WO1999046136A1

WO1999046136A1 - Label apparatus

Info

Publication number: WO1999046136A1
Application number: PCT/US1999/003887
Authority: WO
Inventors: Thomas H. Brinkmann; James A. Knebel; Patrick F. Pierce; David J. Sutcliffe
Original assignee: Diagraph Corporation
Priority date: 1998-03-11
Filing date: 1999-02-24
Publication date: 1999-09-16
Also published as: AU2972999A

Abstract

Label apparatus (1) comprising a roll mounting device for mounting a supply roll (41) of label material, and a web pulling device (47) for pulling the web (W) from the supply roll (41) in a forward direction. The web pulling device (47) is operable to exert intermittent pulls on the web (W) with dwells between successive pulls. A web accumulator (81) is located between the roll mounting device and the web pulling device (47) for accumulating a surplus of web (W). The web accumulator (81) includes a rotatable wheel and two generally parallel dancer rollers extending out from the wheel for engagement by the web as it travels from the supply roll to the web pulling device (47). A spring device rotates the wheel in a first direction during the dwells of the web pulling device (47) to increase accumulated surplus. The wheel rotates in a second opposite direction when the web pulling device pulls on the web (W), thereby causing a decrease in the accumulated surplus of web (W).

Description

LABEL APPARATUS

Background of the Invention

This invention relates generally to label apparatus and, more particularly, ' to improved web feed apparatus and rewind apparatus for use in label machines.

The present invention is used in label machines equipped to handle a continuous web of label material of the type comprising a web of liner material and a series of labels adhered to the liner at intervals along the web. The invention has particular application to a print-and-apply label machine which prints the labels and then applies them to a series of objects (e.g., cartons) on a conveyor. However, the invention is also applicable to label machines which handle pre-printed labels. A print-and-apply label machine of conventional design includes a printer having a web pulling device (e.g., drive rolls) which operates to exert intermittent pulls on the web with dwells between successive pulls. The printer prints on the labels during the pulls, following which the printed labels are peeled off the web liner and applied during the dwells to objects by an applicator mechanism. Conventional print-and-apply machines are sometimes equipped with web accumulators between the supply roll and the printer. These accumulators operate to accumulate a surplus of web during dwell periods so that after a printing operation is finished, the web pulling device can accelerate the web up to full speed without having to overcome the inertia of the supply roll. Prior accumulators are typically bulky and have various drawbacks. Accordingly, there is a need for an improved accumulator which can be used with a print-and-apply label machine, or with label machines which apply preprinted labels. Conventional label machines also have a rewind mechanism for winding the web liner into a roll after the labels have been printed and applied, or after preprinted labels have been applied. These mechanisms have various drawbacks, and they are not equipped to sense if the web liner breaks.

Summary of the Invention

Among the several objects of this invention may be noted the provision of label apparatus having an improved web accumulator which has the advantages of conventional accumulators but which is more compact and more effective for accumulating a surplus of web using only a small range of movement; the provision of such a web accumulator which is of simple design for more economical manufacture; the provision of such an accumulator which has a brake for braking the supply roll after a surplus of predetermined amount has been accumulated; the provision of label apparatus having an improved rewind mechanism which includes a sensor for sensing a break in the web liner being rewound, the sensor being operable in the event of a break to generate a signal for stopping operation of the machine; the provision of such a rewind mechanism which uses a rewind reel rotated by an air motor; the provision of such a rewind mechanism in which the rotary driving force applied by the air motor to the rewind reel is adjustable to control the tension in the liner; and the provision of such a rewind mechanism which is less expensive and requires less maintenance than many conventional rewind mechanisms . In general, a label apparatus of the present invention comprises a roll mounting device for mounting a supply roll of label material for rotation about a first axis. The label material comprises a continuous web of liner material having labels removably adhered thereto at intervals along the web. The apparatus also includes a web pulling device for pulling web from the supply roll in a forward direction, the web pulling device being operable to exert intermittent pulls on the web with dwells between successive pulls. A web accumulator is located between the roll mounting device and the web pulling device for accumulating a surplus of web. The web accumulator comprises a wheel mounted for rotation about a second axis extending generally parallel to the first axis, and first and second generally parallel dancer rollers mounted on the wheel and extending laterally therefrom for rotation about axes generally parallel to the first and second axes . The dancer rollers are engageable by the web as it travels from the supply roll to the web pulling device. The dancer rollers define a path of travel which creates the surplus of web. The wheel is rotatable in a first direction to increase the surplus of web and in a second opposite direction to decrease the surplus of web. A biasing device urges the accumulator wheel to rotate in the first direction, the arrangement being such that the wheel rotates in the second direction against the urging of the biasing device to decrease the surplus of web when the web pulling device pulls on the web, and such that the wheel rotates in the first direction under the urging of the biasing device to pull web from the supply roll and thus increase said web surplus during a dwell between successive pulls.

In another aspect of this invention, the label apparatus comprises a supply roll mounting device for rotatably mounting a supply roll of label material of the type described above, a label applicator for removing labels from a web of liner material and applying the labels to a series of objects, a rewind reel for winding said web into a roll after the labels have been removed, a rewind motor for rotating the rewind reel, and a sensor system for sensing a break in the web at a location between the rewind reel and said label applicator. The sensor system is operable in the event of a break to generate a stop signal to stop the rewind motor from rotating the rewind reel. Other objects and features will be in part apparent and in part pointed out hereinafter.

Brief Description of the Drawings

Fig. 1 is a front elevation of label apparatus of the present invention; Fig. 2 is a left side elevation of the apparatus of Fig. 1;

Fig. 3 is a top plan of the apparatus of Fig. 1;

Fig. 4 is an enlarged view of a portion of the apparatus of Fig. 1 showing a web accumulator of the present invention;

Fig. 5 is a bottom perspective view of certain parts of the web accumulator;

Fig. 6 is a sectional view taken on line 6—6 of Fig. 4 showing a brake on the web accumulator wheel for engaging the supply reel;

Fig. 7 is an enlarged perspective of an improved rewind mechanism of the apparatus of Fig. 1; and

Fig. 8 is an enlarged vertical section taken on line 8—8 of Fig. 4. Corresponding reference numbers designate corresponding parts throughout the Figures.

Detailed Description of the Preferred Embodiment

Referring now to the drawings, and first more particularly to Figs. 1-4, label apparatus incorporating the present invention is designated in its entirety by the reference numeral 1. The apparatus 1 is illustrated as being a print-and-apply label machine for printing labels and then applying them to objects 3 on a conveyor 5. It will be understood, however, that the present invention is also applicable to label apparatus which apply preprinted labels. The label material handled by the machine 1 comprises ^'a continuous web W of liner material having labels L removably adhered to one face thereof at intervals along the web (see Fig. 4) . This label material is typically sold in rolls mounted on hollow cores.

Apparatus 1 comprises a frame, generally designated 11, which includes a base 13 with wheels 15, a vertical post 17 extending up from the base, a horizontal beam 19 extending forward from the post (Figs. 2 and 3), and a mounting panel 21 attached to the forward end of the beam. Operation of the apparatus is controlled by a programmable logic controller (or microprocessor) and suitable controls on a control box 25 held by an arm 27 mounted at the top of the post 17 for rotation about a generally vertical axis so that the control box can be swung to a position convenient to an operator.

A freewheeling supply reel, generally designated 41, is mounted on the mounting panel 21 and holds a roll 43 of label material for rotation about a first axis, the axis being generally horizontal as shown in Fig. 2. The web W is pulled in a generally forward direction from the roll by a web pulling device which, in the embodiment shown, comprises a printer, generally designated 47, mounted on the mounting panel 21. By way of example, the printer 47 may be direct thermal or thermal transfer printer of the type sold by Sato America, part No. 8485S (203dpi) . As will be understood by those skilled in this field, a printer of this type is operable to exert intermittent pulls on the web with dwells between successive pulls. The printer 47 prints on the labels L during the pulls. As a label is printed, the web W is fed in a forward direction to a label removal device 51 (Fig. 4) typically having a relatively sharp edge over which the web is pulled to cause the label to peel off the web. A label applicator, generally designated 53, (e.g., a reciprocating tamping cylinder) then applies the label L during a dwell to an object 3 passing below the applicator on the conveyor 5. The bare web of liner material is rewound on a rewind reel, generally designated 55, mounted on the mounting panel 21. The rewind reel 55 is rotated by a rewind motor 57.

As illustrated in Fig. 2, the supply reel 41 comprises a shaft 61 rotatable in a bearing 63 attached to the back side of the mounting panel 21. The shaft 61 extends through an opening in the panel 21 and outwardly therefrom in cantilever fashion. The reel 41 also includes a pair of generally parallel circular side members 65, 67 on the shaft 61 spaced apart for receiving the supply roll 43 therebetween. The side member 67 of the reel 41 farthest from the mounting panel 21 is removable from the shaft 61 for placement of a roll of label material on the shaft, following which the side member can be remounted on the shaft. This side member 67 is preferably transparent so that the amount of web remaining on the roll 43 may be monitored. In accordance with the present invention, a web accumulator, generally indicated at 81 in Figs. 4 and 5, is mounted on the mounting panel 21 at a location between the supply reel 41 (which may be broadly referred to as a roll mounting device) and the printer 47. The web accumulator 81 functions to accumulate a surplus of web for reasons which will become apparent. The accumulator 7

81 comprises a wheel 83 mounted on a shaft S for rotation about a second horizontal axis extending generally parallel to the axis of the supply reel 41, and first and second generally parallel dancer rollers, generally designated 85, 87, mounted on the wheel and extending laterally outwardly therefrom in cantilever fashion for rotation about axes generally parallel to the aforementioned axes of the supply reel and accumulator wheel. The dancer rollers 85, 87 are engageable by the web W as it travels from the supply roll 41 to the printer 47 (referred to broadly as one form of a web pulling device) . The dancer rollers 85, 87 define a path of travel for the web which creates a surplus of web, the accumulator wheel 81 being rotatable in a first direction (counterclockwise as viewed in Figs. 1 and 4) to increase the surplus of web and in a second opposite (clockwise) direction to decrease the surplus of web. As used herein, the term "surplus" means a length of web greater than the length of web which would exist between the supply reel 41 and the printer 47 if the accumulator 81 were not present. In effect, rotation of the wheel 83 in the stated first direction moves the dancer rollers 85, 87 to lengthen the distance the web must travel from the supply roll 41 to the printer 47, thereby increasing the "surplus," whereas rotation of the wheel in the opposite direction moves the dancer rollers to shorten the path of travel, thereby decreasing the "surplus . "

The accumulator wheel 83 in the embodiment shown is a flat relatively thin wheel having a circular rim (this shape may vary) and a central hub 91 for receiving the shaft S which is rotatable in spaced bearings 93, 95 mounted on a bracket 103 fastened to the back side of the mounting panel 21, as shown in Fig. 5. A biasing device in the form of a spring device comprising a coil spring 101 is mounted around the shaft S between the bearings 8

93, 95, one end of the coil spring being engageable with the bracket 103 and its other end with a collar 105 around the shaft. The spring 101 is tensioned so that it urges the shaft S and the accumulator wheel 83 thereon to rotate in the aforementioned first direction for increasing the surplus of web W accumulated by the accumulator 81. The spring force (torque) exerted by the spring 101 on the shaft S can be adjusted by rotatably adjusting the collar 105 on the shaft and then securing it in position, as by using a setscrew (not shown) or other suitable means.

Each of the two dancer rollers 85, 87 on the accumulator wheel 83 comprises a tubular roller 89 rotatable on a fixed spindle 88 having its inner end secured to the wheel 83 by a suitable fastener 90. The tubular roller 89 is retained on the spindle 88 by a retaining ring 78 received in a groove adjacent the outer end of the spindle, the retaining ring being engageable with the roller 85, 87 to hold it captive on the spindle. As shown in Fig. 4, the web extends from the supply roll 41, under the first (upstream) dancer roller 85, and over the second (downstream) dancer roller 87 to the printer 47. It will be observed that the tubular roller 89 of the upstream dancer roller 85 has a relatively small outside diameter but that the tubular roller of the downstream dancer roller 87 has a substantially greater outside diameter which is sufficiently large to prevent peeling of the labels off the web W as the web travels around the roller. By way of example, the outer diameter of the downstream dancer roller 87 may be about 1-2 in.

A web guide 77 is slidably mounted on the upstream dancer roller 87 for maintaining the web in proper position with respect to the roller. The web guide 77 has a friction fit on the roller 87 so that it may be moved along the roller according to the width of web W being handled. As noted above, the printer 47 exerts intermittent pulls on the web W. During these pulls the tension on the web W causes the accumulator wheel 83 to rotate in the aforementioned second direction (clockwise in Figs. 1 and 4) against the urging of the spring 101. This results in a decrease in the distance the web W must travel before it reaches the printer 47, so that the "surplus" of web accumulated by the accumulator 81 decreases. On the other hand, during a dwell of the printer 47, the wheel 83 rotates in the opposite direction under the urging of the spring 101 to pull additional web W from the supply roll 41 and thus increase the web surplus . The advantage of this system is that the pull mechanism of the printer 47 need not overcome the large inertia of the supply reel 41 at the onset of the next pull cycle. Because a surplus of web W is provided by the accumulator 81, the only force the printer pull mechanism must overcome is the relatively light tension of the spring 101 and the relatively small inertia of the various parts of the accumulator 81. As a result, the pull mechanism can accelerate the web quickly and smoothly up to full speed for more efficient printing and improved print quality. The pull mechanism is also subjected to less wear. For best results, the torque on the shaft S exerted by the spring 101 should be sufficiently large to cause the accumulator 81 to move quickly to increase the surplus during a dwell cycle of the printer 47, but sufficiently small to provide only a minimum force against which the pull mechanism of the printer 47 must work to accelerate the web W. For example, the spring 101 is preferably sized and selected so that the web W is held by the dancer rollers 85, 87 under a tension of about 2 pounds. Where the dancer rollers 85, 87 are spaced apart about 3.7 in. on the wheel 83, this may be 10 accomplished by using a spring 101 which exerts a torque of about 5-10 in. -lbs. on the shaft S.

A brake in the form of a cylindric brake member 121 is mounted adjacent the periphery of the accumulator wheel 83 in a position where it is engageable with the peripheral edge of the side member 65 of the supply reel 41 closest the mounting panel 21 to stop rotation of the freewheeling supply reel after a predetermined amount of web W surplus has been accumulated. As illustrated in Fig. 6, the brake member 121 is mounted at one end of an arm 123 secured in a recess in the back face of the wheel 83 by means of suitable fasteners 125. The brake member 121 may be of any suitable material (e.g., polyurethane having a Shore A durometer of about 85) so long as the material is sufficiently soft to brake the supply reel 41 relatively quickly and quietly and yet sufficiently hard to wear well over time.. In operation, the brake 121 described above engages the supply reel 41 after a pull cycle is complete and after a predetermined amount of web W is accumulated. Without the brake 121, the freewheeling supply reel 41 would continue to rotate and feed an undesirable surplus of web W off the supply roll 43.

The accumulator 81 of the present design has significant advantages over prior accumulator designs, some of which include a pivoting arm arrangement. The use of a wheel 83 is a much more compact design taking up less space while allowing for the accumulation of large amounts of surplus web. The present design, for example, allows for the accumulation of surplus web W having a length corresponding to a distance of up to twice the distance between the two dancer rollers 85, 87. The amount of surplus accumulated can be controlled by the varying the distance between the two dancer rollers 85, 87 and/or by varying the extent to which the wheel 83 is allowed to rotate before the brake 121 engages the supply 11 reel 41. A spacing of about 3.7 in. between dancer rollers 85, 87 has been found to be suitable, for example. Generally, an accumulation of surplus in the range of 2-5 in. has been found to be generally satisfactory for a printer 47 of the type mentioned above .

A pair of vertically spaced guide rollers 131, 133 (Fig. 4) mounted on the mounting panel direct the web W from the accumulator 81 down past a sensor system, generally designated 141, and then to the printer 47. Both rollers 131, 133 are suitably mounted on the mounting panel 21 for rotation about generally horizontal axes. The sensor system 141 preferably comprises an optical sensor 143 capable of detecting a break in the web W or the trailing end of the web (indicating that the web on the supply roll 41 is exhausted) , in which case the sensor generates a signal to the programmable logic controller (or microprocessor) to stop the machine. A suitable sensor 143 is commercially available from Optek, Part No. OPB815W. This sensor is a non-contact slotted optical switch comprising an infrared emitting diode and an NPN silicon phototransmitter mounted in a plastic housing on opposite sides of a slot which receives the web W as it is fed to the printer 47. The machine 1 operates so long as the beam emitted by the diode is interrupted by the web W. If the beam is sensed by the phototransmitter, indicating that the web W has broken or that the web supply has been exhausted, the phototransmitter sends a signal to the PLC (or microprocessor) which then stops the printer 47 and other parts of the machine 1, as necessary.

Referring now to Figs. 7 and 8, the rewind reel 55 comprises a large-diameter hollow shaft or hub 151. The hub 151 is mounted on a coaxial rewind shaft 153 journalled in a pair of bearings 155, 157 fastened to a bracket 159 mounted on the back side of the mounting 12 panel 21. The hub 151 is cup-shaped, having a cylindric outer surface 161 and a back wall 163. It is preferably formed from plastic (e.g., Delrin® plastic). A side plate 165 is fastened to the back wall 163 of the hub 151 in a position between the hub and the mounting panel 21 for ensuring proper web rewind on the hub. The rewind shaft 153 has a knurled end which is press fit in a central opening formed in the back wall of the hub 151. The shaft 153 is further secured in this opening by a bolt 171 threaded into the end of the shaft 153 to clamp the back wall 163 of the hub between a washer 173 and a shoulder 175 on the shaft, the result being that the hub 151, side plate 165 and shaft 153 rotate as a single unit. The rewind motor 57 is mounted on the bracket 159 as shown in Fig. 7, with its output shaft 181 drivingly connected to the rewind shaft by a belt and pulley combination, generally designated 183. Thus, the motor 57 is operable to rotate the rewind shaft 181, thereby causing the hub 151 to turn to take up the web W exiting the printer 47. The outer surface 161 of the hub 151 has a pair of diametrically opposing grooves therein for slidably receiving the two legs of a bail-like spacer 187 which, when pulled off the hub after a roll 189 of web W is rewound, creates sufficient clearance between the hub and the roll to permit ready removal of the roll from the hub (see Fig. 8) .

The rewind motor 57 is preferably an air motor supplied with pressurized air from a suitable source 191 (Fig. 2) . The air motor operates to apply a predetermined maximum rotary driving force (torque) to the rewind reel 55. As will be understood by those skilled in this field, the magnitude of this force will vary depending on the pressure of the air delivered to the motor 57. (Higher air pressures will result in higher output torques.) ^' A regulator 193 is provided in the air supply line for adjusting the pressure of the air 13 to the air motor, so that the driving force provided by the motor can be varied as needed. In this manner, the tension applied to the web W being rewound can be maintained in a closely controlled range (e.g., 2-4 pounds) , thereby reducing the risk of the web breaking and also preventing the printer 47 from being subjected to excessive pulling forces by the rewind mechanism 55. The air motor and pressure regulator can be of any suitable design. For example, the air motor may be a Gast air motor, Model number NL22-NCC-1, having a 0.375 in. diameter output shaft and a maximum output power of 0.18 HP. The air motor preferably has a muffler 195 for quiet operation.

In operation, the pull mechanism of the printer 47 may reverse direction toward the end of pull cycle to move a label L on the web W into proper printing position. Use of an air motor allows this reverse pull motion to take place without the use of a clutch or similar device which would be required if an electric motor were used. For proper operation, the air pressure to the air motor 57 is set at a level which provides an output torque significantly less than the pulling force exerted by the pull mechanism on the printer 47. Thus, when the pull mechanism reverses direction, the air motor simply "stalls" and allows the rewind shaft 153 and hub 151 to rotate in a reverse direction to feed web W back to the pull mechanism of the printer 47 without creating a tension in the web sufficient to break it. (When in a "stall" condition, the air motor continues to apply the stated maximum rotary driving force, but the force is overcome by the force exerted by the pull mechanism 47.)

The tension in the web W being rewound is a function of the output torque of the rewind motor 57 and the ever- increasing diameter of the roll as the web rewinds on the hub 151. To maintain the tension in the web W within a fairly narrow and controllable range as the diameter of 14 roll 189 increases, it is preferable to size the hub 151 so that it has a relatively large diameter (e.g, 2-6 in., and preferably about 4 in.). By using a large-diameter hub 151, the proportional change in the diameter of the roll as it increases over time is reduced, thereby reducing the variation in the range of tension in the web W.

A second pair of guide rollers 201, 203 mounted on the mounting panel 21 direct web W from the printer 47 past a second sensor system, generally designated 207, and then to the rewind hub 151. Both rollers 201, 201 are suitably mounted for rotation about generally horizontal axes. The second sensor system 207 preferably comprises an optical sensor 209 identical or similar to the optical sensor 143 of system 141 described above.

The sensor functions to detect a break in the web and, in the event of a break, to generate a signal to the PLC (or microprocessor) to stop the rewind motor 57 from rotating the rewind reel 55. The PLC may also signal other parts of the machine (e.g., the printer 47) to stop.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

15Claims

WHAT IS CLAIMED IS 1. Label apparatus comprising

a roll mounting device for mounting a supply roll of label material for rotation about a first axis, said label material comprising a continuous web of liner material having labels removably adhered thereto at intervals along the web,

a web pulling device for pulling said web from the supply roll in a forward direction, said web pulling device being operable to exert intermittent pulls on the web with dwells between successive pulls,

a web accumulator located between the roll mounting device and the web pulling device for accumulating a surplus of web,

said web accumulator comprising

a wheel mounted for rotation about a second axis extending generally parallel to said first axis,

first and second generally parallel dancer rollers mounted on the wheel and extending laterally therefrom for rotation about axes generally parallel to said first and second axes, said dancer rollers being engageable by the web as it travels from the supply roll to the web pulling device, said dancer rollers defining a path of travel which creates said surplus of web, said wheel being rotatable in a first direction to increase said surplus of web and in a second opposite direction to decrease said surplus of web, and 16 a biasing device urging said wheel to rotate in said first direction,

the arrangement being such that the wheel rotates in said second direction against the urging of said biasing device to decrease said surplus of web when the web pulling device pulls on the web, and such that the wheel rotates in said first direction under the urging of the biasing device to pull web from the supply roll and thus increase said web surplus during a dwell between successive pulls.

2. Label apparatus as set forth in claim 1 wherein said web extends from the supply roll, under the first dancer roller, and over the second dancer roller to the web pulling device, said first dancer roller having a first diameter and said second dancer roller having a second diameter greater than said first diameter, said second diameter being sufficiently large to prevent peeling of the labels off the web as the web travels over the second roller .

3. Label apparatus as set forth in claim 1 wherein said roll mounting device comprises a freewheeling supply reel, and wherein said web accumulator further comprises a brake on said wheel engageable with the supply reel to stop rotation of the supply reel after a predetermined amount of web surplus has been accumulated.

4. Label apparatus as set forth in claim 3 wherein said supply reel comprises a rotatable shaft for supporting said supply roll and a pair of generally parallel side members on the shaft spaced apart for receiving the supply roll therebetween, said brake being affixed to the wheel adjacent a peripheral edge thereof for engagement with a peripheral edge of one of said side members. 17

5. Label apparatus as set forth in claim 4 further comprising a guide member on said first dancer roller for defining one side of said path of web travel, said guide member being adjustable along the length of the dancer roller to accommodate webs of different widths.

6. Label apparatus as set forth in claim 1 wherein said biasing device comprises a spring device.

7. Label apparatus as set forth in claim 6 wherein said wheel is affixed to a shaft and wherein said spring device comprises a coil spring around said shaft for urging said shaft and wheel in said first direction.

8. Label apparatus as set forth in claim 1 wherein said web pulling device is a label printer operable to print on said labels before the labels are applied to objects.

9. Label apparatus as set forth in claim 1 wherein each of said first and second dancer rollers comprises a tubular roller rotatable on a spindle affixed to the wheel .

10. Label apparatus as set forth in claim 1 further comprising

a rewind reel for winding said web into a roll after the labels have been removed,

a rewind motor for rotating said rewind reel, and

a sensor system for sensing a break in the web at a location between the rewind reel and said label applicator, said sensor system being operable in the event of a break to generate a stop signal to stop the rewind motor from rotating the rewind reel.

11. Label apparatus as set forth in claim 10 wherein said rewind motor is an air motor.

12. Label apparatus as set forth in claim 11 wherein said air motor is operable to apply a rotary driving force to the rewind reel, said driving force having an upper limit at which the air motor stalls, thereby preventing overtensioning of the web as it is wound on the rewind reel.

13. Label apparatus as set forth in claim 12 further comprising a regulator for controlling air pressure to said air motor, said regulator being adjustable to vary the air pressure and thus vary said upper limit at which the air motor stalls.

14. Label apparatus comprising

a supply roll mounting device for rotatably mounting a supply roll of label material of the type comprising a continuous web of liner material having labels removably adhered thereto at intervals along the web,

a label applicator for removing labels from a web of liner material and applying the labels to a series of objects,

a rewind motor for rotating said rewind reel, and

a sensor system for sensing a break in the web at a location between the rewind reel and said label 19 applicator, said sensor system being operable in the event of a break to generate a stop signal to stop the rewind motor from rotating the rewind reel.

15. Label apparatus as set forth in claim 14 wherein said rewind motor is an air motor.

16. Label apparatus as set forth in claim 15 wherein said air motor is operable to apply up to a predetermined maximum rotary driving force to the rewind reel and to stall in the event the tension in the web being rewound reaches an amount sufficient to overcome said predetermined rotary driving force .

17. Label apparatus as set forth in claim 16 further comprising a regulator for controlling air pressure to said air motor, said regulator being adjustable to adjust said predetermined maximum rotary driving force .

18. Label apparatus as set forth in claim 15 wherein said sensor system comprises an optical sensor upstream of said rewind reel .

19. Label apparatus as set forth in claim 18 further comprising a series of guide rollers upstream of the rewind roller for guiding the web along a path adjacent said sensor.

20. Label apparatus as set forth in claim 15 wherein said rewind reel comprises a hollow cylindric hub having an outside diameter in the range of 2-6 inches.

21. Label apparatus as set forth in claim 20 wherein said hub is affixed to a coaxial shaft rotated by said air motor.