CA1062600A - Apparatus for securing plastic straps - Google Patents
Apparatus for securing plastic strapsInfo
- Publication number
- CA1062600A CA1062600A CA288,068A CA288068A CA1062600A CA 1062600 A CA1062600 A CA 1062600A CA 288068 A CA288068 A CA 288068A CA 1062600 A CA1062600 A CA 1062600A
- Authority
- CA
- Canada
- Prior art keywords
- strap
- overlapping
- ribs
- heater
- pressure block
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
A manually operable combination strapping tool for ap-plying plastic strapping around an object includes a strap-ten-sioning and gripping mechanism for holding the strap in a ten-sioned loop around the object with the supply portion of the strap overlapping the loading end thereof, and a heat-sealing mechanism which includes a movable pressure block and a heater movable to and from a heating position between the overlapping strap portions. As the heater is moved between the overlapping strap portions, the pressure block is moved to cooperate with an anvil to press together the heating element and strap portions for melting thereof. After retraction of the pressure block and the heater by separate bias means, the pressure block is moved for cooperation with the anvil to clamp therebetween and bond together the melted strap portions and sever the supply portion of the strap. Ridges on the pressure block cooperate with com-plementary grooves in the anvil to deform the overlapping strap portions during bonding thereof and form a corrugated joint therebetween. Means limiting the pressure with which the strap and the heater are pressed together and cooling means are also provided.
A manually operable combination strapping tool for ap-plying plastic strapping around an object includes a strap-ten-sioning and gripping mechanism for holding the strap in a ten-sioned loop around the object with the supply portion of the strap overlapping the loading end thereof, and a heat-sealing mechanism which includes a movable pressure block and a heater movable to and from a heating position between the overlapping strap portions. As the heater is moved between the overlapping strap portions, the pressure block is moved to cooperate with an anvil to press together the heating element and strap portions for melting thereof. After retraction of the pressure block and the heater by separate bias means, the pressure block is moved for cooperation with the anvil to clamp therebetween and bond together the melted strap portions and sever the supply portion of the strap. Ridges on the pressure block cooperate with com-plementary grooves in the anvil to deform the overlapping strap portions during bonding thereof and form a corrugated joint therebetween. Means limiting the pressure with which the strap and the heater are pressed together and cooling means are also provided.
Description
The present invention relates to apparatus for apply-ing strapping around an object. More particularly, the inven-tion relates to apparatus ~or tensioning plastic strapping ln a loop around an ob~ect and forming a heat-sealed joint in the strap loop for securing it about the ob~ect.
The present inventi~n is an improvement o~ the strap-ping apparatus disclosed ln U.S. Patent No. 3,944,460. That strapping tool has a heat-sealing mechanism including a cam shaftadapted for camming engagement with a movable pressure block and with a rocker arm which is in turn releasably coupled to a movable heater. As the cam shaft is rotated, the rocker arm moves the heater between the overlapping strap portions and the pressure block is moved to press together the heating ele-ment and the strap portions for melting thereof. Further rota-tion of the cam sha~t disengages it ~rom the pressure block and decouples the rocker arm from the heater to permit retraction of the pressure block and the heater by separate bias means.
Further rotation of the cam sha~t again effects cammed movement of the pressure block to bond together the melted strap por-tions and to sever the supply portion of the strap.
In that prior strapping tool, the pressure block co-operates with a strap guide surface on an anvil-like base mem-ber for pressing therebetween the overlapping strap portions~
both the strap guide surface and the pressure block having sub-stantially smooth planar pressure surfaces thereon. Because of manufacturing imperfections in producing such surfaces economic-ally, it is not possible with the prior art strapping tool to achieve a truly even distribution o~ pressure throughout the seal area. Furthermore, it has been found that the bond be-tween the overlapping melted strap portions formed by the priorstrapping tool is not su~ficiently strong for certain high load ~ .
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~62600 applications.
The ob~ect of the present invention is to proYlde a strapping tool wlth lmproved pressure means for providing an improved and strengthened ~oint in the overlapping strap ~r-tions.
Accordingly, the present invention provides strapping apparatus for securing a length of plastic strap around an ob-~ect, said apparatus comprising a frame, strap-gripping means mounted on said frame for holding the strap encircled in a loop in a tensioned condition about the object with the leading end of the strap overlapping the supply portion thereof, heating means carried by said frame adjacent to the overlapping strap portions ~or ef~ecting melting of the ~acing portions thereof, a first pressure member carried by said frame and having a plu-rality of elongated and equal-width first grooves therein equi-distantly spaced apart by first ribs, and a second pressure member carried by said frame and having a plurality of elon-gated and equal-width second ribs pro~ecting therefrom equi- :
distantly spaced apart by second grooves~ each of said first 2Q and second grooves being rectangular in transverse cross sec-tion and havlng an elongated flat rectangular recessed surI'ace, each o~ said first and second ribs being rectangular in tr~ s-verse cross section and having an elongated flat rectangular end surface with the width of each said end surface being sub stantially less than the width of each groove recessed sur-face, said end surfaces of said ~irst and second ribs being re-spectively disposed centrally of and in parallel facing rela-tionship with said second and first groove recessed surfaces in longitudinal alignment therewith, said pressure members being movable with respect to each other to a sealing configuration wherein said ribs and said grooves cooperate to press together therebetween the melted overlapping strap portions and to de-~orm the overlapping strap portions in a predetermined pattern ; as they are pressed together, whereby the pressure of said pressure means is substantially evenly distributed throughout the inter~ace between the melted overlapping strap portions ~or formation o~ a strong joint therebetween.
In the drawings:
Figure 1 is a side elevational v~ew of the strapping apparatus of the present invention shown in its operative po-sition for applying plastic strapping around an object, Figure 2 is a top plan view of the strapping appara-tu~ shown in Figure l;
Figure 3 is an enlarged fragmentary side elevational view of the strapping apparatus o~ the present invention taken along the line 3-3 in Figure 2 more clearly to show the inter-nal construction thereo~, with the tensioning handle shown ln an unlatched position and with the sealing handle shown in its home position, Figure 4 is an enlarged view in vertical section o~
the heat-sealing portion o~ the strapplng apparatus taken along the line 4-4 in Figure 2;
Figure 5 is a fragmentary bottom plan view o~ the pressure block of the present invention, taken along the line 5-5 in Figure 4, .-Figure 6 is a ~ragmentar~ top plan view of the fixed anvil block Or the present invention, taken along the line 6-6 in Figure 4j Figure 7 is an enlarged ~ragmentary view in vertical section~ illustrating the overlapping strap portions between the pressure members immediatel~ a~ter the strap heater has been removed from therebetween, .
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Figure 8 i9 a viewJ similar to Figure 7J but with the overlapping strap portlons not shown, illustrating the position of the pre~sure members during the seallng and em-boB8i.ng operation;
Flgure 9 i~ an enlarged, frag~entary, front per-specti~e vlew o~ a portion of the corrugated seal ~olnt ~o~med ~n the overlapping strap portion~ by the pressure members when they are moved to the position illustrated ln ~:
Figure 8;
Figure lO i8 a fragmentary view ~n vertical sectlon slmilar to Figure 4~ lllustratlng the sealing apparatus in the strap-heating configuration thereo~; -Figure lOA i~ a fragmentary ~ide elevational vlew ~ .
of the cam shaft of the sealing mechanlsm in the coniiguration .
lllu8tr~ted in Figure 10;
Figure 11 i8 a view s~milar to Figure lO, showlng the seallng apparatus disposed in the sealing con~iguration thereo~; and Flgure llA i8 a side elevational view slmilar to 20 Figure lOA of the cam sha~t ln the con~i~uration illustrated ln Figure ll. ~
Referring no~ in particular to Figures l and 2 o~ :
th~ drawing~, there i8 illustrated a 8trapplng apparatus conslsting o~ a combination tensioning and heat-sealing tool constructed in accordance wlth and embodying the features o~
the present inventlon, and generally deslgnated by the nu-meral 50.
In Figure 1, the combination tool 50 is illustrated in it~ operative position ~or applying a length o~ plastlc 30 ~trap~ such as polypropylene ~trap, ~or example, ~n a ten-~ioned loop about a package or other ob~ect 41, the strap 106;~;00 being dldposed in the combination tool 50 80 that the gupply portion 57 of the ~trap 1B dlsposed ln overlapplng relation-ship wlth the leadlng end 56 thereo~. The combinatlon tool 50 lncludes a common baseplate, generally de~ignated by the numeral 60, on which i9 mounted gripping and tensloning ap-paratus, generally deslgnated by the numeral lO0, and heat-sealing and shearing apparatus, generally designated by the numeral 200.
Referring now al~o to Figure~ 3 through 9 o~ the :lO drawings, the baseplate 60 includes a maln body 61 Or a.pre-determined thicknes3 and havlng formed thereln toward the rear portion thereof a generally L-shaped heater contrnl reces6 62 (see Flgure 4), and a generally rectangular tension-ing apparatus recess 63 in the front portlon thereo~ the heater control recess 62 hhving a pair of spaced-apart paral-lel rails 70 thereln extending laterally thereof (one shown ln Figure 4). ~ormed along one side of the baseplate 60 is an anvll block 64 havlng a ~lat strap guide gurface or apron 65 which has formed in the front end thereo~ an internally .
20 threaded opening having threadedly dlsposed therein a strap rest button 68, ~or a purpose to be described more ~ully hereinafter. A heat buffar 66 may be received in a comple-mentary recess 67 ad~acent to the inner edge of the anvil block 64.
The grlpping and tensloning apparatus lO0 includes an elongated rear strap spacer lOl secured to the baseplate 60 ad~acent to the rear end thereof ~nd pro~ecting laterally there-from at the rear end o~ the strap guide apron 65. The rear ,, , ' : '~ .' , ' . ' strap spacer 101 has a ~lat planar upper guide aur~ace 102 ana a flat planar lower guide surface 103 spaced apart a predeter-mined distance, both of the surfaces 102 and 103 being disposed substantially parallel to the strap guide apron 65 and spaced vertically therefrom. Formed along the front edge o~ the rear strap spacer 101 and e~tending substantially normal to the longitudinal axis o~ the strap guide apron 65 is a ~ixed shear blade 104 Secured to the baseplate 60 a~d spaced a predeter- : ~
' mined distance ~orwardly of the rear strap spacer 101 and ex- . .
tended substantially parallel thereto is an elongated ~ront strap spacer 105 having upper and lower strap guide sur~aces 106 and 107 which are respectively substantially coplanar with the strap guide sur~aces 102 and 10~ ~h the rear strap spacer ¦ 101. Disposed adjacent to the front end of the strap guide apron 65 substantially parallel thereto is a separating plate, generally designated by the numeral 110, and ~ixedly secured adjacent to the inner end thereo~ by mounting bolts 111 to the baseplate 60.
Disposed immediately rearwardly of the separating plate 110 is a li~ting link, generally designated by the numer-al 115, which includes an attachment arm 116 and a li~ting ~in-ger 68, respectively disposed in use in slots in the baseplate 60. Formed in the attachment arm 116 and the lifting finger 118 are coaxial bores aligned in use coaxially with a corre-sponding transverse bore in the baseplate 60, all ~or receiving therethrough a roll pin 117 ~or pivotally mounting the li~ting link 115 on the baseplate 60. In use, the lifting finger 118 extends beneath the separating plate llo ~or engagement with the bottom surface thereof. Also formed on the 1~ ting link 115 is a cam arm 119 which curves upwardly and ~orwardly ~rom the lifting ~inger 118 to overlie the separating plate 110 ~or ':, .
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a purpose to be described more fully below.
A cradle support member, generally designated ~y the numeral 120, includss an angle attachment bracket 121 secured by means of mounting screws 122 to a cradle support mounting block (not shown). Integral with the attachment bracket 121 and extending upwardly therefrom at the end thereof ad~acent to the strap apron 65 is a cradle clevis 125 having an upwardly extending bight portion 123 and a pair of spaced-apart rearward-ly extending legs 124. Integral with the bight portions 123 of the cradle clevis 125 and extending upwardly therefrom is a mounting post 126.
Mounted on the cradle support member 120 is a cradle, generally designated by the numeral 130, having a body portion 131 provided with a pair of forwardly extending mounting arms 132 respectively disposed in use along the outer side surfaces of the legs 124 o~ the cradle clevis 125. Bxtending through aligned openings in the cradle clevis legs 124 and the cradle mount~ng arms 132 is a pivot pin 133 ~or pivotally mount~ng the cradle 130 on the cradle support member 120. Coiled about the pivot pin 133 between the cradle clevis legs 124 is a tor-sion leaf spring 134 having one end thereof disposed in engage-ment with the mounting post 126 and having the other end there-of disposed in engagement with the cradle body 131 for resil-iently urging the cradle 130 toward rotation in a counterclock-wise direction about the pivot pin 133, as viewed in Figure 3.
Formed on the cradle body 131 at the rear end thereof is a ~lat :
planar sur~ace (not shown) disposed for camming engagement with ~ -the cam arm 119 of the lifting link 115, for a purpose to be explained hereina~ter. Formed integrally with the cradle body 131 at the rear end thereof toward the side thereof away ~rom the strap apron 65 is a pawl cylinder 138.
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~ Carried by the cradle 130 is a rotary dog assembly~
; generally deslgnated by the numeral 140, and including an elon-gated rotary dog shaft 141 disposed in a complementary bore and extending completely therethrough. Fixedly secured to the sha~t 141 adjacent to one end thereof is a rotary dog 148 dis-posed in a complementary shaped recess in the cradle body 131.
The cylindrical outer surface of the rotary dog 148 is serrat-ed or knurled and projects from the cradle body 131 at the bot-~ tom thereof for engagement with the supply portion 57 of the i 10 strap in a manner to be described more fully below. The adja-~ cent end of the sha~t 141 is rotatably supported in a bear~ng ,` 149 to ~acilitate rotation of the sha~t 141.
Disposed in and extending through a complementary bore in the cradle body 131 is a handle pi~ot p~n 161 ha~ng ~e e~ ~e~e~ a~3acent to the pawl cylinder 138 extending a j predQ~ermined distance outwardl~ beyond the ad~a~ent end ~ the cradle body ~3~. ~h~s pro~ecting end o~ the pivot pin 161 ex-tends through complementary openin~s ad~acent to the lower ends o~ inner and outer elongated handle plates 162 and 163, the up-per ends thereof having sandwiched therebetween the lower end of a tensioning handle 160. Coaxially mounted on the pivot pin 161 between the handle plates 162 and 163 is a drive gear 165 ' disposed for meshing engagement with the outer teeth on another drive gear tnot shown) The handle 160 and the handle plates 162 and 163 are all secured together by bolts 167 and 167aJ the bolt 167 having a head 169 and the bolt 167a having an enlarged , spa~er head 168.
The lower end o~ the tensioning handle 160 has a re-cess 166 ~ormed in the inner s~de surface thereof, in which is received a pawl member, generally designated by the numeral 170~
having an opening therein through which is received the bolt 167 for pivotally mounting the pawl member 170. The p~wl member 170 is provided with a pawl tooth disposed for ratcheting en-gagement with the teeth of the drive gear 165 to prevent rota-tion thereof in a clockwi~e direction, as viewed in F~gure 3.
Pro~ecting outwardly from the opposite end o~ the pawl member 170 ls a spring seat finger 173, for a purpose to be described more ~ully below. The lower end o~ the pawl member 170 pro-aects downwardly and forwardly beneath the handle plates 162 and 163 and has formed thereon an arcuate seat 175 and a cam-ming surface (not shown).
A positioning lever, generally designated by thenumeral 180, has a flat side plate 181 which is disposed in use to the inner handle plate 162 and is secured to the outer surface thereof by the bolt 167a for pivotal movement with re-spect thereto. Integral with side plate 181 and extending up-wardly therefrom substantially normal thereto a predetermined distance above the tensioning handle 160 is a handle portion 182 for manipulating the positioning lever 180. Projecting downwardly and rearwardly from the side plate 181 is a stop finger 183 disposed ~or engagement wi~h the head 169 o~ the bolt 167, for limiting pivotal movement of the positioning ~, lever 180 in the counterclockwise direction, as viewed in Fig-ures 1 and 3. Both the pawl member 170 and the positior.ing lever 180 are simultaneously resiliently urged toward rotation in a counterclockwise direction, as viewed in Figure 3, by ; spring counter means (not shown).
Respectively secured to the opposite ends of the ~ cradle body 131 by means of screws 198 are two end plates 197 'A which securely hold in place the pivot pins 133 and 161 and the sha~t 141. Projecting downwardly ~rom the r~ar end of one of the side plates 197 is a strap guide finger 199 which projects ., ~g _ .~. .
a slight distance downwardly below the surface of the strap apron 65 adjacent to the outer edge thereof for guiding the strap and confining it to a path overlying the strap apron 65.
Referring now also to Figures 4 and 10 through llA of the drawings, the sealing and shearing apparatus 200 will be described. The apparatus 200 i9 mounted on an irregularly shaped frame or housing 201 which is fixedly secured to the baseplate 60 and overlies the heater control recess 62 therein.
The ~rame 201 is provided with a relatively thick upwardly ex-tending end wall 205 overlying the strap apron 65 and spaced apredetermined distance thereabove and a relatively thin up-standing end wall 207 adjacent to the opposite side of the baseplate 65 and an upstanding bearing wall 203 disposed be-tween the end walls 205 and 207 substantially parallel thereto.
The bottom o~ the bearing wall 203 is disposed well above the baseplate 60 and has formed thereon, at the side thereof fac-ing the end wall 207, a downwardly extendlng lip pr pro~ection 202. Disposed between the end wall 205 and the bearing wall .3203 are two longitudinally spaced-apart cylindrical bearing i,20 turrets 204 extending coaxially with each other and substan-tiall~ parallel to the walls 203 and 205.
;,Formed in the outer surface o~ the end wall 205, be- ~.
tween the front and rear,strap spacers 105 and 101, is a deep slot or channel 206 substantially rectangular in transverse cross section, the inner wall of the channel 206 in turn having 'formed therein adjacent to the rear end thereof a narrow elon-gated slot 209. The rear upper surface o~ the end wall 205 has an inclined surface 208 which slopes downwardly and ~orward-ly to the channel 206, ~or a purpose to be described below.
Dispo~ed in khe channel 206 is a complementary shaped pressure block~ generally designated by the numeral 210, having .. --10 -.,~'1 , , .. ~ . . . . .
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at the upper rear end thereof an ~nclined cam surface 211 which slopes downwardly ~nd rearwardly to the rear surface of the pressure bLock 210adjacent to the lower edge of the inclined surface 208. Extending vertically through the pressure block 210 inwardly of the cam surface 211 i5 a cylindrical bore 212 having disposed in the lower end thereof a regulating ~crew 213. Disposed in the bore 212 abo~e the screw 213 in engage-ment therewith is a coil compressinn spring 214, upon the upper end of which is seated a plunger member 216 which normally pro-jects a predetermined distance upwardly above the top surface of the pressure block 210. Preferably, the plunger 216 is provided with an enlarged base portion 216a adapted for engage-ment with a complementary shoulder (not shown) in the bore 212 for limiting the upward movement of the plunger 216 under the urging of the compresslon spring 214. Preferably~ the modulus of elasticity of the compression spring 214 is relatively hi~h~
the amount of force necessary to depress the plunger 216 against the urging of the bias spring 214 being variable by ad~ustment of the regulating screw 213.
A shear bl~de 215 is disposed in a complementary re~
cess 217 and the rear surfaces of the pressure block 210 and is fixedly secured thereto by means of a mounting screw 218, the inner end of the shear blade 215 projecting inwardly beyond the inner surface of the pressure block 210 and being accommodated in the slot 209. The shear blade 215 is disposed in use a very slight distance forwardly of the shear blade 104 on the rear strap spacer 101 for cooperation therewith to sever the supply portion of the strap in a manner to be described more fully below.
A generally rectangular end plate 220 is secured to the outer surface of the end wall 205, the inner sur~ace of the - ~, , ,, :
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10621;~) end plate 220 having ~ormed therein a vertically extending part-cylindri^al recess 2~2 receiving therein the outer portion of a vertically extending coll compression spring 223, the in-ner portion of wh~ch is received ln a complementary part-cylin-drical openlng of recess 219 in the outer surface of the pres-sure block 210, the compression spring 223 serving to inhiblt vertical movement o~ the pressure block 210. Also formed in the inner surface of the end plate 220 and extending upwardly from the bottom end thereof is an elongated slots 224 ~or ac-commodating therein the outer end o~ the shear blade 215 whichproaects outwardly beyond the outer surface of the pressure block 210. The end plate 220 extends a substantial distance upwardly above the upper surfaces o~ the end wall 205 and the pressure block 210 and has mounted thereon a roll pin 225 which extends inwardly of the end plate 220 a predetermined distance above the top of the end wall 205 for a purpose to be described below.
Also carried in the end plate 220 above the top of the end wall 205 and rearwardl~ o~ the roll pin 225 is a bear-ing 226 having journalled therein the reduced diameter end 231of an elongated cam sha~t 230 which extends inwardly o~ the end plate 220 substantially normal thereto, the opposite end o~
the cam sha~t 230 also being provided with a reduced diameter portion 232 journalled in a bearing 233 in the bearing wall 203.
A lever handle 235 is threadedly engaged with the cam sha~t 230 and extends radially outwardly therefrom a slight distance in'-wardly of the end plate 220 ~or manually rotating the cam shaft 230 about the longitudinal axis thereo~, the handle 235 being engageable with the roll pin 225 ~or limiting the rotation o~
the cam shaft 230 in a clockwise direction, as viewed in Figure 1. Projecting from the cam sha~t 230 are a number of cam lobes ~z~ov including (progressing from the inner end ~o the outer end ofthe cam shaft 230) a heater drive lobe 240 having a drive cam surface 241 and a first dwell surface 242 and a retract cam surface 243 and a second dwell surface 243a thereon, a heater latching lobe 245 having a cam surface 244 thereon, a pressure block plunger lobe 246 having a cam surface 247 thereon and a pressure block sealing lobe 248 having a cam surface 249 there-on.
A rocker arm, generally designated by the numeral 250, is disposed between the bearing turrets 204, the rocker arm 250 being fixedly secured to an elongated pivot pin 251 ex-tending therethrough, the opposite ends of which pin are respec-tively received in complementary openings extending coaxially through the turrets 204 for pi~otally mounting the rocker arm 250 thereon. The rocker arm 250 includes a downwardly extend-ing coupling arm 252 having an opening therein through which is received a coupling bolt 253 secured in place by a nut 254.
The rocker arm 250 is also provided with a drive cam member 255 projecting inwardly there~rom and having a camming surface 256 thereon disposed for engagement with the surfaces 241, 242 243 and 243a of the cam lobe 240 on the cam shaft 230. The rocker arm 250 is also provided with a latch cam member 257 pro~ecting upwardly and outwardly thereof and having thereon a camming surface (not shown) on the front side thereof disposed for engagement with the camming surface 244 o~ the cam lobe 245 on the cam shaft 230.
Disposed in the heater control recess 62 beneath the bearing wall 203 and the bearing turrets 204 is a heater car-riage, generally designated by the numeral 260~ provided with a pair of vertically spaced-apart flat retaining flanges 262 projecting therefrom toward the strap apron 65, the lower one .
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o~ the retaining flanges 262 extending forwardly and rearwardly of the heater control recess 62 a sufficient distance ~o that the opposite ends thereof respectively rest upon the rails 70 for sliding engage~ent therewith. Formed in the heater car-riage 260 is a generally rectangular connector recess 261 com-municating with the space between the retaining ~ange~ 262,the carriage 260 also having a pair of bearing arms 263 ex-tending upwardly and outwardly therefrom in a direction oppo-site to the direction o~ the retaining flanges 262 and adapted ~or sliding engagement with the underside of the bearing wall 203, the distal ends of the bearing arms 263 being engageable with the lip 202 on the bearing wall 203 for limiting the slid-ing movement of the heater carriage 260 along the rails 70. The bearing arms 263 are spaced apart laterally of the heater car-riage 260 (forwardly and rearwardly of the baseplate 60) and are interconnected at the inner ends thereof by a relatlvely small diameter roll pin 264 and a relatively large dlameter latch pin 266.
Also disposed between the bearing arms 263 is a latch clip, generally designated b~ the numeral 265, and preferably formed of spring steel, the clip 265 being generally U-sh~ped and having a bight portion wrapped around the coupling bolt 253 on the rocker arm 250 and a pair of legs extending outwardly to-ward the distal end of the bearing arms 263. The upper one of the legs o~ the latch clip 265 is bent adjacent to the distal end thereof downwardly toward the lower leg of the clip 265 to ~orm a hook portion 268, the lower end of the hook portion 268 being normally spaced from the lower leg of the latch clip 265 a distance less than the diameter of the roll pin 264 and ter-minating in an upwardly inclined cam flange 269. Normally, thehook portion 268 o~ the latch clip 26~ is hooked over the latch , 1~)6Z60V
pin 266, as illustrated in Figure 4, ~or coupling the heatercarriage 260 to the rocker arm 250.
Disposed between the retaining flanges 262 of the heater carriage 260 substantially parallel thereto is an elon-gated electrically resistive heating eilement 270 projecting laterally well beyond the ends o~ the retaining ~langes 262 toward the strap apron 65. The inner end o~ the heating ele-ment 270 is preferably provided with a pair o~ plugs or prongs (not shown) adapted to be received in complementary sockets in ..
a crystal connector 275 which is received in the recess261 in the heater carriage 260, the heating element 270 and the :
crystal connector 275 being respectively fixedly secured to the heater carriage 260 b~ means of mounting screws 272 and 273.
The crystal connector 275 is in turn provided with a pair of terminals 274 to which may be connected the conductors of an :;
A.C. electrical power input line. Fixedly secured to the inner surface of the bearing wall 203 by means o~ a mountlng screw 277 is one end of a coil torsion spring 276, the other end o~ :
which ~orms a return spring lea~ 278 disposed ~or engagement with the rear end o~ the latch pin 266 which projects rearward-ly ~rom the heater carriage bearing arms 263 ~or resiliently urging the heater carriage 260 toward a retracted position, il-lustrated in Figure 4, wherein the distal ends o~ the bearing arms 263 are disposed in engagement with the lip 202 on the b~iærin~ wall 203.
Disposed between the end wall 207 and the bearing wall 203 of the frame 201 is a ~an or blower assembly, general-ly designated by the numeral 280, which includes an electric motor 281~ which is pre~erably a single phase induction motor o~ the shaded pole type spaced ~rom the end wall 207 by a pair of cylindrical spacers 282 through which are received mounting :1062600 screws for fixedly mounting the motor 281 on the ena wall 207.
The motor 281 has an output sha~t 285 projecting inwardly therefrom substantially perpendicular to the bearing wall 203.
The opposite ends o~ the shaft 285 are respectively ~ournalled in bearlngs 286 fixedly secured to the opposite sides o~ the motor pole plates b~ a bracket 289. Fixedly secured to the shaft 285 inwardly of the inner bearing 286 is a fan blade as-sembly 287 for directing a stream o~ cooling air inwardly of the sealing and shearing apparatus 200 when the fan motor is energized ~or cooling the apparatus and removing therefrom vapors caused by the heating o~ the strap 55.
The entire portion of the heating and sealing appara~
tus 200 from the inner sur~ace of the end wall 205 to the end wall 207 is enclosed by a cover 290 which is pre~erably ~ormed of plastic, but which may be ~ormed of any suitable material, the cover 290 being provided with a series o~ louvers 295 in the upper sur~ace thereo~ overlying the fan assembly 280 permitting cooling air to be drawn into the heating and sealing apparatus 200 by the ~an blade 287. Mounted in the top of the cover 290 is an electrical light ~ixture 297 adapted to be connected to and energized by the source o~ ~C. electric current ~o.r indicat-ing when the heater is turned on. In the preferred embodiment of the invention, the fan assembly 280, the heater element 270 and the light fixture 297 are all connected in parallel across the conductors o~ an A.C. power input line 293 secured to the cover 290 by plug 294 (see Figure 2), each o~ these electrical ~ixtures pre~erably being adapted to be operated ~rom a standard 60 Hz. 120-volt electrical power source.
The combination tool 50 is pre~erably also provided with a utility handle 291 ~or transporting the tool, the handle 291 being provided at one end thereo~ with a generally rectangu-,, -- ' ~
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lar coupling block 292 receivable in a complementary opening at the rear end o~ the frame 201 for li~ting the apparatus 50, the handle 291 belng readily removable from the apparatus when the apparatus is in use so as not to interfere with the operation of the tensioning handle 160 and the cam shaft lever handle 235- ~.
Re~erring now to Figures 5 through 9 o~ the drawings, the strap guide surface 65 o~ the anvil block 64 has ~ormed ~.
therein at the rear end thereo~ a plurality of elongated paral-lel grooves or channels 300 which extend longitudinally o~ the anvil block 64 ~rom the rear end thereof to rounded forward ends 303, the channels 300 being respectively separated ~rom one another by a plurality of narrow elongated parallel ribs 301. The ribs 301 are respectively provided with ~lat upper surfaces 302 which are substantially coplanar with the guide surface 65. The channels 300 are identically dimensioned, as are the ribs 301, the channels 300 having a width several times as great as the width o~ the ribs 301.
The pressure block 210 is provided with a ~lat bot- :
tom sur~ace 304 directly overlying the strap guide sur~ace 65 of the anvil block 64 substantially parallel thereto. Project-ing downwardly ~rom the bottom sur~ace 304 are a plurality of longitudinally extending and laterally spaced-apart parallel ribs 305 which are, respectively, substantially identical in transverse cross section to the ribs 301 on the anvil block 64.
The ribs 305 serve to de~ine a plurality of parallel channels 306 therebetween along the bottom surface 304 of the pressure bloc~ 210, the bottom surfaces 307 o~ the ribs 305 being sub-stantially coplanar. The ribs 305 are equidistantly spaced apart and are so arranged as to be respectively disposed cen-trally o~ the channels 300 in the anvil block 64, the ribs 301 . ~ : . ~ .. .
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on the anvil block 64 being in turn respectively disposed cen-trally of the channels 30~.
In operation, it will be appreciated that when the overlapping strap portions 56 and 57 are pressed togethar be-tween the anvil block 64 and the pressure block 210, the ribs 301 and 305 cooperate to deform the overlapping and bonded-together strap portions 56 and 57 into the channels 306 and 300, thereby to form in the supply portion 57 of the strap a plurality of grooves or valleys 3I2 separated by and alternat-ing with ridges. 311, and to form in the leading end 56 of thestrap a plurality of grooves or valleys 314, separated by and alternating with ridges 313, thereby to form a substantially corrugated ~oint 310, as best seen in Figure 9.
The operation of the combination tool 50 will now be described in detail. Initially, the cord 293 o~ the apparatus 50 is plugged into a 110-120 VAC outlet and allowed to heat up for a suf~icient time for the heating element 270 to reach the desired operating temperature which, in the preferred embodi-ment o~ this invention, is at least 725F. Plugging in of the 20 cord 293 also energizes the fan motor 281 and the light 297.
The tool 50 is then placed by use o~ the utility handle 291 atop the ob3ect 51 to be strapped, as shown in Figure l, with the oper~tor preferably being positioned behind the tool 50 (to the left as viewed in Figure l), and the handles 235 and 160 are placed in their forwardmost positions, i.e., with the handle 235 resting upon the roll pin 225, and with the tension-ing handle 160 latched in a downward position by means not shown.
During this downward latching movement of the ten-sioning handle 160, it acts as a ~irst order lever with the ~ulcrum being the pivot pin 133 ~or exerting an upward ~orce : ~. . . .
. .
1~)62600 against the pivot pin 161 to li~t the entire cradle 130 and pivot it about the axis o~ the pivot pin 133 against the urging of the tension spring 134. As the cradle 130 is pivoted upward-ly, a camming surface thereon eng~ges the cam arm 119 on the lifting link 115 to effect a pivotal move~ent thereo~ about the axls of the roll pin 117 in a counterclockwise direction, as viewed in Figure 3, thereby bringing the lifting finger 118 into engagement with the underside of the separating plate 110 to lift the outer end of the plate 110 up a predetermined distance above the strap apron 65. In this position, the pawl member 170 will have been pivoted out of engagement with the drive gear 165.
When the tensioning handle 160 has been latched in its downward position, the leading end 56 of a length of plas-tic strap is inserted forwardly along the strap apron 65 and beneath the rear guide member 101 and the front guide member 105 and the raised separating plate 110 and inwardly of the raised guide projection 199 on the side plate 197 until the leading end 56 projects a slight distance forwardly of the separating plate 110. With the leading end 56 of the strap thus positioned in the combination tool 50, the handle portion 182 of the positioning lever 180 is depressed toward the ten-sioning handle 160~ thereby pivoting the positioning lever 180 about the ax~s of the bolt 167a against the urging of a com-pression spring (not shown) ~or releasing the tensioning handle 160 from its latched position.
The cradle 130 is now pivoted back downwardly in a counterclockwise direction, as viewed in Figure 3, about the axis of the pivot pin 133 under the urging of the torsion spring 134 until the enlarged head 168 of the bolk 167a enga~es a spring-biased rearwardly pro~ecting detent 193 (see Figure 3).
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l~iZ~iOO
The modulus of elasticity of the detent bias s?ring (not shown~
is such that the proJecting detent 193 limits further upward movement of the tensioning handle 160 under the urging of the torsion spring 134~ the applicat.ion o~ ~urther manual ~orce to the tensioning handle 160 being necessary to depress the detent 193 and move the tensioning handle 160 back up past its detent position. The movement of the tensioning handle 160 from its latched position back up to the detent position permits the lifting link 115 to be pivoted back in a clockwise direction, as viewed in Figure 3, to its original position under the urg-ing of the deflected separating plate 110, thereby permitting the separating plate 110 to return to its original position wherein it cooperates with the strap rest button 68 for secure-ly clamping therebetween the leading end 56 of the strap~ The strap rest button 68 is threadedly engaged in the baseplate 60 and by appropriate adjustment of this screw-type button 68 the force with which the leading end 56 of the strap is clamped in place may be ad~usted.
It will be noted that when the apparatus is in the detent position the cradle 730 has not been fully lowered to its original position and the rotary dog 148 remains spaced a slight distance above the separating plate 110 to accommodate the passage of the supply portion 57 of the strap therebetween.
A1SOJ it will be noted that in this position, the strap guide finger 199 on the side plate 197 will also be disposed a pre-determined distance above the strap apron 65 to accommodate in-sertion of the supply portion 57 of the strap ~rom the side of the tool 50. Thus, at this point, the supply portion 57 of the strap is slid into place between the separating plate 110 and the rotar~ dog 148 and above the rear guide member 101 and the ~ront guide member 105. In this position, it will be noted .~
,.
10t;260~
that the portions o~ the leading end 56 and supply porti~n 57 of the strap extendlng between the front and rear guide members 101 and 105 are vertically spaced apart thereby and are dis-posed in overlapping relationship ~herebetween, all ~or a pur-pose to be described more fully below.
At this point~ the tensioning handle 160 is manually pulled back up past the detent position thereof~ thereby de-pressing the detent member 193 and pivoting the cradle 130 back down to its original position, as illustrated in Figure 3, wherein the serrated peripheral surface o~ the rotary dog 148 cooperates with an insert 113 (Figure 3) in the separating plate 110 firmly to gr~p therebetween the supply portion 57 of the strap. It will be appreciated that the force with which the supply portion 57 o~ the strap engages the rotary dog 148 is also variable by appropriate adjustment o~ the strap rest button 68. When the tensioning handle 160 has been moved back to the positions illustrated in Figure 3, it will be noted that the strap guide ~inger 199 on the side plate 197 has been moved back down into its original position extending below the surface o~ the strap apron 65 for preventing the strap from being displaced laterally ~rom the combination tool 50. In :
addition, it will be noted that as the tensioning handle 160 moves up past the detent position thereof, the pawl member 170 is moved back into engagement with the teeth of the drive gear 165.
At this point, the strap which is looped about the object 51 may be tensioned by a back and ~orth movement of the tensioning handle 160 between the position illustrated in Fig- :
ure 3 and a rearward position in engagement with the cover 290, the operator pre~erably operating the tensioning handle 160 with his le~ hand while he grips the handle 235 with his right hand. As the handle 160 is moved rearwardly, in a counter-clockwise direction as viewed in Figure 3, the drive gear 165 is rotated in a clockwise direction by engagement therewith of the pawl 170, thereby resulting in rotation of drive mechanism (not shown) to effect corresponding rotation of the rotary dog shaft 141 and the rotary dog 148 for moving the supply portion 57 of the strap rearwardly of the combination tool 50, thereby taking up slack in the strap and ef~ecting tensioning thereof.
When the tensioning handle 160 has reached the limit of its 10 rearward travel, it is moved back forwardly to the position il-lustrated in Figure 3 for another stroke, with the pawl 170 ratcheting over the teeth of the drive gear 165 during this forward movement o~ the handle 160. This tensionihg operation continues ~ntil the desired tension in the strap has been achieved.
When the strap has been sufficiently tensioned, the operator grips the tensioning handle 160 with his left hand and grips the cam shaft lever handle 235 with his right hand and moves the handle 235 rearwardly i~ a counterclockwise direc-20 tion, as viewed in Figure 3J for sealing the overlapping por-tions 56 and 57 of the strap and severing the supply portion thereof. Preferably, the sealing and shearing operation is ef-fective by a single continuous movement of the handle 235 from the position illustrated in Figures 1 through 4 to the position illustrated in Figure 11, which movement pre~erably takes ap-proximately two seconds, thereby effecting a counterclockwise rotation of the cam shaft 230, as viewed in Figure 3, for se-quentially effecting a series of operations.
When the lever handle 235 is in its initial or home s 30 position illustrated in Figures 1 through 4, it rests upon the roll pin 225, with none of the cam lobes on the cam shaft 230 .. :
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:
being in engagement. The latch clip 265 is clipped over the latch pin 266 for coupling the heater carriage 260 to the rocker arm 250, and the heater carriage 260 is held in its re-tracted position with the distal ends of the bearing arms 263 in engagement with the lip 202 on the bearing wall 203 by the action of the return spring 276, thereby holding the heater element 270 retracted from between the overlapping portions of the strap 56 and 57 and holding the rocker arm 250 back in the position illustrated in Figure 4. The pressure block 210 is held with the upper sur~aces thereof substantially flush with the upper surface o~ the end wall 205 by the action o~ the I ?
compression spring 223, with the movable shear blade 215 being disposed above and out of engagement with the supply portion 57 of the strap. The plunger 216 projects upwardly above the top surface of the pressure block 210 under the urging of the com- -pression sprlng 214.
During about the ~irst thirt~ degrees of the rearward movement of the h~hdle 235, the cam surface 241 on the cam lobe 240 engages the cam surface 256 on the rocker arm drive cam 255 to effect a cammed pivotal movement o~ the rocker arm 250 in a counterclockwise direction about the axis of the pivot pin 251, as viewed in Figure 4, thereby sliding the heater carr~ge 260 along the rails 70 to the right, as viewed in Figure 4, under the coupling action of the latch clips 265, for moving the dis-tal end of the heating element 270 between the spaced-apart ~ .
overlapping portions 56 and 57 of the strap in the region be-tween the front and rear strap spacers 105 and 101. As the heating element 270 is being moved between the porti~ns 56 and : ~ .
57 of the strap, the cam surface 247 on the cam lobe 246 en- :
gages the projecting plunger 216, the modulus of elasticity of the compression spring 214 being greater than that of the com--23- : -~
-106Z60~
pression spring 223 so that the camm~ng engagement between the cam sur~ace 247 and the plunger 216 effects a downward movement of the pressure block 210 against the urging o~ the compression spring 223, while the plunger 216 remains substantially unde-pressed with respect to the pressure block 210. The pivotal movement of the rocker arm 250 o~ the heating element 270 con-tinues until the arcuate dwell sur~ace 242 on the cam lobe 240 engages the rocker arm drive cam 255, at which point the heating element 270 is ~ully e~tended between the strap portions 56 and lo 57 in the position illustrated in Figure 10, with the distal end of the upper retaining flange 262 bearing against the inner surface of the end wall 205 ~or limiting the outward movement of the heater carriage 260 and the heating element 270.
As the backward motion of the handle 235 continues, and while the dwell surface 242 of the cam lobe 240 rides over the rocker arm drive cam 255, the pressure block 210 bottoms out against the supply portion 57 of the strap and cooperates with the strap apron 65 for firmly pressing therebetween the overlapping portions 56 and 57 of the strap with the heater ele-20 ment 270 therebetween. The force with which the heater element270 and the strap portions 56 and 57 are pressed together is limited by the compression spring 214, ~orce applied by the cam lobe 246 beyond a predetermined ~orce serving to depress the .
plunger 216 and thus be absorbed by the compression spring 214, so that the overlapping strap portions 56 and 57 are not signif-icantly deformed by the ribs 301 and 305. The predetermined force at which the plunger 216 is depressed can be varied by ap-propriate ad~ustment of the regulating screw 213, as we de-scribed above. When the overlapping portions 56 and 57 o~ the strap are thus ~irmly pressed into contact with the heating ele-ments 270, the surfaces thereo~ in contact with the heating : - - ~ . - .
106Z60~
element 270 are ~elted. It will be noted that when the pres-sure block 210 is thus held in its strap-heating position, the shear blade 215 remains up out of contact with the supply por-tion 57 of the strap.
As the rearward movement of the handle 235 continues, the cam sur~ace 247 on the cam lobe 245 moves past the plunger 216 permitting it to return to its projecting position and then permitting the pressure block 210 to return upwardly to its or-iginal position out of contact with the strap supply portion 57 under the urging of the compression spring 223. Simultaneously, the camming surface 243 on the cam lobe 240 is brought into en-ga~ement with the rocker arm drive cam 255 for effecting a fur-ther counterclockwise pivotal movement of the rocker arm 250, as viewed in Figure 10. However, since further outward move-ment of the heater carriage 260 is prevented by engagement of the retaining flange 262 with the end wall 205, this further pivotal movement of the rocker arm 250 results in the hook por-tion 268 of the latch clip 265 being cammed up over the latch pin 266 to permit the latch pin 266 to pass therebeneath~ As soon as the hook portion 268 has cleared the latch pin 266, khe heater carriage 260 is snapped back into its retracted position ~ ~ ;
illustrated in Figure 4, under the urging of the return spring 276. A further slight rearward movement of the handle 235 brings the second dwell surface 243a on the cam lobe 240 into engagement with the rocker arm 255 for holding the rocker arm 250 in the position illustrated in broken line in Figure 11.
As the rearward movement of the handle 235 continues, the cam surface 249 of the cam lobe 248 is bro~ght into camming engagement with the cam surface 211 on the pressure block 210, again forcing the pressure block 210 downwardly against the urging of the compression spring 2~3 to a sealing condition ~O~iZ600 illustrated in Figures 8 and 11, wherein the top surfaces 302of the ribs 301 are substantially coplanar with the bottom surfaces 307 of the ribs 305. As this downward movement of the pressure block 210 continues, the melted surfaces of the overlapping portions 56 and 57 of the strap are brought into engagement with each other and are firmly pressed together be-tween the ribs 305 of the pressure block 210 and the ribs 301 of the strap apron 65 of the anvil block 64 to effect a firm corrugated heat-sealed joint between the overlapping strap portions 56 and 57 which are accommodated by the channels 300 and 306.
As the pressure blo~k 210 is moved to the position illustrated in Figures 8 and 11, the overlapping strap portions 56 and 57 are deformed by the ribs 301 and 305 into the channels 306 and 300, thereby to produce in the overlapping strap por-tions the ridges 311 and 313 and the valleys 312 and 314 il-lustrated in Figure 9, the formation of which ridges and val-leys produces a kneading-like motion of the molten strapping sur~aces, and serves substantially to increase the total con-20 tact area between the molten overlapping surfaces of the strapportions 56 and 57, thereby to effect a much stronger interface bond therebetween. ~urthermore, the deformation of the over-lapping strap portions 56 and 57 to form the corrugated joint 310 effects a substantially evenly distributed appl~c~tiQn of pressure throughout the joint area, thereby further to enhance the strength o~ the bond.
The pressure with which the strap portions 56 and 57 are pressed together is controlled by the amount o~ force ap-plied to the handle 235 by the operator. As the pres~re block 210 bottoms out, in the position illustrated in Figure 11, the shear blade 215 passes downwardly past the shear blade 104 and cooperates therewith to sever the supply portion 57of the strap at the rear guide member 201.
At this point, the heat-sealed joint in the strap has been completed and the operator moves the tensioning handle 160 with his left hand all the way forward to the latched position, for a~ain elevating the cradle 130 and the separating plate 110 and the strap guide finger 199 to permit removal of the strap from the strap-gripping apparatus 100. Then, with his right hand, the operator moves the sealing lever handle 235 ba~k to the forward position thereof illustrated in Figure 4, thereby permitting the pressure block 210 to return upwardly to its original position under the urging of the compression spring 223. This forward m~vement of the handle 235 also brings the camming surface 24~ of the ca~ lobe 245 into engagement with the latch cam 257 on the rocker arm 250 for pivoting the rocker arm 250 in a clockwise directlon from the broken line position to the solid line position illustrated in Figure 11. As the rocker arm 250 pivots back to its original position, the cam flange 269 on the latch clip 265 engages the roll pin 264 on 20 the heater carriage 260 and rides up thereover, slightly sepa~
rating the legs of the latch clip 265 and bringing the cam flange 269 into position for camming engagement with the latch ~ -pin 266. The cam ~lange 269 then rides up over the latch pin : ~ ;
266 and therebehind for relatching the latch clip 265 in place for coupling the rocker arm 250 to the heater carriage 260.
With the handles 235 and 160 now returned to their forwardmost positions, the combined tool 50 can be moved sideways to strip it from the strap and the object 51 by use of the utility handle 291.
From the ~oregoing, it ^an be seen that there has been provided an improved combination strapping tool for bo~h :
' ' ' '- ~ '' -`
gripping and tensioning a length of pl.astic strap about an ob-~ect and then forming a heat-sealed bonded joint between the ends of the length of strap and severing the length of strap from the supply thereof.
More particularly, there has been provided a combina-tion strapping tool of the character described, whereln there is formed a corrugated ~oint between the overlapping strap portions having alternating ridges and valleys extending lon-gitudinally of the strap.
There has also been provided a combination strapping tool of the character described, wherein the corrugated ~oint is formed by complementary ridges and grooves respectively formed on a moving pressure block and a stationary anvil block, between which the overlapping strap portions are pressed after having the facing surfaces thereof heated to a molten condi-tion.
~.".. . ' :' :
The present inventi~n is an improvement o~ the strap-ping apparatus disclosed ln U.S. Patent No. 3,944,460. That strapping tool has a heat-sealing mechanism including a cam shaftadapted for camming engagement with a movable pressure block and with a rocker arm which is in turn releasably coupled to a movable heater. As the cam shaft is rotated, the rocker arm moves the heater between the overlapping strap portions and the pressure block is moved to press together the heating ele-ment and the strap portions for melting thereof. Further rota-tion of the cam sha~t disengages it ~rom the pressure block and decouples the rocker arm from the heater to permit retraction of the pressure block and the heater by separate bias means.
Further rotation of the cam sha~t again effects cammed movement of the pressure block to bond together the melted strap por-tions and to sever the supply portion of the strap.
In that prior strapping tool, the pressure block co-operates with a strap guide surface on an anvil-like base mem-ber for pressing therebetween the overlapping strap portions~
both the strap guide surface and the pressure block having sub-stantially smooth planar pressure surfaces thereon. Because of manufacturing imperfections in producing such surfaces economic-ally, it is not possible with the prior art strapping tool to achieve a truly even distribution o~ pressure throughout the seal area. Furthermore, it has been found that the bond be-tween the overlapping melted strap portions formed by the priorstrapping tool is not su~ficiently strong for certain high load ~ .
., .,.. , . ~ ~ , - . .
~62600 applications.
The ob~ect of the present invention is to proYlde a strapping tool wlth lmproved pressure means for providing an improved and strengthened ~oint in the overlapping strap ~r-tions.
Accordingly, the present invention provides strapping apparatus for securing a length of plastic strap around an ob-~ect, said apparatus comprising a frame, strap-gripping means mounted on said frame for holding the strap encircled in a loop in a tensioned condition about the object with the leading end of the strap overlapping the supply portion thereof, heating means carried by said frame adjacent to the overlapping strap portions ~or ef~ecting melting of the ~acing portions thereof, a first pressure member carried by said frame and having a plu-rality of elongated and equal-width first grooves therein equi-distantly spaced apart by first ribs, and a second pressure member carried by said frame and having a plurality of elon-gated and equal-width second ribs pro~ecting therefrom equi- :
distantly spaced apart by second grooves~ each of said first 2Q and second grooves being rectangular in transverse cross sec-tion and havlng an elongated flat rectangular recessed surI'ace, each o~ said first and second ribs being rectangular in tr~ s-verse cross section and having an elongated flat rectangular end surface with the width of each said end surface being sub stantially less than the width of each groove recessed sur-face, said end surfaces of said ~irst and second ribs being re-spectively disposed centrally of and in parallel facing rela-tionship with said second and first groove recessed surfaces in longitudinal alignment therewith, said pressure members being movable with respect to each other to a sealing configuration wherein said ribs and said grooves cooperate to press together therebetween the melted overlapping strap portions and to de-~orm the overlapping strap portions in a predetermined pattern ; as they are pressed together, whereby the pressure of said pressure means is substantially evenly distributed throughout the inter~ace between the melted overlapping strap portions ~or formation o~ a strong joint therebetween.
In the drawings:
Figure 1 is a side elevational v~ew of the strapping apparatus of the present invention shown in its operative po-sition for applying plastic strapping around an object, Figure 2 is a top plan view of the strapping appara-tu~ shown in Figure l;
Figure 3 is an enlarged fragmentary side elevational view of the strapping apparatus o~ the present invention taken along the line 3-3 in Figure 2 more clearly to show the inter-nal construction thereo~, with the tensioning handle shown ln an unlatched position and with the sealing handle shown in its home position, Figure 4 is an enlarged view in vertical section o~
the heat-sealing portion o~ the strapplng apparatus taken along the line 4-4 in Figure 2;
Figure 5 is a fragmentary bottom plan view o~ the pressure block of the present invention, taken along the line 5-5 in Figure 4, .-Figure 6 is a ~ragmentar~ top plan view of the fixed anvil block Or the present invention, taken along the line 6-6 in Figure 4j Figure 7 is an enlarged ~ragmentary view in vertical section~ illustrating the overlapping strap portions between the pressure members immediatel~ a~ter the strap heater has been removed from therebetween, .
106260~
Figure 8 i9 a viewJ similar to Figure 7J but with the overlapping strap portlons not shown, illustrating the position of the pre~sure members during the seallng and em-boB8i.ng operation;
Flgure 9 i~ an enlarged, frag~entary, front per-specti~e vlew o~ a portion of the corrugated seal ~olnt ~o~med ~n the overlapping strap portion~ by the pressure members when they are moved to the position illustrated ln ~:
Figure 8;
Figure lO i8 a fragmentary view ~n vertical sectlon slmilar to Figure 4~ lllustratlng the sealing apparatus in the strap-heating configuration thereo~; -Figure lOA i~ a fragmentary ~ide elevational vlew ~ .
of the cam shaft of the sealing mechanlsm in the coniiguration .
lllu8tr~ted in Figure 10;
Figure 11 i8 a view s~milar to Figure lO, showlng the seallng apparatus disposed in the sealing con~iguration thereo~; and Flgure llA i8 a side elevational view slmilar to 20 Figure lOA of the cam sha~t ln the con~i~uration illustrated ln Figure ll. ~
Referring no~ in particular to Figures l and 2 o~ :
th~ drawing~, there i8 illustrated a 8trapplng apparatus conslsting o~ a combination tensioning and heat-sealing tool constructed in accordance wlth and embodying the features o~
the present inventlon, and generally deslgnated by the nu-meral 50.
In Figure 1, the combination tool 50 is illustrated in it~ operative position ~or applying a length o~ plastlc 30 ~trap~ such as polypropylene ~trap, ~or example, ~n a ten-~ioned loop about a package or other ob~ect 41, the strap 106;~;00 being dldposed in the combination tool 50 80 that the gupply portion 57 of the ~trap 1B dlsposed ln overlapplng relation-ship wlth the leadlng end 56 thereo~. The combinatlon tool 50 lncludes a common baseplate, generally de~ignated by the numeral 60, on which i9 mounted gripping and tensloning ap-paratus, generally deslgnated by the numeral lO0, and heat-sealing and shearing apparatus, generally designated by the numeral 200.
Referring now al~o to Figure~ 3 through 9 o~ the :lO drawings, the baseplate 60 includes a maln body 61 Or a.pre-determined thicknes3 and havlng formed thereln toward the rear portion thereof a generally L-shaped heater contrnl reces6 62 (see Flgure 4), and a generally rectangular tension-ing apparatus recess 63 in the front portlon thereo~ the heater control recess 62 hhving a pair of spaced-apart paral-lel rails 70 thereln extending laterally thereof (one shown ln Figure 4). ~ormed along one side of the baseplate 60 is an anvll block 64 havlng a ~lat strap guide gurface or apron 65 which has formed in the front end thereo~ an internally .
20 threaded opening having threadedly dlsposed therein a strap rest button 68, ~or a purpose to be described more ~ully hereinafter. A heat buffar 66 may be received in a comple-mentary recess 67 ad~acent to the inner edge of the anvil block 64.
The grlpping and tensloning apparatus lO0 includes an elongated rear strap spacer lOl secured to the baseplate 60 ad~acent to the rear end thereof ~nd pro~ecting laterally there-from at the rear end o~ the strap guide apron 65. The rear ,, , ' : '~ .' , ' . ' strap spacer 101 has a ~lat planar upper guide aur~ace 102 ana a flat planar lower guide surface 103 spaced apart a predeter-mined distance, both of the surfaces 102 and 103 being disposed substantially parallel to the strap guide apron 65 and spaced vertically therefrom. Formed along the front edge o~ the rear strap spacer 101 and e~tending substantially normal to the longitudinal axis o~ the strap guide apron 65 is a ~ixed shear blade 104 Secured to the baseplate 60 a~d spaced a predeter- : ~
' mined distance ~orwardly of the rear strap spacer 101 and ex- . .
tended substantially parallel thereto is an elongated ~ront strap spacer 105 having upper and lower strap guide sur~aces 106 and 107 which are respectively substantially coplanar with the strap guide sur~aces 102 and 10~ ~h the rear strap spacer ¦ 101. Disposed adjacent to the front end of the strap guide apron 65 substantially parallel thereto is a separating plate, generally designated by the numeral 110, and ~ixedly secured adjacent to the inner end thereo~ by mounting bolts 111 to the baseplate 60.
Disposed immediately rearwardly of the separating plate 110 is a li~ting link, generally designated by the numer-al 115, which includes an attachment arm 116 and a li~ting ~in-ger 68, respectively disposed in use in slots in the baseplate 60. Formed in the attachment arm 116 and the lifting finger 118 are coaxial bores aligned in use coaxially with a corre-sponding transverse bore in the baseplate 60, all ~or receiving therethrough a roll pin 117 ~or pivotally mounting the li~ting link 115 on the baseplate 60. In use, the lifting finger 118 extends beneath the separating plate llo ~or engagement with the bottom surface thereof. Also formed on the 1~ ting link 115 is a cam arm 119 which curves upwardly and ~orwardly ~rom the lifting ~inger 118 to overlie the separating plate 110 ~or ':, .
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~06Z60(~
a purpose to be described more fully below.
A cradle support member, generally designated ~y the numeral 120, includss an angle attachment bracket 121 secured by means of mounting screws 122 to a cradle support mounting block (not shown). Integral with the attachment bracket 121 and extending upwardly therefrom at the end thereof ad~acent to the strap apron 65 is a cradle clevis 125 having an upwardly extending bight portion 123 and a pair of spaced-apart rearward-ly extending legs 124. Integral with the bight portions 123 of the cradle clevis 125 and extending upwardly therefrom is a mounting post 126.
Mounted on the cradle support member 120 is a cradle, generally designated by the numeral 130, having a body portion 131 provided with a pair of forwardly extending mounting arms 132 respectively disposed in use along the outer side surfaces of the legs 124 o~ the cradle clevis 125. Bxtending through aligned openings in the cradle clevis legs 124 and the cradle mount~ng arms 132 is a pivot pin 133 ~or pivotally mount~ng the cradle 130 on the cradle support member 120. Coiled about the pivot pin 133 between the cradle clevis legs 124 is a tor-sion leaf spring 134 having one end thereof disposed in engage-ment with the mounting post 126 and having the other end there-of disposed in engagement with the cradle body 131 for resil-iently urging the cradle 130 toward rotation in a counterclock-wise direction about the pivot pin 133, as viewed in Figure 3.
Formed on the cradle body 131 at the rear end thereof is a ~lat :
planar sur~ace (not shown) disposed for camming engagement with ~ -the cam arm 119 of the lifting link 115, for a purpose to be explained hereina~ter. Formed integrally with the cradle body 131 at the rear end thereof toward the side thereof away ~rom the strap apron 65 is a pawl cylinder 138.
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~ Carried by the cradle 130 is a rotary dog assembly~
; generally deslgnated by the numeral 140, and including an elon-gated rotary dog shaft 141 disposed in a complementary bore and extending completely therethrough. Fixedly secured to the sha~t 141 adjacent to one end thereof is a rotary dog 148 dis-posed in a complementary shaped recess in the cradle body 131.
The cylindrical outer surface of the rotary dog 148 is serrat-ed or knurled and projects from the cradle body 131 at the bot-~ tom thereof for engagement with the supply portion 57 of the i 10 strap in a manner to be described more fully below. The adja-~ cent end of the sha~t 141 is rotatably supported in a bear~ng ,` 149 to ~acilitate rotation of the sha~t 141.
Disposed in and extending through a complementary bore in the cradle body 131 is a handle pi~ot p~n 161 ha~ng ~e e~ ~e~e~ a~3acent to the pawl cylinder 138 extending a j predQ~ermined distance outwardl~ beyond the ad~a~ent end ~ the cradle body ~3~. ~h~s pro~ecting end o~ the pivot pin 161 ex-tends through complementary openin~s ad~acent to the lower ends o~ inner and outer elongated handle plates 162 and 163, the up-per ends thereof having sandwiched therebetween the lower end of a tensioning handle 160. Coaxially mounted on the pivot pin 161 between the handle plates 162 and 163 is a drive gear 165 ' disposed for meshing engagement with the outer teeth on another drive gear tnot shown) The handle 160 and the handle plates 162 and 163 are all secured together by bolts 167 and 167aJ the bolt 167 having a head 169 and the bolt 167a having an enlarged , spa~er head 168.
The lower end o~ the tensioning handle 160 has a re-cess 166 ~ormed in the inner s~de surface thereof, in which is received a pawl member, generally designated by the numeral 170~
having an opening therein through which is received the bolt 167 for pivotally mounting the pawl member 170. The p~wl member 170 is provided with a pawl tooth disposed for ratcheting en-gagement with the teeth of the drive gear 165 to prevent rota-tion thereof in a clockwi~e direction, as viewed in F~gure 3.
Pro~ecting outwardly from the opposite end o~ the pawl member 170 ls a spring seat finger 173, for a purpose to be described more ~ully below. The lower end o~ the pawl member 170 pro-aects downwardly and forwardly beneath the handle plates 162 and 163 and has formed thereon an arcuate seat 175 and a cam-ming surface (not shown).
A positioning lever, generally designated by thenumeral 180, has a flat side plate 181 which is disposed in use to the inner handle plate 162 and is secured to the outer surface thereof by the bolt 167a for pivotal movement with re-spect thereto. Integral with side plate 181 and extending up-wardly therefrom substantially normal thereto a predetermined distance above the tensioning handle 160 is a handle portion 182 for manipulating the positioning lever 180. Projecting downwardly and rearwardly from the side plate 181 is a stop finger 183 disposed ~or engagement wi~h the head 169 o~ the bolt 167, for limiting pivotal movement of the positioning ~, lever 180 in the counterclockwise direction, as viewed in Fig-ures 1 and 3. Both the pawl member 170 and the positior.ing lever 180 are simultaneously resiliently urged toward rotation in a counterclockwise direction, as viewed in Figure 3, by ; spring counter means (not shown).
Respectively secured to the opposite ends of the ~ cradle body 131 by means of screws 198 are two end plates 197 'A which securely hold in place the pivot pins 133 and 161 and the sha~t 141. Projecting downwardly ~rom the r~ar end of one of the side plates 197 is a strap guide finger 199 which projects ., ~g _ .~. .
a slight distance downwardly below the surface of the strap apron 65 adjacent to the outer edge thereof for guiding the strap and confining it to a path overlying the strap apron 65.
Referring now also to Figures 4 and 10 through llA of the drawings, the sealing and shearing apparatus 200 will be described. The apparatus 200 i9 mounted on an irregularly shaped frame or housing 201 which is fixedly secured to the baseplate 60 and overlies the heater control recess 62 therein.
The ~rame 201 is provided with a relatively thick upwardly ex-tending end wall 205 overlying the strap apron 65 and spaced apredetermined distance thereabove and a relatively thin up-standing end wall 207 adjacent to the opposite side of the baseplate 65 and an upstanding bearing wall 203 disposed be-tween the end walls 205 and 207 substantially parallel thereto.
The bottom o~ the bearing wall 203 is disposed well above the baseplate 60 and has formed thereon, at the side thereof fac-ing the end wall 207, a downwardly extendlng lip pr pro~ection 202. Disposed between the end wall 205 and the bearing wall .3203 are two longitudinally spaced-apart cylindrical bearing i,20 turrets 204 extending coaxially with each other and substan-tiall~ parallel to the walls 203 and 205.
;,Formed in the outer surface o~ the end wall 205, be- ~.
tween the front and rear,strap spacers 105 and 101, is a deep slot or channel 206 substantially rectangular in transverse cross section, the inner wall of the channel 206 in turn having 'formed therein adjacent to the rear end thereof a narrow elon-gated slot 209. The rear upper surface o~ the end wall 205 has an inclined surface 208 which slopes downwardly and ~orward-ly to the channel 206, ~or a purpose to be described below.
Dispo~ed in khe channel 206 is a complementary shaped pressure block~ generally designated by the numeral 210, having .. --10 -.,~'1 , , .. ~ . . . . .
. .
lO~Ztj(~O
at the upper rear end thereof an ~nclined cam surface 211 which slopes downwardly ~nd rearwardly to the rear surface of the pressure bLock 210adjacent to the lower edge of the inclined surface 208. Extending vertically through the pressure block 210 inwardly of the cam surface 211 i5 a cylindrical bore 212 having disposed in the lower end thereof a regulating ~crew 213. Disposed in the bore 212 abo~e the screw 213 in engage-ment therewith is a coil compressinn spring 214, upon the upper end of which is seated a plunger member 216 which normally pro-jects a predetermined distance upwardly above the top surface of the pressure block 210. Preferably, the plunger 216 is provided with an enlarged base portion 216a adapted for engage-ment with a complementary shoulder (not shown) in the bore 212 for limiting the upward movement of the plunger 216 under the urging of the compresslon spring 214. Preferably~ the modulus of elasticity of the compression spring 214 is relatively hi~h~
the amount of force necessary to depress the plunger 216 against the urging of the bias spring 214 being variable by ad~ustment of the regulating screw 213.
A shear bl~de 215 is disposed in a complementary re~
cess 217 and the rear surfaces of the pressure block 210 and is fixedly secured thereto by means of a mounting screw 218, the inner end of the shear blade 215 projecting inwardly beyond the inner surface of the pressure block 210 and being accommodated in the slot 209. The shear blade 215 is disposed in use a very slight distance forwardly of the shear blade 104 on the rear strap spacer 101 for cooperation therewith to sever the supply portion of the strap in a manner to be described more fully below.
A generally rectangular end plate 220 is secured to the outer surface of the end wall 205, the inner sur~ace of the - ~, , ,, :
, ~ .
,. . . .
10621;~) end plate 220 having ~ormed therein a vertically extending part-cylindri^al recess 2~2 receiving therein the outer portion of a vertically extending coll compression spring 223, the in-ner portion of wh~ch is received ln a complementary part-cylin-drical openlng of recess 219 in the outer surface of the pres-sure block 210, the compression spring 223 serving to inhiblt vertical movement o~ the pressure block 210. Also formed in the inner surface of the end plate 220 and extending upwardly from the bottom end thereof is an elongated slots 224 ~or ac-commodating therein the outer end o~ the shear blade 215 whichproaects outwardly beyond the outer surface of the pressure block 210. The end plate 220 extends a substantial distance upwardly above the upper surfaces o~ the end wall 205 and the pressure block 210 and has mounted thereon a roll pin 225 which extends inwardly of the end plate 220 a predetermined distance above the top of the end wall 205 for a purpose to be described below.
Also carried in the end plate 220 above the top of the end wall 205 and rearwardl~ o~ the roll pin 225 is a bear-ing 226 having journalled therein the reduced diameter end 231of an elongated cam sha~t 230 which extends inwardly o~ the end plate 220 substantially normal thereto, the opposite end o~
the cam sha~t 230 also being provided with a reduced diameter portion 232 journalled in a bearing 233 in the bearing wall 203.
A lever handle 235 is threadedly engaged with the cam sha~t 230 and extends radially outwardly therefrom a slight distance in'-wardly of the end plate 220 ~or manually rotating the cam shaft 230 about the longitudinal axis thereo~, the handle 235 being engageable with the roll pin 225 ~or limiting the rotation o~
the cam shaft 230 in a clockwise direction, as viewed in Figure 1. Projecting from the cam sha~t 230 are a number of cam lobes ~z~ov including (progressing from the inner end ~o the outer end ofthe cam shaft 230) a heater drive lobe 240 having a drive cam surface 241 and a first dwell surface 242 and a retract cam surface 243 and a second dwell surface 243a thereon, a heater latching lobe 245 having a cam surface 244 thereon, a pressure block plunger lobe 246 having a cam surface 247 thereon and a pressure block sealing lobe 248 having a cam surface 249 there-on.
A rocker arm, generally designated by the numeral 250, is disposed between the bearing turrets 204, the rocker arm 250 being fixedly secured to an elongated pivot pin 251 ex-tending therethrough, the opposite ends of which pin are respec-tively received in complementary openings extending coaxially through the turrets 204 for pi~otally mounting the rocker arm 250 thereon. The rocker arm 250 includes a downwardly extend-ing coupling arm 252 having an opening therein through which is received a coupling bolt 253 secured in place by a nut 254.
The rocker arm 250 is also provided with a drive cam member 255 projecting inwardly there~rom and having a camming surface 256 thereon disposed for engagement with the surfaces 241, 242 243 and 243a of the cam lobe 240 on the cam shaft 230. The rocker arm 250 is also provided with a latch cam member 257 pro~ecting upwardly and outwardly thereof and having thereon a camming surface (not shown) on the front side thereof disposed for engagement with the camming surface 244 o~ the cam lobe 245 on the cam shaft 230.
Disposed in the heater control recess 62 beneath the bearing wall 203 and the bearing turrets 204 is a heater car-riage, generally designated by the numeral 260~ provided with a pair of vertically spaced-apart flat retaining flanges 262 projecting therefrom toward the strap apron 65, the lower one .
- .
o~ the retaining flanges 262 extending forwardly and rearwardly of the heater control recess 62 a sufficient distance ~o that the opposite ends thereof respectively rest upon the rails 70 for sliding engage~ent therewith. Formed in the heater car-riage 260 is a generally rectangular connector recess 261 com-municating with the space between the retaining ~ange~ 262,the carriage 260 also having a pair of bearing arms 263 ex-tending upwardly and outwardly therefrom in a direction oppo-site to the direction o~ the retaining flanges 262 and adapted ~or sliding engagement with the underside of the bearing wall 203, the distal ends of the bearing arms 263 being engageable with the lip 202 on the bearing wall 203 for limiting the slid-ing movement of the heater carriage 260 along the rails 70. The bearing arms 263 are spaced apart laterally of the heater car-riage 260 (forwardly and rearwardly of the baseplate 60) and are interconnected at the inner ends thereof by a relatlvely small diameter roll pin 264 and a relatively large dlameter latch pin 266.
Also disposed between the bearing arms 263 is a latch clip, generally designated b~ the numeral 265, and preferably formed of spring steel, the clip 265 being generally U-sh~ped and having a bight portion wrapped around the coupling bolt 253 on the rocker arm 250 and a pair of legs extending outwardly to-ward the distal end of the bearing arms 263. The upper one of the legs o~ the latch clip 265 is bent adjacent to the distal end thereof downwardly toward the lower leg of the clip 265 to ~orm a hook portion 268, the lower end of the hook portion 268 being normally spaced from the lower leg of the latch clip 265 a distance less than the diameter of the roll pin 264 and ter-minating in an upwardly inclined cam flange 269. Normally, thehook portion 268 o~ the latch clip 26~ is hooked over the latch , 1~)6Z60V
pin 266, as illustrated in Figure 4, ~or coupling the heatercarriage 260 to the rocker arm 250.
Disposed between the retaining flanges 262 of the heater carriage 260 substantially parallel thereto is an elon-gated electrically resistive heating eilement 270 projecting laterally well beyond the ends o~ the retaining ~langes 262 toward the strap apron 65. The inner end o~ the heating ele-ment 270 is preferably provided with a pair o~ plugs or prongs (not shown) adapted to be received in complementary sockets in ..
a crystal connector 275 which is received in the recess261 in the heater carriage 260, the heating element 270 and the :
crystal connector 275 being respectively fixedly secured to the heater carriage 260 b~ means of mounting screws 272 and 273.
The crystal connector 275 is in turn provided with a pair of terminals 274 to which may be connected the conductors of an :;
A.C. electrical power input line. Fixedly secured to the inner surface of the bearing wall 203 by means o~ a mountlng screw 277 is one end of a coil torsion spring 276, the other end o~ :
which ~orms a return spring lea~ 278 disposed ~or engagement with the rear end o~ the latch pin 266 which projects rearward-ly ~rom the heater carriage bearing arms 263 ~or resiliently urging the heater carriage 260 toward a retracted position, il-lustrated in Figure 4, wherein the distal ends o~ the bearing arms 263 are disposed in engagement with the lip 202 on the b~iærin~ wall 203.
Disposed between the end wall 207 and the bearing wall 203 of the frame 201 is a ~an or blower assembly, general-ly designated by the numeral 280, which includes an electric motor 281~ which is pre~erably a single phase induction motor o~ the shaded pole type spaced ~rom the end wall 207 by a pair of cylindrical spacers 282 through which are received mounting :1062600 screws for fixedly mounting the motor 281 on the ena wall 207.
The motor 281 has an output sha~t 285 projecting inwardly therefrom substantially perpendicular to the bearing wall 203.
The opposite ends o~ the shaft 285 are respectively ~ournalled in bearlngs 286 fixedly secured to the opposite sides o~ the motor pole plates b~ a bracket 289. Fixedly secured to the shaft 285 inwardly of the inner bearing 286 is a fan blade as-sembly 287 for directing a stream o~ cooling air inwardly of the sealing and shearing apparatus 200 when the fan motor is energized ~or cooling the apparatus and removing therefrom vapors caused by the heating o~ the strap 55.
The entire portion of the heating and sealing appara~
tus 200 from the inner sur~ace of the end wall 205 to the end wall 207 is enclosed by a cover 290 which is pre~erably ~ormed of plastic, but which may be ~ormed of any suitable material, the cover 290 being provided with a series o~ louvers 295 in the upper sur~ace thereo~ overlying the fan assembly 280 permitting cooling air to be drawn into the heating and sealing apparatus 200 by the ~an blade 287. Mounted in the top of the cover 290 is an electrical light ~ixture 297 adapted to be connected to and energized by the source o~ ~C. electric current ~o.r indicat-ing when the heater is turned on. In the preferred embodiment of the invention, the fan assembly 280, the heater element 270 and the light fixture 297 are all connected in parallel across the conductors o~ an A.C. power input line 293 secured to the cover 290 by plug 294 (see Figure 2), each o~ these electrical ~ixtures pre~erably being adapted to be operated ~rom a standard 60 Hz. 120-volt electrical power source.
The combination tool 50 is pre~erably also provided with a utility handle 291 ~or transporting the tool, the handle 291 being provided at one end thereo~ with a generally rectangu-,, -- ' ~
10~260~
lar coupling block 292 receivable in a complementary opening at the rear end o~ the frame 201 for li~ting the apparatus 50, the handle 291 belng readily removable from the apparatus when the apparatus is in use so as not to interfere with the operation of the tensioning handle 160 and the cam shaft lever handle 235- ~.
Re~erring now to Figures 5 through 9 o~ the drawings, the strap guide surface 65 o~ the anvil block 64 has ~ormed ~.
therein at the rear end thereo~ a plurality of elongated paral-lel grooves or channels 300 which extend longitudinally o~ the anvil block 64 ~rom the rear end thereof to rounded forward ends 303, the channels 300 being respectively separated ~rom one another by a plurality of narrow elongated parallel ribs 301. The ribs 301 are respectively provided with ~lat upper surfaces 302 which are substantially coplanar with the guide surface 65. The channels 300 are identically dimensioned, as are the ribs 301, the channels 300 having a width several times as great as the width o~ the ribs 301.
The pressure block 210 is provided with a ~lat bot- :
tom sur~ace 304 directly overlying the strap guide sur~ace 65 of the anvil block 64 substantially parallel thereto. Project-ing downwardly ~rom the bottom sur~ace 304 are a plurality of longitudinally extending and laterally spaced-apart parallel ribs 305 which are, respectively, substantially identical in transverse cross section to the ribs 301 on the anvil block 64.
The ribs 305 serve to de~ine a plurality of parallel channels 306 therebetween along the bottom surface 304 of the pressure bloc~ 210, the bottom surfaces 307 o~ the ribs 305 being sub-stantially coplanar. The ribs 305 are equidistantly spaced apart and are so arranged as to be respectively disposed cen-trally o~ the channels 300 in the anvil block 64, the ribs 301 . ~ : . ~ .. .
10 6Z~OV
on the anvil block 64 being in turn respectively disposed cen-trally of the channels 30~.
In operation, it will be appreciated that when the overlapping strap portions 56 and 57 are pressed togethar be-tween the anvil block 64 and the pressure block 210, the ribs 301 and 305 cooperate to deform the overlapping and bonded-together strap portions 56 and 57 into the channels 306 and 300, thereby to form in the supply portion 57 of the strap a plurality of grooves or valleys 3I2 separated by and alternat-ing with ridges. 311, and to form in the leading end 56 of thestrap a plurality of grooves or valleys 314, separated by and alternating with ridges 313, thereby to form a substantially corrugated ~oint 310, as best seen in Figure 9.
The operation of the combination tool 50 will now be described in detail. Initially, the cord 293 o~ the apparatus 50 is plugged into a 110-120 VAC outlet and allowed to heat up for a suf~icient time for the heating element 270 to reach the desired operating temperature which, in the preferred embodi-ment o~ this invention, is at least 725F. Plugging in of the 20 cord 293 also energizes the fan motor 281 and the light 297.
The tool 50 is then placed by use o~ the utility handle 291 atop the ob3ect 51 to be strapped, as shown in Figure l, with the oper~tor preferably being positioned behind the tool 50 (to the left as viewed in Figure l), and the handles 235 and 160 are placed in their forwardmost positions, i.e., with the handle 235 resting upon the roll pin 225, and with the tension-ing handle 160 latched in a downward position by means not shown.
During this downward latching movement of the ten-sioning handle 160, it acts as a ~irst order lever with the ~ulcrum being the pivot pin 133 ~or exerting an upward ~orce : ~. . . .
. .
1~)62600 against the pivot pin 161 to li~t the entire cradle 130 and pivot it about the axis o~ the pivot pin 133 against the urging of the tension spring 134. As the cradle 130 is pivoted upward-ly, a camming surface thereon eng~ges the cam arm 119 on the lifting link 115 to effect a pivotal move~ent thereo~ about the axls of the roll pin 117 in a counterclockwise direction, as viewed in Figure 3, thereby bringing the lifting finger 118 into engagement with the underside of the separating plate 110 to lift the outer end of the plate 110 up a predetermined distance above the strap apron 65. In this position, the pawl member 170 will have been pivoted out of engagement with the drive gear 165.
When the tensioning handle 160 has been latched in its downward position, the leading end 56 of a length of plas-tic strap is inserted forwardly along the strap apron 65 and beneath the rear guide member 101 and the front guide member 105 and the raised separating plate 110 and inwardly of the raised guide projection 199 on the side plate 197 until the leading end 56 projects a slight distance forwardly of the separating plate 110. With the leading end 56 of the strap thus positioned in the combination tool 50, the handle portion 182 of the positioning lever 180 is depressed toward the ten-sioning handle 160~ thereby pivoting the positioning lever 180 about the ax~s of the bolt 167a against the urging of a com-pression spring (not shown) ~or releasing the tensioning handle 160 from its latched position.
The cradle 130 is now pivoted back downwardly in a counterclockwise direction, as viewed in Figure 3, about the axis of the pivot pin 133 under the urging of the torsion spring 134 until the enlarged head 168 of the bolk 167a enga~es a spring-biased rearwardly pro~ecting detent 193 (see Figure 3).
, - .: . , . .
l~iZ~iOO
The modulus of elasticity of the detent bias s?ring (not shown~
is such that the proJecting detent 193 limits further upward movement of the tensioning handle 160 under the urging of the torsion spring 134~ the applicat.ion o~ ~urther manual ~orce to the tensioning handle 160 being necessary to depress the detent 193 and move the tensioning handle 160 back up past its detent position. The movement of the tensioning handle 160 from its latched position back up to the detent position permits the lifting link 115 to be pivoted back in a clockwise direction, as viewed in Figure 3, to its original position under the urg-ing of the deflected separating plate 110, thereby permitting the separating plate 110 to return to its original position wherein it cooperates with the strap rest button 68 for secure-ly clamping therebetween the leading end 56 of the strap~ The strap rest button 68 is threadedly engaged in the baseplate 60 and by appropriate adjustment of this screw-type button 68 the force with which the leading end 56 of the strap is clamped in place may be ad~usted.
It will be noted that when the apparatus is in the detent position the cradle 730 has not been fully lowered to its original position and the rotary dog 148 remains spaced a slight distance above the separating plate 110 to accommodate the passage of the supply portion 57 of the strap therebetween.
A1SOJ it will be noted that in this position, the strap guide finger 199 on the side plate 197 will also be disposed a pre-determined distance above the strap apron 65 to accommodate in-sertion of the supply portion 57 of the strap ~rom the side of the tool 50. Thus, at this point, the supply portion 57 of the strap is slid into place between the separating plate 110 and the rotar~ dog 148 and above the rear guide member 101 and the ~ront guide member 105. In this position, it will be noted .~
,.
10t;260~
that the portions o~ the leading end 56 and supply porti~n 57 of the strap extendlng between the front and rear guide members 101 and 105 are vertically spaced apart thereby and are dis-posed in overlapping relationship ~herebetween, all ~or a pur-pose to be described more fully below.
At this point~ the tensioning handle 160 is manually pulled back up past the detent position thereof~ thereby de-pressing the detent member 193 and pivoting the cradle 130 back down to its original position, as illustrated in Figure 3, wherein the serrated peripheral surface o~ the rotary dog 148 cooperates with an insert 113 (Figure 3) in the separating plate 110 firmly to gr~p therebetween the supply portion 57 of the strap. It will be appreciated that the force with which the supply portion 57 o~ the strap engages the rotary dog 148 is also variable by appropriate adjustment o~ the strap rest button 68. When the tensioning handle 160 has been moved back to the positions illustrated in Figure 3, it will be noted that the strap guide ~inger 199 on the side plate 197 has been moved back down into its original position extending below the surface o~ the strap apron 65 for preventing the strap from being displaced laterally ~rom the combination tool 50. In :
addition, it will be noted that as the tensioning handle 160 moves up past the detent position thereof, the pawl member 170 is moved back into engagement with the teeth of the drive gear 165.
At this point, the strap which is looped about the object 51 may be tensioned by a back and ~orth movement of the tensioning handle 160 between the position illustrated in Fig- :
ure 3 and a rearward position in engagement with the cover 290, the operator pre~erably operating the tensioning handle 160 with his le~ hand while he grips the handle 235 with his right hand. As the handle 160 is moved rearwardly, in a counter-clockwise direction as viewed in Figure 3, the drive gear 165 is rotated in a clockwise direction by engagement therewith of the pawl 170, thereby resulting in rotation of drive mechanism (not shown) to effect corresponding rotation of the rotary dog shaft 141 and the rotary dog 148 for moving the supply portion 57 of the strap rearwardly of the combination tool 50, thereby taking up slack in the strap and ef~ecting tensioning thereof.
When the tensioning handle 160 has reached the limit of its 10 rearward travel, it is moved back forwardly to the position il-lustrated in Figure 3 for another stroke, with the pawl 170 ratcheting over the teeth of the drive gear 165 during this forward movement o~ the handle 160. This tensionihg operation continues ~ntil the desired tension in the strap has been achieved.
When the strap has been sufficiently tensioned, the operator grips the tensioning handle 160 with his left hand and grips the cam shaft lever handle 235 with his right hand and moves the handle 235 rearwardly i~ a counterclockwise direc-20 tion, as viewed in Figure 3J for sealing the overlapping por-tions 56 and 57 of the strap and severing the supply portion thereof. Preferably, the sealing and shearing operation is ef-fective by a single continuous movement of the handle 235 from the position illustrated in Figures 1 through 4 to the position illustrated in Figure 11, which movement pre~erably takes ap-proximately two seconds, thereby effecting a counterclockwise rotation of the cam shaft 230, as viewed in Figure 3, for se-quentially effecting a series of operations.
When the lever handle 235 is in its initial or home s 30 position illustrated in Figures 1 through 4, it rests upon the roll pin 225, with none of the cam lobes on the cam shaft 230 .. :
.
:
being in engagement. The latch clip 265 is clipped over the latch pin 266 for coupling the heater carriage 260 to the rocker arm 250, and the heater carriage 260 is held in its re-tracted position with the distal ends of the bearing arms 263 in engagement with the lip 202 on the bearing wall 203 by the action of the return spring 276, thereby holding the heater element 270 retracted from between the overlapping portions of the strap 56 and 57 and holding the rocker arm 250 back in the position illustrated in Figure 4. The pressure block 210 is held with the upper sur~aces thereof substantially flush with the upper surface o~ the end wall 205 by the action o~ the I ?
compression spring 223, with the movable shear blade 215 being disposed above and out of engagement with the supply portion 57 of the strap. The plunger 216 projects upwardly above the top surface of the pressure block 210 under the urging of the com- -pression sprlng 214.
During about the ~irst thirt~ degrees of the rearward movement of the h~hdle 235, the cam surface 241 on the cam lobe 240 engages the cam surface 256 on the rocker arm drive cam 255 to effect a cammed pivotal movement o~ the rocker arm 250 in a counterclockwise direction about the axis of the pivot pin 251, as viewed in Figure 4, thereby sliding the heater carr~ge 260 along the rails 70 to the right, as viewed in Figure 4, under the coupling action of the latch clips 265, for moving the dis-tal end of the heating element 270 between the spaced-apart ~ .
overlapping portions 56 and 57 of the strap in the region be-tween the front and rear strap spacers 105 and 101. As the heating element 270 is being moved between the porti~ns 56 and : ~ .
57 of the strap, the cam surface 247 on the cam lobe 246 en- :
gages the projecting plunger 216, the modulus of elasticity of the compression spring 214 being greater than that of the com--23- : -~
-106Z60~
pression spring 223 so that the camm~ng engagement between the cam sur~ace 247 and the plunger 216 effects a downward movement of the pressure block 210 against the urging o~ the compression spring 223, while the plunger 216 remains substantially unde-pressed with respect to the pressure block 210. The pivotal movement of the rocker arm 250 o~ the heating element 270 con-tinues until the arcuate dwell sur~ace 242 on the cam lobe 240 engages the rocker arm drive cam 255, at which point the heating element 270 is ~ully e~tended between the strap portions 56 and lo 57 in the position illustrated in Figure 10, with the distal end of the upper retaining flange 262 bearing against the inner surface of the end wall 205 ~or limiting the outward movement of the heater carriage 260 and the heating element 270.
As the backward motion of the handle 235 continues, and while the dwell surface 242 of the cam lobe 240 rides over the rocker arm drive cam 255, the pressure block 210 bottoms out against the supply portion 57 of the strap and cooperates with the strap apron 65 for firmly pressing therebetween the overlapping portions 56 and 57 of the strap with the heater ele-20 ment 270 therebetween. The force with which the heater element270 and the strap portions 56 and 57 are pressed together is limited by the compression spring 214, ~orce applied by the cam lobe 246 beyond a predetermined ~orce serving to depress the .
plunger 216 and thus be absorbed by the compression spring 214, so that the overlapping strap portions 56 and 57 are not signif-icantly deformed by the ribs 301 and 305. The predetermined force at which the plunger 216 is depressed can be varied by ap-propriate ad~ustment of the regulating screw 213, as we de-scribed above. When the overlapping portions 56 and 57 o~ the strap are thus ~irmly pressed into contact with the heating ele-ments 270, the surfaces thereo~ in contact with the heating : - - ~ . - .
106Z60~
element 270 are ~elted. It will be noted that when the pres-sure block 210 is thus held in its strap-heating position, the shear blade 215 remains up out of contact with the supply por-tion 57 of the strap.
As the rearward movement of the handle 235 continues, the cam sur~ace 247 on the cam lobe 245 moves past the plunger 216 permitting it to return to its projecting position and then permitting the pressure block 210 to return upwardly to its or-iginal position out of contact with the strap supply portion 57 under the urging of the compression spring 223. Simultaneously, the camming surface 243 on the cam lobe 240 is brought into en-ga~ement with the rocker arm drive cam 255 for effecting a fur-ther counterclockwise pivotal movement of the rocker arm 250, as viewed in Figure 10. However, since further outward move-ment of the heater carriage 260 is prevented by engagement of the retaining flange 262 with the end wall 205, this further pivotal movement of the rocker arm 250 results in the hook por-tion 268 of the latch clip 265 being cammed up over the latch pin 266 to permit the latch pin 266 to pass therebeneath~ As soon as the hook portion 268 has cleared the latch pin 266, khe heater carriage 260 is snapped back into its retracted position ~ ~ ;
illustrated in Figure 4, under the urging of the return spring 276. A further slight rearward movement of the handle 235 brings the second dwell surface 243a on the cam lobe 240 into engagement with the rocker arm 255 for holding the rocker arm 250 in the position illustrated in broken line in Figure 11.
As the rearward movement of the handle 235 continues, the cam surface 249 of the cam lobe 248 is bro~ght into camming engagement with the cam surface 211 on the pressure block 210, again forcing the pressure block 210 downwardly against the urging of the compression spring 2~3 to a sealing condition ~O~iZ600 illustrated in Figures 8 and 11, wherein the top surfaces 302of the ribs 301 are substantially coplanar with the bottom surfaces 307 of the ribs 305. As this downward movement of the pressure block 210 continues, the melted surfaces of the overlapping portions 56 and 57 of the strap are brought into engagement with each other and are firmly pressed together be-tween the ribs 305 of the pressure block 210 and the ribs 301 of the strap apron 65 of the anvil block 64 to effect a firm corrugated heat-sealed joint between the overlapping strap portions 56 and 57 which are accommodated by the channels 300 and 306.
As the pressure blo~k 210 is moved to the position illustrated in Figures 8 and 11, the overlapping strap portions 56 and 57 are deformed by the ribs 301 and 305 into the channels 306 and 300, thereby to produce in the overlapping strap por-tions the ridges 311 and 313 and the valleys 312 and 314 il-lustrated in Figure 9, the formation of which ridges and val-leys produces a kneading-like motion of the molten strapping sur~aces, and serves substantially to increase the total con-20 tact area between the molten overlapping surfaces of the strapportions 56 and 57, thereby to effect a much stronger interface bond therebetween. ~urthermore, the deformation of the over-lapping strap portions 56 and 57 to form the corrugated joint 310 effects a substantially evenly distributed appl~c~tiQn of pressure throughout the joint area, thereby further to enhance the strength o~ the bond.
The pressure with which the strap portions 56 and 57 are pressed together is controlled by the amount o~ force ap-plied to the handle 235 by the operator. As the pres~re block 210 bottoms out, in the position illustrated in Figure 11, the shear blade 215 passes downwardly past the shear blade 104 and cooperates therewith to sever the supply portion 57of the strap at the rear guide member 201.
At this point, the heat-sealed joint in the strap has been completed and the operator moves the tensioning handle 160 with his left hand all the way forward to the latched position, for a~ain elevating the cradle 130 and the separating plate 110 and the strap guide finger 199 to permit removal of the strap from the strap-gripping apparatus 100. Then, with his right hand, the operator moves the sealing lever handle 235 ba~k to the forward position thereof illustrated in Figure 4, thereby permitting the pressure block 210 to return upwardly to its original position under the urging of the compression spring 223. This forward m~vement of the handle 235 also brings the camming surface 24~ of the ca~ lobe 245 into engagement with the latch cam 257 on the rocker arm 250 for pivoting the rocker arm 250 in a clockwise directlon from the broken line position to the solid line position illustrated in Figure 11. As the rocker arm 250 pivots back to its original position, the cam flange 269 on the latch clip 265 engages the roll pin 264 on 20 the heater carriage 260 and rides up thereover, slightly sepa~
rating the legs of the latch clip 265 and bringing the cam flange 269 into position for camming engagement with the latch ~ -pin 266. The cam ~lange 269 then rides up over the latch pin : ~ ;
266 and therebehind for relatching the latch clip 265 in place for coupling the rocker arm 250 to the heater carriage 260.
With the handles 235 and 160 now returned to their forwardmost positions, the combined tool 50 can be moved sideways to strip it from the strap and the object 51 by use of the utility handle 291.
From the ~oregoing, it ^an be seen that there has been provided an improved combination strapping tool for bo~h :
' ' ' '- ~ '' -`
gripping and tensioning a length of pl.astic strap about an ob-~ect and then forming a heat-sealed bonded joint between the ends of the length of strap and severing the length of strap from the supply thereof.
More particularly, there has been provided a combina-tion strapping tool of the character described, whereln there is formed a corrugated ~oint between the overlapping strap portions having alternating ridges and valleys extending lon-gitudinally of the strap.
There has also been provided a combination strapping tool of the character described, wherein the corrugated ~oint is formed by complementary ridges and grooves respectively formed on a moving pressure block and a stationary anvil block, between which the overlapping strap portions are pressed after having the facing surfaces thereof heated to a molten condi-tion.
~.".. . ' :' :
Claims (4)
1. Strapping apparatus for securing a length of plas-tic strap around an object, said apparatus comprising a frame, strap-gripping means mounted on said frame for holding the strap encircled in a loop in a tensioned condition about the object with the leading end of the strap overlapping the supply portion thereof, heating means carried by said frame adjacent to the overlapping strap portions for effecting melting of the facing portions thereof, a first pressure member carried by said frame and having a plurality of elongated and equal-width first grooves therein equidistantly spaced apart by first ribs, and a second pressure member carried by said frame and having a plurality of elongated and equal-width second ribs protecting therefrom equidistantly spaced apart by second grooves, each of said first and second grooves being rectangular in transverse cross section and having an elongated flat rectangular recessed surface, each of said first and second ribs being rectangular in transverse cross section and having an elongated flat rec-tangular end surface with the width of each said end surface being substantially less than the width of each groove recessed surface, said end surface of said first and second ribs being respectively disposed centrally of and in parallel facing rela-tionship with said second and first groove recessed surfaces in longitudinal alignment therewith, said pressure members being movable with respect to each other to a sealing configuration wherein said ribs and said grooves cooperate to press together therebetween the melted overlapping strap portions and to de-form the overlapping strap portions in a predetermined pattern as they are pressed together, whereby the pressure of said pres-sure means is substantially evenly distributed throughout the interface between the melted overlapping strap portions for for-mation of a strong joint therebetween.
2. The strapping apparatus set forth in claim 1, wherein only said second pressure member is movable with re-spect to said frame.
3. The strapping apparatus set forth in claim 1, wherein said grooves and said ribs are substantially straight and parallel to one another.
4. The strapping apparatus set forth in claim 1, wherein said ribs and said grooves extend longitudinally of the overlapping strap portions and are spaced apart laterally thereof when said pressure members are disposed in the sealing configuration thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA288,068A CA1062600A (en) | 1977-10-04 | 1977-10-04 | Apparatus for securing plastic straps |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA288,068A CA1062600A (en) | 1977-10-04 | 1977-10-04 | Apparatus for securing plastic straps |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1062600A true CA1062600A (en) | 1979-09-18 |
Family
ID=4109698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA288,068A Expired CA1062600A (en) | 1977-10-04 | 1977-10-04 | Apparatus for securing plastic straps |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1062600A (en) |
-
1977
- 1977-10-04 CA CA288,068A patent/CA1062600A/en not_active Expired
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