US2916801A

US2916801A - Machine control means including work feed programming means

Info

Publication number: US2916801A
Application number: US685032A
Authority: US
Inventors: Lyttle James Cameron
Original assignee: TORONTO TYPE FOUNDRY
Current assignee: TORONTO TYPE FOUNDRY
Priority date: 1957-09-19
Filing date: 1957-09-19
Publication date: 1959-12-15
Anticipated expiration: 1976-12-15

Description

2,916,801 IIACHINE CONTROL MEANS INCLUDING WORK FEED PROGRAIIIING MEANS FilOd 56M. 19, 1957 J. C. LYTTLE Dec. 15, 1959 2 Sheets-Sheet 1 INYENmR MES CAMERON LYTTLE er: 4% a ATTOMEYS J. C- LYTTLE Dec. 15, 1959 MACHINE CONTROL MEANS INCLUDING WORK FEED PROGRAMMING MEANS 2 Sheets-Sheet 2 Filed Sept. 19, 1957 IN VENTUR JAMES CAMERON LYTTLE DY: ATTOIWEYS United States Patent MACHINE CONTROL MEANS INCLUDING WORK FEED PROGRAMMING MEANS James Cameron Lyttle, Scarborough Township, Ontario, Canada, assignor to Toronto Type Foundry, Toronto, v Canada, a corporation Application September 19, 1957, Serial No. 685,032

Claims. (Cl. 29--93) This invention relates to apparatus comprising two members and means to control the movement of one of the members relatively to the other member. The invention is particularly applicable to paper cutting machines in relation towhich it will be specifically described, but the invention may also be applied to other apparatus in which two members are movable relatively to one another and it is desired to control the relative movements of the members in a predetermined manner.

Paper cutters as used in the printing trade include a table, a back gauge movable relatively to the table and a cutter blade to cut through a stack of paper supported upon the table against the back gauge. The back gauge is movable along thetable by traversing means so as to be capable of positioning a stack of paper under the cutter blade. Such paper cutters are used to cut large sheets of paper into smaller sheets of specific sizes. Sometimes the large paper sheets are cut to a predetermined size and sometimes the cutting is effected along lines marked on the paper; in either case it is often necessary that the paper be cut to size within very close tolerances.

Various constructions for setting the position of back gauges on paper cutters are already known. In one known construction the back gauge is moved along the table by manually operated screw means and a graduated flexible metallic tape is connected to the back gauge and runs around fore and aft pulleys so that the position of the back gauge on the table may be read off the tape by the operator. After a period of use the tape may stretch and render the setting of the back gauge inaccurate so that cutting to close tolerances becomes impossible.

Moreover foreign matter may accumulate on the pulleys,

thus introducing errors, and the attachment of the tape to the back gauge may not remain rigid after prolonged use.

In another known construction for operating the back gauge, the gauge is moved by a flexible graduated tape, the tape itself providing the traction element. The disadvantages of this construction are the same as the disadvantages of the first construction, in addition the tape may slip and alter its position relative to the back gauge, thus introducing further inaccuracy.

Furthermore, it is sometimes required to set up a definite programme of movements to be followed by the back gauge. For example, it may be required that the cutter blade shall make a first cut with the back gauge three feet behind the cutter blade, a second cut when the back gauge is two feet behind the cutter blade and a third cut when the back gauge is one foot behind the cutter blade. Various methods of setting up such a programme mechanically are known.

For example, one method of mechanical setting employs a cam wheel having a circumferential graduated tape and stops which may be adjusted in position around the periphery, of the wheel and which operate limit switches to start and stop an electric motor driving the traversing means of the back gauge. A very experienced operator is required to set up such an arrangement since there may be varying discrepancies between the scale on.

2,916,801 Patented Dec. 15, 1959 the cam wheel and the scale against which the position of the back gauge is read. Moreover the physical difiiculty of setting the stops accurately is considerable. Moreover, not only is an experienced operator required to set up such a machine, but the setting up time is considerable so that it is only economical when a large number of runs each requiring to be cut at the same positions is contemplated.

It has also been proposed to control the back gauge of a paper cutting machine by means of an optical system using a photo-electric cell and a strip bearing optical signals. A mechanical linkage is provided between the photo-electric cell and back gauge to efiect traversing movement of the photo-electric cell across the strip in dependence on the movement of the back gauge. This mechanical linkage wears after a period of use and causes inaccuracies.

It will be appreciated that similar difiiculties arise in automatic and semi-automatic machinery in which one member is moved relatively to another member along a predetermined path by traversing means and in which it is desired to cause the movable member to follow a particular sequence of movements relatively to the other member.

It has previously been proposed for machine tools to record a particular programme of events onto a magnetic tape and then to run the magnetic tape through a reproducing device to reproduce the events recorded on the tape in the machine tool. One disadvantage of such an arrangement is that relatively complicated means have to be provided for driving and reversing the tape. Another disadvantage is that, since the tape is not fixed relatively to any part of the tool, difficulties arise in synchronizing the programme on the tape with the positions of the parts of the machine tool. Moreover, once a pro gramme has been recorded on the tape it is a comparatively lengthy operation to erase the programme and to record another programme and it is not possible, during the operation of the machine, easily to erase a single signal from the tape at a particular point and to substitute another signal.

It is an object of the present invention to provide apparatus having two members movable relatively to one another and means to traverse one of the members relatively to the other with a simple and versatile means for operating controls for the traversing means according to a predetermined but easily variable programme and in such a manner that mechanical linkages between the members and the means for operating the controls are reduced to a minimum to avoid inaccuracies due to mechanical wear.

It is also an object of the invention to provide a paper cutter having a table and a back gauge movable along the table, traversing means to move the back gauge and means to control the back gauge in its movements so that it may be caused to follow a predetermined programme which may be quickly changed or amended, the control means including a minimum of mechanical linkages to avoid inaccuracies consequent upon mechanical wear.

According to one aspect of the invention, apparatus comprises a first member, a guideway on the first member, a second member movable relatively to the first member in said guideway, a signal track of material capable of having electromagnetic signals erasably recorded thereon, the signal track extending longitudinally in a direction parallel to the direction of movement of the second member relatively to the first member and being mounted on the first member to be stationary relatively thereto, a support mounted on the second member, the support moving along a path adjacent to the signal track as the second member moves in the guideway, a recording and receiving head assembly mounted on the support, said assembly being energizable to record electromagnetic signals on the track and being capable of receiving electromagnetic signals which may have been recorded on the track, means for energizing said assembly to record signals on the track, structure for traversing the second member along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received by the recording and receiving head assembly from the signal track to operate the controls, and a selector operable to render one of said first and second means eifective to operate the controls.

According to the second aspect of the invention, a paper cutter includes a table, a guideway on the table, a back gauge movable relatively to the table in said guideway, a signal track of material capable of having electromagnetic signals erasably recorded thereon, the signal track extending longitudinally in a direction parallel to the direction of movement of the back gauge relatively to the table and being mounted on the table to be stationary relatively thereto, a support mounted on the back gauge, the support moving along a path adjacent to the signal track as the back gauge moves in the guideway, a recording and receiving head assembly mounted on the support, said assembly being energizable to record electromagnetic signals on the track and being capable of receiving electromagnetic signals Which may have been recorded on the track, means for energizing said assembly to record signals on the track, structure for traversing the back gauge along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received by the receiving and recording head assembly from the signal track to operate the controls, and a selector operable to render one of said means effective to operate the controls.

The invention will be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic perspective view of a paper cutter according to the invention, and

Figures 2, 3 and 4 are block diagrams showing the electric controls of the paper cutter of Figure 1.

Referring now to Figure l, the paper cutter comprises a horizontal table having a bridge structure 11 which carries a cutter blade 12. The cutter blade is carried by a channel member 13 the ends of which slide in grooves 14 in the pillars of the bridge structure 11.

A clamp 15 slides in grooves 16 in the bridge structure 11 and in Figure l is shown in its lower position Where it grips a stack of paper 17 on the table 10. Both the cutter blade 12 and the clamp 15 are operated by a motor 18 driving an eccentric gear 19 which is connected to the clamp 15 and to the channel member 13. The motor 18 drives the eccentric gear 19 through an electromagnetic clutch 20.

The eccentric gear 19 is so arranged that, upon rotation of the motor 18, the clamp 15 descends to grip the paper on the table, then the cutter blade 12 descends to cut the paper, then the cutter blade rises and the clamp 15 rises and releases the paper. A wooden strip 21 is provided across the table 10 to act as a lower abutment for the cutter blade after it has cut through a stack of paper.

A back gauge is indicated at 22 and has a serrated forward surface 23. The back gauge moves in guideways 24 in the table 10 and is threadably engaged by a lead screw 25 arranged under the table 10 and driven by a motor 26 through a clutch-brake (not shown in Figure 1). A horizontal bar 27 of non-magnetic material is supported at its forward end by the bridge member 11 and at its rear end by an abutment 28 fixed to the table. The bar 27 is provided with a longitudinal transparent graduated scale 29 and also with two

magnetic tapes

30 and 31 on its underside, one on each side of the scale 29.

The bar 27 is stationary relatively to the table 10, that is to say, the bar does not move relatively to the table during normal operation of the machine although it may of course be unbolted from the machine and dismounted for disassembly or servicing purposes.

Upstanding from the top surface of the back gauge is a pillar 32 which is slotted to give passage to the bar 27 and is provided at its upper end with a translucent screen 33 having a cross-line 34. An optical system (not shown) projects an image of the graduated scale 29 onto the screen 33 so that an operator standing at the front of the machine can read off the position of the back gauge, indicated by the cross-line 34, on the image of the scale 29 on the screen 33.

Mounted on the rear of the pillar 32 and beneath the bar 27 is a support 35 which carries seven combined recording and receiving heads, each head being capable of recording, receiving or erasing a signal on one of the tapes 30, 31'. The

magnetic tapes

30, 31 provide seven signal tracks in all and each head is associated with and located under one of the signal tracks.

Manually operable means for controlling the machine are grouped on a control panel 10a at the front of the table 11) and consist of two

pushbutton switches

37, 38 spaced at opposite ends of the control panel'and arranged to operate the motor 18 as will be described more fully hereinafter. Push button 39 is a start button for the motor 18 and push button 40 is a stop button for the motor 13. A first selector 41 has four positions which will be described more fully hereinafter, the positions being, space, off, mark, and erase.

A push button 42 controls the forward movement of the back gauge, that is towards the cutter blade, and a push button 43 controls the reverse movement of the back gauge. A push button 44 is provided for energizing an oscillator to record signals on the tapes 3%, 31 and a second selector 45 is provided to select which of the seven heads shall be in circuit. A two-position switch 46 is also provided, in one of the positions of the switch 46, the cutter blade is operated manually by the

push buttons

37, 38, and in the other position of the switch the cutter blade is operated in dependence on signals received from the

tapes

30, 31.

The controls of the paper cutter will now be described with reference to Figures 2, 3 and 4. The numeral 47 is used to designate a conventional tape recorder which includes the oscillator operated by the switch 44, but does not include the normal tape transport mechanism. The output of the tape recorder is connected to a control contactor 48 having a pair of contacts 48a which are open when the contactor is de-energized and two pairs of

contacts

48b and 48c which are closed when the contactor is de-energized. The output of the tape rccorder 47 is connected to the control contactor 48 when the first selector 41, is in its space position through a switch 41c forming part of the selector 41, the switch 41c otherwise remaining open. When the selector 41. is in this position, the input to the tape recorder is from one of the heads carried by the support 35, the particular head being selected by the second selector 45. in Figure 2 the heads are indicated diagrammatically at 49, 50, 51, 52, 53, 54 and 55 and are connected by a cable 56 to the fixed contacts 49a, 50a, 51a, 52a, 53a, 54a and 55a respectively of the second selector 45.

The heads are mounted on the support 35 so that each head underlies one of the seven signal tracks provided by the

tapes

30, 31. The heads are slidable relatively to the support 35 and are normally urged against

stops

57, 58 by tension springs 59. A solenoid 60 has its movable armature connected to the rearward end of the heads and is operable to draw the heads rearwardly against

stops

61, 62. When the solenoid is de-energized, the springs 59 pull the heads forwardly against the

stops

57, 58.

A line 63 leads through the switch 40, the switch 39 and a contactor 65. Power is applied to the motor 18 along

lines

66, 67 and 68 through contacts a, 65b and and 650 of the contactor 65. A fourth pair of contacts 65d of the contactor 65 is connected in parallel with the switch 39, the pair of contacts being normally in open position as shown. To start the main motor 18, the switch 39 is depressed thus allowing current to flow through the contactor 65. When the contactor 65 becomes energized, the pairs of

contacts

65a, 65b, 65c and 65d close, thus starting the motor 18 and also, in the case of the contacts 65d, allowing current to continue to fiow through the contactor 65 thereby holding the contactor energized and the motor on after the switch 39 has been released. To stop the motor 18, the switch 40 is depressed, thus opening the line 63, interrupting the current flowing through contactor 65 and therefore opening the pairs of

contacts

65a, 65b, 65c and 65d.

The motor 18 drives the cutter blade 12 and the clamp 15 through the electromagnetic clutch 20 which is controlled by a contactor 69 having a pair of contacts 69a which are open when the contactor is de-energized. To energize the clutch 20, the

switches

37, 38 have to be pressed simultaneously to allow current to flow along a line 70 through the contactor 69 which is thereby energized and closes the pair of contacts 69a thus allowing power to be fed to the clutch along

lines

71 and 72. The contactor 69 will only be energized so long as both

switches

37, 38 are held depressed and the switches are spaced apart on the control panel so that the operator will have to use both hands to press them both, thereby ensuring that as the cutter blade descends the operators hands are not underneath it.

A line 73 is connected in parallel with the switches .37, 38 and is connected to the line 70 on the switch side of the contactor 69. In the line 73 is the switch 46, a pair of normally open contacts 48a of the control contactor 48, and a switch 41a forming part of the first selector 41 and which is open except when the selector 41 is in its space position. Also connected in parallel with the

switches

37, 38 is a further line 74 containing a limit switch 75. The limit switch 75 is normally open but, as the cutter blade reaches a point near the bottom of its stroke it closes the limit switch 75 so allowing the

switches

37, 38 to be released without de-energizing the contactor 69. The cutter blade and clamp will then return to their uppermost positions automatically. As the cutter blade approaches its uppermost position it will open the limit switch 75 thereby de-energizing the contactor 69 thus opening the pair of contacts 69a, de-energizing the clutch 20 and dis connecting the eccentric gear 19 from the motor 18.

The reverse motion of the back gauge is controlled by the switch 43. A ,line 76 leads through the switch 43, one part of a ganged switch 42, a limit switch 77 and a contactor 78. The contactor 78 has six pairs of

contacts

78a, 78b, 78c, 78d, 78c and 78g, all of which are open when the contactor is de-energized, and a seventh pair of contacts 78 which are closed. A line 79 is connected in parallel with the switch 43 and contains the pair of contacts 78d and the pair of contacts 48b of the control contactor 48.

The part of the switch 42 that is in the line 76 is normally closed and to start the motor 26 in a reverse direction the switch 43 is closed allowing current to flow along the line 76 to energize the contactor 78 which will close the

contacts

78a, 78b, 78c, 78d, 78:: and 78g and will open the contacts 78 The closing of the

contacts

78a, 78b and 780 allows current to flow along the

lines

80, 81 and 82 to the motor 26 which then rotates in a direction such as to move the back gauge away from the cutter blade. The pair of contacts 780! acts to maintain the current through the contactor 78 when switch 43 has been released and therefore to keep the back gauge motor running in the reverse direction.

The control for the back gauge motor in the forward direction is along a line 83 through the other part of switch 42, a limit switch 84 and a contactor 85 having five sets of

contacts

85a, 85b, 85c, 85d and 85e, all of which are in the open position when the contactor is de-energized. When the switch 42 is operated it closes the line 83 allowing current to flow through the limit switch 84 and the contactor thus closing the pairs of

contacts

85a, 85b, 85c, 85d and 85a. The

contacts

85a, 85b and 85c when closed permit current to flow along the

lines

80, 81 and 82 to the motor 26. It will be seen from Figure 4 that the arrangement of the

contacts

78a, 78b, 780, 85a, 85b and 850 is such that when the contactor 78 is energized the phase sequence of the

lines

80, 81 and 82 is reversed relatively to the motor 26 compared with the phase sequence of the lines when the contactor 85 is energized. This arrangement allows the motor 26 to be rotated in either direction, the direction depending upon which set of contacts is closed.

it will be noted that as the switch 42 is operated it opens the line 76 thereby ensuring that the motor 26 shall not be energized to move in a reverse direction and a forward direction at the same time. The pair of contacts 85a is in a line 86 which also contains the pair of contacts 480 of the control contactor 48 and a switch 41b which forms part of the first selector 41. The switch 41b is open except when the selector 41 is in the space position and thus the contacts 85d, which operate to hold the contactor 85 energized, will only operate when the selector 41 is in the space position.

The limit switch 77 is a reverse limit switch which opens the line 76 when the back gauge reaches the end of its travel in a rearward direction. The limit switch 84 is a forward limit switch and opens the ,line 83 when the back gauge reaches the limit of its forward travel. In both cases opening of the limit switch prevents the back gauge from moving further since the

relevant contactor

78 or 85 is de-energized and the power supply to the motor 26 is cut off. A further limit switch 87 is located in a line 88 and is connected in parallel with the pair of contacts 85d. The limit switch 87 is momentarily closed and then reopened by the cutter blade as it approaches the top of its travel after having descended to cut through a stack of paper.

The motor 26 operates the back gauge through an electromagnetic clutch-brake 89 connected to the lead screw 25. In its deenergized position the clutch-brake 89 acts as a brake and prevents the back gauge from moving. When the clutch-brake is energized it acts as a clutch transmitting rotation of the motor 26 to the lead screw 25 and hence to the back gauge 22. The clutch-brake 89 is controlled by a contactor 90 which is in a line 91. Also in the line 91 is'the pair of contacts 85c of the contactor 85 which are connected in parallel with the pair of contacts 78e in a line 92. The contactor 90 has a pair of contacts 90a in the line 94 of two

lines

93, 94 which are connected to the clutch-brake 89. When either of the

contactors

78 or 85 is energized the contacts 78e or 85c will close thus energizing the contactor 90, closing the contacts 9041 thus energizing the clutch-brake 89 and allowing the rotation of the motor 26 to be transmitted to the back gauge.

The solenoid 60 is operated by closing the switch 44 thus allowing current to flow along a line 95 and energize a contactor 96 having a pair of contacts 96a. The contacts 96a are in a line 97 of two

lines

97, 98 leading to the solenoid and as the contacts are closed, the solenoid 60 is energized and moves the heads 49 to 55 rearwardly against the

stops

61 and 62.

When the first selector 41 is in the space position the switches 41a, 41b and 410 are closed, the output of the tape recorder 47 is connected to the control contactor 48 and the heads 49 to 55 are connected through the second selector 45 and the

contacts

78f or 78g to the input of the tape recorder 47 so that a signal received from a head will be amplified by the tape recorder 47 and will energize the control contactor 48. Between the movable terminal of the second selector 45 and the tape recorder 47 is the pair of contacts 7 81 of the contactor 78, the contacts being in a closed position when the contactor is de energized. Connected to the fixed terminal 55a of the second selector 45 is the pair of contacts 78g of the contactor 78 which are open when the contactor is deenergized. The pair of contacts 78g is in parallel with the contacts 78 so that when the contacts 78 are closed the input to the tape recorder 47 is through the movable part of the selector 45 whereas when the contacts 78g are closed the contacts 78 will be opened and the input to the tape recorder is through the pair of contacts 7 8g.

When the first selector 41 is in one of the off, mark or erase positions the switches 41a, 41b and 41c are open as shown in Figure 2. In the off position the tape recorder 47 is not operative. In the mark position, operation of the switch 44 besides operating the solenoid 60, also, after a delay to enable the solenoid to move the heads, operates the oscillator in the tape recorder 47. The signal from the oscillator is fed into the head which is connected to the tape recorder, either through the movable arm of the selector 45 or through the pair of contacts 78g. In the erase position, the oscillator in the tape recorder is energized to produce an erase signal which is continuously fed out to the particular head which is connected to the tape recorder via the movable arm of the selector 45 or the pair of contacts 78g.

The terminals of a three phase power Supply are indicated at L1, L2 and L3. As shown in Figure 2, one end of each of the

lines

63, 70, 73, 74, 76, 79, 83, 86, 88, 91, 92 and 95 is connected to L1 as is one side of the power'input for the tape recorder 47. The other ends of the

lines

63, 70, 73, 74, 76, 79, 83, 86, 88, 91, 92 and 95 are connected to the line L2 as is the other side of the power input for the tape recorder 47. A return line 99 for the

heads

49, 50, 51, 52, 53, 54 and 55 also is connected to L2, as shown in Figure 2.

The

lines

66, 71, 80, 93 and 97 are connected to L1, while the lines 67 and 81 are connected to L2. The

lines

68, 72, 82, 94 and 98 are connected to L3.

The operation of the paper cutter is as follows. Let it be assumed that there are no signals on the tapes 3!), 31, that the back gauge is at the rear extremity of its travel and that the controls are in the positions shown in Figures 2, 3 and 4. programme for the back gauge whereby once the programme has been set up the back gauge may be started to move forward and will thereafter cut at predetermined points until it reaches the front extremity of its travel.

To set up the programme the first selector 41 is switched to the mark position. The switch 42 is depressed, current is fed along the line 83 to energize the contactor 85 and to close the five sets of

contacts

85a, 85b, 85c, 85d and 85:2. The contacts 85a, 85b and 850 upon closing will supply power to the motor 26 which will begin to rotate. As the pair of contacts 85e closes the contactor 90 will be energized thereby closing the pair of contacts 90a and energizing the electromagnetic clutch-brake 89. The clutch-brake then acts as a clutch and transmits the rotation of the motor 26 to the back gauge. Since the first selector 41 is in the mark position, the switch 41b will be open and therefore the contacts 85d will be nonoperative to hold the contactor 85 energized. When the back gauge approaches the desired position, as indicated by the reading of the cross-line 34 against the projection of the scale 29 on the screen 33, the switch 42 is released. The back gauge then comes to rest since the contactor 85 is de-energized thereby opening all the

contacts

85a, 85b, 85c, 85d and 85:2, stopping the motor 26 and de-energizing the contactor 90 and hence the electromagnetic clutchbrake 89 which then acts as a brake and brings the back gauge to a standstill.

To record a mark on one of the

tapes

30, 31, the switch 44 is depressed thus energizing the contactor 96, closing the contacts 96a, operating the solenoid 60 to draw the It is now desired to set up a cutting heads rearwardly and then causing the oscillator in the tape recorder 47 to generate a signal which is passed through the second selector to the particular head connected by the selector to the tape recorder. It will be appreciated that any of the heads 49 to and therefore any one of the seven signal tracks may be selected by the selector 45 to have a signal recorder thereon. As will be seen hereafter, only the head 55 is in circuit to feed into the tape recorder when the contactor 78 is energized, although the head 55 may be connected to the oscillator through the selector 45 in the same manner as the other heads and without the contactor 78 being energized.

The switch 42 is then depressed to start the back gauge moving forward again and is released when it is desired to record another signal on the tape. The sequence is repeated until all the desired signals have been set up on the tape by which time the back gauge will be near to the front of its travel. To cause the back gauge to return to the rear of the table, the switch 43 is depressed thus energizing the contactor 78 and closing all the pairs of contacts of that contactor. Closure of the pair of contacts 78d will hold the contactor 78 energized and closure of the pairs of

contacts

78a, 78b and 780 will cause the motor 26 to rotate in the reverse direction. Closure of the pair of contacts 78c energizes the contactor 90 thus closing the pair of contacts 90a and energizing the electromagnetic clutch-brake 89 so that it acts as a clutch. The pair of contacts 78 will open, thus disconnecting the movable member of the second selector 45 from the tape recorder, and the pair of contacts 78g will close thus connecting the head 55 to the tape recorder.

If it is desired to record signals on a signal track so that the back gauge will stop at a desired position when reversing, the switch 42 is depressed momentarily at the desired spot thus breaking the circuit through the contactor 78 and opening all the contacts associated therewith. The second selector is then operated so that its movable arm is against the contact 5512. Depression of the switch 44 will then energize the contactor 96. close the pair of contacts 96a to energize the solenoid which will move the heads rearwardly against the

stops

61 and 62, after the solenoid has operated, the oscillator in the tape recorder 47 provides a signal which is fed out through the closed contacts 78 and the contact 55a to the head 55 and will record a signal on the signal track associated with the head.

The back gauge is restarted in its rearward movement by pressing the switch 43 and the marking sequence is repeated until all the desired marks have been recorded upon the track associated with the head 55. When the back gauge reaches the rearmost extremity of its travel it will open the limit switch 77 and thus de-energize the contactor 78 bringing the back gauge to a stop.

The back gauge may now be started forwardly by depressing the switch 42. If it is desired to make use of the programme which has been recorded on to the tape, the first selector 41 is switched to its space position which closes the switches 41a, 41b and 41c. As the switch 42 is depressed, the contactor will be energized thus closing all the pairs of contacts associated therewith. The pair of contacts 85d when closed will act to hold the contactor 85 energized since current is passed. along the line 86, through the pair of contacts 85d, the closed pair of contacts 480 and the switch 41!; to the contactor 85.

When the head connected to the tape recorder by the second selector 45 picks up a signal from its associated signal track it will feed the signal into the tape recorder which will amplify it and pass it through the closed switch 410 to the control contactor 48. As the contactor 48 is energized the contacts 48:: are closed and the contacts 48b and 480 are opened. The etfect of opening the contact 43c is'to interrupt the power through the contactor 85 thereby opening all the sets of contacts associated therewith. The opening of the contacts 85a,

85b and 85!; interrupts. the power to the motor 26. The opening of the contacts 85e interrupts the power to the clutch-brake 89 thus bringing the back gauge to a halt.

The paper on, the table may then be cut by depressing the

switches

37, 38,v thus energizing the contactor 69, closing the contacts 69a and thus energizing the clutch 20 to cause the cutter blade 12 and clamp 15 to move through the cycle of clamping the paper on the table, cutting the paper and then releasing the clamp. As described above, when the cutter blade reaches the bottom of its stroke, the limit switch 75 is closed allowing the cutter blade to complete its stroke although the

push buttons

37, 38 are released. The control contactor 48 is such that after it has been energized it will maintain the contacts 48a closed and the contacts 48b and 480 open long enough for the cutter blade to reach the bottom of its stroke, thus closing the limit switch 75 and completing the remainder of the cutting cycle. The relay will then become de-energized opening the contacts 48a and closing the contacts 48b and 480.

As the cutter blade approaches the top of its stroke after cutting the paper the limit switch 75 is opened and the motion of the cutter blade ceases. At about the same time as the limit switch 75 is opened the limit switch 87 is closed long enough for the contactor 85 to be energized and locked by the closing of the contacts 85d. As the contactor 85 is energized, the back gauge Will start and will continue to move forward until a further signal is received by the head which is connected to the tape recorder through the second selector 45.

If the switch 46 is closed, the cutter blade and clamp will be caused to operate automatically as the back gauge comes to a standstill as the result of a signal from a tape. Thus, when a signal is received by the control contactor 48, the pair of contacts 48a which are normally open will close, and the contactor 69 will be energized along the line 73 through the switch 46, the pair of contacts 48a and the switch 41a. The cutter blade and clamp will then proceed through their cycle until the limit switch 75 is operated. The contacts 48a will then open near to the end of the cycle and the limit switch 87 will close momentarily and cause the back gauge to start on its forward travel. When a further signal is received by the control contactor 48 the same sequence of operations will be repeated.

If it is desired to reverse the back gauge so that it will stop when signals are received from the track associated with the head 55, the reverse button 43 is pressed with the first selector 41 still in the space position. As the switch 43 is pressed current is fed along the line 76 to energize the contactor 78 thus closing the

contacts

78a, 78b, 78c, 78d, 78:; and 78g and opening the contact 78 The motor 26 Will then begin to drive the back gauge in the reverse direction until a signal picked up by the head 55 is fed through the contacts 78g to the tape recorder 47. The signal will then energize the control contactor 48 and open the contacts 48b thus breaking the circuit through the contactor 78 and bringing the back gauge to a stop. Either of the

switches

42 or 43 may then be pressed to move the back gauge.

Thenormal positions of the

heads

49, 50, 51, 52, 53, 54 and 55 are those shown in Figure 2, i.e., spring urged against the

stops

57, 58 in a forward position i.e. towards the cutter blade. This is the position occupied by the heads when the paper cutter is on automatic operation, signals picked up from the heads being relayed to the control contactor 48 through the tape recorder 47.

When a programme is being recorded on the

tapes

30, 31, every time the switch 44 is depressed the solenoid 69 is energizedthus moving the heads to a rearward position against the

stops

61, 62. It is in this rearward position that signals are recorded upon the tape. It will be seen therefore that the signal is recorded at a point on the tape which is to the rear of the actual point at which it is desired that the back gauge should stop. When a head picks up a signal it is passed through the tape recorder 47 to the contactor 48 which responds so that the back gauge is brought to a halt, this operation takes an appreciable, although short, length of time. The distance between the signal and the desired stopping point of the back gauge is adjusted so that in the time taken to bring the back gauge to a halt the back gauge has covered this distance and comes to a stop at the desired position.

It will be appreciated that a programme for the forward movement of the back gauge may be set up on each of the six signal tracks associated with the heads 49 to 54, and that the desired programme may be selected by means of a second selector 45. When it is desired to erase a programme from one of the signal tracks, the corresponding head is selected by the second selector 45, the first selector 41 is turned to the erase position and the back gauge moved along its guideway. In the erase position the tape recorder feeds an erase signal out through the second selector 45 to the head which has been selected and erases a signal or all the signals on the associated track. In order to be able to erase a signal, or all the signals, on any of the tracks associated with the heads 49 to 54 it is necessary that the contactor 78 be de-energized so that the pair of contacts 78 are closed and the required head may be selected by the selector 45. It follows that if all the signals on a track are to be erased, the back gauge must be moving in a forward direction, otherwise the contactor 78 will be energized. To amend the signals on a track the back gauge may be moved forwardly over just that portion of the track concerned. If desired the back gauge could be brought to a stop over the signal it is desired to erase and the signal then erased. It will be seen that any one signal may be erased and replaced by a signal in a different position. If all the signals on a track have been erased a new programme may then be set up in the manner described above.

The same procedure may be used to erase signals marked on the track corresponding to the head 55, i.e., the track which provides the stopping signal for the back gauge during its reverse motion, although if all the signals are to be erased this can be done with the contactor 78 energized and the contacts 78g closed. The settings on the track associated with the head 55 will only be approximate due to the fact that the time taken for the back gauge to come to a standstill plus the distance the head was moved by the solenoid during recording will be cumulative when the back gauge is in reverse instead of cancelling out as they do when the back gauge is moving forwards. If it is only desired to make one cut which is, say, one foot away from the cutter blade, then after each cut it would be a waste of time to send the back gauge to the reverse limit of its travel and then advance it to a position one foot away from the cutter blade. In this case a signal is recorded on the track associated with the head 55 at, say, one foot six inches away from the cutter. The back'gauge will stop near this position and then may be started on its forward travel and will only have to advance, say, six inches before it is stopped. This procedure saves the time which would be required for the back gauge to travel to and fro along the whole length of its path between cuts.

When the first selector 41 is in the off position the tape recorder 47 and the control relay 48 are non-operative, the paper cutter being operable only by the manual switches 37, 38, 39, 40, 42 and 43 the functions of which have been described above.

Although the invention has been described with reference to a paper cutter using seven combined recording and receiving heads, any convenient number of heads may be used. Also if desired separate heads may be used for recording and receiving, e.g., seven heads may be used for recording and another seven heads for receiving. When separate sets of heads are used the recording heads will be disposed rearwardly of the receiving heads and it will be unnecessary to provide a solenoid to move either set of heads since they will be permanently in the correct positions for recording and receiving.

It will be seen that the invention provides a simple and versatile means for controlling the back gauge of a paper cutter in a desired sequence of movements. The whole length of each of the tapes providing the signal tracks is always available for the recording or erasure of signals and is stationary relatively to the table so that no misalignment can occur and give rise to inaccuracies.

It will be seen that there are no mechanical linkages to go wrong, the only movement of the signalling parts being the .movement of the heads on the support 35. This can be the only mechanical source of error in the setting up of a programme on the tape and this error may be reduced to a minimum by careful design of the device for moving the heads. The heads are either spring urged against

stops

57, and 58 which may be adjustable or urged by the solenoid against

stops

61 and 62, which may also be adjustable. The stops 57, 58, 61 and 62, are adjustably secured to the support 35 and may be accurately postioned. The invention is very simple and its mechanical concept and the components of the electronic system associated with the machine are conventional and easily serviced.

It will also be appreciated that the invention is applicable to apparatus other than paper cutters wherein one member is movable relatively to the other and it is desired to control the movements of the members by means of erasable signals and without introducing mechanical linkages which, when worn, will cause inaccuracies, and which are subject to the accumulation of foreign matter and slippage.

It will be understood that the form of the invention herewith shown and described is a preferred example and various modifications can be carried out without departing from the spirit of the invention or the scope of the appended claims.

What I claim as my invention is:

1. Apparatus comprising a first member, a guideway on the first member, a second member movable rel atively to the first member in said guideway, a signal track of material capable of having electromagnetic signals erasably recorded thereon, the signal track extending longitudinally in a direction parallel to the direction of movement of the second member relatively to the first member and being mounted on the first member to be stationary relatively thereto, a support mounted on the second member, the support moving along a path adjacent to the signal track as the second member moves in the guideway, a recording and receiving head assembly mounted on the support, said assembly being energizable to record electromagnetic signals on the track and being capable of receiving electromagnetic signals recorded on the track, means for energizing said assembly to record signals on the track, structure for traversing the second member along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received by the re cording and receiving head assembly from the signal track to operate the controls, and a selector operable to render one of said first and second means effective to operate the controls.

2. Apparatus comprising a first member, a guideway in the first member, a second member movable relatively to the first member in said guideway, a signal track of material capable of having electromagnetic signals erasably recorded thereon, the signal track extending longitudinally in a direction parallel to the direction of movement of the second member relatively to the first member and being mounted on the first member to be stationary relatively thereto, a support mounted on the second member, the support moving along a path adjacent to the signal track as the second member moves in the guideway, a recording and receiving head assembly mounted on the support, said assembly being energizable to record electromagnetic signals on the track and being capable of receiving electromagnetic signals recorded on the track, means for energizing said assembly to record signals on the track, spring means normally urging said assembly to a first position on the support, shifting means operable to move said assembly on said support to a second position, said shifting means being operable in conjunction with said means for energising the assembly, structure for traversing the second member along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received by the recording and receiving head assembly from the signal track to operate the controls, and a selector operable to render one of said first and second means effective to operate the controls.

3. Apparatus comprising a first member, a guideway on the first member, a second member movable relatively to the first member in said guideway, a pinrality of parallel signal tracks of material capable of having electromagnetic signals erasably recorded thereon, the signal tracks extending longitudinally in a direction parallel to the direction of movement of the second member relatively to the first member and being mounted on the first member to be stationary relatively thereto, a support mounted on the second member and arranged to move along a path adjacent to the tracks as the second member moves in the guideway, a plurality of receiving heads mounted on the support, each head being associated with a different track to receive electromagnetic signals recorded on the track, a plurality of recording heads mounted on the support, each recording head being associated with a different track and energizable to record electromagnetic signals on the track, means for energizing said recording heads to record signals on the tracks, structure for traversing the second member along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received from one of the receiving heads to operate the controls, a first selector operable to render one of said first and second means effective to operate the controls and a second selector operable to connect a desired receiving read to the second means.

4. Apparatus comprising a first member, a guideway on the first member, a second member movable rel atively to the first member in said guideway, a plurality of parallel signal tracks of material capable of having electromagnetic signals erasably recorded thereon, the signal tracks extending longitudinaly in a direction parallel to the direction of movement of the second member relatively to the first member and being mounted on the first member to be stationary relatively thereto, a support mounted on the second member and arranged to move along a path adjacent to the tracks as the second member moves in the guideway, a plurality of combined receiving and recording heads mounted on the support, each head being associated with a different track and being energizable to record electromagnetic signals on the track and being capable of receiving electromagnetic signals recorded on the track, means for energizing said heads to record signals on said tracks, structure for traversing the second member along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received from one of the combined receiving and recording heads to operate the controls, a first selector operable to render one of said means effective to operate the controls, and a second selector operable to connect a desired combined receiving and recording head to the second means.

i l l l E 5. Apparatus asclaimed in claim 4, including spring means normally urging said combined receiving and recording heads to first positions on the support, and shifting means operable to move said heads to second positions on the support, said shifting means being operable in conjunction with said means for energizing the heads to record signals on the tracks.

6. A paper cutter including a table, a guideway on the table, a back gauge movable relatively to the table in said guideway, a signal track of material capable of having electromagnetic signals erasably recorded there on, the signal track extending longitudinally in a direction parallel to the direction of movement of the back gauge relatively to the table and being mounted on the table to be stationary relatively thereto, a support mounted on the back gauge, the support moving along a path adjacent to the signal track as the back gauge moves in the guideway, a recording and receiving head assembly mounted on the support, said assembly being energizable to record electromagnetic signals on the track and being capable of receiving electromagnetic signals recorded on the track, means for energizing said assembly to record signals on the track, structure for traversing the back gauge along the guideway, controls to operate said struc ture, manually operable first means to operate the controls, second means operable in dependence on signals received by the receiving and recording head assembly from the signal track to operate the controls, and a selector operable to render one of said means effective to operate the controls.

7. A paper cutter including a table, a guideway on the table, a back gauge movable relatively to the table 7 in said guideway, a signal track of material capable of having electromagnetic signals erasably recorded thereon, the signal track extending longitudinally in a direction parallel to the direction of movement of the back gauge relatively to the table and being mounted on the table to be stationary relatively thereto, a support mounted on the back gauge, the support moving along a path adjacent to the signal track as the back gauge moves in the guideway, a recording and receiving head assembly mounted on the support, said assembly being energizable to record electromagnetic signals on the track and being capable of receiving electromagnetic signals recorded on the track, means for energizing said assembly to record signals on the track, spring means normally urging said assembly to a first position on said support, shifting means to move said assembly on said support to a second position against said spring means, said shifting means being operable in conjunction with said means for energizing said assembly, structure for traversing the back gauge along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received by the recording and receiving head assembly from the signal track to operate the controls, and a selector operable to render one of said first and second means effective to operate the controls.

8. A paper cutter including a table, a guideway on the table, a back gauge movable relatively to the table in said guideway, a plurality of parallel signal tracks of material capable of having electromagnetic signals erasably recorded thereon, the signal tracks extending longitudinally in a direction parallel to the direction of movement of the back gauge relatively to the table and being mounted on the table to be stationary relatively thereto, a support mounted on the back gauge and arranged to move along a path adjacent to the tracks as the back gauge moves in the guideway, a plurality of receiving heads mounted on the support, each head being associatcd with a different track to receive electromagnetic signals recorded on the track, a plurality of recording heads mounted on the support, each recording head being associated with a different track and energizable to record electromagnetic signals on the track, means to energize said recording heads to record signals on the tracks, structure for traversing the back gauge along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received from one of the receiving heads to operate the controls, a first selector operable to render one of said means effective to operate the controls, and a second selector operable to connect a desired receiving head to the second means.

9. A paper cutter including a table, a guideway on the table, a back gauge movable relatively to the table in said guideway, a plurality of parallel signal tracks of material capable of having electromagnetic signals erasably recorded thereon, the signal tracks extending longitudinally in a direction parallel to the direction of movement of the back gauge relatively to the table and being mounted on the table to be stationary relatively thereto, a support mounted on the back gauge and arranged to move along a path adjacent to the tracks as the back gauge moves in the guideway, a plurality of combined receiving and recording heads mounted on the support, each head being associated with a different track to receive electromagnetic signals recorded on the track and energizable to record electromagnetic signals on the track, means to energize said heads to record signals on the tracks, structure for traversing the back gauge along the guideway, controls to operate said structure, manually operable first means to operate the controls, second means operable in dependence on signals received from one of the combined receiving and recording heads to operate the controls, a first selector operable to render one of said first and second means effective to operate the controls, and a second selector operable to connect a desired combined receiving and recording head to the second means.

10. A paper cutter as claimed in claim 9, including spring means normally urging said combined receiving and recording heads to first positions on the support, and shifting means operable to move said heads to second positions on the support, said shifting means being operable in conjunction With said means for energizing the heads to record signals on the tracks.

References Cited in the file of this patent UNITED STATES PATENTS 2,065,420 Bennett Dec. 22, 1936 2,262,599 Bolz Nov. 11, 1941 2,553,395 Adrian May 15, 1951 2,628,539 Neergaard Feb. 17, 1953 2,628,680 Seybold Feb. 17, 1953 2,649,155 Spiller Aug. 18, 1953 2,690,532 Johnson Sept. 28, 1954