Sealless strap retention

Abstract: A sealess strap retention apparatus (100) for sealess joining of overlapping strap portions (S) usable in combination with a tool for tensioning strap about a load (L). The apparatus includes a first die portion (130) and a second die portion (140) movable relative to the first die portion (130) to form a die assembly having a punch recess (110) and a support surface (120) for supporting the overlapping strap portions (S). A punch member (200) is movable relative to the punch recess (110) of die assembly for joining overlapping strap portions (S) supported on the support (120). In one embodiment of the invention, the second die portion (140) is pivotally and translatably coupled to a frame member (300) substantially opposite the punch recess (110) to release the joined overlapped strap portions. Two or more punches (200) maybe provided which are movable sequentially relative to corresponding punch recesses (110) in the dies assembly to reduce loading on it during joining of the overlapping strap portions (S).

Description: The application of tensioned strap about articles is a well known means for packaging and otherwise retaining the articles, and for this purpose there is great demand in the market place for a variety of strap and strapping tools, which apply strap about the articles. The application of sealess steel strap applied about relatively small, or rigid, or irregular shaped loads, however, has a tendency to lose tension after removal of the strapping tool. More specifically, sealess strapping tools include generally a relatively large base plate portion that is disposed between the load and the strap during tensioning and joining the strap. The large base plate is required to support and withstand the relatively large forces exerted by a die and punch assembly that joins overlapping portions of tensioned strap and resist forces exerted by the tensioning and strap cutting arrangement. The loss in strap tension is accordingly related to the size of the base portion disposed between the strap and the load. Also, sealess strapping tools often require an actuatable pin or other means for separating a portion of the joined overlapping strap portions from the punch to facilitate removal of the strapping tool from between the strap and the load. Highly tensioned strap, however, tends to interfere with separation of the strap from the punch, and therefore interferes also with the removal of the strapping tool. Sealess type strapping tools include, for example, the Manual Combination Strapping Tools, SHC-l2/ 58/34 and SAM-1/58/34 both available from Signode, Glenview, Illinois, USA as well as automatically operated strapping tools. An alternative strapping tool suitable for applying strap to relatively small, or rigid, or irregular shaped loads are push tensioning type strapping tools that apply a preformed seal to join overlapping portions of the tensioned strap. Generally, the seal is first disposed over the strap and the free end of the strap is then disposed about the load, threaded through the seal, and folded over the seal. The push strapping tools include a strap feed wheel and a foot portion that pushes the seal toward the folded end portion of the strap as the feed wheel tensions the strap about the load. The foot portion which includes a cutter and strap tensioner acts on an outer end or edge portion of the seal, which is outside the strap loop, and the seal is cut or crimped along its edges. As a result, a relatively small portion of the push strapping tool is disposed between strap and the load compared to sealess strapping tools of the type discussed above. Push strapping tools therefore substantially reduce loss of strap tension after removal of the strapping tool. Some examples of push strapping tools include the Push Type Combination Strapping Tool, PNSC-12/58/34, and the Push Type Power Combination Strapping Tools, PRH2114 and PRH-lT-1444, all available from Signode, Glenview, Illinois, USA. In some applications, however, it is desirable to eliminate the seal, which must be manually assembled with strap by threading overlapping portions of the strap through the seal as discussed above. In view of the discussion above, there exists a demonstrated need for an advancement in the art of sealess strap retention of overlapping strap portions disposed about a load. CH-655 069A discloses an apparatus for sealess strapping for a steel band around an article in accordance with the preamble of appended claim 1. It comprises die assembly with a first die portion and a second die portion, the second die portion being movable away from the first die portion. According to this invention a sealless strap retention apparatus for sealess joining of overlapping strap portions comprising: a frame member; a die assembly with a punch recess and a support surface for supporting overlapping strap portions; a first die portion coupled to the frame member by at least one arm member; a first end portion of the arm member coupled to the second die portion, and a second end portion of the arm member being pivotally coupled to the frame member, and a second die portion movably coupled to the frame member, the second die portion being movable away from the first die portion to permit separation of joined overlapping strap portions from the apparatus; and, at least one punch member movable relative to the punch recess of the die assembly for joining overlapping strap portions supported on the support of the die assembly; is characterised by an elongated slot in the second end portion of the arm member, and a pin extended through the elongated slot for coupling the arm member to the frame member substantially opposite the punch recess of the die portion, assembly, wherein the arm member is both laterally translatable and pivotable relative to the pin and the frame member for translating and pivoting the second die portion relative to the first die portion. The invention also embraces a strapping machine comprising a sealess strap retention apparatus in accordance with the invention with a strap engaging end portion formed by the first die portion for engaging a folded strap portion; and, a strap feed wheel for tensioning a strap portion overlapping the folded strap portion engaged by the strap engaging end portion before the overlapping strap portions are joined. The invention also embraces a sealless strap retention method for sealless joining of overlapping strap portions, the method comprising the use of an apparatus in accordance with the invention in combination with a tool for push tensioning strap about a load. An advantage of the present invention is the provision of a sealess strap retention for sealess joining of overlapping strap portions without substantial loss of strap tension. A particular embodiment of a strapping tool in accordance with the present invention will now be described with reference to the accompanying drawings; in which:- Figure 1 is a partial side view of a sealess strap retention apparatus in combination with a strapping tool for push tensioning, a strap about a load; Figures 2a and b are partial sectional views taken along lines I - I of Figure 3 illustrating a punch in upward and downward positions relative to the die assembly respectively; Figure 3 is a partial plan view illustrating the two part die assembly having a fixed die portion and a movable die portion; and, Figures 4a - 4c are a series of partial end views taken along lines II - II of Figure 1 illustrating translational and pivotal movement of a movable die portion relative to a fixed die portion of the two part die assembly. Figure 1 is a partial side view of a sealess strap retention apparatus illustrated in combination with a strapping tool for push tensioning a strap S about a load L according to an exemplary embodiment of the invention. The operation of the combination strap tensioning and sealess strap retention apparatus according to this example is discussed further below. The sealess strap retention apparatus of the present invention, however, is usable for a variety of strap joining applications. Figures 2 and 3 show the sealess strap retention apparatus comprising generally a die assembly 100 with a punch recess 110 and a support surface 120 for supporting overlapping portions of a strap S, and a punch 200 movable toward the punch recess 110 of the die assembly 100 for sealess joining of the overlapping strap portions. The punch 200 is also movable away from the punch recess 110 of the die assembly 100 for ready removal of the strap from therebetween. According to one aspect of the invention, illustrated in Figure 3, the die assembly 100 is formed by a first die portion 130 and a second die portion 140 both coupled to a frame member 300. In one configuration, the first die portion 130 is fixed to the frame member 300 and the second die portion 140 is movably coupled to the frame member 300 wherein the second die portion 140 is movable toward the first die 130 portion to form the die assembly 100 whereupon the punch 200 is movable relative to the die assembly for joining overlapping strap portions as further discussed below. The second die portion 140 is also movable away from the first die portion 130 to permit removal of the joined overlapping strap portions from the apparatus. In Figures 3 and 4, at least one arm member 150 couples the second die portion 140 to the frame member 300, and in the exemplary embodiment substantially similar arm members 150 are located on opposing end portions 142 of the second die portion 140 for coupling the second die portion 140 to the frame member. A first end portion 152 of the arm member 150 is coupled to the second die portion 140 and a second end portion 15 of the arm member 150 is coupled to the frame member 300 wherein the second die portion 140 is movable relative to the first die portion 130. In the exemplary embodiments, the arm member 150 is coupled to the frame member 300 substantially opposite the punch recess 110 of the die assembly 100, which is substantially along the centerline of the strap aligned on the support surface 120 of the die assembly 100, to substantially eliminate any lateral forces exerted on the die assembly 100 by the punch 200 and to reduce the load on the die assembly 100 during joining of the strap. Lateral forces exerted by the punch 200 on the die assembly 100 tend to separate the second die portion 140 from the first die portion 130 absent some means for retaining the movable die portion, which retention means are advantageously not required by the exemplary embodiments. In the exemplary embodiments of Figures 4a-4c an elongated slot 156 is disposed in the second end portion 154 of the arm member 10, and pin 310 extends through the elongated slot 156 for coupling the arm member 150 to the frame member 300 substantially opposite the punch recess of the die member 100. According to this configuration, the arm member 150 is translatable and pivotable relative to the pin 310 and the frame member 300 for translating and pivoting the second die portion 140 relative to the first die portion 130. Figure 4a shows the second die portion 140 positioned toward the first die portion 130 to the extent permitted by the elongated slot 156 to form the die assembly 100 with the punch recess 110 and the support surface 120. Figure 4b shows the arm member 150 and the second die portion 140 laterally translated relative to the pin 310 wherein the second die portion 140 is laterally translated away from the first die portion 130 to the extent permitted by the elongated slot 156. Figure 4c shows the arm member 150 and the second die portion 140 pivoted about the pin 310 wherein the second die portion 140 is pivoted away from the first die portion 130. According to the exemplary embodiment, the translation and pivoting action of the second die member 140 is effected by a lever arm linkage 320 pivotally coupled to the second end portion 154 of the arm member 150. The lever arm linkage 320 is actuatable manually or automatically depending on application requirements. The punch 200 is movable manually or automatically toward the punch recess in the die assembly 100 to join the overlapping strap portions by cutting and bending edge portions of overlapping cut strap portions, which forms a reliable joint therebetween. According to another aspect of the invention, strap joint strength is increased by including at least two or more punch members 200 movable toward corresponding recesses 110 and 112 in the die assembly 100, shown in Figure 2 to form a series of joints along the overlapping strap portions. According to a related aspect of the invention, the load on the die assembly 100 is substantially reduced by sequentially operating, or moving, the two or more punch members 200 toward the corresponding punch recesses in the die member 100 one at a time. Reducing the material and overall size requirements of the die assembly 100 permits reducing the material and overall size requirements of the die assembly 100, which has the beneficial effect of reducing loss of strap tension after the die assembly 100 is removed from between the strap and the load L. According to another aspect of the invention shown in Figures 3 and 4, the die assembly 100 forms a strap guide for aligning overlapping strap portions on the support surface 120 of the die assembly 100. The strap guide is defined in part by a side portion 134 of the frame member 300 or first die portion 130 and an opposing side portion 144 of the second die portion 140 wherein overlapping strap portions supported on the support surface 120 of the die assembly 100 are disposed and retained between the opposing side portions 134 and 144 thereby ensuring proper alignment of overlapping strap portions during the strap joining operation of the punch member or members 200. Movement of the second die portion 140 away from the first fixed die portion 130 permits ready removal of the joined overlapping strap portions from the strap guide of the apparatus. Figure 1 illustrates a combination strap tensioning and sealess strap retention apparatus for sealess joining of overlapping strap portions push tensioned about a load L. In addition to one of the die assembly 100 and punch 200 configurations discussed above, the combined apparatus includes a strap engaging end portion 110 formed by the first die portion 130, which may include a recessed portion 182, shown in Figure 3, for seating a folded strap portion F. The combined apparatus includes a strap feed wheel 330 rotatably coupled to the frame 300 and pivotally positionable relative to a tensioner plate 340. A gripper plug 342 may alternatively be disposed in a recess in the tensioner plate to facilitate feeding the strap S between the strep feed wheel 330 and the tensioner plate 340. Figure 4a shows the combined apparatus including a strap cutting blade 350 for severing a free strap end portion from the joined strap. In the exemplary embodiment, the strap cutting blade has a concave blade portion 352 for folding downwardly cut end portions of the strap S and substantially reduces any sharp edges. In one exemplary mode of operation shown in Figure 1, a folded strap end portion F is disposed over the strap engaging end portion 10 when the second die portion 140 is moved away from the first die portion 130, and the strap S is formed in a loop about the load L. A free end of the strap S is disposed overlapping the folded strap portion F on the support surface 120 of the die assembly 100 when the second die 140 is moved away from the first die 130, and the free end of the strap S is disposed between the strap feed wheel 330 and the tensioner plate 340. The overlapping strap portions are maintained in alignment on the support surface 120 of the die assembly 100 by the side portions 134 and 144 of the strap guide when the second die portion 140 is moved toward the first die portion 130. The feed wheel 330, which may be operated manually or automatically, tensions the strap about the load L whereafter the overlapping strap portions are joined by the die assembly 100 and punch 200 as discussed above. The joined strap is then cut with the cutting blade, which may also be operated either manually-or automatically. The second die portion 140 is then moved away from the first die portion 130 as discussed above to separate or remove the combination strap tensioning and sealess strap retention apparatus from the strap. Figure 1 illustrates most clearly that a relatively small portion of the die assembly 100 is disposed between the strap S and the load L thereby minimizing the loss of strap tension upon removal of the apparatus, and the relatively reduced size of the die assembly 100 obtained by using a split two-part die assembly and by supporting the second die 140 from the frame opposite the punch recess 110, or strap centerline, substantially reduces any adverse affect on strap tension after removal of the apparatus as discussed above.

Claims: A sealless strap retention apparatus (100) for sealess joining of overlapping strap portions (s) comprising: a frame member (300); a die assembly with a punch recess (110) and a support surface (120) for supporting overlapping strap portions (s); a first die portion (130) coupled to the frame member (300); and a second die portion (140) movably coupled to the frame member (300) by at least one arm member (150); a first end portion of the arm member (150) coupled to the second die portion (140), and a second end portion of the arm member being pivotally coupled to the frame member (300), the second die portion being (140) movable away from the first die portion (130) to permit separation of joined overlapping strap portions (s) from the apparatus; and, at least one punch member (200) movable relative to the punch recess (110) of the die assembly for joining overlapping strap portions (s) supported on the support (120) of the die assembly; characterised by an elongated slot (156) in the second end portion of the arm member (150), and a pin (310) extended through the elongated slot (156) for coupling the arm member (150) to the frame member (300) substantially opposite the punch recess (110) of the die assembly, wherein the arm member (150) is both laterally translatable and pivotable relative to the pin (310) and the frame member (300) for translating and pivoting the second die portion (140) relative to the first die portion (130). An apparatus according to claim 1, further comprising a base with a strap guide (134,144) formed by the die assembly for aligning overlapping strap portions (S) on the surface (120) of the die assembly, and a strap engaging end portion (182) formed by the first die portion (130) for engaging a folded strap portion (F). An apparatus according to claim 1 or 2, further comprising at least two punch members (200) sequentially movable toward corresponding punch recesses (110) in the die assembly for reducing the load on the die assembly when joining overlapping strap portions (S) supported on the support (120) of the die assembly. A strapping machine comprising a sealless strap retention apparatus (100) in accordance with any one of the preceding claims; further comprising a strap engaging end portion (182) formed by the first die portion (130) for engaging a folded strap portion (F); and, a strap feed wheel (330) for tensioning a strap portion (S) overlapping the folded strap portion (F) engaged by the strap engaging end portion (182) before the overlapping strap portions (F&S) are joined. A strapping machine according to claim 4, further comprising a strap cutting mechanism (352) located between the strap retention apparatus (100) and the strap feed wheel (330) and outside of the loop of strap (S). A sealless strap retention method for sealless joining of overlapping strap portions, the method comprising the use of an apparatus in accordance with any of the preceding claims in combination with a tool for push tensioning strap about a load.

Inventors: DRABAREK PETER, FIGIEL JANUSZ, PODEDWORNY PAUL, DRABAREK, PETER, FIGIEL, JANUSZ, PODEDWORNY, PAUL
Applicants: ILLINOIS TOOL WORKS, ILLINOIS TOOL WORKS INC.
Application year: 1997
Main classification: B65B13
IPC codes: B65B13