US3665844A

US3665844A - Zero rotation sensor for drive assembly idler

Info

Publication number: US3665844A
Application number: US44380A
Authority: US
Inventors: Robert P Clark
Original assignee: Stanley Works
Current assignee: Stanley Works
Priority date: 1970-06-08
Filing date: 1970-06-08
Publication date: 1972-05-30
Anticipated expiration: 1989-05-30

Abstract

Apparatus for use in a material handling machine and including drive means and an idler for maintaining material being driven by the drive means in engagement therewith, the idler being rotatable responsive to movement of the material, and a zero rotation sensor in the idler for detecting when the idler stops rotating for indicating a motionless condition of the material.

Description

O United States Patent 1151 3,665,844

Clark 1 May 30, 1972 54 ZERO ROTATION SENSOR FOR DRIVE 3,215,064 11/1965 140611161 ..100 4 ASSEIVIBLY IDLER 2,134,998 1 1/1938 Cavalcante 2,775,753 12/1956 Kennedy ..340/259 [72] Inventor: Robert P. Clark, Cheshire, Conn. Y

Primary Examiner-Billy J. Wilhite [73] Assignee. The Stanley Works, New Bntam, Conn. Anomw-Prutlman, y Kalb & Chilton [22] Filed: June 8, 1970 [57] ABSTRACT [21] App]. No.: 44,380

Apparatus for use in a material handling machine and including drive means and an idler for maintaining material being [52] US. Cl. ..100/4, 226/1 1, 242/36 driven by the drive means in engagement therewih' the idler [51] Int. Cl ..B65b 13/18 being rotatable responsive to movement f the material and a Field of Search 226/143, 1 zero rotation sensor in the idler for detecting when the idler 100/4 stops rotating for indicating a motionless condition of the material.

[56] References Cited 8 Claims, 3 Drawing Figures UNITED STATES PATENTS 3,130,394 4/1964 l-linz et a] ..340/259 [4 j START SIGNAL L M I 4 I 7/ w H] L gfl 4 1 r- SIGNAL PRESSURE OUT 5'] afiemed ay 30, 1972 2 Sheets-61mm 1 INVENTOR ROBERT F. CLARK ATTORNEYS ZERO ROTATION SENSOR FOR DRIVE ASSEMBLY IDLER FIELD OF THE INVENTION This invention generally relates to machines for handling strap and the like and particularly concerns zero speed sensor devices usable in drive assemblies for such machines.

BACKGROUND OF THE INVENTION While this invention is capable of being used in a wide variety of equipment for handling elongated flexible material such as wire and sheet material, for example, in different applications, this invention has particular utility in strapping machines for tying packages or articles.

Conventional strapping machines automatically provide a predetermined sequence of steps which include looping strap around an article, tensioning the strap, applying a seal to overlapping portions of strap and severing a supply end of the strap. Each-of the foregoingfunctions are normally provided by a single machine, and it is frequently important to minimize the time required for completion of the entire strapping operation- A preset timer often has been used for signaling completion of strap tensioning, and the appropriate time base nor- OBJECTS OF THE INVENTION A primary object of this invention is to provide a zero speed sensor usable with a drive assembly of material handling equipment for detecting when the material being driven has stopped moving.

Another object of this invention is to provide a sensor particularly suited for use in a strapping machine for sensing a taut condition of strap about'an article for significantly reducing the required time cycle without depending upon any timing means even though the machine is used for strapping articles of a wide range of sizes. I

A further object 05 this invention is to provide a sensor of the above-described type which upon detecting proper tensioning of strap about an article may produce an output signal for automatically initiating a succeeding step in a strapping operation.

Other objects will be in part obvious and in part pointed out in more detail hereinafter.

A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth an illustrative embodiment and are indicative of the various ways in which the principle of the invention is employed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view, partly broken away and partly in section, of

DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawings in detail wherein a preferred embodiment of this invention is shown, a drive assembly 10 is shown having a feed roll 12 supported for rotation about a fixed axis on a power operated drive shaft 14 in parallel aligned relation to a stationary shaft 16 suitably secured to a fixed frame 18 and rotatably supporting a back-up or idler subassembly 20. As previously noted, while this invention is capable of a wide variety of uses, it has particular utility with a strapping machine and will be described in connection with such an application. It will be understood that the drive shaft 14 may be power operated in a selected angular direction to rotate the feed roll 12 for withdrawing and tensioning strap, such as that shown at 22, about an article, not shown. The strap 22 is maintained in engagement with the feed roll 12 by the idler subassembly 20 which includes a pressure sleeve 24 supported by conventional roller bearing assemblies 26 for rotation about the shaft 16 responsive to the transmission of motion by the moving strap 22 engaging the pressure sleeve 24.

To immediately produce a signal vwhen the strap 22 is withdrawn to an extent determined by termination of further strap movement responsive to the driving power of the feed roll 12, and to significantly reduce the required time cycle for a strapping operation irrespective of the size of the articles about which the strap 22 is being applied, a zero rotation sensor 30 is incorporated in the idler subassembly 20 of this invention for immediately detecting when the pressure sleeve 24 stops rotating.

Referring more specifically to FIGS. 1 and 2, the sensor 30 includes vent ports 32, 34 which are formed adjacent opposite ends of the stationary shaft 16. The ports 32, 34 are shown for illustrative purposes as extending vertically upwardly from axial compartments 36, 38 in their respective ends of the shaft 16 to open in an upper bearing surface of the shaft 16. The compartments 36, 38 in the shaft 16 are suitably connected through fluid couplings 40, 42 to

vent lines

44, 46 extending to

junctures

48, 50 which are respectively connected through fluid lines 52, 54 to valve actuators 56, 58 and to a supply line 60 which will be understood to be connected to a source of pressurized fluid such as air which is made available during a strap take-up or tensioning step of the strapping operation.

The

junctures

48, 50 are also connected with the source of air through suitable line restrictions 62, 64 leading to a common inlet passage 66 from the supply line 60 which in turn is shown connected through valve supply lines 68, 70 to supply ports 72, 74 in

control valves

76, 78. The

control valves

76, 78 are respectively operated by the valve actuators 56, 58 against the bias of springs 80,82 and are shown (schematically with USA Standard fluid power graphic symbols) as being twoposition, three-way pneumatic valves. Upon being operated, each

valve

76 and 78 will act to apply supply line pressure to a suitable double-acting check valve 84 to produce an output signal pressure.

The pressure sleeve 24 carries a pair of

end plates

86, 88 having inner annular surfaces such as at 90 in circumferentially surrounding relation to the shaft 16. To maintain the fluid circuit in a nonsignaling condition during strap tensioning, the sensor 30 further includes a plurality of spaced apart ports or exhaust openings 92, 94 and 96, 98 formed in the annular surface of

end plates

86 and 88 for confronting registration with their respective .vent ports 32 and 34. Upon rotation, the pressure sleeve 24 thus acts to exhaust the

vent lines

44, 46 to atmosphere and prevent back pressure build-up in the fluid lines 52, 54 leading to the

control valves

76, 78. To ensure that one of the vent ports 32, 34 is always covered by one of the

end plates

86, 88 to produce an output signal when the sleeve 24 stops rotating, the exhaust openings 92, 94 and 96, 98 in each of the

end plates

86 and 88 are shown suitably dimensioned relative to the vent ports 32 and 34 and arranged in diametrically opposed relation to one another and in 90 offset angular relation to the openings in the other end plate.

When the strap 22 is sufficiently tightened about an article and the feed roll 12 is no longer capable of withdrawing further strap, the pressure sleeve 24 will stop rotating and the air pressure in the

vent lines

44, 46 corresponding to that vent port 32, 34 covered by its

end plate

86, 88 will increase to a sufficient level to activate the valve actuator 56, 58 of its

respective control valve

76, 78. The activated valve is then operated against its spring bias to connect its supply port (72 or 74) to the check valve 84 whereupon line pressure is applied to produce an output signal indicative of the tensioned condition of the strap.

In the specific illustrated embodiment, one or both vent ports 32, 34 may simultaneously be in nonaligned relation to its respective exhaust openings 92, 94 and 96, 98, at any given time, it having been found that, with proper design and dimensioning of the flow passages and orifices, alternate intermittent venting of the fluid lines 52, 54 during rotation of the sleeve 24 will provide sufficient pressure relief to prevent inadvertent operation of the

control valves

76, 78. Should both

control valves

76, 78 be simultaneously operated upon stopping rotation of the pressure sleeve 24, sufficient air flow-is assured through the check valve 84 to produce an effective signal pressure output.

vThe signal emitted by the above-described control circuit may be utilized in a variety of ways depending on the application with which this invention is intended to be utilized. In the above-described application, for example, the output signal may be applied to actuate a high torque motor (not shown) to apply even greater tensioning to the strap 22 or, if desired, to initiate a subsequent sealing and shearing step in the strapping operation.

In FIG. 3, another control circuit is schematically illustrated, it being understood that the drive assembly is identical to that described in FIGS. 1 and 2 and that identical reference numerals are used to identify like parts of the drive assembly and control circuit of FIG. 3. The

vent lines

44, 46 are connected via lines 60, 66 to a source of air providing a start signal available during the take-up portion of the cycle and to opposite sides of a double-acting check valve 100 having an outlet passage 102 connected to a pilot actuator 104 for a two-position, four-way, five-ported pneumatic signal control valve 106. The valve 106 includes one blocked port 108, two

.exhaust ports 110, 112, and a service port 114 which, upon operation of the valve 106, communicates with a supply port 116 connected to a constant air supply line 118 for emitting output signal pressures.

During strap take-up, start signal pressure is applied through supply line 60 to the opposite ends of the shaft 16 supporting the pressure sleeve 24, as described in connection with FIGS. 1 and 2, and also to a pilot operator 120 of a springreturned, two-position, three-way, ON/OFF reset valve 122 for disconnecting its supply port 124 to the constant air supply line 118 for relieving an air pressure bias applied to valve 106 via line 126. It will be understood that air pressure is normally supplied to pilot actuator 128 to reset the valve 106 to an inoperative position, and that valve 106 is biased by any suitable means such as a spring detent, not shown, to nonsignaling ready condition during strap take-up.

With the pressure sleeve 24 continuously rotating to permit air to be discharged to atmosphere through the vent ports 32, 34 and exhaust openings in the idler subassembly 20, it will be understood that any air pressure transmitted through the check valve 100 is insufficient to overcome the bias imposed on the valve 106. Once the strap stops moving, causing the pressure sleeve 24 to stop rotating, the

end plates

86, 88 of the pressure sleeve 24 will cover one of the vent ports 32, 34 in the shaft l6'to obstruct discharge of the air through its

vent line

44, 46 whereupon back pressure will increase to a sufficiently high level in its respective valve supply line 52, 54 leading to the check valve 100 to actuate the pilot operator 104 and overcome the opposing bias to operate the signal control valve 106. Upon being operated, the signal control valve 106 immediately connects the air supply line 118 to the output service port 114 to signal completion of the strap tensioning.

As in the previously described embodiment, a subsequent step in the automatic operation of the strapping machine may be actuated by means ofthe output signal pressure from port 114 to complete the strapping operation.

A zero rotation sensor constructed in accordance with this invention may be utilized in a variety of applications to pro- -vide a significant reduction in the required time cycle to minimize interruption of a material handling operation. The

use of this invention in a strapping machine application not only immediately detects completion of strap tensioning regardless of the size of the article being tied, but also produces an output signal which may be desirably used to actuate another component of the machine in a continued automatic sequence of steps.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

ICLAIM:

1. Driving and sensing apparatus for detecting a motionless condition of strap material and the like being driven thereby and comprising drive means for driving the material along a path, a rotary idler engageable with the material for maintaining it in driving engagement with the drive means, the idler being rotatable responsive to the transmission of motion thereto by the material being driven by the drive means, a fluid circuit, and a pressure actuated sensor including means for selectively venting the fluid circuit operable in response to the idler being stopped when the movement of the material is terminated for varying the fluid pressure in the fluid circuit and actuating the sensor to produce a signal indicative of the motionless condition of the material.

2. Driving and sensing apparatus for detecting a motionless condition of strap material and the like being driven thereby and comprising drive means for driving the material along a path, a rotary idler engageable with the material for maintaining it in driving engagement with the drive means, the idler being rotatable responsive to the transmission of motion thereto by thematerial being driven by the drive means, a sensor operable in response to the idler being stopped when the movement of the material is terminated for producing a signal indicative of the motionless condition of the material, the sensor including fluid porting means carried by the idler, and a fluid circuit including fluid operated signal control means and passage means for supplying fluid under pressure, the passage means being connected between the signal control means and the idler porting means, the idler porting means being registrable with the fluid passage means and automatically assuming a predetermined flow control position in relation to the fluid pusage means when the idler is stopped to cause a change in fluid pressure in the passage means for activating the signal control means.

3. The apparatus of claim 2 wherein a stationary shaft is provided for supporting the idler for rotation, wherein the fluid passage means includes vent potting means formed in he stationary idler shaft, and wherein the idler porting means includes a plurality of exhaust openings circumferentially arranged about the idler shaft for communication with the vent porting means during rotation of the idler, the idler being in obstructing relation to the vent porting means upon termination of idler movement, causing pressure build-up in the fluid passage means for activating the signal control means.

4. The apparatus of claim 2 wherein said predetermined flow control position of the idler porting means is in at least partially blocked relation to the passage means to effect pressure build-up therein for activating the signal control means when the idler is stopped.

5. Driving and sensing apparatus for detecting a motionless condition of strap material and the like being driven thereby and comprising drive means for driving the material along a path, a rotary idler engageable with the material for maintaining it in driving engagement with the drive means, a stationary shaft for rotatably supporting the idler, the idler being rotatable responsive to the transmission of motion thereto by the material being driven by the drive means, a sensor operable in response to the idler being stopped when the movement of the material is terminated for producing a signal indicative of the motionless condition of the material, the sensor including first shaft, and fluid operated signal control means communicating with the first fluid porting means in the shaft, said first and second fluid porting means being registrable for exhausting fluid from the first fluid porting means during rotation of the idler and being in nonaligned relation when the idler stops rotating for effecting an increase in fluid pressure to operate the signal control means.

6. The apparatus of claim 5 wherein the idler includes an annular surface surrounding the stationary shaft, wherein said first fluid porting means formed in the stationary shaft is in confronting relation to the annular surface of the idler, and wherein the annular surface includes a plurality of spaced apart exhaust openings constituting said second fluid porting means.

7. Driving and sensing apparatus for detecting a motionless condition of flexible strap of binding an article and comprising a powered feed roll rotatable about a fixed axis for driving the strap along a path and tensioning the strap about the article, a rotary idler engageable with the strap for maintaining it in driving engagement with the feed roll, a stationary shaft, the idler being rotatable on the stationary shaft responsive to the transmission of motion to the idler by the strap being driven by the feed roll, a sensor operable in response to the idler being stopped when the movement of the strap is terminated for producing a signal indicative of the motionless condition of the strap, the sensor including vent porting means formed in one of the shaft and idler members and exhaust openings formed in the other of the shaft and idler members for registering with the vent porting means, and a pneumatic circuit including signal control means and passage means for supplying air under pressure, the passage means being connected between the signal control means and the vent porting means, the venting porting means in said one member communicating with the exhaust openings in the other member during rotation of the idler to prevent air pressure build-up in the passage means during strap tensioning, the vent porting means being at least partially blocked by said other member when the idler stops rotating to cause pressure build-up in the passage means for activating the signal control means".

8. Apparatus usable in a strapping machine for tightening flexible strap about an article and comprising powered drive means for tensioning strap about the article, a freely rotatable idler engageable with the strap for maintaining it in engagement with the drive means and rotatable responsive to movement of the strap during tensioning, and a fluid circuit including fluid operated signal control means, a source of pressurized fluid and passage means in communication therewith, the passage means having vent porting means mounted adjacent the idler and connected to the signal control means, the idler having exhaust porting means carried thereon registrable with the vent porting means, and the exhaust porting means automatically assuming a predetermined flow control position in relation to the vent porting means when the idler stops rotating to cause a change in fluid pressure in the passage means for activating the signal control means for indicating a predetermined tensioning of the strap.

Claims

2. Driving and sensing apparatus for detecting a motionless condition of strap material and the like being driven thereby and comprising drive means for driving the material along a path, a rotary idler engageable with the material for maintaining it in driving engagement with the drive means, the idler being rotatable responsive to the transmission of motion thereto by the material being driven by the drive means, a sensor operable in response to the idler being stopped when the movement of the material is terminated for producing a signal indicative of the motionless condition of the material, the sensor including fluid porting means carried by the idler, and a fluid circuit including fluid operated signal control means and passage means for supplying fluid under pressure, the passage means being connected between the signal control means and the idler porting means, the idler porting means being registrable with the fluid passage means and automatically assuming a predetermined flow control position in relation to the fluid passage means when the idler is stopped to cause a change in fluid pressure in the passage means for activating the signal control means.

3. The apparatus of claim 2 wherein a stationary shaft is provided for supporting the idler for rotation, wherein the fluid passage means includes vent porting means formed in he stationary idler shaft, and wherein the idler porting means includes a plurality of exhaust openings circumferentially arranged about the idler shaft for communication with the vent porting means during rotation of the idler, the idler being in obstructing relation To the vent porting means upon termination of idler movement, causing pressure build-up in the fluid passage means for activating the signal control means.

5. Driving and sensing apparatus for detecting a motionless condition of strap material and the like being driven thereby and comprising drive means for driving the material along a path, a rotary idler engageable with the material for maintaining it in driving engagement with the drive means, a stationary shaft for rotatably supporting the idler, the idler being rotatable responsive to the transmission of motion thereto by the material being driven by the drive means, a sensor operable in response to the idler being stopped when the movement of the material is terminated for producing a signal indicative of the motionless condition of the material, the sensor including first and second fluid porting means respectively formed in the stationary shaft and the idler, fluid passage means for supplying fluid under pressure to the first fluid porting means in the shaft, and fluid operated signal control means communicating with the first fluid porting means in the shaft, said first and second fluid porting means being registrable for exhausting fluid from the first fluid porting means during rotation of the idler and being in nonaligned relation when the idler stops rotating for effecting an increase in fluid pressure to operate the signal control means.

7. Driving and sensing apparatus for detecting a motionless condition of flexible strap of binding an article and comprising a powered feed roll rotatable about a fixed axis for driving the strap along a path and tensioning the strap about the article, a rotary idler engageable with the strap for maintaining it in driving engagement with the feed roll, a stationary shaft, the idler being rotatable on the stationary shaft responsive to the transmission of motion to the idler by the strap being driven by the feed roll, a sensor operable in response to the idler being stopped when the movement of the strap is terminated for producing a signal indicative of the motionless condition of the strap, the sensor including vent porting means formed in one of the shaft and idler members and exhaust openings formed in the other of the shaft and idler members for registering with the vent porting means, and a pneumatic circuit including signal control means and passage means for supplying air under pressure, the passage means being connected between the signal control means and the vent porting means, the venting porting means in said one member communicating with the exhaust openings in the other member during rotation of the idler to prevent air pressure build-up in the passage means during strap tensioning, the vent porting means being at least partially blocked by said other member when the idler stops rotating to cause pressure build-up in the passage means for activating the signal control means--.