US1978118A - Riveting gun - Google Patents

Description

@cfh 23,, 134. E, w; STEVENS RIVETING GUN Filed Oct. 31, 1929 ATTORNEY.

range simple, compact and easily operated manthe escape of motive fluid. Still another object 'varied at will from a light tap for setting a rivet Patented Oct. 23, 1934 PATENT oFFics RIVETING GUN Edward W. Stevens, Detroit, Mich., assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application October 31, 1929, Serial No. 403,694

14 Claims. (01. 121-21) This invention relates to fluid pressure perm cussive tools and in particular to single acting riveting hammers or guns adapted to head a rivet with one blow. Such tools are for use in driving small rivets as in aircraft construction work and similar operations. 1

One object of the invention is to provide an improved tool of simple and strong design and which is positive in action. Another object is to vary at will the force of the blow and to arual means for so doing. Another object is to provide a novel throttle and exhaust control arrangement. Still another object is to utilize the die, rivet set, or other working tool, to prevent is to retard the initial movement of the impact member to insure ample volume of pressure fluid behind the same. Still .another objectinvolves automatic means for restoring the impact member to position for striking another blow. Other Objects will be apparent from the detailed description which follows.

The invention involves a pneumatic tool striking one blow at a time, which blow may be to a powerful smashing stroke which expands, heads, and clinches a rivet in a single operation. Releasable holding means for the piston at the beginning of its stroke permits nicety of control of the force of the blow and preferably takes the form of a vacuum grip. The same holding means may form a cushion stop for the piston on its back stroke. A single manually operated member governs the exhaust for the opposite ends of the piston chamber as well as the admission of the motive fluid. The inletpipe for the motive fluid supply. may serve as a stop for the control member. The piston is automatically returned for the next blow by fluid pressure -means and the working tool is utilized to prevent.

ing drawing, in which:

Fig. 1 is a longitudinal sectional view substantially on the broken line ll of Fig. 3, showing a tool embodying the invention ready for use;

Fig. 2 is a sectional View similar to Fig. 1 show- "ing the tool at the moment of striking the blow;

Fig. 3 is a transverse sectional view substantially on the line 33 of Fig. 2; and

Fig. 4 is an enlarged detail sectional view show- .ing a modification.

The embodiment ofthe invention chosen, for the purpose of illustration, comprises a riveting gun having a cylinder 5 providing a piston chamber in which reciprocates hammer piston 6 to strike blows upon a working tool such as a rivet set 7 slidably supported in a front head 8 which is threaded into the forward end of cylinder 5 and serves both as a guide and a retainer for the working tool. To this end working tool 7 has a stop collar or flange 7a which on outward movement engages a seat 8a on front head 8 after the manner of a poppet valve for a purpose presently to be described. On its inward movement stop' collar 7a engages retainer ring 9 for piston 6, which ring is clamped against a shoulder in cylinder 5, by front head 8 and defines the front end of the piston chamber. 1

By preference, and as a manufacturing expedient, cylinder 5 may be formed by inner and outer. sleeves 5b and 5a, respectively, having a press fit with each other and maintained in assembled relation by any suitable means as by welding. Sleeves 5a and 5?) form therebetween an air chamber 10 which communicates with the forward end of the piston chamber by a series, of ports ll in sleeve 5b and at its other end has a'transverse series of exhaust ports 12 through the outer sleeve 50.. In spaced relation to ports 12 is another transverse series of exhaust ports 13 which extend through both sleeves of cylinder 5 and communicate with the rear end of the piston chamber which is defined by a throttle head 14 having a flange abutting the end of inner sleeve 51) and a thimble like hollow projection 14a extending axially within the piston chamber to cooperate with recess 6a inthe rearward end of piston 6 for a purpose presently to be described.

Slidably mounted within projecting portion 14a of the throttle head and controlling a series of inwardlyinclined inlet ports 15 substantially in the plane of exhaust ports 13, is a throttle valve 16 having a restricted port 17 therethrough, to equalize the pressure on the opposite sides thereof. Valve16 is continuously forced outward by a coil spring 18 disposed ina recessed portion of the valve. Throttle valve16 may be moved inwardly to open position by a stem or push rod 19 having one end seated in a recess in the valve andthe other end guided by a bore 20 in back head 21, the latter being threaded into the projecting end of outer sleeve 5a of the cylinder and acting through suitable spacing means, such asspring 22, upon throttle head 14. to maintain the latter. in place.

i The control means for throttle valve 16 and for cylinder exhaust ports 12 and 13 comprises a push handle 23 having a closed end to engage rod 19 and a cylindrical portion 23a which is sleeved over cylinder 5 and provided with a single transverse series of exhaust ports 24 arranged to register with ports 13 when in its rearward position (Fig. 1) and with ports 12 when in its forward position (Fig. 2). The motive fluid supply pipe 25 extends through handle 23, through bore 26 in cylinder sleeve 5a and has threaded engagement with a bore 21a in back head 21 thereby serving as a lock to secure and maintain the handle and associated parts in the rear end of the gun in assembled relation. Inlet pipe 25 also serves as a stop for the rearward movement of control handle 23 (Fig. 1) which is efiected automatically through the action of a coil spring 2'7 seated against throttle head 14 on the one hand and a cup member 28 engaging collar 19a on rod 19.

When handle 23 is in its rearward position (Fig. 1) piston 6 is always returned to and maintained at the limit of its rearward stroke in position for the next blow by pressure fluid passing in limited amount through a constantly open port 29 in the flange of throttle head 14, which port communicates through a restricted port in a plug 30 with a passage 31 communicating with annular chamber 10 and thence through ports 11 with the front end of the piston chamber. The pressure fluid thus supplied acts on working tool 7 forcing it outwardly so that stop flange 7a acts as a poppet valve against seat 8a to seal the front end of the piston chamber. Exhaust ports 12 are sealed by sleeve portion 23a of the handle so that there is no escape for the pressure fluid. Recess 6a and piston 6 make a sliding fit with projection 14a but there is just sufficient clearance to permit a slow outward or inward movement of air so that an air cushion is provided for the rearward movement of the piston, thereby preventing breakage. The constant pressure applied by the motive fluid in the forward end of the piston chamber gradually forces out the air trapped between the head of piston 6 and the end of projection 14a so that piston 6 comes to rest normally in the position shown in Fig. 1. The rearward edge of piston 6 is inwardly tapered at 62) to assist in the escape of trapped air from recess 6a. This tapered edge also provides clearance for the fillet at the base of projection 14a and permits motive fluid issuing from ports 15 to circulate around the end of piston 6.

When the operator uses the tool he directs working tool 7 to the work and as he applies pressure he forces tool 7 inwardly until flange 7a engages retainer ring 9. Control handle 23 is then forced forwardly bringing ports 24 and 12 into register, thus opening the front end of thepiston chamber to exhaust. At the same time throttle valve 16 is moved to the position shown in Fig. 2 admitting motive fluid through inlet ports 15 against the inwardly tapered edge 61) of piston 6. If throttle valve 16 is opened slowly, the small amount of motive fluid thus admitted moves piston 6 gradually away from projection 14a and the piston strikes a light blow or tap upon tool 7 to set the rivet. On release of the handle, throttle valve 16 closes and exhaust ports 24 and 13 are brought into register relieving the pressure in the rear end of the piston chamber (Fig. l) at the same time permitting the motive fluid flowing through passages 29 and plug 30 and passages 31 to build up and become effective to move piston 6 back for the next blow. The operator then forces handle 23 sharply forward until the handle strikes back head 21. The large volume of motive fluid suddenly striking piston 6 tends to move it quickly forward. This produces a suction hold within recess 6a with the result that a strong suction hold is effective upon piston 6. This retards the movement of the piston and permits air in full volume to enter the rear end of the piston chamber so that when the suction hold is finally released the piston 6 shoots forward and delivers a powerful smashing blow which expands, heads, and clinches the rivet.

Fig. 4 shows a slight modification of the control arrangement whereby motive fluid passes into chamber 10 for the back stroke of piston 6 only when control handle 23 is in its rearward position. To accomplish this the port through the flange of throttle head 14 is omitted and in place thereof spaced ports 32 and 33 are provided in outer cylinder casing 5a, which ports are bridged by a groove 34 in handle sleeve 23a. Plug 30a, with its restricted port, establishes communication between port 32 and passage 31.

While the invention has been herein described in what is now considered to be a preferred embodiment, it is to be understood that the invention 1 is not restricted to the specific details thereof but covers all changes, modifications, and adaptations within the scope of the appended claims.

I claim as my invention:

1. A fluid pressure percussive tool having a pis- 1 ton chamber, a piston reciprocable therein having a recess in its rearward end, a retarding device for the piston comprising a projection within said cylinder conforming to said recess and making a sliding fit with said piston, thereby to 1 provide both a cushion stop and a suction hold for said piston, means for exhausting the pressure fluid from said recess, and manually controlled fluid pressure means for breaking said suction hold. 1

2. A fluid pressure percussive tool having a piston chamber, a piston reciprocable therein having a recess in its rearward end, a projection within said cylinder conforming to said recess and making a sliding fit with said piston, means for 1 simultaneously moving said piston into nested engagement with the projection and exhausting the air within said recess, thereby to provide a suction hold for said piston, and means in said projection for admitting motive fluid behind said 1 piston when the latter engages said projection.

3. A fluid pressure percussive tool having a piston chamber, a piston reciprocable therein having a recess in its rearward end, a projection within said cylinder conforming to said recess 1 and making a sliding fit with said piston, said projection having ports for admitting motive fluid behind said piston when the latter closely engages said projection, and a valve movably supported by said projection for controlling said 1 ports.

4. A fluid pressure tool having a cylinder, a piston reciprocable therein, a throttle head within said cylinder defining one end of the piston chamber, a throttle valve in said head, a back head for 1 said cylinder in spaced relation to said throttle head, said spaced heads forming therebetween a chamber for pressure fluid, a control handle having a grip portion and a portion sleeved over said cylinder, a pressure fluid conduit extending 1 through said grip portion of said handle and secured to said back head, and means whereby movement of said handle on said cylinder operates said throttle valve, said conduit serving as a stop for such movement. 1

5. A fluid pressure percussive tool having a piston chamber, a piston reciprocable therein having a recess in its rearward end, a projection within said cylinder conforming to said recess and making a sliding fit with said piston, means within said projection for supplying motive fluid to said piston chamber to drive said piston away from said projection, and means acting automatically to restore said piston to telescoping relation with said projection when said first-named means is inoperative.

6. A fluid pressure percussive tool having a piston chamber, a piston reciprocable therein having a recess in its rearward end, a hollow member having a portion projecting within said cylinder and conforming to said piston recess so that said piston may telescope thereover with a slight clearance, said projecting portion having ports therethrough to admit motive fluid behind said piston, and a manually operablevalve slidably mounted within said hollow member for controlling said ports.

'7. A fluid pressure percussive tool having a piston chamber, a piston reciprocable therein having a recess in its rearward end, a projection within said cylinder conforming to said recess and making a sliding fit with said piston, said projection having ports for admitting motive fluid behind said piston when the latter closely engages said projection, a valve movably supported by said projection for controlling said ports, and means operating automatically when said valve is in port-closing position to restore said piston to telescoping relation with said projection.

8. A fluid pressure percussive tool having a piston chamber, a piston reciprocable therein having a recess in its rearward end, a projection within said cylinder conforming to said recess and making a sliding fit with said piston, said projection having ports for admitting motive fluid behind said piston when the latter closely engages said projection, a valve movably supported by said projection for controlling said ports, and means independent of control by said valve for admitting motive fluid to the opposite end of said piston chamber to restore said piston to telescoping relation with said projection.

9. A fluid pressure percussive tool having a piston chamber, a piston reciprocable therein having a recess in its rearward end, a hollow member having a portion projecting within said cylinder and conforming to said piston recess so that said piston may telescope thereover with a slight clearance, said projecting portion having ports therethrough to admitmotive fluid behind said piston, a manually operable valve slidably mounted within said hollow member for controlling said ports, and means supplying motive fluid in restricted amount to the opposite end of the piston chamber to return said piston when said valve is in position to close said ports.

10. A fluid pressure percussive tool comprising inner and outer sleeves forming a cylinder, said inner sleeve providing a piston chamber and said outer sleeve extending beyond said inner sleeve at one end, a head within said outer sleeve in engagement with the end of said inner sleeve, a back head secured in the free end of said outer sleeve, and resilient means engaging said heads for yieldingly maintaining said first head in place.

11. A fluid pressure percussive tool comprising inner and outer sleeves forming a cylinder, said inner sleeve providing a piston chamber and said outer sleeve extending beyond said inner sleeve at one end, a head within said outer sleeve in engagement with the end of said inner sleeve, a back head secured in the free end of said outer sleeve, spacing means between said heads, means for controlling admission of motive fluid to one end of said piston chamber comprising a throttle valve supported by said first-named head, and an operating member for said valve extending through said back head. i

12. A one-shot fluid pressure percussive tool 100 having a piston chamber, a piston reciprocable therein, means for admitting pressure fluid behind said piston, means at the rear end of said chamber for subjecting said piston to a suction hold to retard initial movement of the piston, said means comprising interfitting cylindrical parts on the piston and the rear end of the chamber respectively, and means for holding the piston at said end of the chamber over a continuous period.

13. A fluid pressure tool comprising a cylinder having a piston chamber therein, a piston reciprocable in said chamber, a combined cushion and retarding device interposed between the rear ends of the piston and chamber respectively, one of said last-mentioned parts having a cylindrical recess adapted to receive a close fitting projection on the other of said parts, said recess being adapted to cushion the piston at the end of the rear stroke thereof, means for urging said piston rearwardly for a sufficient length of time to exhaust air or pressure fluid from said recess, whereby a vacuum is subsequently formed in said recess when the piston is forced forwardly,'and means for admitting pressure fluid behind the piston to force the same forwardly, said pressure fluid being adapted first to oppose the suction in the recess and then break the suction hold.

EDWARD W. STEVENS.

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