US 3204312 A
Description (OCR text may contain errors)
p 965 M. o. DERRICKSON ETAL 3,204,312
STRAP GRIPPING DEVICE FOR A STRAP TENSIONING TOOL Filed June so, 1964 United States Patent 3,204,312 STRAP GRIPPING DEVICE FOR A STRAP TENSIGNING TOOL Michael O. Derrickson and Harry E. Papa, Norwood, Pa.,
assignors to FMC Corporation, Philadelphia, Pa., a
corporation of Delaware Filed June 30, 1964, Ser. No. 379,251 3 Claims. (Cl. 24-134) This invention relates to strapping tools of the type employed for stretching or tensioning fiat bands or straps about boxes, cartons and the like. More particularly the invention relates to an improved means for gripping the strap, especially a plastic or polymeric strap of the type now coming into popularity as a substitute for the long-used steel band strapping, and to a strapping tool incorporating the new gripping device.
Straps or bands are commonly secured tightly about boxes, packages and the like for reinforcement purposes and to prevent them from breaking open during rough handling frequently encountered during shipment. Such bands are also used to secure a number of individual items together into a unitized bundle for ease of handling. The general procedure in strapping a package consists of pulling a length of strapping material from a supply such as a roll or coil and looping it about the package or packages with the free leading end of the strap positioned beneath a portion of the strap extending to the supply. By means of suitable tools, the thus positioned strap is tensioned tightly about the object and a metal seal or other fastening means is employed for securing the overlapping portions of the strap together. The thus secured strap is then cut away from the supply at a place near the point of securement.
While the strap tensioning tools, of course, vary widely in the specific mode of operation, in general the operation involves gripping or otherwise engaging the strap at two places and then relatively moving the engaged places so as to draw tight the loop of strap which has been positioned about the article or articles being strapped. The strap gripping devices must be of such nature as to hold the strap firmly without slipping and without damaging the strap even when considerable tension is applied. It has been found that the type of gripping devices used with steel strap and certain other types of strap are not entirely satisfactory for use with the plastic or polymeric strapping now becoming popular.
It is an object of the invention to provide a strap gripping device which will hold a plastic or polymeric strap without slipping while the strap is being tensioned about a package.
A further object of the invention is to provide, for a strap tensioning tool, a strap gripping device which will hold the strap without damaging it even when the strap is subjected to considerable tension.
A still further object of the invention is to provide, in a strap tensioning tool, a strap gripping device which can be easily engaged with and disengaged from the strap.
Another object of the invention is to provide, in a strap tensioning tool, a strap gripping device having a minimum number of parts and not involving the use of springs.
These and other objects, features [and advantages of the invention will become apparent as the description of a preferred embodiment thereof proceeds.
Referring now to the drawing:
FIG. 1 is a side elevational view showing in use a tool embodying the present invention;
FIG. 2 is an enlarged elevational view of the strap gripping device showing the same in strap gripping position;
FIG. 3 is a view partially in elevation and partially in section showing the manner in which the gripping device is associated with the tensioning tool;
FIG. 4 is :a perspective view showing one of the two elements of the strap gripping device;
FIG. 5 is a perspective view of the other one of the two elements; and
FIG. 6 is an exploded side elevational view partially in section showing the manner of assembling the two elements of the gripping device.
The tool chosen to illustrate the invention is of the Well known pusher type and comprises a main body 10 which includes a handle portion 11. Slidably mounted within the main body of the tool is a shaft 12 secured to the forward end of which is a strap engaging member 13. Pivoted within the main body 10 is an operating lever 14 and as said lever is squeezed toward handle portion 11 the shaft 12 is caused to move forward by any suitable mechanism not in itself forming a part of the present invention. When the tool is not in use the strap engaging member 13 is located closely adjacent a forward shoulder 15 of the main body of the tool and upon repeated movements of the lever 14 strap engaging member 13 is caused to move away from shoulder 15. There is a release lever 16 which upon being pushed forward releases shaft 12 from its operative connection with the lever 14 so that after the tensioning operation has been completed the strap engaging member 13 may be moved back against shoulder 15. Strap engaging member 13 includes a slotted beak 17, the purpose of which will presently be explained, and a strap cutting member 18 is rotatably mounted within beak 17 and member 13. An operating arm 19 is secured to cutting member 18 and when said arm is swung clockwise from the position shown in FIG. 1 cutter 18 is rocked intocutting engagement with the strap. The tool as thus far described is generally old in the art. The novelty of the present invention resides in a strap gripping device indicated generally in FIG. 1 at 20.
Before describing the strap gripping device 20 in detail the manner of use of the tool will be explained in connection with FIG. 1, wherein the object being strapped is indicated at 21. A length of plastic strap material 22 is withdrawn from a suitable supply such as a coil and the free end of the strap is threaded through a suitable seal 23 and then looped about object 21 after which it is again threaded through seal 23 and bent back beneath the seal as shown at 24. The free end of the strap is thus efiectively anchored to the seal. The strap engaging member 13 of the tool is then engaged with the strap in the vicinity of seal 23 in such manner that the portion of strap 22 between the seal and the supply extends through an open sided slot 25 in beak 17 and then between beak 17 and the supply the strap is laced to strap gripper 20 in a manner presently to be explained. With the forward end of beak 17 bearing against one end of seal 23, lever 14 is repeatedly squeezed toward handle 11 so as to cause relative movement between beak 17 and strap gripping device 20 whereby the loop of the strap is tightened about the article 21. When the desired amount of tension has been applied, seal 23 is crimped by means of a suitable tool so as to hold the strap in tightened condition, after which cutter 18 is employed to sever the secured strap loop from the portion of strap extending to the supply.
Strap gripping device 20 comprises two principle elements 26 and 27 shown in detail respectively in FIGS. 4 and 5. Element 26 is formed of a piece of cylindrical stock and consists of a cylindrical portion 28 extending from which is a portion having a cylindrical face of the same radius of curvature as cylindrical portion 28 and having a first fiat face 29 and a second flat face 30. Faces 29 and 30 are arranged at such an angle to one another as to provide a relatively sharp edge or corner 31 and ad- Patented Sept. 7, 1965 jacent the inner end of faces 29 and 30 the cylindrical portion 28 is provided with a shoulder 32.
Element 27 of the gripping device is also formed of piece of cylindrical stock and comprises a hollow cylindrical portion 33 the inner wall 34 of which is of suchdiameter as to snugly but rotatably accommodate the cylindrical portion 28 of element 26, as will presently be explained. Element 27 also includes an end portion having a cylindrical wall 35 which constitutes an extension of the outer cylindrical surface of portion 33 and a flat face 36 provided with a groove 37. The inner end of the extending portion of element 27 provides a shoulder 38, see FIG. 6, facing the hollow interior of cylindrical portion 33 and the outer end of the extending portion is tapered as indicated at 29 in FIGS. 3 and 6.
Elements 26 and 27 are assembled together as indicated in FIG. 6 by inserting element 26 into the hollow interior of cylindrical portion 33 until shoulder 32 of element 26 abuts the shoulder 38 of element 27. With the two elements thus associated element 26 may rotate to an extent limited by the edge 31 striking into the groove 37 in one direction and by an edge or corner 40 striking against the flat face 36 in the other direction. FIG. 3 that the outer end of element 26 extends beyond the outer end of element 27.
The main body of the tool is divided longitudinally into two sections 41 and 42 as shown in FIG. 3. A cylindrical opening 50 is provided in section ,42 and the cylindrical portion 33 of element 27 is fitted into this cylin-, drical opening after the two elements 26 and 27 have been assembled. A threaded opening 43 extends into the section 42 from the forward shoulder and communicates with cylindrical opening 50, as shown in FIG. 2. A groove 44 is cut into the outer face of cylindrical portion 33 of the member 27 and set screw 45 threadedinto the opening 43 extends into groove 44 to hold the element 27 in position. Element 26 is prevented from slipping longitudinally by engagement of the inner end thereof against section 41 of the tool. I
In connecting the gripping device to the strap after the strap engaging member 13 has been positioned about the strap and against seal 23 as aforesaid, the outer end of' element 26 is placed against the strap and the strap is looped as indicated in FIG. 2 so as to extend around the end of said element. By such action element 26 is easily rocked to position flat face 30 substantially parallel to flat face 36 and then by a slight sidewise movement of the tool the strap is caused to slip back into the space between flat faces 30 and 36 as indicated in FIG. 3. The tapered end 39 of element 27 facilitates this final positioning of the tool. When lever 14 is squeezed toward handle 11 as aforesaid to apply tension to the strap, the pull on the strap causes member 26 to rock into the position shown in FIG. 2, this rocking being caused primarily by the fact that the strap passes about the sharp corner 40 of the element 26. The rocking of element 26 causes the strap to be pinched between the edge 31 of member 26 and an edge 46 between flat face 36 and groove 37 of the element 27. It has been found that because of the combined It will be noted from a 4c snubbing action of the edge 40 and'the pinching action of edges 31 and 46 very considerable tension may be applied to the strap without damaging it. Thus the gripping device effectively holds the strap at two spaced points, at one point with a snubbing action and at the other with a pinching action, so that the pressure at neither point is great enough to cut or damage the strap.
Element 26 is freely rockable within the above referred to limits and ordinarily can be sufiiciently manipulated between gripping and non-gripping positions merely by engagement with the strap. This of course is advantageous since most other gripping devices employ springs for holding them in gripping condition and must be manually released from such condition both after a tensioning operation and again before the next operation.
Having thus described a preferred embodiment of the invention, What is claimed is:
1. A strap tensioning tool comprising a main body, a strap gripping device comprisinga first member having a hollow cylindrical portion secured in saidmain body and a strap gripping portion extending longitudinally from said cylindrical portion andoutwardly from said main body, said, strap gripping portion having a flat face extending parallel to-the longitudinal axis of said cylindrical portion, a second member, said second member having a cylindrical portion rotatably mounted in the hollow cylindrical portion of said first member and having a strap gripping portion extending longitudinally from said cylindrical portion, the strap gripping portion of said second member having a flat face with edges parallel to the 'axis of the cylindrical portion of said member, the fiat face of the strap gripping portion of said second member being parallel to and spaced from the fiat face of the strap gripping portion of said first member when said second member is in a particular rotated position with respect to said first member, and the edges of the flat face of said second member contacting the fiat face of said first member to limit the amount of rotation impartable to said second member.
2. The tool set forth in claim 1 wherein the strap gripping portion of said first member has a free end which is sloped inwardly toward the flat face of said strap gripping portion.
3. The tool set forth in claim 2 wherein the strap gripping portion of said second member has a free end extending beyond the free end of the strap gripping portion of said first member. 2
References Cited by the Examiner UNITED STATES PATENTS 1,575,872 3/26 Strohl 24--134 X 1,841,742 1/32 Lampert 254-79 2,553,341 5/51 Stonehill 33974 3,059,300 10/62 N-oel' 24134 3,129,728 4/63 Sharko I -1 254-51 X WILLIAM FELDMAN, Priniary Examiner. MILTON S. MEHR, Exam iner.