US2846218A

US2846218A - Strip feed measuring device

Info

Publication number: US2846218A
Application number: US356056A
Authority: US
Inventors: Alvin L Winkler; James N Wognum
Original assignee: Acme Steel Co
Current assignee: Acme Steel Co
Priority date: 1953-05-19
Filing date: 1953-05-19
Publication date: 1958-08-05
Anticipated expiration: 1975-08-05

Description

5, 1958 A. WINKLER ET AL 2,846,218

STRIP FEED MEASURING DEVICE Filed May 19, 1953 4 Sheets-Sheet l INVENTORS.

7 BY [409mm,

1958 A. WINKLER ET-AL 2,846,218

STRIP FEED MEASURING DEVICE 4 Sheets-Sheet 2 Filed May 19, 1953 Aug. 5, 1958 Filed May 19, 1953 A. L. WlNKLER ET AL STRIP FEED MEASURING DEVICE 4 Sheets-Sheet 3 INVENTORS.

CZZZ/L'Wl. Z02, BY JZZJZZGSZYM Aug. 5, 1958 A. L. WINKLER ET AL STRIP FEED MEASURING DEVICE 4 Sheets-Sheet 4 Filed May 19, 1953 7 INVEI VTO CZZz/Lnl United States Patent STRIP FEED MEASURING DEVICE Alvin L. Winkler and James N. Wognum, Chicago, Ill.,

assignors to Acme Steel Company, Chicago, 11]., a corporation of Illinois Application May 19, 1953, Serial No. 356,056 11 Claims. (Cl. 2712.4)

This invention relates to improvements in strip feeding devices and its purpose is to provide improved means for measuring the lengths of metal strapping or the like which are utilized in sucessive operations of apparatus, such as a machine for applying binding straps about boxes, packages and other objects.

In the construction and operation of machines for applying metal binding straps around boxes, wherein the strapping is fed automatically to or around the object to be bound, it is desirable thata measured length of strapping be fed at each operation in order to obtain uniformity in'the results of successive binding operations. It has been proposed to solve this problem by the use of a control circuit comprising switches and relays actuated by the leading end of the advancing strip to control the length of strapping fed during one operation but it has been found that the inherent delays in the operation of such control devices are not uniform, particularly when the strapping is fed at high speed, so that the successive measured portions are not of equal length. When strap feeding mechanisms are operated or controlled by devices actuated by alternating electric current, a further inequality in operation arises from the sinusoidal variation in voltage and'current during each cycle with a resulting variation in the response of electric control devices depending upon the point in the cycle when the current is applied to the device. These delays and irregularities have resulted in substantial variations in the lengths of different portions of strapping measured by such apparatus so that the desired objective has not been attained.

it is therefore the principal object of the present invention to provide a strap measuring and feeding device which overcomes the above mentioned difliculties and operates with a high degree of accuracy. A further object is to provide a strap feeding device capable of measuring the strap with accuracy and of being adjusted to measure straps of different lengths. Other objects relate to various features of construction and arrangement which will appear morefully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which one embodiment is illustrated. In the drawings,

Figure 1 shows a perspective view of a portion of a box strapping machine illustrating a part of the mechanism of the present invention by which the feeding of the binding strap is controlled;

Fig. 2 shows an enlarged vertical section taken on the line 2-2 of Fig. 1;

Fig. 3 shows a partial elevation of and a partial verti cal section through the timing mechanism which is illustrated in Fig. 1; v

Fig. 4 shows a sectional view taken on the line 4-4 .of Fig. 2;

Fig. 5 shoWs'a sectional view taken on the line 5-5 of Fig. 4;

Fig. 6 shows a schematic diagram of the electric cir- I 2,846,218 C6 Patented 'Aug. '5, 1958 2 cuit connections of the system by which the feeding of the strap is automatically controlled; and

Fig. 7 shows a perspective view of a box strapping machine-of a type which is adapted to be equipped with the features of the present invention. i The strap feeding mechanism of the present invention may be applied to various forms of apparatus for controlling the feeding of a strap or the like and the measuring of successive lengths of strap which are moved in successive feeding operations. In the accompanying drawings, the invention is shown in a form which is particularly adapted for use in connection with the type of box strapping machine which is described and claimed in the copending application-of Alvin L. Winkler, Robert E. Hager, and Kjell A.-Falck-Pedersen, Serial No. 284,634, filed April 26, 1952. The box strapping machine dis closed in that application is semi-automatic in that each feeding operation feeds out a length of strap which is suflicient 'to be extended around the box or package to be bound and then, after this length of strap has been manually extended around the box or package and its free end gripped, the feeding apparatus is reversed so that the strap is then drawn taut about the object being bound. In that machine, it is not important that a precise length of strap be fed on each feeding operation because the act of completing the operation of extending the strap around the package is performed manually and the excess amount of slack in the strap is then taken up by the reverse feeding operation. The present invention may be employed to convert a machine of that type into a fully automatic machine by providing a guide which con fines the loop of strap as it is fed from the source of supply and by regulating the feeding operation so that the feeding is terminated when an exact length of strap has been extended into the loop.

In Fig. 7 of the accompanying drawings, there is shown a box strapping machine 10 which, in external appearance, is similar to the semi-automatic machine referred to above except for the provision of a guide for directing the strap during the feeding operation. This machine comprises a casing'llhaving two series of horizontal rollers 12 and 13 over which the boxor package is adapted to be moved to and from the strapping position illustrated generally at 14. The strap feeding mechanism .is mounted within the casing 11 and is adapted to feed forming a joint between the overlapping ends of the strap and then cutting it. off. The table which provides the strapping position is provided with a slot 14a through which the strap is adapted to extend during the feeding operation and during the reverse operation by which the strap is drawn taut.

The present invention is directed particularly to the control of the feeding mechanism by which the strapping is drawn from the source of supply and moved to the strapping position. As illustrated particularly in Figs. 1 and 2, it comprises 'a power driven shaft 20 which is illustrated as being connected by a gear 21 to a pinion 22 mounted upon the shaft 23 of a rotary switch 24 which in themselves do not constitute a part of the present in .vention. :shafthaving mounted thereon a feed roll, not shown, with The shaft 20 may be considered to be the feed which the strapping is held in contact by a pressure roll as it is drawn from the source of supply, not shown. At

theaendnf a feedingwperaticn, the free end of the strap is gripped .and .theieedshaitis .thenireversed .to .draw the strap taut. This feed shaft has mounted thereon a sprocket pinion 25 connected by an endless sprocket chain 26 ito ra :sproclket gear .27 rnnunted a-upon a timer shaft 28. As shownxparticdlarlyihizliigs.41,:3and4, this timer :sh'afLZB .is Zjournaled "in two :ball bearing '-.units 29 whicheare :mounted ."in :a hearing bracket 80 carried :by a horizontal plate 30a rwhichiisssecured .by studs .3110 the ho'rizontalrsframe member :32 which maytionmta part of thezframestructnre of theicasingifl'shown. in Fig. 7.

At the :end act the bearing zsleeve 30 .opposite to the sprocket zgear 27, 'ithe :shaftL28 :is provided With antintegra'lly .aform'e'd :ra'dial :tflange. 28a 'on :the miter ofi'thiszflange, "there'is :provided :a rcylindricaluportion 28b whichzisrormed integrally-with the: reduced extremity 28c 'ofithe shaft. A momnetallic clutch ring .33 :fits :over the part .28'b cof 'iheisha'ft and seats against :t'he radia1 .dlange 28a; lathicam 3'4 ismotatably'mounted on 1116 part 28b for [the :shaft adjacent ":to tthe clutch ring 33 and .'a timing loam l35iifitstover-the extreniity zof'tthe rshaftrportion 18b :against the outer facetrifdhelatch cam 34. .Thestwo oams 34 'and.:35 are secured against-irelative rotationfby two 'studs 36 whichcengage Tarcuate slots 35a intthe .timin'g cam and which :threa'dedly -:engage circular :apertures formed in th'e cam 34. By'releasingthestuds 3.6,are1ative angular adjustment: of 'the two cams-may be made in order to regulate the timing operations hereinafter refer-red *to.

The clutch tcing 33 i=and'fthe two oams 134 :and 35 are retained in position on the portion 28b ot'theeshaft rby 'a-disk 38 which is centrally apertured :to ifit .over the reduced extremity 28c of the shaft land which bears against the' inner portion o'f' the outer'tace of'the cam 35.

A pin 39 has 'a drive fit 'in 'an aperture rformed 'in 'the enlargedportion zsb of the shaft and theexn'emity of: this pin engages-anaperture 38a int'h'e disk 38 so-tthatthe disk revolves 'with the shaft but is capable of en'dwise movement thereon. This disk 38 is maintained in conta'ct -'with the outer face :o'ffthecam 35 by means of a helical spring 40 which is mounted *upon the portion 28c of the shaft 'between the :disk 38 and a collar 41 mounted on the outer end of the shaftand secured in position by a pin JZ -arrangedto ext'end with aidrivefit througha transverse aperture-'formedein l-the shaft. "With the j-foregoing arrangement, "the :clutch ring 33 and the cams 34 and '35 are fIee to rotate on the portioni'2'8b f the shaft, being 'r'esttained only by frictional-contact ==with the ra'di'al flange 28a -'of i the shaft and with the spring pressed disk-38.

.tAnelec'tric suu'tch 15 is secured to one side o'f the hearing bracket '30 and has a reoiprocating plunger t'sa provided with a roller-43b arranged -to contact with the periph'eralsurfa'ce o'f-the=cam 3'5. surface includes an arcuate ap'ortionGS'b of srnallevradius which; is eonnected by twoinclined portions 13Sc =and 35tl with a *portion '3'5e of larger radius. 'As' the pinion L25 is rotated in the direction 'o'f -the arrow 4'6, shown in Fig; 2,'- the-'cam 3'5 rotates in the same direction and'the roller-45b rides over thep'eripheral 'sur'fac'es of-the cam 35, thus controlling the operation of'the switch 45 which is Connected inthe electric control circuit hereinafter described.

There is also mounted upon the bearing br-ac'ket 30 a stud 47 which extends laterally therefrom and *has pivotally mounted onits-outer *end a "latc'h'or "detent 48 adapted to engage a shouIHer BWb'iformed-on the latch cam 34, as shown in Fig. '5. "The nutersmface 34a of this 'cam "iso'f 'spiralj'fornration and 'the extrernities of this su'rface terminate at the radial shoulder 34!). The la'tchfor detent 48-is pressed-aga'instthe cam '34 by a-coil 'spring'49 whihi'is "mounte'dupon the stud 47 without: 'extremitylthereof eng-aging' thebraeket 3'0 and=the other *extrernity thereot engaging the latch 48 so that the latch is -maintained in =contac't with the peripheral sui'fac'e er the cam.

In the operation of the apparatus just described, the

. cams.andihe parts whichcoacttherewith arein the relative positions shown in Figs. 2 and 5 at the beginning of each cycle, with the latch 48 abutting against the shoulder 34b and the roller 45b riding on the surface 35b of the cam 35 at a point adjacent to the incline 35c, with the switch 45 in one of its .twoclosed positions. When the feeding of the strap begins, lnresponse to an operation hereinafter described, 11heishaft 20 and :the cams 34 and 35rotate in counterclockwise directions. As the :cam 3'5 rotates, "the roller 45b rides on the surface 135?; of lesser radius and then rides up thetincline 35d, thereby depressing the plunger 45a and moving the switch 45 to the otherof its two 'closed positions. This condition continues as thetsurfacefiseoflarger radius travels past the roller 45b and the feed wheel rotates to feed the strap. The roller 45b then rides down the incline 350 to the position shown in Fig. 2, thereby stopping the feedingnperation. At the sametime,'-the latch 48 moves .intopositionin contact with or-adjacent to the shoulder 54b. ilftthere .tis ea space betwe'en the shoulder 34b and .theilatch-zdu'e tomverrunning of'the cam, this is corrected when the ffefid IIlCClTfllllSlTlLlS-IQVCISCH to draw the strap taut around the package, since the shaft 28 then rotates inzzthe'oppnsite direction and 'moves the shoulder 34b into Contact with .the .latch '48. During this reverse :rotation, the latch 48 holds the cams 54 and 3'5:.stationary while the shaft 28, clutch :ring Sianddisk 38rotate with respect to these cams,

.as zpermitted'iby the spring 10. This spring is of such strength that it permits this slipping action duringthe reverse "feeding although tcausing the

cams

34 and 35 to move with the "shaft during the feeding operation. lTheparts remain in the'relative positions shown in Fig. 2 attthe end of the-reversefeeding operation so that they are "then in readiness for the next feeding cycle.

Having-described the mechanical feeding mechanism and the means-for actuating the 'control switch 45, refer- *ence will now he made to Fig. 6 in which an electric controlcirouitiincluding the switch 45, is diagrammatically illustrated. "Ihis'circuit comprises a double pole =masterswitch-50'which connects'the supply conductors 51, leading from an alternating current supply source, with the lineconductors =52-and '53 by which current is supplied to the operating parts of the electrical "apfparatus. 'Iwo'condu'ctors "54 and '55 lead'from the conductors"'52'and-53, respectively, to the electronic timer "56. This timer includes "a solenoid operated switch 56s, switch contacts 56a controlled .by the solenoid, a vacuum tri-ode tube Slit, a condenser 56c and 'a potentiometer 56p.

"The "contacts'ifia are 'connected'in aline 57 leading "from the line conductor S2'to one terminal of a strap feed relay 58 which has its other terminal connected by'a-conductor 5910 the other line conductor '53. The solenoid *58'has a'plunger58awhich operates a contact -inerriber'SSba'dapted .to connect'th'e terminals of either one of twospaced pairs of "contacts :60 and 61, thus forming adoribleptole doublethrow .switch.

."The line Tconductors 52 and "53 lead to the input terminals of "a. "current rectifier 63 from which .direct currentflows through the

conductors

64 and 65. The conductor 64'lea'ds to one contact of each pair of con- =.tacts roman. The conductor65 leadsto the terminals of the feed drive brake :66 and .the feed drive :clutch 6 which :-include condensers 6611 and 67a and

solenoids

66b and 67b, respectively. The feed drive brake 66 is -connected through a :resistor 68-to one terminal 450 -ofithe switch 45. .ZEhetother zterminal 45d of this'switch is connected by a conductor 69 to a conductor '70 leading through a resistor 71 'from the feed drive clutch 67 to the other contact terminal 60. The movable con "tact 45e or the switch -45 is connected througha line 72 and a switch 73 to the other contact 61 The starting of each cycle is controlled from the electronic timer through connections made by conductors 74 to the contacts of a master switch 75 operated by a rotary cam 77. This cam is mounted on a shaft driven intermittently from one of the power driven shafts of the strapping machine and makes one revolution for each strapping cycle. The contacts of this switch are closed to initiate the cycle by the portion of the cam 77 of larger radius and when they are opened by the part of the cam of smaller radius, the condenser 560 is recharged in preparation for the next cycle. The closing of the switch 75 is initiated manually by means, not shown, whereby the rotation of the cam 77 is controlled by the operator. When the switch 75 is closed by the cam 77, the solenoid 56s of the electronic timer closes the contacts 56a and thereby energizes the solenoid 58 to close the contacts 60 and thereby close the circuit of the feed drive clutch 67, thus causing the rotation of the feed wheel and the feeding of the strap. After the cycle has been thus started, the timer cam 35 rotates and the roller 45b of the switch 45 moves onto the surface 35c of the cam and the timing of the cycle is then taken over by the cam 35. The end of the cycle is reached when the roller 45b passes down the incline 350 to rest upon the surface 35b of the timer cam as the cam completes its revolution and is stopped by the latch 48 engaging the shoulder 34b of the cam 34. The potentiometer 56p of the timer 56 should be regulated so that the action of this timer terminates before the roller 45b rolls down the incline 350 of the cam 35, so that the end of the cycle will be determined by the switch 45 rather than by the electronic timer.

Referring further to the action of the electronic timer 56, when this device has been warmed up by electrical energy supplied through the

conductors

54 and 55, the plunger of the solenoid 56s is then in the upper position shown in Fig. 6, because current is then flowing through the triode vacuum tube 56t, and the contacts 5611 are open. When the switch 75 is closed the timing condenser 560 places a high negative potential on the grid of the triode vacuum tube 56: and blocks the flow of current therethrough. The solenoid 56s is then deenergized and the relay contacts 56a close. The timing condenser 560 then promptly discharges through the potentiometer 56p. The discharge time of the timing condenser 560 determines the timing period through which the triode vacumn tube does not conduct and, in turn, the time period during which the solenoid 56s is deenergized and, thereby, the time period during which the contacts 56a are closed. Since the contacts 56a are in series with the strap feed relay solenoid 58, this same time period is the period during which the relay solenoid is energized. This period can be varied by adjusting the potentiometer 56p. When the switch 75 is opened after the timing period, the timing condenser 560 is permitted to be recharged in preparation for another timing operation.

While the roller 45b is in contact with the cam surface, the electronic timer 56 terminates its timing operation as the condenser 560 is discharged sufficiently to cause the solenoid 56s to become energized again as the vacuum tube 56t again starts to conduct current. When this occurs the switch contacts 56:: are opened and the strap feed relay 58 is deenergized to open the contacts 60 and close the contacts 61. Since the switch 45 now has it contacts 45d closed and its contacts 450 open, the closing of the contacts 61 does not affect the feeding of the strip material since the contacts 45d keep the feed drive clutch 67 energized after the contacts 450 are opened. Also, since the contacts 45c are open, the feed drive brake 66 remains deenergized. Thus, after the electronic timer has finished a timing cycle, the feeding of the strap continues because the contacts 45d are held closed by the timer cam 35. When, after further rotation of the cam 35, the roller 45b passes down the incline 35c onto the cam surface 35b, the switch plunger 45a operates to open the contacts 45d and close the contacts 45c, thereby deenergizing the clutch 67 and energizing the brake 66 so that the rotation of the feed wheel is promptly arrested.

It will be apparent that the

cams

34 and 35 may be relatively adjusted by regulating the positions of the studs 36 in the slots 35a in order to vary the length of strip material precisely for accurately locating the leading end of the strip at the end of the feeding operation.v Also, the speed of rotation of the timing shaft 28 may be varied by changing the

sprockets

25 and 27 for others of different sizes. An important advantage of the invention is that the switch 45 operates the feed drive clutch 67 and the feed drive brake 66 directly by connections which are in a direct current circuit so that the device avoids the objectionable delays and variations in speed of response which are inherent in the operation of control devices by alternating current. Thus, the strip feed is promptly terminated and the lengths of strip material fed in successive operations are substantially uniform.

If desired, the cam 77 could be connected to operate the switch contacts 56a while eliminating the electronic timer 56. The cam 77 would then hold the switch contacts 56a closed for a period of time sufficient to permit the roller 45b to roll up the incline 35d onto the cam surface 35a. The cam 77 would then allow the contacts 56a to open. Among the advantages of using the electronic timer is that it may be adjusted to permit multiple revolutions of the cam 35 before cutting out of operation to allow the cam 35 and the switch 45 to take over control of the feeding cycle.

Although one form of the invention has been shown and described by way of illustration, it will be understood that it may be constructed in various other embodiments which come within the scope of the appended claims.

We claim:

1. The combination in strip feed measuring apparatus, of strip feeding means, means for starting the operation of said feeding means, a cam means for actuating said cam in unison with said feeding means, and means including control devices connected in an electric circuit and controlled by said cam for stopping the operation of said feeding means.

2. The combination in strap feed measuring apparatus, of strap feeding means, a cam, means for actuating said cam in unison with said feeding means, an electric circuit having connected therein devices for controlling the operation of said feeding means, means actuated by said cam for controlling said circuit, and means associated with said cam for arresting its rotation in one direction.

3. The combination in strap feed measuring apparatus, of strap feeding means, a cam, means for actuating said cam in unison with said feeding means, an electric circuit having connected therein devices for controlling the operation of said feeding means, means actuated by said cam for controlling said circuit, a second cam movable with said first named cam, and means coacting with said second cam for arresting the rotation of said cams in one direction.

4. The combination in strap feed measuring apparatus, of strap feeding means, a cam, means for actuating said cam in unison with said feeding means, an electric control circuit, a feed drive clutch connected in said circuit for controlling the actuation of said feeding means, and means including a cam operated switch connected in said circuit for controlling said feed drive clutch.

5. The combination in strap feed measuring apparatus, of strap feeding means, cam in unison with said feeding means, an electric control circuit, a feed drive clutch connected in said circuit for controlling the actuation of said feeding means, means a cam, means for actuating said ascents 7 including -aacam operated switch connectedinsaidcircuit for controlling :said iced drive-clutch, and .a I braking de vice connected .in said 'icircnt and .controlled by said switch -.for -'stopping said feeding means when said feed drive chltchds deenergized.

:6. .T he combination in-strap feed measuring apparatus, of strap feeding means, a cam, means for actuating said cam in unison with said feeding means, an electric control circuit, ateed' drive clutch connected insaidcircuit for controlling theactuation of said feeding means, means including .a cam operated switch connected in said circuit for controlling said 'feed drive .clutch, and means independent of-said cam for energizing said feeddrive clutch to start the operation of said feedingmeans.

7. The combinationin strap feed measuring apparatus, of strap feeding'means, an alternating current circuit, an electronic timing device :connected in said circuit, means including a feed drive clutch adapted -to be actuated .by said electronic :devicefor starting theoperation of said feeding means, a current rectifier connected in said circuit,. a direct current circuit supplied by said rectifier, said feeddrive clutch being connected in said directcurrent circuit, a switchconnected in saiddirectcurrentcir- .cuit,.means in said direct current circuit controlled by said switch for stopping the operation of said feeding means, and a .cam movable in unison with said feeding means for actuating said switch to stop the operation of said feeding means.

8. The combination in strap feed measuring apparatus, of strap fee-ding means, an alternating current circuit, an electronic timingdevice connected in said circuit, means including a 'feed drive clutch adapted to'be actuated by saidlectronicdevice for starting the operation of said feeding means, a current rectifier connected in said circuit, a direct current circuit supplied by said rectifier, said feed drive clutch beingconnected in said direct current circuit, a switch connected in said direct current circuit, a cam movable in unison with said feeding means for actuating said switch to stop the operation of said feeding means, means for arresting the rotation of said cam in one direction, and a brakeconnected in saiddirect current circuit and controlledby said switch for arresting the operation of said feedingmeans.

9. The combination in strap feed measuring apparatus, of strap-feeding means, a cam, means for actuating said cam in unison with said feeding means, an electriccircuithaving connected therein devices for controlling :the operationcf .saidieedingnieans, .means actuated: by said cam ior controllingfsaid circuit, a second cam connected to move with first named cam .and having a shoulder, and ia..latc'h actuated .to engage said shoulder at the end of a'feeding cycle to ,stop .the rotation of .both of said carns'in one direction.

111' The combination in strap feed measuring apparatus, of strapffeeding means, a cam, .means for actuating said cam in unison with said fecdingmeans, "an electric circuit'having connected therein devices forcontrolling the operation of said'feeding means, means actuated by said cam"for controlling said circuit, a second cam connected to move with first named cam and haVingashoulder, a latch actuated to engage said shoulder at the end of a feeding cycle to stopthe rotation .of both of said cams in one direction, and means for adjusting the relative positions of said-cams.

11. Thecombination in strap feed measuringapparatus, of strap feeding means, a timer shaft movable .in unison with'said feeding means, an electric circuithaving connected thereindevices for controlling the operation -of-said feeding means, a carnmounted on said shaft and actuated thereby,'means actuated by said cam for contrlling said-circuit, a second cam connected to move with said'first-named'cam, a latch actuated to engage a part'of said'second named cam attbe end of a feeding 'cyeleto limittherotation of said cams in one direction, an'd'means including a spring for causing said cams to rotate withsaid shaft.

'zReterences Cited in'zthe file'of this patent UNITED STATES PATENTS