US3094158A - Mechanism for forming prongs or barbs in sheet metal strips - Google Patents

Description

1. s. REID 3,094,158 MECHANISM FOR FORMING PEoNGs 0R BARBs 1N SHEET METAL STRIPS 5 Sheets-Sheet l June 18, 1963 Filed June 27, 1960 INVENToR. rv/156 Havo grr-ORNE YS 3 Sheets-Sheet 2 J. S. REID MECHANISM FOR FORMING PRONGS OR BARBS IN SHEET METAL STRIPS June 18, 1963 Filed June 2'?, 1960 June 18, 1963 REID 3,094,158

J. S. MECHANISM FOR FORMING PRONGS OR BARBS IN SHEET METAL STRIPS Filed June 2'?, 1960 5 Sheets-Sheet 3 INVENTOR. fsf/vas o. Revo Ohio Filed .lune 27, 1960, Ser. No. 38,920 6 Claims. (Cl. 153-2) 'Ihis invention relates to apparatus for forming attaching prongs or barbs in sheet metal strip material such as core material in trim structures, sealing structures and the A like. 'I'he prongs or barbs are formed while the strip material is fiat, prior to its being bent into channel shape, and the present invention relates, in particular, to a punch and die -set adapted for sequentially lforming the barbs in successive lengths of the ilat strip as it is indexed through the apparatus.

ln the form of the invention as herein illustrated and described, the sheet metal strip in which the prongs or barbs are formed is constructed by arranging a narrow band or ribbon of sheet metal in partially overlapping folds which are angularly inclined relative to each other t in generally zigzag form and wherein the prongs or barbs are located in the overlapping end portions of the zigzag band. This type of strip structure has the particular advantage that it remains completely flexible when bent into channel-like configuration or other similar form preparatory to its being used as core material. Said core strip structure which has been thus formed with, for example, the barbs bent inwardly toward the center of the channel, may be covered with cloth or other resilient sealing material and utilized as a trim strip, sealing strip, or the like whereby said channel-like structure may be placed over an exposed, sheet metal edge such that the inwardly projecting barbs grip or bite into opposed surfaces of the sheet metal 4adjoining said edge, th-us preventing removal of the strip structure, while enabling said sealing material to overlie said edge.

It will be understood that the above is given merely by way of example indicating one particular utility of the strip structure as thus formed by the apparatus of the present invention and is not intended to limit the scope thereof.

It is therefore an object of the present invention to prov-ide apparatus `especially `designed for forming a plu- Vrality of barbs or projections along a predetermined length of strip material.

Another object of this invention is to provide novel and improved forming apparatus which is especially designed for fabricating a series of barbs or projections adjacent the longitudinal edges of strip material.

Still another object of the present invention is to provide in an apparatus of the above type means for automaticallyv removing the strip material from the forming apparatus after the projections or barbs have been formed therein.

A further object is to provide strip forming apparatus which includes means for automatically disengaging the projection forming means from the strip material after saidbarbs are formed therein.

Other objects and advantages of this invention and the invention itself will be understood from the following specification and the accompanying drawings, and in which said drawings:

FIG. l is a front elevationof forming apparatus embodying the present invention;

FIG. 2 is a top plan view;

FIG. 3 is an end elevation; l

s FIG. 4 is a view similar to FIG. 3 and showing the forming apparatus in its closed or forming position;

VUnited States Patent O M 3,094,158 VPatented June 18, 1963 lCe 2 FIG. 5 is a longitudinal section taken along the line 5-5 of FIG. 3;

FIG. 6 is an enlarged detail plan view of the punchreceiving grooves in the die part of the forming apparatus of the present invention;

FIG. 7 is a side elevation of one barb forming tool of the instant apparatus;

FIG. 8 is a front elevation of the tool of FIG. 7;

FIG. 9 is a section taken along the line 9-9 of FIG. 7; FIG. l0 is a transverse detail section taken through the forming apparatus in its closed position as shown in FIG. 4, and,

FIG, lvl is a plan v-iew of one type of core strip material for which the forming apparatus of the present invention is especially designed.

Referring now to the drawings in all of which like parts are designated by =like reference characters, the `forming apparatus of this invention is herein disclosed in an embodiment of a punch and die generally indicated by the reference numerals 1 and 2, respectively. The die 2 is adapted to -be rigidly secured to a base 1i` of a punch press in any suitable manner such as by means of bolts 4. The punch 1 is similarly secured in any suitable manner to a vertically reciprocable head 5 of the press. Strip material indicated at 6 is indexed through the punch and die of this invention by suitable indexing means (not shown) 1 whereby a uniform, predetermined length of said strip material is presented above the die 2 for each downward movement of the punch 1.

Referring now particularly to FIGS. l, 3, and 5, the punch 1 comprises a pair of elongated, rectangular retainer blocks 10 each rigidly and uniformly mounting a plurality of `downwardly directed punching or piercing tools 11. The tools 11 are telescopically interftted into a plurality of longitudinally evenly interspaced, vertical apertures 12 in the retainer blocks 10. The punches 11 are positioned in straight rows through the medial portions of the retainer block 10, and said retainer blocks are secured together by bolts 23 with Ione of the 'longer lateral sides of each said block being in atwise contact Y with a similar side of the other block.

As best seen in lFIGS. 3 and 4 each punching tool 11 is -held securely within its respective aperture 12 by means of a horizontally directed set screw 13' which is thread tted into the respective retainer block from the inner surface of said block. Each retainer block 10 is also stepped outwardly adjacent its lower surface as indicated at 14, the stepped portions 14 being complementary to form a downwardly open and longitudinally continuous inverted channel inthe pair of contiguous blocks, said channel being' indicated at 15. Adjacent the lowermost edge of each of the steps 14 there is provided an inwardly directed lip or track -16` which is continuous throughout the length of each retainer block.

`-rpair of complementary sockets which are formed by matching, semi-circular, concave grooves 20 in the retainer blocks 10. Intermediate the guide pins 19, the

stripper block is provided with a plurality of upwardly open, preferably cylindrical sockets 21 adapted to seal telescopically intertting coil springs 22. 'The coil springs t 22 are compressed between the sockets 21 and the matching retainer blocks 10 within the recess 15 whereby the stripper block 17 is resiliently and retractively biased downwardly with the shoulders 18 resting upon the lips 16 to limit the downward movement of said stripper block. The stripper block 17 is normally biased downwardly to a position whereby the lowermost surface of said stripper block is below the lower ends of the punching tools 11, said stripper block having sufficient vertical mobility whereby it can be retracted upwardly to a position slightly above the lower tips of the punching tools, as best seen in FIGS. 4 and ll0.

Referring now particularly to FIGS. 7-9, each punching tool 1-1 preferably comprises an elongated shank 30 lhaving a attened :area 31 spaced downwardly a short distance from the upper end thereof and positioned on the front side of said tool, said flattened area adapted to coact with one of the said screws 13 to retain said tool within its respective retainer block and to prevent rotation of the same.

The lowermost end or piercing portion 32 of the tool is preferably triangular in section with the apex of the triangle being directed toward the front of the tool. The rear surface of the piercing portion 32 tapers downwardly toward the front or apex of the triangle as indicated at 33 in FIG. 7. The lowermost tip 34 of said piercing portion is flattened slightly, and the rear surface 33 intersects a horizontal shoulder 35 in an upward direction. The resulting structure comprises a tool having a very small, triangular piercing tip 34 which rst penetrates the metal, said metal being sliced or cut by continued downward movement of the tool to form a downwardly angled, sharp triangular barb in the strip material 6.

As best seen in FIGS. 1, 2 and 5, the die 2 comprises yan elongated die block 40 which .is substantially narrower in its transverse dimension than the combined width of the contiguous container blocks 10 and 4is provided at the ends thereof with -longitudinally extending, downwardly stepped, integral mounting blocks 41. The blocks 41 are suitably apertured at 41a to receive the bolts 4 by which the die block 40 is secured to the base or bed 3 of the press. The sides of the die blocks -are recessed inwardly as indicated at 42 in the longitudinal medial region of the die blocks, said recess extending from the bottom edge of the die blocks upwardly approximately 1/2 of the vertical dimension of the die blocks.

Above the recess `42 on each lateral side, said die block is provided with vertically disposed V-shaped grooves 43 corresponding with the number of downwardly directed punching tools 11. The tools 11, as shown in FIGS. 3, 4 and 10, are all positioned with the apexes of the piercing portions 32 facing inwardly in such manner that the tools will interiit the V-shaped groove 43. In the form of the invention as herein illustrated, the grooves 43 and the corresponding punching tools 1.1 are longitudinally staggered in their spacing to correspond with the zigzag type of strip material 6 being formed.

The die block 40 is provided with a longitudinal channel 44 in its upper surface adapted to slidably receive a clearance block 45. The clearance block 45 is vertically aligned with the stripper block 17 and is preferably of substantially the same -transverse dimension. Said clearance block has downwardly directed guide pins 46 which slidably interlit complementary apertures 47 in the guide block 40. Intermediate the guide pins 46, said guide block is provided with a plurality of upwardly open sockets 48 providing seating means for compression springs 49 which project upwardly above the bottom of the channel 44 and normally maintain the clearance block 45 in the elevated position as shown in FIGS. 3 and 5.

Side plates 50 are contiguously secured in fiatwise engagement against the lateral or grooved sides of the die block 40 by means of bolts 51. Said side plates are of the same vertical dimension as the die block 40 and of such length as to iit longitudinally between the mounting blocks 41 which overlap the ends of said side plates.

The strip material 6 herein illustrated comprises a narrow band of sheet metal in generally zigzag form such as that attained by Winding `said band iuto a continuous series of helical loops and subsequently attening the same. The resulting strip material comprises a series of longitudinally interspaced, overlapping end portions 60 of double thickness. The barbs which are formed by the punch and die set of this invention and which are indicated at 61 (FIG. l0) have unusual strength and effectiveness due to the double thickness of the metal in the present instance. Strip of this type has the particular advantage that it can be transversely formed in any desired contiguration without losing its inherent strength and flexibility.

As the strip material 6 is indexed through the punch `and die set, it rests upon and is supported by the clearance block 45 which maintains the strip in vertically spaced relationship with the upper surface of the `die block 40 whereby newly formed barbs or prongs 61 are clear of the V-shaped grooves 43. With the punch and die in the open position, the strip is indexed longitudinally a distance equal to that covered by the punching tools 11 'and their respective grooves 43. At this time, the stripper block 17 is in its lowermost position Ias shown in FIG. 3 somewhat below the punching tools 11.

After the strip 6 has been moved along the correct distance, the punch 1 closes downwardly upon the die 2 to perform the forming operation. The stripper block 17 first contacts the upper surface of the strip material 6 whereby said material is firmly held by the resilient pressures exerted upon it by said stripper block and the clearance block 45. This insures that the strip will remain in the proper position while it is being punched.

As the punch 1 continues downwardly, the clearance block 45 retracts i-nto the die block 40 and the strip 6 is pressed downwardly against the upper surface of the die block 40 and the upper edge surfaces of the side plates 50. The stripper block 17 concurrently retracts upwardly allowing the punching tools 11 to project downwardly below said stripper block, to pierce the strip 6, :and enter the grooves 43. As well illustrated in FIG. 10, the piercing portions 32 of the tools 11 penetrate the end portions 60 of the strip material only suiciently to form the barb 61 without cutting laterally through to the edges of said end portions.

As the punch 1 retracts upwardly on its return stroke, the strip 6 is simultaneously disengaged from both the punching tools 11 and the grooves 43 of the die block 40. The clearance block 45 immediately elevates the strip 6 upwardly to pull the barbs 61 out of the grooves 43, and the downward pressure of the stripper block 17 effectively removes said strip from the piercing portions 32 of the punching tools. Because the barbs 61 are formed in straight rows in laterally spaced relationship to the clearance block I45, there is, of course, no interference between said barbs and said clearance block.

As a result of the construction as herein disclosed, strip material may be rapidly and eflciently indexed through 1a punch press machine to form prongs or barbs adjacent the edges of strip material without interference of the newly `formed barbs with either the punch or the die. The triangular shape of the lbarbs as formed has been found to provide optimum holding power in installations for which strip material of this type is adapted.

It will be understood that many departures from the details of this invention as herein disclosed and illustrated may be made without, however, departing from the spirit thereof or the scope of the appended claims.

What is claimed is:

1. In forming apparatus for forming barbs in deformable strip material, a die block having a pair of parallel rows of punch receiving grooves in parallel sides thereof and retractable support means disposed between said rows of grooves `and normally projecting upwardly above said die block and supporting said strip material.

2. Apparatus for forming barbs in deformable strip material comprising a die block having rows of punch receiving grooves in parallel sides thereof, retractable support means projecting upwardly from said die block between said rows of grooves to support said strip material, and a punch having penetrating means adapted to depress said strip into contact with said die block and coact with said openings to form barbs in said strip.

3. A device for forming barbs in deformable strip material comprising a die and a complementary punch, means for bringing said punch and die into operating relationship in a sequence of repeated forming operations, said die comprising a die block having two rows of evenly spaced, vertical grooves in parallel sides of said lblock, said punch comprising retainer means having parallel rows of downwardly directed punching tools adapted to pass downwardly and enter said grooves, a resiliently retractable stripper block mounted in said punch between said rows of tools ,and normally projecting downwardly therefrom below said punching tools, a resiliently retractable clear- Iance block mounted in said die -block `between said rows of grooves and projecting upwardly 'above said die block, said clearance block adapted to support strip material threaded through said die beneath said punch, said tools being formed `complementarily to said grooves whereby in each forming operation they force said strip downwardly upon said die block and penetrate said strip to form downwardly projecting barbs therein, said stripper rblock retracting upwardly above the lower ends of said punching tools during each for-ming operation, said stripper lblock extending downwardly when said punch moves away from said die to remove said strip material from said punching tools and said clearance block concurrently returning to its upwardly biased position and disposing said barbs above said grooves.

4. An apparatus -for continuously forming barbs in deformable strip material as the material is indexed through said apparatus, said apparatus comprising an elongated rectangular die block having vertical, V-shaped grooves in lateral sides thereof, a pair of side plates contiguously positioned against said lateral sides, said die block having a longitudinally centrally disposed channel therein, a clearance block 4for supporting strip material disposed within said channel having downwardly directed guide pins slidably disposed within sockets located in the bottom of said recess, spring means normally biasing said clearance block upwardly above the upper surface of said die block, a punch comprising retainer means having tools adapted to be projected downwardly into said grooves in a forming operation, said retainer means having a longitudinally centrally disposed, inverted channel, a stripper block disposed within said inverted channel having upwardly directed guide pins slidably disposed within sockets located in said retainer means, spring means normally biasing said stripper block in a downward direction, means associated with said stripper block and said retainer means limiting the downward movement of said stripper block, said punch movable in a sequence of forming operations coordinated with the indexing of strip material through said apparatus, said clearance block and said stripper block retracting when said punch comes into operating relation to said die whereby said cutting tools penetrate said strip while said strip is held between said stripper block and said clearance block, and upon movement of said punch upwardly, said material is stripped from said punching tools by said stripper block as it returns to a downward position, and said strip material is lifted to an elevated position above said die block by said clearance block in which position said strip is moved longitudinally through said die a predetermined amount.

5. A device for forming barbs in deformable strip material comprising a die and a complementary punch, means Ifor bringing said punch and die into operating relationship in a sequence of repeated forming operations, said die comprising a die block having vertical grooves in parallel sides of said block, said punch comprising retainer means having downwardly directed punching tools adapted to pass downwardly and enter said grooves, a resiliently retractable clearance block mounted in said die block between said rows of grooves and projecting upwardly above said die block, said clearance block adapted to support strip material threaded through said die beneath said punch, said tools being formed complementarily to said grooves whereby in each forming operation they force said strip downwardly upon said die block against the upward bias of said clearance block and penetrate said strip to form downwardly projecting barbs therein, said clearance block returning to its upwardly biased position after each forming operation and disposing said barbs above said grooves.

6. An apparatus for continuously forming barbs in deormable strip material as the material is indexed through said appa-ratus, said apparatus comprising an elongated rectangular die block having vertical grooves in lateral sides thereof, a pair of side plates contiguously positioned against said lateral sides, said die block having a longitudinally centrally disposed channel therein, a clearance block for supporting strip material disposed within said channel having downwardly directed guide pins slidably disposed within sockets located in the bottom of said recess, spring means normally biasing said clearance block upwardly above the upper surface of said die block, a punch comprising retainer means having tools adapted to be projected downwardly into said grooves in a forming operation, said punch movable downwardly in a sequence of forming operations coordinated with the indexing of strip material through said apparatus, said clearance block retracting when said punch comes into operating relation to said die whereby said cutting tools penetrate said strip and upon movement of said punch upwardly, said strip material is lifted to an elevated position above said die block by said clearance block i-n which position said strip is moved longitudinally through said die a pre* determined amount with the newly formed barbs passing on either side of said clearance block.

References Cited in the tile of this patent UNITED STATES PATENTS 1,468,271 Bechtel Sept. 18, 192-3 1,925,034 Fitzgerald Aug. 29, 1933 1,931,420 Wakeeld Oct. 17, 1933 2,003,448 Kruse June 4, l1935 2,800,960 Cutler July 30, 11957 2,834,096 Norton May 13, 1958

Claims (1)

1. IN FORMING APPARATUS FOR FORMING BARBS IN DEFORMABLE STRIP MATERIAL, A DIE BLOCK HAVING A PAIR OF PARALLEL ROWS OF PUNCH RECEIVING GROOVES IN PARALLEL SIDES THEREOF AND RETRACTABLE SUPPORT MEANS DISPOSED BETWEEN SAID ROWS OF GROOVES AND NORMALLY PROJECTING UPWARDLY ABOVE SAID DIE BLOCK AND SUPPORTING SAID STRIP MATERIAL.

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