Solenoid powered riveting tool

Abstract

 A solenoid (34,71) actuated blind rivet tool having pulling impulse intensifying means co-acting with the mandrel pulling mechanism (14,20,22,86). One type of impulse intensifying means is a slideable connection of the tool's nose housing (11), housing the assembly for engaging and tensioning the mandrel, and power chamber (36) which comprises the remainder of the tool housing, which power chamber carries a solenoid (34) for powering the tool. The solenoid pulls the nose housing (11) rearwardly until it impacts against the power chamber (55), creating a high-magnitude impulse force to break the mandrel. In lieu of a slideably mounted nosepiece (11), the tool may include a member (86) linked to the pulling mechanism (14,20,22) and a ram (75) which is driven against the member by the solenoid (71) thereby creating an impulse force which is transmitted to the pulling mechanism.

Description

[0001] This invention relates to blind rivet tools and more particularly to blind rivet tools having an electromagnetic solenoid for actuating the rivet pulling mechanism.

[0002] In the field of tools for setting blind rivets, it is conventional to use a pneumatic or hydraulic power source to pull the mandrel of the rivet to set the rivet and break the mandrel stem. An example of such a tool is shown in commonly owned our European Patent Specification EP 0130040 (U.S.P. 4517820).

[0003] Attempts have been made to use an electric power source to set a blind rivet. However, these devices require a gear reduction mechanism to obtain sufficient pulling force to break the mandrel stem. An example of such a blind rivet tool is shown in U.S.P. 3095106. Tools of this type have longer rivet setting cycles than the pneumatic or hydraulic type.

[0004] Another attempt at using an electric power source is shown in U.S.P. 3646791 wherein a stress wave is passed through the rivet to render it momentarily plastic so the rivet can be set.

[0005] It is the purpose of the invention to provide an improved blind rivet tool utilising an electromagnetic power source for the pulling mechanism of the tool.

[0006] According to the present invention, an electromagnetically-powered blind rivet setting tool comprises rivet engaging means for engaging a rivet mandrel;
sliding element means connected to said rivet engaging means for moving said rivet engaging means between advanced and retracted positions;
stop means for colliding with said sliding element means when said rivet engaging means reaches the retracted position thereby to provide an impulse force, and
solenoid means linked to said sliding element means for moving said sliding element means and adapted such that upon energizing said solenoid means said sliding element means moves said rivet engaging means from the advanced to the retracted position;
wherein said sliding element means and rivet engaging means have sufficient mass, and said solenoid means has sufficient pulling force, to accelerate said sliding element means and rivet engaging means such that upon collision with said stop means a sufficiently large impulse force is created to break the rivet mandrel.

[0007] Thus the invention utilises a solenoid to operate a rivet engaging and pulling mechanism of a blind rivet tool, with an impulse intensifier creating a large impulse force to break the stem of the mandrel of a blind rivet.

[0008] In a preferred embodiment, the invention provides a slideable interconnection between a nosepiece for housing the pulling mechanism, and a "power chamber" for housing the remaining tool components including the solenoid. The force induced by the solenoid on the nose housing-pulling mechanism draws these structures toward the solenoid and causes the nose housing and power chamber to collide after the initial operation of the pulling mechanism of the tool. This impact creates an intensified impulse force to break the mandrel stem of a blind rivet. The solenoid pulling force should accelerate and decelerate in a brief enough time, and the moving components should have enough mass, to create a sufficiently large impulse force to break the mandrel.

[0009] One version of this embodiment fixedly mounts the solenoid coil within the power chamber and the solenoid plunger is drawn rearwardly to draw back the pulling mechanism of the tool. Advantageously, the power chamber includes a sleeve, the nosepiece being mounted to slide on the sleeve in a direction generally axial to the fastener.

[0010] In a second preferred embodiment of the invention, the solenoid is reciprocably mounted within the tool body. The solenoid, when energised rearwardly, drives a ram until this abuts against a member which is linked to the rivet pulling mechanism, creating an impulse which serves to break the mandrel stem. Advantageously, the action of the solenoid on the ram prior to such impact causes the tensioning of the mandrel stem. For this purpose, a spring other biasing means may be interposed between the ram and the member so that the solenoid force on the ram is transmitted to the member during such period prior to impact.

[0011] In a variation of the second embodiment, the rivet mandrel gripping and tensioning assembly may be modified, or a different type of rivet may be employed, to reduce or eliminate the need for the rivet mandrel stem for tensioning the mandrel.

[0012] In order that the invention be better understood, the two preferred embodiments will now be described by way of example in further detail with reference to the accompanying drawings in which:

Figure 1 is a sectional view of the blind rivet tool of a first embodiment of this invention, in its rest configuration;

Figure 2 is a sectional view of the tool embodiment of Figure 1 showing the position of the nose housing after the solenoid has been energised to draw the pulling mechanism and slideable nose housing to the position at which the impulse force is generated;

Figure 3 is a sectional view of a blind rivet tool according to a second embodiment of the invention, in its rest configuration;

Figure 4 is a sectional view of the tool of Figure 3, in its jaw tensioning configuration;

Figure 5 is a sectional view of the tool of Figure 3, in its impulse force configuration;

Figure 6 is a sectional view of the nosepiece portion of an alternative version of the tool of Figures 3-5, in its rest position, shown engaging a double-headed rivet seated in a workpiece; and

Figured 7 is a sectional view corresponding to the view of Figure 6, showing the rivet pulling mechanism drawn rearwardly to set the rivet.

[0013] Reference should be made to Figures 1 and 2 which illustrate a solenoid-powered blind rivet tool in accordance with a first embodiment of the invention. The blind rivet tool 10 of this embodiment contains a nose housing 11 into which a conventional nosepiece 12 is threaded (See Figure 1). Positioned in nose housing 11 is a pair of jaws 14 which are adapted to grip mandrel stem 16 of blind rivet 18 in the conventional manner disclosed in our U.S.P. 3254522. Jaw guide 20 surrounds the jaws 14 and is attached to draw bar 22. Spring 24 is positioned in the draw bar 22 and biases jaw pusher 26 to maintain the jaws 14 open to accept insertion of the mandrel stem 16. When the mandrel stem 16 is inserted into the nosepiece 12 and jaws 14, a rearward force on the draw bar 22 will pull the mandrel stem and set the blind rivet.

[0014] Threaded into rear 28 of draw bar 22 is front end 30 of core 32 of solenoid 34, these structures being retained in housing 36 of the tool. The tool housing (or power chamber) 36 comprises a rear portion 40 and a forward portion 38 which is secured to rear portion 40 by any convenient means. A conical spring 50 is biased between wall 51 of the forward portion 38 of the housing 36 and a washer 52 positioned on the rear of the draw bar 22. The spring 50 biases the draw bar 22 toward the front of the tool.

[0015] A sleeve 54 has a flange 55 positioned in end cap 46 and surrounds the draw bar 22. The nose housing 11 has an enlarged rear portion 56 slideably disposed about the sleeve 54. A guide pin 58 in sleeve 54 rides in slot 60 of the nosepiece 11 to maintain the nose housing 11 and sleeve 54 axially aligned.

[0016] In operation, as the solenoid 34 is energised, the solenoid core 32 will be drawn rearwardly (See Figure 2). This will cause the enlarged rear portion 56 of nose housing 11 to move rearwardly until shoulder 66 abuts flange 55 on sleeve 54. At this instant, the pulling force of the solenoid 34 will be intensified to break the mandrel stem. The magnitude of the impulse force resulting from this abutment increases in proportion to the mass which accelerates and decelerates in conjunction with the rivet gripping and tensioning mechanism, and increases inversely with the square of the time interval over which acceleration and deceleration occurs.

[0017] Mounted on the rear portion 56 of nose housing 11 is a spring biased pin 68 which is positioned in detent 70 in the sleeve 54. After the rivet is set and the solenoid released, the spring 50 will return the nosepiece 11 to the forward position and the pin 68 will re-engage the detent 70 to eliminate any bounce of the nosepiece on its return to the forward position.

[0018] It can thus be seen with the sliding interconnection of the sleeve 54 and nosepiece 11, as the shoulder 66 on nosepiece 11 abuts flange 55 on the sleeve 54, the pulling force of solenoid will be momentarily intensified to set the rivet and break the mandrel stem.

[0019] A second embodiment of the invention is illustrated in the sectional views of Figures 3-5, in which like numerals refer to structures corresponding to those shown in Figures 1 and 2. This second tool incorporates a fixed nosepiece and conventional mandrel pulling mechanism in accordance with U.S.P.3254522, and utilises a movable solenoid-ram structure to provide an impulse force within the tool in lieu of that provided by the movable nosepiece in the embodiment of Figure 1. This arrangement avoids the disadvantage that movement of the nosepiece away from the workpiece complicates the setting of a rivet therein.

[0020] Solenoid 71 is slideably mounted with housing 45 the inner wall of which is suitably machined for this purpose. Solenoid 71 is slideably mounted around alloy steel tube 74; retaining member 77 (illustratively comprised of an E ring) is fitted to tube 74 after sliding solenoid 71 thereon. Steel tube 74 in turn is slideably mounted around hollow steel rod 85, which includes a forward portion 86 threaded into draw bar 22 and a rear portion 87 slideably mounted in rear cap 47 of power chamber 45. A ring 73 of dampening material (such as a foam polymer) and an alloy steel tube 75 (or, in functional terms, "ram") are secured around steel tube 74 at the rear of solenoid 71. Steel tubes 74 and 75 provide high mass and magnetic characteristics suited to the operation of the tool. Solenoid 71 is forwardly biased by outer compression spring 80, while steel tube 74 (with affixed structures 73 and 75) is forwardly biased relative to an elongated member in the form of steel rod 85 by inner compression spring 81 placed between rod 74 and flange portion 89 of rod 85.

[0021] In the initial, rest position shown in Figure 3, solenoid 71 and tube 74 are in their forward locations due to the action of springs 80 and 81. Upon energising solenoid 71, it presses against pliant ring 73 and steel tube 75, overcoming the respective spring forces to drive tubes 74 and 75 rearwardly until ram 75 impacts against flange 89. During this period, illustrated in Figure 4, the compression of spring 81 exerts a rearward force on flange 89 which produces rearward motion of rod 85, draw bar 22, and jaw guide 20 while causing jaws 14 to bite into and tension the mandrel stem 16. At the point of impact between ram 75 and flange 89, illustrated in Figure 5, an impulse force is generated and transmitted to the jaws 14 via jaw guide 20 in order to break the mandrel stem 16. Thereafter the solenoid drives rod 85 rearwardly until flange 89 rests against dampening material 95 at the rear of tool 70. Deenergising solenoid 71 permits the return of these mechanisms to their rest configuration of Figure 3.

[0022] The embodiment of Figures 3-5 shows a colinear, fixed connection between the rod 85 and the pulling mechanisms in nosepiece 11, wherein rod 85 acts as an energy transfer member to transmit the impulse force. Other mechanical linkages may be employed for this purpose. For example, the solenoid and related structures for generating the impulse force could be located in a tool handle at an angle to the nosepiece, and would be coupled to the draw bar by a translation-to-translation linkage.

[0023] The embodiments of Figures 1-5 have been illustrated using the mandrel pulling mechanism of U.S.P. 3254522 to engage and tension a conventional single-headed rivet 18 (i.e. one having only a rivet-setting head 19). One may also adapt the apparatus of the invention for use with a double-headed rivet, such as that disclosed in our UK patent 2149709. Figures 6 and 7 show in section an alternative nosepiece arrangement for engaging and tensioning a rivet 100 which has a pulling head 105 in addition to the rivet setting head 107. In this embodiment jaw pusher 110 includes a clearance region 111 to accommodate pulling head 105. Rearward motion of the rivet tensioning mechanisms causes jaws 114 to engage and pull back pulling head 105, for setting of the rivet and breaking of the mandrel stem, in accordance with UK patent 2149709. By eliminating the need for gripping of the mandrel by the jaws 114, this embodiment reduces or eliminates the need for tensioning the mandrel stem for gripping purposes in the embodiment of Figures 3-5, and facilitates the breaking of the mandrel stem which would depend essentially on the sudden pulling back on pulling head 105 at the time of generating the impulse force.

Claims

1. An electromagnetically-powered blind rivet setting tool comprising rivet engaging means (14,20,22) for engaging a rivet mandrel (16);
sliding element means (11,86,75) connected to said rivet engaging means for moving said rivet engaging means between advanced and retracted positions;
stop means (54,55,89) for colliding with said sliding element means when said rivet engaging means reaches the retracted position thereby to provide an impulse force, and
solenoid means (34,71) linked to said sliding element means (11,86,75) for moving said sliding element means and adapted such that upon energizing said solenoid means (34,71) said sliding element means (11,86,75) moves said rivet engaging means (14,20,22) from the advanced to the retracted position;
wherein said sliding element means (11,86,75) and rivet engaging means (14,20,22) have sufficient mass, and said solenoid means (34,71) has sufficient pulling force, to accelerate said sliding element means and rivet engaging means such that upon collision with said stop means a sufficiently large impulse force is created to break the rivet mandrel.

2. A blind rivet setting tool according to claim 1 wherein said sliding element means (11) comprises a nose housing (11) in which said rivet engaging means (14,20,22) is located; and
said stop means (54,55) comprises a sleeve (54), said nose housing (11) being slideably mounted thereto.

3. A rivet-setting tool according to claim 2 further comprising means for maintaining the sleeve (54) and nose housing (11) in axial alignment.

4. A rivet-setting tool according to claim 2 or 3, further comprising a spring biased pin (68) on said nose housing (11) engageable with a detent (70) on said sleeve (54).

5. A rivet-setting tool according to any one of the preceding claims wherein the rivet engaging means includes a pair of jaws (14), a jaw guide (20) for causing the jaws to grip the mandrel when said jaw guide is pulled, and a draw bar (22) for pulling the jaw guide, said draw bar being linked to a solenoid core (32).

6. A rivet-setting tool according to any one of the preceding claims wherein the nose housing (11) is mounted to the sleeve (54) so as to slide parallel to the major axis of the rivet.

7. A rivet-setting tool according to any one of the preceding claims wherein said solenoid menas (34) is housed in a power chamber (36) located adjacent said sleeve (54).

8. A rivet-setting tool according to any one of the preceding claims comprising:
a power chamber (36) containing a solenoid (34);
rivet engaging means (14,20,22) for engaging a rivet mandrel (16), said rivet engaging means located within a nose housing (11), said nose housing (11) being slideably mounted to a sleeve (54) mounted upon said power chamber (36) and adapted to slide between advanced and retracted positions;
stop means (55) comprising said sleeve for colliding with said nose housing when said nose housing reaches the retracted position;
said solenoid having a core (32) which is linked to said nose housing (11) and rivet engaging means (14,20,22) so that, upon energizing the solenoid, the core pulls the nose housing and rivet engaging means from the advanced to the retracted position;
said nose housing (11), rivet engaging means (14,20,22), and core (32) having sufficient mass and said solenoid (34) having sufficient pulling force to accelerate said nose housing, rivet engaging means and plunger such that, upon collision of said nose housing with said stop means, a sufficiently large impulse force is created to break said rivet mandrel.

9. A blind rivet setting tool according to claim 1 wherein said sliding element means comprises a member (85) attached to said rivet engaging means and a ram (75) in sliding engagement with said member (85).

10. A rivet-setting tool according to claim 9 wherein said solenoid means is slideably mounted upon said member (85).

11. A rivet-setting tool according to claims 9 or 10 wherein said stop means (89) comprises a flange (89) located upon said member (85) at the end thereof, opposite the end which is attached to said rivet engaging means.

12. A rivet-setting tool according to any one of claims 9 to 11 further comprising a spring (81) interposed between the ram (75) and the stop means (89) wherein the driving of the ram towards the member causes the rivet engaging means to tension the rivet mandrel prior to the collision of said ram and said stop means.

13. A rivet-setting tool according to any one of the claims 9 to 12 further comprising a housing (45), said solenoid (71) being slideable mounted within said housing to move generally axially to said rivet.

14. A rivet-setting tool according to any one of claims 9 to 13 comprising:
rivet engaging means (14,20,22) for engaging a rivet mandrel (16);
an elongated member (85) having an outwardly projecting annular flange (89) stop means at one end thereof and secured to said rivet engaging means at the other end;
means for supporting said member (85) for axial displacement from an advanced position for contacting mandrel (16) of a rivet to a retracted position when the rivet body has been deformed and the mandrel broken;
a solenoid (71) for slideably receiving said member (85), said solenoid being located on said member intermediate said rivet engaging means and said annular flange (89);
a ram (75) slideably mounted on said member (85) and located between said solenoid (71) and said annular flange (89);
spring means (81) located upon said member between said solenoid (71) and said annular flange (89) for maintaining said solenoid (34) at a selected distance from said annular flange (89); and
means for energizing said solenoid (71) thereby causing it to move toward said annular flange (89) wherein said solenoid (34) has sufficient pulling force that upon collision of said ram (75) with said annular flange (89) a sufficiently large impact force is created to break said mandrel (16).

Drawing