US2363996A - Letoff mechanism for looms - Google Patents

Description

Nov. 28, 1944. w. Y. ROBB LET-OFF MECHANISM FOR LOOMS Filed April 12, 1943 3 Sheets-Sheet l flNvEN'roR WALTERY ROBE ATTORNEY Nov. 28, 1944. w. Y. ROBB LET-OFF MECHANISM FOR LOOMS Filed April 12, 1943 5 Sheets-Sheet 2 .2 @w @WW QMAR L R o n 3j 5 A .2 a o R N hm; T 5 N Y R 9: Q m. E m 0 RE MH m m n Ai H Y 12 I M A Nov. 28, 1944. w. Y. ROBB LET-OFF MECHANISM FOR LOOMS Filed April 12, 1943 s Sheets-Sheet s l NvE'NTo R WALTER Y; Rose ATTO RNEY Patented Nov. 28; 1944 UNITED 'STATES PATENT OFFICE 2,863,996 Ls'rorr MECHANISM roa LOOMS Walter Y. Robb, Whitlnsv-lllc, Mass, assignor to Crompton & Knowles Loom Works, Worcester, Mass, a corporation of Massachusetts Application April 12, 194:, Serial No. 482,683 9 Claims. (of. 139-352) .more beams all of which turn to feed their respective sheets of warps. When looms of this type are of-considerable width such as 20/4, it is difllcult to use beams to supply warp for the full width of the fabric and I overcome this difllculty by aligning two or more warp beams to supply a group of sheets of warp threads. Each beam has its own let-ofi' mechanism which operates independently of other similar mechanisms and because of this fact there is a possibility that one of the beams may fail to let off as much warp as the other beam which is aligned with it.

The warp threads of each sheet pass over a whip roll the position of which is determined in P t by the warp tension and it is a more important object of my present invention to Drovide means for stopping the loom if the warp tension in any sheet increases sufficiently to move the corresponding whip roll to an abnormal position. I

It is another object of my present invention to provide each of the warp systems with a loom controlling electric switch in position to be operated by the associated whip roll when the latter moves to abnormal position for the purpose of eflecting loom stopp ge before'the warp tension becomes high enough to cause thread breakage or distortion of the fabric.

.With these and other objects in view which will appear as the description proceeds, my invention resides in the combination and arrangement of parts hereinafter described and set forth.

In the accompanying drawings, wherein a convenient embodiment of my invention is set forth,

Fig. l is a side elevation of part of an Axminster loom having my invention applied thereto,

Fig. 2 is an enlargement of part of Fig. 1 showing the whip rolls and the let-off mechanism for one beam, Y

Fig. 3.is a plan view of Fig. 2 looking in the direction of arrow 3,

Fig. 4 is a detailed front elevation in the direction of arrow 4, Fig. .2 showing the electric switch and its operating mechanism on an enlarged scale,

Fig. 5 is a detail vertical section on line [-5 of Fig. 2,

Fig. 6 is a plan view of the loom looking in the direction of arrow 6, Fig. 1,

Fig. 7 is a detail side elevation locking in the directionof arrow 1, Fig. 6 showing the weights for the whip rolls, and

Fig. 8 is a diagrammatic view of the electric circuit and loom shipper control mechanism used with my invention.

Referring particularly to Figs. 1 and 6 I have shown the lower part of an Axminster loom frame in and a shaft l I appropriately driven by a motor M indicated in Fig. 8 which causes the shaft to have a rotation every third pick or beat of the loom for the weaving of so-called three-shot Axminster. Mounted on each end of shaft II is a cam 12 having a groove I3 and a face It. The

a pinion 20 which meshes with a gear 2| secured to the take-up roll 22 mounted as at 23 for rotation in the front part of the loom. A hold pawl 24 prevents retrograde movement of the ratchet wheel on theidle or non-working stroke of the pawl I'L- i As will be understood from Fig. l a comple rotationof shaft II will cause three rockings of lever IS in a counterclockwise direction to advance the take-up roll 22 by three successive steps, one step for each beat of the loom. The lay L has a forward motion for each beat and the weft needle N is inserted through the warp shed once for each beat.

The fabric F extends forwardly from its fell and over the cloth board 25 down to and around a guide roll 25 and then up to the take-up roll,

from which point it goes to a wind-up cloth roll not shown. The fabric iscomposed of shots of filling laid by the needle N and warp threads designated generally at W in Fig. 1 which form the sheds for the needle. These warp threads extend through harness mechanism H and then rearwardly to the warp beams.

The loom set forth herein is used more particularly for the weaving of heavy fabrics requiring a large number of warp threads and the latter are derived from warp beams located at the back part of the loom as shown in Fig. 6, and considering the left hand part of the loom as viewed in Fig. 6 as its front, I show three pairs of aligned beams, the right hand beams being designated RI, R2 and R3, respectively, while their corresponding left hand beams are indicated at Ll, L2 and L3.

The beams are thus arranged in pairs. each right hand beam aligning with its corresponding left beam.

- frame 33 accommodates the inner ends of the shafts 30. The beams are preferably all of the same size and will be wound with the same kind of warp and for all practical purposes are identical with each other. Each beam is rotatable independently of all the other beams and the rate of its rotation is independent of the rate of rotation of the remaining beams.

Each beam has its own let-off mechanism which in the present instance is positive and includes means for turning the beam gradually during loom operation so that its warp will be unwound. As shown in Fig. 6 the let-01f mechanism which effects feeding of the warp for beams RI, R2 and R3 are designated generally at Fl. F2 and F3, respectively, and in similar manner, the let-oil. mechanisms for the left hand beams Ll, L2 and L3 are designated generally at F4, F3 and F6, respectively. Since these let-oil mechanisms are substantially the same only one of them will be described.

The shaft of each warp beam has secured thereto a worm wheel 33 which meshes with a worm 36 secured to a vertical shaft 31 the lower end of which turns in and is supported by a bearing 38 fastened to the adjacent part of the loom frame. A second bearing 33 also fastened to the loom frame affords support and bearing for the upper part of the shaft 31, as shown in Figs. 2 and 3.

'Secured to each shaft 31 is a ratchet wheel. actuated by a pawl ll pivoted at 42 on an arm 43 having a bearing 43 which is loose on the shaft 31 and free to rock back and forth thereon. A spring 43 carried by the arm 43 tends to turn the pawl into operative position with respect to the ratchet wheel 40 but permits the pawl to be moved to non-driving position relatively to the ratchet. v

The pawls of the several let-oil's are'operated in unison by means of jointed rods, those pawls at the right of the loom have their arms 43 pivotally connected as at 48 to a rod 49 which extends forwardly to an upright lever 50 pivoted as at about a fixed axis. Lever 50 carries a roll 52 located in the groove l3 of the right hand cam I2 which causes forward movement of lever 50, or movement to the left as viewed in Fig. 1, three times for each complete rotation of the shaft II. It will thus be seen that the pawls for the let-offs Fl F2 and F3 all have feeding strokes in unison and these strokes occur each beat of the loom.

The let-oil's F4, F3 and F6 at the left side of the loom are operated by mechanism similar to that already described and including a rod 53 similar to rod 49 extending forwardly to a lever 53 similar to lever 50. The left hand let-offs are therefore also operated in unison and preferably though not necessarily synchronous with the right hand let-offs.

Provision is made for interrupting the feeding of each of the ratchet wheels 40 by its ratchet for one or more beats of the loom to prevent tuming of the associated warp beam should the corresponding sheet of warp be too slack. Accordinsly. each shaft 31 has loosely mounted thereon a shield 60 for engagement with a roll 3| on the corresponding pawl II and the shield has an arm 82 connected to an operating rod, see Fig. 3. Each let-off has its own shield operating rod, the letofl's Fl, F2 and F3 having rods 83, 63 and 35, respectively, while the let-offs F4, F5 and F6 have similar rods 86, 61 and 68, respectively. Since the control mechanism for the shields are the same on both sides of the loom I will describe only the mechanism at the right and shown in Fig. 2.

A fixed stud 10 affords support for three levers ".12 and 13 which are connected, respectively,

to the rods 63, 34 and 65. These levers are the means by which the corresponding shields are moved either to idle or shielding position. Thus, if lever 1| is rocked to the left as viewed in Fig. 2 its rod 33 acting through arm 62 will move the shield 30 of let-oil Fl to the position shown in Fig. 3 and permit the associated pawl to feed its ratchet wheel 40. If, on the other hand, lever 1! is moved to the right as viewed in Fig. 2 the rod 33 will be moved rearwardly'to cause rocking of the shield 30 in a clockwise direction as viewed in Fig. 3 into engagement with corresponding roll 6| to rock the associated pawl 4| around its axis and thereby move the pawl to inoperative position with respect to the ratchet wheel 40. So long as the shield 30 is in shielding position due to rearward movement of lever 1| the corresponding pawl will have idle strokes and the associated worm 36 will remain at rest. When the shield is in idle or non-shielding position as shown in Fig. 3, however, each operating movement of the pawl will advance the ratchet wheel 40 and give the worm 33 a partial turn for the purpose of rotating the corresponding warp beam through its worm wheel 35. While the detailed operation of the shield and pawl have been given with respect to the front let-off on the right hand side of the I loom, yet it is to be understood that each of the let-oil's will operate in the same manner, levers 12 and 13 controlling the shields of let-ofls F2 and F3, while the let-offsFl, F3 and F6 at the left hand side of the loom have their shields similariy controlled by rods 66, 61 and 68.

Each warp beam has its own whip roll and in the drawings I show-three whip rolls DI, D2 and D3 for the beams RI, R2 and R3, and whip rolls D3, D5 and D6 for the beams Ll, L2 and L3 respectively. These whip rolls are substantially the same and each includes a 15 rotatable in bearings 18 on the loom frame. The outer end of each shaft 15 has secured thereto a weight lever 11 which supports and is urged downwardly by a variable weight 80, as suggested in Fig.

Each shaft 15 is provided with several small forwardly, depending upon the tension of the frame and then to the middle pair of rods 82,

corresponding sheet of warp. As shown in Fig. l the warp sheets from the front pair of aligned beams RI and LI pass in front of a stationary guide rod and thence upwardly to the rear of the back pair of rods 32 and then forwardly to the harnesses H. In similar manner the warp sheets from the middle beams R2 and L2 extend around guide rods 86, 81 and 88 fixed to the loom while the sheets of warp from the back pair of beams R3 and L3 pass around guides 90, 9| and 32 to the front whip rods 32. There are thus six relatively heavy shaft manner. I

In order that the position of each rod 82 may determine the position of the corresponding shield I use the mechanism shown in Figs. 1 and 2. The front right hand shaft I! has'secured thereto a collar I80 which is pivotally connected at III to the upper end of a rod I82 having secured there-- to an adjustable collar I83. The lower end of rod I02 slides through a swivel I pivotally mounted on arm I85 of lever 13. A compression spring I06 extends between the collar II: and swivel I04 and exerts a downward force on arm I08 tending to move the lever 13 forwardly, or in such direction as to move the rod 85 toward the front of the loom and therefore keep the corresponding shield in idle or non-shielding position. In similar manner the middle right hand rod II is provided with the collar IIB connected to a rod III surrounded by a spring II2 which exerts a downward force on arm II3 of lever I2, and the rear right hand shaft I8 carries a collar II! connected toa rod IIi surrounded by a spring II! which exerts a downward force on arm III of lever II. The forces exerted by the several springs can be adjusted by the collars on the associated rods, and the position of the collars I00, I III and I II can be adjusted on the associated shafts 15 by means of set screws I20. Similar mechanism at the left side of the loom is provided for the shafts II corresponding to beams LI, L2 and L3.

The stopping mechanism for the loom includes an electric switch and a controller therefor on each whip roll. The right hand side of the loom frame is provided with a small stand I25 on which are mounted three electric switches I28, I21 and I28, corresponding to beams RI, R2 and R3. Each switch has an arm I38 to operate a plunger I3I forming part of the switch. These switches are so placed on the support I25 that their arms can be operated conveniently by their respective whip rolls and each of the latter is provided with a collar I35 angularly adjustable on the associated shaft I5 and having a projecting switch actuating arm I36. Each arm I38 is capable of operating its corresponding arm I30 for, operation of the associated switch when the whip rolls rocks toward the left as viewed in Fig. 2 to an abnormal position. Similar switches I31, I38 and I38 are provided for the whip rolls of beams LI, L2 and L3 at the left hand side of the loom to be operated by arms I40 on the associated whip rolls.

In operation, the warp beams will all have adequate supplies of warp wound thereon and then placed in the loom as suggested in Fig. 6. The sheet of warp from each of the beams will be laid around the guides already described and over the appropriate bars 82 and thence forwardly to the weaving instrumentalities. The weights 88 normally act to hold the bars 82 rearwardly so that the arms I36 on the shafts ill will all be either spaced from their associated switch operating arms I30, or at least will be in such position as not to effect opening of the latter switches. With each beat of the loom the rods 39 and will be moved forwardly to give all of the pawls II a working stroke, but under normal conditions the levers II, 12 and 13 will be turned to the left as viewed in Fig. 2 to place the shields in idle position and the pawls will be active to turn their respective beams. Continued operation of the loom under these conditions causes backward movement of the rods 82 and rearward movement of the shield controlling rods 83-. Eventually the shields III engage their rolls 8| and the pawls are temporarily disabled and stop feeding of the warp. The rods "then move for-' wardly incident to consumption of warp and the shields start to move toward non-shielding position. This alternate stopping and starting of the turning mechanism for the warp beams go on so long as all parts of the several let-off mechanisms function properly, but if one or another of the feeding mechanisms should fail to operate the corresponding beam will remain at rest and its sheet of warp tightened sufiiciently to move the associated whip roll bar 82 forwardly to an abnormal position. I Y

Fig; 8 shows diagrammatically the circuit and loom motor control used with my invention. Wires E and E represent the power lines, M the loom driving motor appropriately connected to shaft II, and B the solenoid which when energized maintains the main loom switch I closed. The six switch units in Fig. 8 controlled by'the whip rolls are designated at 1' r and r, and 1 F and l and correspond to the beams RI, R2 and R3, and LI, L2 and 1.3, respectively.

When the loom operates as described the conditions shown in Fig. 8 will continue, and electric current will flow in the following circuit: wire E, switch I39 of the front left whip roll, wire ISO to the next switch in unit P, and then in succession through the switches I31, I28, I21. I28 of units 1 r 1' and 1", respectively, to solenoid S via wire Iii, and thence by wire I52 to power wire III, This circuit is kept closed so long as all the switches I28 are closed and results in energization of solenoid S to keep switch Illr closed. Current therefore flows from wire E, over wire I" to closed switch I", thence by wire I58 to motor M and then back by wire I" to the opposite side E of the power source.

If any one of the warp sheets should become too tight and move its whip roll rod 82 to' abnormal forward position, the associated arm I38 will depress its switch arm I30 and plunger ill to open the corresponding switch I28, whereupon the flrst'traced circuit will be opened and solenoid S will be deenergized. The resultant opening of switch I" will cause stoppage of the motor and the loom will come to rest. The weaver can then advance the ratchet wheel III of the tight warp sheet sufliciently to pay off enough warp to permit the associated rod 82 to move rearwardly to its normal range of movement and effect closure of its switch. Normal warp conditions will then have been established and weaving can be resumed, since switch I 48 will by this time be closed.

From the foregoing it will be seen that 'I have provided an electrically operating control for the loom which acts to stop the loom until a warp sheet becomes too tight. It will further be seen that I have provided a loom having a plurality of warp beams each associated with an electric switch and wherein the switches are all connected electrically to means for controlling the loom motor in such a way that if any switch is open the loom will be stopped. Also, I have provided a series circuit including a normally closed switch for each warp beam when its sheet of warp is under normal tension, abnormal tension in any sheet being effected to open the corresponding switch and thereby break the circuit so that the loom will be stopped.

Having thus described my invention it will be 4. h aseaaoo seen that changes and modifications may be 'made therein by those. skilled in the art withoutto stop, a sheet of warp subject to change from.

normal to excessive tension, an auxiliary electric switch controlled by said sheet 01. warp normally closed when warp tension is normal and opened by excessive tension of the warp, and electric circuit means controlling the motor switch and controlled by said auxiliary switch and effective when the auxiliary switch is closed to maintain said motor switch closed and effective when said auxiliary switch is open to eflect opening oi said motor switch. h

2. In a loom having a driving motor and an electric motor switchtherei'or which when closed causes the motor to operate and when open eflects stoppage ot the motor, a warp beam supplying a sheet of warp, a whip roll over which the sheet of warp passes, said whip roll being moved from normal to abnormal position by the warp sheet when the tension of the latter becomes excessive, normally closed electric circuit means eflective only when closed to keep said motor switch closed, said switch opening when the circuit means is opened, and means operated by the whip roll when the'latter moves to abnormal position to open said circuit means to effect opening of the motor switch for the purpose oi stopping the motor. I

3. In a loom having a driving motor and a master electric switch therefor and an electromagnetic controller which when energized maintains said master switch closed to cause running of the motor but when deenergized etiects opening of the master switch to stop the motor, a warp beam having'a sheet of warp, a whip roll over which the sheet or warp passes, means tending to maintain the whip roll in normal operating position, the sheet of warp when under excessive tension moving the whip roll to abnormal position against the action of said means, a normally closed auxiliary electric switch, an electric circuit including said auxiliary switch and said electro-magnetic controller and normally effective to maintain the latter energized to hold the master switch closed, and means moving with the whip roll when the latter moves sheet of warp moving from normal to abnormal position when the sheet of warp is under excessive-tension, and an auxiliary switch normally closed when the whip roll is in normal position, an electric circuit including said solenoid and auxiliary switch to maintain said solenoid energized to keep the master switch closed when the auxiliary switch is closed, and means moved by the whip roll when the latter moves to abnormal position to open the auxiliary switch and thereby break said circuit to effect deenergizatlon of the solenoid and cause opening at the master switch to stop the motor.

5. In a loom having a plurality of warp beams each supplying a sheet or warp, the loom having an electric driving motor and a motor switch operated by an electro-magnetic controller e!- fecting. opening and closing or the motor switch, a normally closed auxiliary electric switch for each warp beam, an electric circuit including said auxiliary switches and controller in series and normally closed and causing the controller to maintain the motor switch closed to eflect running of the motor, said controller eflecting opening of the motor switch when said circuit is .broken, a whip roll for each warp beam movable from normal to abnormal position, and means on each whip roll operative when the latter moves to abnormal position to open the associated auxiliary switch and break said circuit.

6. In a loom having a driving electric motor and a master electric switch which when closed causes the motor to run and when open causes the motor to stop. a pluralityof warp beams each controller and all the auxiliary switches and eifective only when closed to cause said controller to keep the master switch closed, and means operative when the tension 01' any sheet of warp becomes excessive to open the corresponding auxiliary switch and thereby break said series circuit.

'7. In a loom having a plurality of warp beams and a driving motor, a master switchfor the motor, an electro-magnetic controller for the master switch, a whip roll for each warp beam movable from normal to abnormal position, an auxiliary switch for each whip roll, an' operator on each whip roll for the corresponding auxiliary switch, and means constituting an electric circuit including said auxiliary switches and electro-magnetic controller normally effective to cause said-controller to keep the master switch closed when all the whip rolls are in normal position, operation of any auxiliary switch by the operator of the corresponding whip roll eflfecting a change in said electric circuit means and altering the condition of the electro-magnetic controller for the purpose of opening said master switch.

8. In a loom having a driving electric motor and a motor switch which when closed causes the motor to run and when open causes the motor to stop, a warp beam from which extends a sheet of warp subject to change from normal,

to excessive tension, an auxiliary electric switch for said sheet of warp capable of being either in open or closed position, an electromagnetic controller zfor the motor switch, and means constituting an electric circuit including said auxiliary switch and said electromagnetic controller normally efiective when said auxiliary switch is in one of the positions thereof to cause the electromagnetic controller to keep the motor switch closed when the sheet of warp is under normal tension, occurrence of excessive tension in said sheet of warp causing the auxiliary switch to move to the other position thereof and effecting a change in said electric circuit means and altering the condition of the electromagnetic controller for the purpose of efiecting opening said motor switch.

9. In a loom having a driving motor and a motor switch which when closed causes the motor to run and when open causes the motor to stop, a sheetof warp subject to change from normal to excessive tension, an electromagnetic controller for the motor switch, an auxiliary switch controlled by the sheet of warp, and means constituting an electric circuit including said electromagnetic controller and said auxiliary switch normally effective to cause said electromagnetic controller to keep the motor switch closed when the tension of the sheet of warp is under normal tension, operation of the auxiliary switch incident to a change in the warp sheet from normal to excessive tension effecting a change in said circuit means and altering the condition of the electromagnetic controller for the purpose of effecting opening'said motor switch.

WALTER Y. ROBB.

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