USRE26315E

USRE26315E - Strapping machine control

Info

Publication number: USRE26315E
Authority: US
Publication date: 1967-12-05

Description

D. W. RHEA Dec. 5, 1967 STRAPPING MACHINE CONTROL 4 Sheets-Sheet 1 Original Filed March 17. 1964 22-10(2)? 702/ fivza IQew Dec. 5, 1967 D, w RHEA STRAPPING MACHINE CONTROL 4 Sheets-Sheet 2 Original Filed March 17 1964 NW mm W UN WEI/3 A D. W. RHEA Dec. 5, 1967 STHAPPING MACHINE CONTROL 4 Sheets-Sheet 3 Original Filed March 17, 1964 .Dazzafd 4 Sheets-Sheet L D. W, RHEA STRAPPING MACHINE CONTROL i i no D.C.

MOTOR DOWN PHOTO SvuuTCH 4 6 (ARRIAGE DOWN Dec. 5, 1967 Original Filed March 17, 1964 INVENTOR fwd-Ki }h,%@ a

a: fior/vza q 1/4 W MOTOE P BRAKE AT T ti 1 I11 il |-1i CONT ROLS F0 R ST RAPP\ NG MACHINE United States Patent 26,315 STRAPPING MACHINE CONTROL Donald W. Rhea, Norridge, Ill., assignor to Interlake Steel Corporation, a corporation of New York Original No. 3,225,683, dated Dec. 28, 1965, Ser. No. 352,562, Mar. 17, 1964. Application for reissue Oct. 17, 1966, Ser. No. 595,549

14 Claims. (Cl. 100-4) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to control systems and particularly to a control system for automatically controlling the travel of a movable carriage to predetermined locations relative to a work piece as, for example, the movement of a strapping device relative to an object around which the strapping device is to apply an encircling binder strap.

In one type of strapping machine used for strapping or binding coils of strip metal, the coils are positioned on end on a conveyor which transports them to a strapping machine. The strapping machine is provided with a carriage which is mounted for vertical movement between a position above the level of the highest coil to be strapped and a position intermediate of the height of the shortest coil to be strapped. If a single strap is to be applied around the coil it is desirable that the strap be positioned at the mid-level of the coil. If two straps are to be applied, it is desirable that the two straps be placed one at each one-third level of the coil. If more than two straps are to be applied, it is desirable that they be spaced at equal increments from each other and the ends of the coil. In the particular type of strapping machine mentioned, the carriage supports a strapping head which feeds a length of strapping from a supply source into a closed loop while the carriage is in its elevated position above the level of a coil to be strapped. Suitable mechanism is provided for lowering the carriage and the formed strap loop to position the strap loop around the coil in readiness for allowing the strapping head to shrink the strap loop onto the coil and secure it in place. After the strap loop is secured in place, the strapping head has mechanism which severs the loop from the supply of strap and allows the strapping head to be returned to its upper position in readiness for producing another strap loop for the next cycle of operation.

It is an important object of this invention to provide a control means for the type of apparatus mentioned which automatically locates the strapping head at a level of a coil corresponding to any predeterimned fraction of the height of the coil to be strapped, independent of the actual height of the coil, within the strapping head movement limits of the apparatus. For example, with this invention it is possible to cause the strapping head to be automatically moved to alignment with the mid-point of the coil where it can apply a binder strap to the coil or the strapping head can be automatically moved to any desired level of the coil as, for further example, to the onethird level of the coil.

It is another object of the invention to provide a control device of the type mentioned which can automatically operate the strapping unit to cause it to sequentially move to a multiple number of different fractional levels of the coil or object to be strapped.

In order to accomplish these objects, it is still another object of the invention to provide a control device which has means for establishing the bottom level of a coil or object and its top level and through different rotational ratios of a control shaft relative to a drive shaft estab lish the different fractional levels at which the carriage of the strapping head or mechanism is to be arrested for application of a binder strap to the object.

lt is still another object to provide such a control means which is electrically controlled by means of switches and magnetic clutches selectively operated to cause sprockets of different speed ratios to be actuated for arriving at selective levels of movement of the strapping carriage,

Another object is to provide a control device embodying a photoelectric cell for obtaining an electric impulse to establish the top level of an object or coil, although a switch contacting the upper level of the coil is suitable under certain conditions. In the more usual case, the diameters of the coils vary so widely that the light beam is the simpler to use effectively. It is more difficult to arrange structure for a mechanical switch to be properly positioned to insure reliable contact with a full range of coil sizes.

It is another object to provide a control device embodying sprockets on a control shaft for driving sprockets on a drive shaft which are selectively driven by the drive shaft as magnetic clutches are selectively activated.

Other objects and advantages of the invention should become apparent upon reference to the accompanying drawings in which:

FIG. 1 shows a perspective view of a typical coil strapping machine in which the invention is embodied;

P16. 2 shows a top plan view of the principal components of the control means embodied in the strapping machine of FIG. 1;

FIG. 3 shows a view along the line 3-3 of FIG. 2 and particularly shows the relationship of a control cam with two switches actuated by it; and

FIG. 4 shows a simplified wiring diagram for the control means of FIG. 2.

The strapping machine 1 in which the invention is shown embodied consists of two bases 2 and 3; the base 2 sup ports two corner posts 4 and 5 while the base 3 supports two corner posts 6 and 7. An I-beam 8 is connected between the upper ends of the two posts 4 and 5 while another I-beam 9 is connected across the upper ends of the two posts 6 and 7. Mounted between the posts 4 and 6 at their upper ends is another l-beam 10. Similarly, mounted between the posts 5 and 7 at their upper ends is another I-beam 11. A carriage 12 is mounted for vertical movement between the posts 4 and 5 and is supported by two

chains

13 and 14 which are driven by means of sprockets at 15 attached to a shaft 16. Likewise, a carriage 17 is mounted for vertical movement between the two posts 6 and 7 and supported by means of two chains 18 and 19 driven by means of two sprockets at 20 secured to the shaft 16. The shaft 16 is driven in one direction or the other by means of a motor 21 suitably mounted on a platform 22 secured to the post 7.

The

chains

13 and 14 are connected at their opposite ends to a counterweight 23 which is guided along the post 5. In a similar manner, the opposite ends of the chains 18 and 19 are secured to another counterweight 24 guided along the corner post 7. With this arrangement, rotation of the shaft 16 by the motor 21 in one direction causes both carriages 12 and 17 to be lowered together while rotation of the shaft 16 by the motor 21 in the opposite direction causes both carriages 12 and 17 to be elevated.

The carriage 17 supports a strapping head 25 secured to a frame 26 mounted for movement toward and away from the object to be strapped on the two end plates 17a and 17b of the carriage 17. The strapping head 25 can be of many types, but one particularly suited for such a structure is shown in copending application Serial No. 711,663, filed January 28, 1958, now Patent No. 3,120,- 171, in the names of Marchand B. Hall and Sidney V. Hettinger, Jr. Such a strapping head automatically feeds U a length or" strap from a supply source, permits the length of strap to be encircled into a strap loop, automatically shrinks the strap loop onto an object, and secures the overlapping ends of the strap loop together and severs the strap loop from the supply source.

When the carriages 12 and 17 are in their upper posilions. a strap guide 27 secured to the strapping head has its ends aligned with two strap guide segments 28 and 29 supported from the l-

beams

10 and 11. Also, the strap guide segments 28 and 29 have their ends aligned with the ends of another strap guide segment 30 mounted on the carriage 12. When all of these strap guide segments are in alignment with each other, the strapping head 25 can feed a strap in a continuous path through them to form a strap loop. Then, when a coil 31 is positioned on a conveyor 32 centrally below the strap guide segments 28 and 29, the carriages l2 and 17 are lowered to lower the strap loop 33 formed by actuation of the strapping head 25 around to a positon encircling the coil 31. Arms 134, positioned one on either side of the coil position location, are pivotally mounted on the carriage 12 to be elevated and lowered with such movement of the carriage 12. They are intended as support for the strap loop 33 during the downward movement of the carriage l2 and the strapping head 25 so that the strap loop 33 does not sag. The slrap guides 28 and 29 are provided with well known releasable means for releasably holding strap therein. An example of this type oi releasable means is disclosed in United States Patent 2.853.938, issued September 30, 1958, in the names of Marchand B. Hall and Alvin L. W'inkler.

Also mounted on the l-beam I1 is a control box 34 in which is the control mechanism shown in HUS, 2 and 3.

The control mechanism consists of a mounting plate 35 carrying a driven shaft 36 journal-2d in two

bearings

37 and 38 secured to the support plate 35. it also carries a control or cam shaft 39 iournalcd in two bearings 40 and 41. The end of the driven shall 36 has secured to it a sprocket 42 which drives a chain 43 encircling it, an idler sprocket 44 journalcd in a llf-lCLl location on the apparatus and another sprocket 45. The sprocket 45 is secured to the main drive shaft 16 shown in FIG. 1. As this main drive shaft 16 is rotated, this causes rotation of the driven shaft 36. This driven shaft 36 is provided with four magnetic clutches 46. 47, 48 and 49 which can be selectively energized electrically. They are provided with

sprockets

46a, 47a, 48a and 49a, respectively. The magnetic clutches are of a well-known type which can be purchased in assembled form. They are of a type which, when energized, cause the sprocket associated with a clutch to be driven by the shaft associated with it. For example, if magnetic clutch 46 is energized, it will cause the shaft 36 to drive the sprocket 46a. Likewise, if any of the other clutches are energized, their respective sprockets will be caused to rotate with the driven shaft 36.

The cam or control shaft 39 is provided with magnetic clutch 50 which is designed to act as a brake and it also carries four

other sprocket

51, 52, 53 and 54. Although the sprockets 46a. 47a, 43a and 49a are all of the same diameter, the

sprockets

51, 52, 53 and 54 are all ditlerent diameters in order to provide different speed ratios between the sprockets. The sprocket 46a drives the sprocket 5]. opposite it by means of a chain 55, the sprocket 47a drives sprocket 52 opposite it by means of a chain 56, the sprocket 48a drives sprocket 53 opposite it by means of a chain 57 and the sprocket 49a drives sprocket 54 opposite it by means of a chain 53. Another sprocket 59 associated with the clutch or brake 50 is prevented from rotation by means of a chain 60 wrapped over it with the ends of the chain secured by two screws 60a to the support plate 35. The ellect of encrgizing the clutch or brake 50 is to arrest rotation of the cam or control shalt 39.

At the end of the shaft 39 opposite to the end on which the sprocket 51 is secured, a cam 61 is mounted. This cam 61 is provided with two

cam segments

62 and 63. These cam segments are aligned with the arm 64c of a switch 64 to cause actuation of the switch 64 as the cam rotates.

With the arangement of parts as shown, the control device can be employed to control the vertical travel of the carriage 17 so that it can stop in alignment with the midlcvel of the coil 31 or at one-third levels of the coil, as hereinafter described, although the components can be replaced or changed to allow the carriage 17 to be aligned at other levels of the coil 31. it should be emphasized that the functioning of the control means is independent of the height of the coil. It operates on ratios of movement rather than actual differences, which should be apparent as the operation is described.

Regardless of the levels at which the carriage 17 is to be arrested in motion, the ratios of th sprockcts 51 and 46a associated with the magnetic clutch 46 are such that, it the clutch 46 is energized for the full time, the control cam 61 is rotated at full revolution as the carriage 17 is lowered by the motor 21 from its fully elevated position to its lowermost position corresponding to the upper stirlace of the conveyor 32 which in all cases the lower edge of a coil 31, regardless of the height of the coil.

Assuming that the carriage 17 is to be lowered to the mid-level ot' a coil, the magnetic clutch 46 is energized as the motor 21 initiates downward travel of the carriage 17. This begins rotation oi the control cam 61. Assuming no coil is in place, the cam would complete a single revolution by the time the cariage 17 reached the upper level of the conveyor 32. However, it a coil 31 is in place as shown in FIG. 1, the situation is dit'lerent. Additional means are provided to sense the upper surface of the coil 31. The means employed consisls of a photoelectric cell 65 mounted in a titted position on the carriage 17. It is in direct alignment to receive impingement of a light beam 66 from a directional light source 67. "the beam 66 is aligned to intersect the path of travel of the coil 31. As the carriage 17 is lowered, the coil 31 intercepts the light beam 66 and prevents it from impinging upon the photoelectric cell 65. As this occurs, the lcctrical circuitry is such that the magnetic clutch 46 is tie-energized and another clutch 48 is energized. In the particular case mentioned, if the ratio of the sprocket 51 to the sprocket 46a is two to one, thcn the ratio of the sprocket S3 to the sprocket 48a is one to one. As a result of this the driven shalt 36 will cause the cam shaft 39 to rotate twice as last after the clutch 48 is energized as when the clutch 46 is energized. The result is that the control cam 61 will have achieved a full revolution by the time the carriage 17 has reached the mid-level ot the coil 3!. The switch 64 is then actuated by the cam 61 to arrest the travel of the carriage 17. At this time the strapping head 25 can be actuated to cause the strap loop 33 to be shrunk and secured onto the coil 31 at the mid-point of: the coil 31 with which it is aligned.

Assuming that the carriage 17 is to be lowered first to a level one-third the ditsance from the top of the coil and then to a level at a distance two-thirds from the top of the coil in order to align the strapping head 25 for positioning straps at the one-third and twoahird levels of the coil, the magnetic clutch 46 is energized when the carriage 17 is in its uppermost position. As the magnetic clutch 46 is energized, the motor 21 is simultaneously energized to initiate the downward travel of the carriage 17 and rotation of the control cam 61 begins. As the light beam 66 is intercepted by the top of the coil 31, the photoelectric cell 65 is such that the magentic clutch 46 is de-energized and the circuit is prearranged so that another clutch 47 is energized. The ratio oi diameters ol the sprocket 52 to the sprocket 47a is one to one and onc-half with the result that the driven e shaft 36 will cause the cam shaft 39 to rotate three times as fast after the clutch 47 is energized as when the clutch 46 is energized. The result is that the cam 61 will have achieved a full revolution by the time the carriage 17 has reached the one-third level from the top of the coil 31. The switch 64 is then actuated by the cam 61 to arrest the travel of the carriage 17. At this time, the strapping head 25 can be actuated to cause the strap loop 33 to be shrunk and secured onto the coil 31 at the one-third level from the top of the coil 31 with which it is aligned.

After application of the strap at the one-third level, the carriage 17 is controlled to be returned to its uppermost position and the clutch 46 is energized simultaneously with energizing the motor 21 for another downward travel of the carriage 17. This time, when the light beam 66 is intercepted by the top of the coil 31, the clutch 46 is de-energized and the clutch 49 is energized. The ratio of the sprocket 54 to the sprocket 49a is one and onethird to one with the result that the driven shaft 36 will cause the cam shaft 39 to rotate one and one-half times as fast after the clutch 49 is energized as when the clutch 46 is energized. This has the effect of allowing the control cam 61 to achieve a full revolution by the time the carriage 17 has reached the two-thirds level from the top of the coil 31. The switch 64 is then actuated by the cam 61 to arrest the travel of the carriage 17. At this time, the strapping head 25 can again be actuated to cause the strap loop 33 to be shrunk and secured onto the coil 31 at the twothirds level of the coil with which it is aligned. After application of a strap at any level, whether it be the mid-level, the one-third or twothirds level or any other level, the carriage 17 is controlled to be returned to its uppermost position in readiness for the next cycle.

In order to more clearly understand the full operation, it is necessary to refer to FlG. 4 which shows a simplified wiring diagram for the clutches and switches used with the apparatus.

A master switch 100 is connected to direct 110 volt DC. current across the

conductors

101 and 102. In one main branch circuit connected between the

connectors

101 and 102 are the contacts 103a of the carriage down control switch 103, switch contacts 109 of the switch 64b, photo switch 65a and magnetic clutch 46. Between the switches 64b and 65a is connected another branch circuit leading to a conductor 102 and it contains a motor down control solenoid 104. In another branch circuit starting at the same point and connected to conductor 102 is another photo switch 65b, selector switch contacts 105a and a magnetic clutch 48. Another branch circuit is connected from between the photo switch 65a and the selector switch contacts 105a to the conductor 102 and it contains selector switch contacts 105b, selector switch contacts 106a and a magnetic clutch 49. Connected between selector switch contacts and selector switch contacts 106a is another branch circuit leading to conductor 102 and it contains selector switch contacts 106b and a magnetic clutch 47.

Another circuit leads from conductor 101 to a carriage up control switch 107, switch contacts 108 of switch 64a and to a point between selector switch contacts 106b and the magnetic clutch 47. A motor up control solenoid 114 is connected from one side of the switch contacts 108 to the conductor 102. Another branch circuit connected between

conductors

101 and 102 contains contacts 103b of the carriage down control switch 103, switch contacts 110 of the switch 64a and the magentic brake 50. Still another branch circuit contains switch contacts 111 of switch 64b which are connected to the controls 112 for the strapping machine connected to the conductor 102.

In operation, assuming, for example, a single strap is to be applied to the mid-level of a coil 31 positioned on the conveyor 32. Under these circumstances, the carriage 17 is elevated to its top position, the strapping machine is actuated by means not shown to feed strap from a source of supply into a strap loop 33 by directing it through the guides 27, 28, 29 and 30. After the strap loop is formed, the carriage down control switch contacts 103b are opened and contacts 10321 are closed by manually operating switch 103. Opening contacts 103b de-energizes the brake 50 to allow rotation of the cam shaft 39. Closing contacts 103a causes the magnetic clutch 46 and the motor down control solenoid 104 to be energized. Energizing the magnetic clutch 46 causes the driven shaft 36 to be in driving relationship with the cam shaft 39. Energizing the solenoid 104 causes the motor 21 to rotate in a direction to cause the carriage 17 to lower. As the carriage 17 lowers, the cam shaft 39 is driven by the driven shaft 36 to cause the cam 61 to rotate in a clockwise direction (FIG. 3) and cause segment 62 to move away from the region of the switch 64a. The switch 64a at this time has its contacts 108 closed and its contacts open.

Switch 64 contains both switches 64a and 64b. Switch 64a has the two sets of

contacts

108 and 110, as mentioned. Switch 64b has the two sets of

contacts

109 and 111. Actually, the four sets of contacts are within a single housing generally referred to as switch 64 and all four sets of contacts are simultaneously actuated as the switch arm 64c is physically actuated. It is only im port-ant to indicate that the switch contacts are in the positions as shown in FIG. 4 when the arm 64c is in the position as shown in FIG. 3 which corresponds to the initial setting of the cam 61 at the start of the cycle. Also, it should be pointed out that the switch arm Me is V-shaped and pivoted on a pivot 64f. Two rollers 64:! and 64e are at the two ends of the V-shaped arm 64c and their relative spacing always remains the same. Further, both of these rollers 64d and 64e are in adjacent planes corresponding to the respective planes of the

cam segments

62 and 63. The result is that earn segment 62 actuates the switch at the position as shown in FIG. 3 as the cam segment 62 moves against the roller 64d. At the other position of the switch arm 64c, the cam segment 63 will have been rotated counter-clockwise around to move against the roller 64c and thereby change the position of the switch arm 64c. It should be apparent from this that the switch arm 64c has two positions, one position being determined by the cam segment 62 and the other position by the cam segment 63.

As the carriage 17 moves down, the light beam 66 is interrupted by the interception of the coil 31. This causes photo switch 65a to be opened and photo switch 65b to be closed. Opening photo switch 65a deenergizes magnetic clutch 46 and closing photo switch 65b energizes the magnetic clutch 48 to change the driving speed of the cam shaft 39 from control by the magnetic clutch 46 to control by the magnetic clutch 48. The carriage continues downwardly at its same speed. but the cam shaft 39 rotates at twice its initial speed with the result that the cam 61 makes a complete revolution by the time the carriage 17 has reached the midlevel of the coil 3-1. At full revolution of the cam 61. its cam segment 63 causes actuation of the switch arm 64c to reverse the position of the switch contacts of switches 64a and 64b to the opposite of how they are shown in FiG. 4. (

ontacts

109 and 110 open and 108 and 111 close. Opening of contacts 109 tie-energizes magnetic clutch 48 which removes the driving connection between the

shaft

36 and 39. Closing contacts 108 merely sets up the cam shaft control circuit and closing contacts 11] initiates the controls 112 for the strapping machine. At this time. the controls 112 cause the strapping head 25 and its related mechanism to shrink the strap loop 33 onto the coil and sever the strap loop from the supply end of the strap. The particular strapping head 25 used and the controls for its operation may be of many types, as previously mentioned. Opening controls 110 has no effect at this time.

After strapping has been completed, the carriage up 7 control switch Hi7 is clo ed to cause the magnetic clutch 47 to b: energized and to likewise causc the motor P contra! solenoid 11-3 to be energized. Encrgizing solenoid 14 causcs the motor 21 to be rotated in a reverse dircction to cause elevation of the carriage i7. Encrgizing ma ititic clutch 37 causes the cam shaft to he rotated. in its revert-c direction at a rapid speed and it is prcicrnblc that the rotation to)? the cam 61 completed prior to lull return of the carri 17 to its fuliy rai cal position. 'Ilte reason lor dis is hat the cam shaft 39 is not driven beyond the time that the carriage is driven because the motor 2! drives both and it is csl icutlal that tho cant 51 c rctur cd to its full iritial position prior to 'a cyclic".

viten t it actuatcs the st H19 and lit] and open contacts W3 and lit. 0pc. contacts H1 rcniovcs the possibility of cycling of the strapping machi'tc. cl 'ng contacts 109 prcnar s the cit cut: for subsequent. downward m vement oi the Cftl'litgl closing o! coma s 1151 applies the brake St] to hold the cam hat't 3) in its i ial position. and o cning contacts H33 discngagcs the magnetic clutch -27. At this time. tlt': carriage .17 is in ltlt upper position ready for another cycle oi' 0pc; alian.

Akslttltt that [Wu straps are to be applied in scqumcc. on: at. the orcah rd lc" l and the other at the two-thirds lc'vcl from the top of e coil 3 Undcr these circumt nccs. the cart" g? 17 is again at its fully elevated po- Slit As already caplaihed fully tor thc single strap v iation. the operation of the machine is the same up thc time the light beam 6 is interrupted by the interception of the coil 3!. The only ditl'crencc is that the selector switch 165 is initially manuaily actuated to cpcn its contacts thin and close its contacts lflih. Open i119 contor 153a insures that the magnetic clutch 43 i l not he operated during [in cycle oi oper. iian. Closing contacts ltiih will al ow etthcr magnetic clutch 47 or magnetic clutch 49 to he Opcrlttcd in its place upon d:- cncrgization of the magnetic clutch 46 when thc light beam 66 is interrupted by the intcrccption ot' the coil 31.

When the light hcani is interrupted. its phot'o switch 65a is opened and its photo switch 65h is clo ed As hclorc. opening photo snitch 65:1 dc-encrgi; s magnetic clutch 45. This time. closing photo st itch G-th energizes magnetic clutch 47 to alt'cr the driving speed of the cam shall 39 from control by the magnetic clutch 46 to control by the magnetic clutch 47. The carriage continuesdovt'mvardiy at its same speed. but the cam shaft 3 now rotates at thrce timcs its initial speed duc to the diamctcr ratics of the sprockets 47a and 52. With this arrangement. by tho time the cam 61 maltcs a con1 tlcte revolution. the carriage will have only rcachcd the onctltird levcl ol' the coil 31. before. the cam segmcnt (:3 repeats the operation of the switch 64 to air rest thc downward movement of ta: carriage i7 and prepare the circuit for the subscqucnt elevation of the cartilage attcr strapping. After strap mg has hccn completed at the one-third le el of the coil the carriage up control snitch It}? is closed and the carriage is again returned to its fully elevated PtHii'iOll. Likewise, magustic clutch 47 is ltcwt energized through closed contacts 1th; to insurc that the cam shaft 3) is returned to its initial position prior to full cievation ot' the carriage l7. When the cunt shaft .11) and its cam til have returned to their initial positions. the circuit is then rcady to cycle again.

ln o der to have the carriage move to the twothirt lcvcl of the coil. instead ot the one-third level. the sclector switch 106 may be manually actuated to close thc contacts 106a and opcn contacts Gb. The rcsuit of this is thtt the cycling will he the same as for application of tltc strap at tho oncthird lcvcl oi lhc. coil, but lltc magnclic clutch 49 will he cncrgi cd instead of the clutch 47 during the downward travel from the time the light on. 'ttchcs 64a and fi ih to close contac's Cir beam is inlcrccplcd until the cam 61 complctcs its full rcvolution.

For convenience, it is possihlc to cycle in the actuation oi tin: sclcctor sw tch 136 with the actuation of the strapping head 25 through the controls {12. Aitcr the strap is applicd at the onethird level. the controls 112 for the strapping machine can be uscd to nutunuttically activate thcv switch '35 aft-:1 the strapping had 25 has applied a ('tl). Then, at'i'cr the next strao has bccn applied at the two-il'ilrtis level. it can cause the selector switch to it: rctcrssu to its initial pos tion so that the next strap can. be applied at the onc-ti'tird icvcl. In this way. no manual operation of the actector switch 1013 is essential.

When the magncti; clutch 49 is energized instead of thc magnetic clutch 47 during the downward movement rs cturiac 17 for appltc .on of a strap at the twos lcvcl. the sproci 3t ratio C()t!-L1-?P() l(lil'tg to the magch. 49 is such that. the cam 61 is rotated one it times as fast as it is when thc clutch 46 is initial no further need of adiusinr the uppermost or the lotvcrmost is required.

rtlthough only a sing'tc prctcrred. embodiment of the invcnlioa has hccn shown and t cscrihcd, it shouid be clearly undctstood that the tnventioa can he math: in many dillcrcnt ways without. dcparting from the true scope or the invcnti'rri as dc ed by the ap ended cla ms.

I claim:

1. The combination in a strapping machine comprising, strapping means, a work picco support, mtatis to raise and lower the strapping means relative to the work piece suppolt, arrczting means to arrest the lowering of the strapping meal... :td control means responsive to passage or" thc strapping means l y thc upper level of a work piece resting on the Work piece support to cause the arresting means to arrest the strapping means at a prc dctcrrnincd lcvcl relative to the upper level of the Work piece. said control means including a light scnsitivc relay and a light beam impinging upon said iclay with the light hcam directed to be interruptcd by the work piccc as the strapping means is lowered to tl'tcrcby cause actuation of said relay.

The combination in a trapping machine comprising. a strapping head. a work picce support. actuating means to raise and lower the strapping head rciativc to thc work piece support. and control means associated with the actuating means for controlling the levcl with respect to a Work piece resting on said support at which the actuating means is caused to arrest the movement of said strapping head. said controi means including a cam shait and a driving shaft for driving said cam shalt. said driving shaft being driven by said actuating means in olrect rcsponse to tlic raising and lowering ol thc strapping head by said actuating means. a plurality of relcasable driving connections between the driving shaft and the cam raft, each driving connection arranged to cause the driving shaft to drive the cam shaft at a different speed. a cam rotated by said cam shaft to actua e means which causes said actuating means to arrest the lower of said strapping head upon a predetermined rotation of said cam, a first of said driving connections having a driving speed which causes a lull movemcnt of said cam (luring lllc l'ull travel ol thc lotvcring ol the strapping hcad, and a sccoud ot tltl driving conncctions having a driving; speed which causes a lull movement of said cam during less than the full travel downward of the lowering of the strapping head, a signal means arranged to respond to the passage of the strapping head by the upper level of the work piece to cause the first said driving connection to be released from driving the cam shaft and the second said driving connection to be connected to drive said cam shaft.

3. The combination defined by claim 2 characterized by, said signal means including a light sensitive relay and a light beam impinging upon said relay with the light beam directed to be interrupted by the work piece as the strapping means is being lowered to thereby cause actuation of the light sensitive relay, said relay being connected to electrically operate said releasable driving connections.

4. The combination in a strapping machine comprising, a strapping head, a work piece support, actuating means to raise and lower the strapping head relative to the work piece support, and control means associated with the actuating means for controlling the level with respect to a work piece resting on said support at which the actuating means is caused to arrest the movement of said strapping head, said control means including a cam shaft and a driving shaft for driving said cam shaft, said driving shaft being driven by said actuating means in direct response to the raising and lowering of the strapping head by said actuating means, a plurality of releasable electric clutches providing driving connections between the driving shaft and the cam shaft, each driving connection arranged to cause the driving shaft to drive the cam shaft at a different speed, a cam rotated by said cam shaft to actuate means which causes said actuating means to arrest the lowering of said strapping head upon a predetermined rotation of said cam, a first of said driving connections having a driving speed which causes a full movement of said cam during the full travel of the lowering of the strapping head and a second of said driving connections having a driving speed which causes a full movement of said cam during less than the full travel downward of the lowering of the strapping head, a signal means arranged to respond to the passage of the strapping head by the upper level of the work piece to cause the first said driving connection to be released from driving the cam shaft and the second said driving connection to be connected to drive said cam shaft, said signal means including a light sensitive relay and a light beam inpinging upon said relay with the light beam directed to be interrupted by the work piece as the strapping means is being lowered to thereby cause actuation of the light sensitive relay, said relay being connected to electrically operate said electric clutches.

5. The combination in a strapping machine comprising, strapping means, a work piece support, a drive means to raise and lower the strapping means relative to the work piece support, control means for controlling the drive means, said control means including two clutches selectively driven by said drive means, a cam means driven by said clutches, each of said clutches having a different driving ratio with respect to the cam means to thereby cause the drive means to drive said cam means at two different driving speeds relative to the speed of the drive means, the first of said two clutches being engaged to drive the cam means as the strapping means is initially lowered toward the work piece, a first switch means associated with said strapping means actuated in response to the strapping means reaching the upper level of the work piece, a second switch, the connections of said first switch being such as to disengage said first clutch from driving engagement with the drive means and to engage said second clutch into driving engagement with said drive means to thereby change the driven speed of the cam means relative to the drive means, said cam means being arranged to travel a predetermined distance at which time it engages said second switch to actuate it, the second 10 switch being connected to cause disengagement of said second clutch from driving engagement with said drive means and thereby arrest the downward travel of said strapping means.

6. The combination defined by claim 5 characterized by, the said driving ratio of said first clutch with said cam means being a proportion to cause the drive means to drive the strapping means from its uppermost position to its lowermost position while the cam means travels its predetermined distance, and said driving ratio of said second clutch being a proportion to cause the cam means to travel its predetermined distance While the strapping means is lowered only a fraction of its full travel from its uppermost position to its lowermost position.

7. The combination in a strapping machine comprising, strapping means, a work piece support, elevating means to raise and lower the strapping means relative to the work piece support, arresting means to arrest the lowering of the strapping means, and control means actuated in response to the passage of the strapping means by a predetermined portion of a work piece on said work piece support, said control means including a cam provided with two selective drives which drive the cam at different speeds, respectively, means to actuate both the elevating means and one of said selective drives simultaneously to initiate lowering of said strapping means and cause driving of said cam at one speed, said actuation of the control means in response to the passage of the strapping means by a predetermined portion of the work piece causing actuation of the other said selective drive to change the driving of said cam to a second speed without any change in the speed of lowering of the strapping means, said cam having a predetermined travel and a switch means actuated at the end of its travel, the actuation of said switch causing said arresting means to arrest the lowering of said strapping means.

8. The combination in a strapping machine comprising, strapping means, a work piece support, elevating means to raise and lower the strapping means relative to the work piece support, and control means for automatically controlling the elevating means to arrest the strapping means at a predetermined level relative to a work piece on said work piece support, said control means including a cam and a plurality of releasable driving connections for said cam, each of said driving connections causing said cam to be driven at a different speed, said cam having a predetermined travel at the end of which it actuatcs a switch means, the first of said driving connections being connected to drive said cam at a first speed corresponding to the speed of the elevating means lowers the strapping means, the second of said driving connections being connected to drive said cam at a second speed which is faster than said first speed, said control means causing said first driving connection to be connected during the initial lowering movement of the elevating means and causing said second driving connection to be connected in response to the strapping means passing by a predetermined level of said work piece.

9. The combination in a strapping machine comprising, strapping means, a Work piece support, elevating means to raise and lower the strapping means relative to the work piece support, and control means for automatically controlling the elevating means to arrest the strapping means at a predetermined level relative to a Work piece on said work piece support, said control means including a light sensitive relay for sensing said predetermined level.

10. The combination defined by claim 8 characterized by, said control means including a light sensitive relay for causing said second driving connection to be connected in response to the strapping means passing by a predetermined level of said work piece.

11. The combination defined by claim 8 characterized by, said driving connections being electrically operated magnetic clutches.

12. The combination in a strapping machine comprising, strapping means, a work piece support, means for causing relative movement between. a work piece supported on the work piece support and the strapping means, arresting means to arrest said relative movement, and control means responsive to the movement of the strapping means and the work piece relative to each other to cause the arresting means to arrest the relative movement at a predetermined location relative to one end of the work piece, said control means including a light sensitive relay and a light beam impinging upon said relay with the light beam directed to be interrupted by interference of the work piece during the relative movement between the strapping means and the work piece.

I3. The combination in a strapping machine comprising, strapping means, a work piece support, drive means for causing relative movement between a work piece supported on the work piece support and strapping means, arresting means to arrest said relative movement, and control means responsive to movement of the strapping means and work piece relative to each other, said control means including a cam means provided with at least two selective drives which selectively drive the cam means at different speeds, respectively, means to sirnultaneons/y actuate both the drive means and one of said selective drives to initiate both relative movement between the strapping means and work piece and cause driving of the cam means at one speed, said actuation of the control means in response to movement of the strapping means and work piece relative to each other by a predetermined amount causing actuation of the other said selective drive to change the driving of said cam means to a second speed without anv change in the speed of the relative movement between the strapping means and work piece, said cam means having a predetermined travel and a switch means actuated in the course of its travel, said switch causing said arresting means to arrest the relative movement between the strapping means and the work piece.

[-1. The combination in a strapping machine comprising, strapping means, a work piece support, drive means for causing relative movement between a work piece supported on the work piece support and strapping means. arresting means to arrest said relative movement, and control means for automatically controlling the movement of the strapping means and work piece relative to each other to arrest said relative movement of strapping means and work piece at a predetermined position, said control means including a cam means and a plurality of releasable driving connections for said cam means, each of said driving connections causing said means to be driven at a different speed, said cam means having a pre determined travel, the first of said driving connections being connected to drive said cam means at a first speed corresponding to the speed of the movement of the strap ping means and work piece relative to each other, the second of said driving connections being connected to drive said cam means at a second speed which is faster than said first speed, said control means causing said first driving connection to be connected during the initial movement of the strapping means and work piece relative to each other and causing said second driving connection to be connected in response to movement of the strapping means and work piece relative to each other by a predetermined amount.

References Cited The Following references, C11CL1 by the Examiner, are of record in the patented file of this patent or the original BILLY I. WlLHl'lE, Primary Examiner.