July 8, 1954 ilnited States Patent BOLT TENSIONER AND WRENCH Joseph May, Parrna Heights, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application July 8, 1954, Serial No. 442,067

Claims. (Cl. 81--52.4)

This invention relates to a tool for tightening bolts or studs and more particularly a device for stressing bolts, studs and the like to a predetermined elongation and axial stress.

The present invention has as its principal object to improve the bolt-stressing and nut-tightening device disclosed in United States patent application Serial No. 442,068, filed July 8, 1954, in the name of Morris W. Carlson, entitled Tool, so as to provide a simpler and more fool-proof mechanism in operation.

The device disclosed in the aforementioned application includes means for first stressing the stud or bolt axially to predetermined values of axial elongating loads and wrench means for subsequently tightening down the mating nut on the elongated bolt to maintain the axial stress within the bolt; a procedure resulting in controlled uniform axial stressing of the bolt to achieve an elasticity and flexibility of the bolted joint not possible with con ventional stud or bolt-tightening methods without a relatively high percentage of failures during and subsequent to the assembly operation. The aforementioned applica tion further discloses a tool including an adaptor member which is adapted to engage the end of the bolt beyond its nut. The adaptor carries a power-operated mechanism which is selectively energizable to react between the opposite end of the bolt or stud through the bolted members to exert a predetermined elongation and stress on the bolt. An integral gear and socket wrenchprovided in the tool is then utilized to advance the nut on the elongated bolt to take up the slack occurring therein and to bring the nut ino snug relation with the adjacent bolted part.

The above stated object of the present invention is attained by replacing the integral gear and socket wrench of the aforementioned application with a wrench assembly which includes a separate socket wrench member and a separate wrench driving gear member biased axially of each other to insure proper engagement of the adaptor member and wrench member with the bolt end and nut, respectively, prior to the bolt-stressing and nut-advancing functions of the device and to prevent the application of excessive torques through the gear member with consequent undesirable torquing of the bolt or breakage of the gear teeth.

This and other objects of the invention will be more thoroughly understood from the following detailed description in which reference is made to the accompanying drawing, in which:

Figure 1 is aview of a tool embodying my invention with portions broken away and in section.

Figure 2 is an exploded perspective view of certain elements shown in Figure 1.

Referring more particularly to the drawing, Figure 1 illustrates a through bolt having a necked-down shank portion 10 and a threaded end portion 11 having a nut 24 threaded thereon. The bolt is shown extended through a bore provided in a member 18 which represents one of a plurality of members to be secured together by the nut and 2,736,219 Patented Feb. as, 1956 bolt, such as one of two diametrically split clamping ring halves for securing individual cylinders to an engine crankcase as disclosed in United States Patent No. 2,674,988. A washer member 22 is shown interposed between the nut 24 and the member 18.

The bolt-stressing and nut-tightening tool, as shown by Figure 1, includes a bolt stressing means comprising an adaptor member 30 provided with a threaded bore 34 at one end for engaging the threaded end 11 of the bolt and with a handwheel 36 secured to the opposite end thereof for turning the adaptor down on the bolt. The bore 34 may be provided with a plug 38 for limiting the threadable engagement of the adaptor member with the bolt end. An intermediate shank portion 32 of the adaptor is slidably and rotatably embraced by an annular cylinder 40 which is connectible to a controllable source of pressure fluid, not shown, by a conduit 44. An annular piston member 42 is reciprocably mounted within the cylinder 40 and forms an expansible chamber therewith. The piston is provided with a sleeve portion 44 and a collar member 46 threaded thereon which serves to transmit the reaction of the piston to the head of the bolt, not shown, through the clamped members when fluid pressure is supplied to the pressure cylinder 40 while the cylinder acts on the threaded end of the bolt 10 through the adaptor 30 and its handwheel 36 to effect a predetermined axially elongating stress on the bolt in accordance with the pressure of the actuating fluid supplied by the controllable source.

The wrench means 43 of my invention, as shown in Figures 1 and 2, is rotatably mounted within the sleeve portion 44 of the piston and is retained therein by the collar 46. The wrench means includes an assembly in which a wrench socket member 49 and a socket driving gear member 50 are formed separately. These two members are provided with telescoping dogs 49 and 50 to form a driving connection therebetween and are spring biased axially of each other by a plurality of springs 48 into abutting relation with the piston-carried collar and a pinion gear 52, respectively. The gear 50 meshes with and is driven by the bevel gear pinion 52 which is journalled in and projects laterally from the side of the piston member 42 as shown at 54. The gear 52 may be rotated either by a manually operable knob 56, as shown, or by a suitable power device, not shown. The springs 48 are seated at one end Within axially extending bores 49 in the socket member and are seated at their opposite end against the geared member 50 which is provided with an internal spring guide pin 50" for each spring. By proper selection of the spring constant for each of the springs 48" the socket driving gear 50 will tend to. be shifted axially out of engagement with the pinion 52 when the nut has been snugged down the desired amount against the washer 22 thereby preventing undesired axial and torsional stressing of the bolt by the nut and thereby insuring precision uniformity in the bolt stressing. The axial shifting of the driving gear 50 will also occur should the nut become frozen on the bolt for any reason, such as cross-threading, which might result in breaking of the gear teeth. It will thus be seen that this spring-biased drive arrangement serves to protect the tool and prevents excessive torque application to the wrench means to thereby avoid over-stressing of the bolt 10 whether the pinion is driven by power or manual means.

The spring-biased drive arrangement of the wrench socket also permits the bolt adaptor 3%) to be threaded upon the bolt end 11 to the proper depth of engagement without the socket necessarily telescopically embracing the nut 24. With the wrench means of this invention, if the socket 49 has not embraced the nut 24, after the threaded adaptor has properly engaged the bolt end and either before or after elongating the bolt .10, .the pinion 52 can be rotated slowly until the socket is in such a position' thatthe springs 48" will urge it axially to telescopically embrace the nut. With integral socket and gear, disclosed in the aforementioned patent application, it necessaryfto utilize mechanical references to insure that the"a'd aptor has engaged the bolt end to a proper depth b'eforeth'e' cylinder was energized to elongate the bolt.

"The tool illustrated maybe utilized for threaded members of different assorted sizes by provision for interchangeableadaptor members 3b and wrench socket members 49. "The adaptor member 30 is axially removable from the tool'by removing the nut 58 and radial or axial pins, not shown, non-rotatably securing the handwheel 36 on the external end of the adaptor. Either the entire wrench assembly 48' or merely the wrench socket 49 are removable "frorn the tool by first removing the retaining collar 46. It will be apparent that the adaptor and socket member can be replaced with similar members of the desired size by reverse procedures' invention contemplates an improved device for tightening nut and-bolt members by a method which basically comprises the steps of first elongating the bolt member with a predetermined axial stress, and secondly advancing the nut member upon the elongated bolt into snug relationship with the adjacent one of a plurality of bolted-together members to maintain the predetermined elongating stress within the bolt. Other secondary steps will become apparent, however, from the detailed discussion below of the operation and use of the aforedescribed nut-and-bolt tightening tool embodying the improved wrench means of my invention.

' The bolt nut may be advanced upon the bolt by either conventional means before using the tool of this invention for tightening purposes or by the socket wrench provided in the tool. If the tool is to be used as an assembly wrench, the nut will be placed within the socket 4-9 before turning on the bolt. If the nut is already threaded on the bolt, the side knob 56 is used to help slip the socket upon the nut. In either case, once the nut has been initially turned down on'the bolt, the adaptor is pushed into engagement with the bolt and is then threadably advanced upon the bolt by rotation until it engages the threaded bolt end to a proper depth as controlled by the plug 38 or similar stop means determined by external or mechanical reference. The expansible chamber formed by the cylinder 4b and the piston 42 is then connected to the controlled fluid pressure source through the fluid pressure line 41 to produce a predetermined hydraulic load axially stressing and elongating the bolt. The socket 49 is then rotatably driven by the gears 50 and 52 advancing the nut toward the head end of the bolt and into snug relation the washer 22 without appreciable application of torque to the bolt. In this manner the looseness resulting from the elongation of the bolt is removed and the nut n its advanced position maintains the predetermined axial stress upon the elongated bolt when the fluid pressure is relieved and the tool is removed.

It should be noted that the bolt or stud tightener of my nvention can be utilized both as an assembly and tightenmg wrench and that it is not necessary to the practice of my invention that the stressing of the bolt members be accomplished during'assembly. It will be appreciated that there are numerous articles of manufacture, such as engmes or the like in which it would be advantageous to precis on tighten all of the bolts only after final assembly.

While the foregoing description and figures have been confined to one specific embodiment of the invention, it

will be apparent to those skilled in the art that numerous modifications can be made Without departing from the SplIlt'flHd scope of the inventive concepts thereof. Accordm gly, it is to be understood that the foregoing ar to be interpreted as illustrative only and not in a limiting sense, reference being had to the appended claims to determine the scope ofv the invention. 7 I

I claim:

'lr'A'nut-and-bolt tightening device comprising a cylinder having means associated therewith for engaging the free end of a bolt above its nut, a piston reciprocably mounted within said cylinder and having one end thereof adapted to react against the opposite end of said bolt, means operable to supply fluid to said cylinder at a given pressure to cause said cylinder and said piston to apply a predetermined axial tensile stress to said bolt thereby ating the bolt, and means carried by said piston for cing the nut toward the opposite end of the bolt while the tensile stress is maintained, said last mentioned means including a spring-biased axially shiftable socket wrench for said nut.

2. A nut-and-bolt tightening device comprising a hydraulic cylinder having means associated therewith for engaging the free end of a bolt above its nut and a plurality of members secured thereby, a piston reciprocably mounted within said cylinder and having one end thereof operable to react against the adjacent one of the members, said cylinder being connectible to a source of hydraulic pressure adapted to supply hydraulic fluid of a given pressure to said cylinder to produce a predetermined axial stress elongating the bolt, and means carried by said piston for advancing the nut into snug relation with the adjacent member to maintain the stress when the device is de-energized and removed, said last mentioned means including a wrench socket member, a socket driving member, and a spring biased telescopic driving connection between said socket member and said driving member.

3. A device for tightening a nut and a bolt securing a plurality of members together comprising means for applying a predetermined axial stress to the bolt to effect an elongation thereof prior to tightening the nut thereon and means associated with said first means for advancing the nut into snug relation with the adjacent one of the plurality of' members to maintain the elongation of said bolt after'the'removal of'the device, said last mentioned means including a spring-biased axially shiftable socket wrench for said nut and a gear member having a telescoping driving connection with said socket'wrench.

4. A device'for applying a predetermined axial stress to a bolt securing a plurality of members together prior to tightening a nut thereon comprising an adaptor for engaging the bolt 'e'nd above the "nut initially placed thereon, a'hydraulic cylinder carried by said adaptor having a piston reciprocably mounted therein, one end of said piston beingadapted to 'rejactagainst the adjacent member of the plurality of members, said cylinder being connectible to a controllable source of hydraulic pressure to apply an axial stress tothe bfolt effecting an elongation thereof, a wrench socket rotatably mounted by said piston and adapted to embrace the nut, and a gear member having a spring-biased telescoping driving connection with said wrench socket and being engageable with geared driving means whereby the nut may be advanced into snug relationship with the adjacent member of said plurality of members to maintain the'stressed elongation of said bolt.

5. A device'for applying a predetermined axial stress to a bolt securing a plurality of members together comprising means for 'elfecting the elongation of the bolt prior to tightening down a nut thereon and means for advancing the nut on' theelongated bolt into snug relationship with the'adjacenfmember of said plurality of members, said second means includinga spring-loaded axially shiftable socket Wrench for said nut.

6. A tool comprising means for initially applying an axially elongating stress to a bolt or stud securing aplurality of members together and means for subsequently tightening a nut thereon into snug relation with the adjacent one of the plurality of members whereby the elongao o the 12 sma nt ines u n. emo a of the d v a a t me ioned mean nclud g. a pr n -b d ving connection releasable to, preyent application of torsional stresses to said bolt. through said. nut.

7. A device for applying a predetermined axial tensile stress to a bolt securing a plurality of members together prior to tightening down a nut thereon, comprising a threaded adaptor for engaging the bolt end beyond the nut, a cylinder carried by said adaptor having a piston reciprocably mounted therein and being connectible to a source of fluid pressure, one end of said piston being adapted to react against the adjacent one of the members whereby a given fluid pressure applied to said cylinder will apply axial tensile stress to the bolt to the predetermined amount, and wrench means rotatably carried by said piston for tightening the nut into snug relation with the adjacent member, said wrench means including an axially shiftable wrench socket, a first gear member having a spring-biased telescopic driving connection with said Wrench socket, and a second gear member drivingly engaging said first gear, said spring-biased telescopic connection permitting axial shifting of the first gear out of driving engagement with said second gear upon application of a predetermined torque to said nut.

8. A tool including power means for first applying axial tensile stresses to a bolt and means for then advancing a nut thereon while maintaining said axial tensile stresses in said bolt, said last mentioned means including a driving connection releasable upon application of a predetermined torque to said nut.

9. In a wrench for tightening down a nut on a bolt to secure a plurality of members together, the combination comprising a housing member having a bore therein, a first gear member journaled in said bore, a second gear member rotatably mounted by said housing member 6 E adapted to drivingly engage said first gear, and a Wrench socket mounted within said housing bore and having a spring biased telescopic driving connection with said first gear member, said spring biased telescopic connection permitting axial shifting of the first gear out of driving engagement with said second gear upon application of a predetermined torque to said nut.

10. A Wrench assembly for tightening a nut upon a bolt to secure a plurality of members together, comprising, in combination, a wrench socket, a gear member hav' ing a spring biased telescopic driving connection with said Wrench socket, geared driving means adapted to drivingly engage said first-mentioned gear, and a casing rotatably mounting said wrench socket and said firstmentioned gear, said casing and said gear driving means restraining the axial shifting of said wrench socket and said gear member in opposite directions, said spring biased telescoping driving connection permitting axial shifting of said Wrench socket toward said first gear and said spring biased telescoping driving connection permitting axial shifting of the gear member toward said socket member and out of driving engagement with said geared driving means upon application of a predetermined torque to said nut.

References Cited in the file of this patent UNITED STATES PATENTS 1,353,600 McBride Sept. 21, 1920 1,389,154 Newhouse Aug. 30, 1921 2,544,522 Bertelsen Mar. 6, 1951 2,631,485 Stuart et a1. Mar. 17, 1953