US3706329A

US3706329A - Method and apparatus for intertwisting lengths of filamentary material

Info

Publication number: US3706329A
Application number: US110531A
Authority: US
Inventors: Arthur T Schofield
Original assignee: MFG BRUSH CO
Current assignee: Milwaukee Brush Manufacturing Co Inc; MFG BRUSH CO
Priority date: 1971-01-28
Filing date: 1971-01-28
Publication date: 1972-12-19
Anticipated expiration: 1989-12-19
Also published as: GB1344396A; DE2203845A1; CA946884A

Abstract

A method and apparatus for intertwisting lengths of relatively stiff, deformable monofilament or multifilament material to form a stranded segment, such as to form the intertwisted ends or legs of a wire bundle comprising a portion of the bristles of a wire brush. The twisting is accomplished by gripping each length to be twisted at one end in a stationary gripping mechanism and slidably holding the lengths in a rotatable twisting head that locates the respective portions of the lengths that are held thereby in fixed relation to one another and symmetrically spaced about the axis of rotation of the twisting head. The twisting head is initially moved axially to a predetermined axial spacing from the gripping mechanism and when the desired spacing is achieved the twisting head is rotated through a predetermined angle to intertwist the lengths. When the rotation is stopped the steps are then repeated sequentially until the lengths are intertwisted a desired number of helical convolutions.

Description

Dec. 19, 1972 METHODIAND APPARATUS FOR INTERTWISTING LENGTHS OF FILAMENTARY MATERIAL Inventor: Arthur T. Schofield, Brecksville,

Ohio

Assignee: The Manufacturers Brush Company,

Cuyahoga, Ohio Filed: Jan. 28, 1971 Appl. No.: 110,531

[52] U.S. Cl ..l40/149, 300/21 [51] Int. Cl. ..B2lf 7/00 [58] Field of Search ..l40/l15, 14 9; 300/2, 21; 15/198, 200, 206

[56] References Cited UNITED STATES PATENTS 1,493,670 5/1924 Galvin ..3()0/2l 2,740,148 4/1956 Nelson et al... 300/21 2,742,327 4/1956 Marks ..300/2 2,755,496 7/1956 Benyak 300/21 3,304,568 2/1967 Nelson ..300/2l IO C Primary ExaminerLowell A. Larson Attorney-McCoy, Greene & Howell [57] ABSTRACT A method and apparatus for intertwisting lengths of relatively stiff, deformable monofilamcnt or multifilament material to form a stranded segment, such as to form the intertwisted ends or legs of a wire bundle comprising a portion of the bristles of a wire brush. The twisting is accomplished by gripping each length to be twisted at one end in a stationary gripping mechanism and slidably holding the lengths in a rotatable twisting head that locates the respective portions of the lengths that are held thereby in fixed relation to one another and symmetrically spaced about the axis of, rotation of the twisting head. The twisting head is initially moved axially to a predetermined axial spacing from the gripping mechanism and when the desired spacing is achieved the twisting head is rotated through a predetermined angle to intertwist the lengths. When the rotation is stopped the steps are then repeated sequentially until the lengths are intertwisted a desired number of helical convolutions 12 Claims, 24 Drawing Figures PAIENTED DEC 19 I972 ROTATION (DEGREES) SHEEI 1 [1F 7 PRIOR ART o 3 l I (A) l2 I H2 2 2/42/2234 3 6 2 INVENTOR.

TRAVEL (INCHES) FIG. 3

ARTHUR T. SCHOFIELD M0804 8 J/awell ATTORNEYS P'A'TENIEMEM m2 3.706.329

SHEET 2 BF 7 W FIG. 2 I5 5523/ 2? 22 IO .1

INVENTOR. ARTHUR T. SCHOFIELD 440604,, Gaeene 8 Jewell ATTORNEYS P'A'TENTED 05c 19 I972 sum 3 or 7 FIG. 5

(PRIOR ART) ARTHUR T. SCHOFIELD BY M0 am a J/ g ATTORNEYS PATENTEDBEB 19 I972 SHEET 5 BF 7 INVENTOR.

ARTHUR T. SCHOFIELD IO BY m Ma 60, Ed/(well ATTORNEYS PA TENTED 19 3. 706, 329

sum 5 OF 7 INVENTOR.

ARTHUR T. SCHOFIELD vM0608 0m a /well ATTORNEYS PA TENTED I97? 3. 706. 329

SHEET 7 BF 7 I PIILSE BALL NUT lO2 l AMPL'F'ER DRIVE MOTOR I PuLsE i I F AMPLIFIER I PULSE SPINDLE READER I MoToR DRIVE MOTOR PULSE AMPLIFIER I I05 I PULSE l PuLsE INDEXING I AMPLIFIER MOTOR MOTOR LIOG J 59 FIG.

56 U- E III 43- Ill I l 4| J FIG. IO

INVENTOR. ARTHUR T. SCHOFIELD BY Ma 60. Gm 8 Jewel! ATTORNEYS BACKGROUND OF THE INVENTION This invention relates to a method and apparatus for intertwisting lengths of relatively stiff deformable filamentary material and especially to such a method and apparatus as used to intertwist the ends or legs of a wire bundle comprising part of the bristles of a wire brush. More particularly the invention relates to industrial wire brushes often called knot wheel brushes and to an improved method and machine for their construction.

Conventional knot wheel brushes are formed with a central anchor portion usually a disc with a plurality of apertures spaced around its peripheral edge, and bundles of wire filaments or bristles that are inserted through the apertures. The bristle bundles are bent in the middle to form a bight and the ends twisted together helically to form the so-called knots. The ends of the knots face radially outward and form a generally disc-like brush body with a narrow, generally cylindrical brush face. Conventional machines for producing such brushes are readily available. Typically such machines are provided with automatic bristle feed mechanisms, such as is shown and described, for example, in US. Pat. No. 2,742,327.

The operative portion of the twisting mechanism includes a member commonly called a nose which is generally a frustoconical element with a bifurcated end portion having an aligned pair of transverse bristle receiving apertures located in the bifurcated portion. In the operation of such prior art devices, an anchor plate is mounted in the machine in the vicinity of the'nose. The nose is then positioned to receive the edge of the anchor plate between the bifurcations of the nose and the plate is indexed to align one ofits apertures with the apertures in the nose. A bristle bundle is then fed into the aligned nose and plate aperture.

In the prior art, twisting has been performed in two stages. In the first stage the nose is backed off a short distance to bend or breadk the bristles and to clear the edge of the plate. In the second stage the nose is backed off the remainder of the length of the bristles while simultaneously undergoing rotation about its longitudinal axis. Thus in the second stage the nose moves helically relative to the anchor plate. It will be appreciated that the helical path of the nose in prior art devices was continuous, being typically generated by a system in which the rotational movement of the nose was synchronized with and directly proportional to its longitudinal movement. The longitudinal movement of the nose was controlled by a cam actuated system.

In machines of the prior art when the wound bristles were released from the nose they would recoil or unwind slightly. The degree to which recoil occurred was a limiting factor as to the degree of tightness with which the knot could be wound. A tight knot is generally desirable inasmuch as the bristles tend to support one another and prevent long bristle fracture-a significant source of brush wear.

Another problem inherent in prior art devices is that the cams which controlled the rotary and axial movement of the nose would wear out at frequent intervals thus requiring shutdown of equipment for repair. Also sincedifferent cams would be required for different brushes the cams would have to be changed and adjusted before each production run, all of which is burdensome and time-consuming.

The methodand apparatus of the present invention, however, resolve the difficulties indicated above and afford other features and advantages heretofore not obtainable.

SUMMARY OF THE INVENTION It is among the objects of the invention to provide an improved method and apparatus for controlling automatically, compound movements of a twisting head or nose used to intertwist a plurality of lengths of relatively stiff deformable filamentary material such as wire bundles. 7

Another object is to facilitate remote adjustment of the compound movements of a twisting mechanismv used to intertwistthe end portions of wire bundles in making knot wheel brushes.

Still another object is to assure accuracy and uniformity during repeated cycling of a machine for intertwisting the end portions of wire filaments to secure the bristles of knot wheel brushes.

A further object is to achieve improved intertwisting of the end portions of wire bundles used in making knot wheels and to thereby produce a brush with improved life and reduced bristle fracture in the ends of the brush bristles.

A still further object is to produce a knot wheel brush capable of handling more rigorous service conditions and having a longer service life than has heretofore been obtainable.

Another object is to provide an apparatus for intertwisting the end portions of wire bundles which apparatus is readily adaptable to numerical control.

These and other objects are accomplished by the method and apparatus of the present invention which, in a broad sense, has application to the intertwisting of a plurality of lengths of any relatively stiff deformable filamentary material.

The method comprises anchoring an end portion of each length of material to fix the respective end portions relative to one another. It will be noted that in the apparatus shown, the anchoring step is accomplished by looping a double-length bundle of filamentary material through an apertured anchor plate, although other anchoring means may be employed with either single or double length bundles of filamentary materials, all as will be apparent to persons of ordinary skill.

At the same time the anchored lengths are slidably held intermediate the respective anchored end portions and the free ends thereof, in a rotatable twisting head that locates the portions of the lengths held by the twisting head in fixed relation to one another and symmetrically spaced about the axis of rotation of the twisting head. With the lengths held in this condition the twisting head is initially moved axially away from the anchored ends a predetermined distance while the lengths slide therethrough. After the axial movement is stopped the twisting head is rotated through a predetermined angle to intertwist the lengths in their respective spans between the anchored ends and the twisting head.

It is preferred that the axial movement be so con trolled during this rotation that there is a relatively small axial retraction away from the gripping mechanism. Accordingly an additional portion of each length of material with slide forwardly through the twisting mechanism to supply the additional material required due to the helical form taken by the intertwisted lengths. The above two steps are then repeated until the lengths have been intertwisted a predetermined number of turns. The invention thus defined produces in the case of knot wheel brushes, an improved knot formation.

According to one particular aspect of the invention the twisting is controlled so as to produce a variable lead or pitch in the intertwisted portions, preferably a progressively increasing lead or pitch so as to reduce fanning of the bristles at the end of a knot wheel brush and to reduce the tendency of ofintertwisted lengths to unwind slightly when released from the twisting head.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view from above showing a knot wheel plate adapted to receive a bundle of wire bristles for forming a knot wheel brush, and a twisting head for intertwisting the legs of the bundle;

FIGS. 2A through 2N comprise a group of fragmentary vertical elevations illustrating sequentially the various steps in the intertwisting of the legs ofa wire bundle to form one segment of the bristles of a knot wheel brush;

FIG. 3 is a chart illustrating graphically a plot of sequential steps taken by the twisting head according to the procedure illustrated in FIG. 2;

FIG. 4 illustrates a knot wheel brush constructed according to the method and apparatus of the present invention;

FIG. 5 illustrates a knot wheel brush constructed according to prior art practices;

. FIG. 6 is a plan view of a machine for twisting wire bundles to form knot wheels;

FIG. 7 is a fragmentary elevation of the machine of FIG. 6;

FIG. 8 is a fragmentary horizontal section on an enlarged scale taken through the machine of FIGS. 6 and FIG. 9 is a fragmentary sectional view taken on the line 9-9 of FIG. 8;

FIG. 10 is a fragmentary sectional view taken on the line 10-10 of FIG. 8; and

FIG. 11 is a basic function block; schematic and fragmentary diagrammatic representation of the control system for the machine of FIGS. 6 to 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings and initially to FIG. 1 there is shown a knot wheel plate 10 mounted on an indexing head 11. The plate 10 has a number of peripheral holes 14 of oblong form symmetrically spaced about the outer margin thereof and each hole 14 is adapted to receive two or more bundles 15 of wire filaments or bristles. The bundles 15 are secured to the knot wheel plate 10 by forming a knot with a twisting head in accordance with the method of the invention. The twisting head 20 has a threaded shank 21 that is threaded into the end of a spindle 22, and a tapered forward end 23 with a transverse slot 24 cut therethrough-to form bifurcations adapted to receive the knot wheel plate 10 therebetween.

Extending through each of the bifurcations in the tapered forward end 23 perpendicular to the slot 24 is a transverse opening 25. The openings 25 are somewhat funnel shaped and flared outwardly and rearwardly toward the conical surface of the tapered forward end 23.

FIG. 2 illustrates sequentially the operation of the twisting head 20 in forming the knot to secure the bun dles 15 to the knot wheel plate 10 and also to form the wire bundles so as to position the ends of the bristles correctly and properly in forming a part of the bristles of a wire brush.

Views illustrating the various sequential steps in the operation of the twisting head 20 are identified by the letters A through N in FIG. 2 and it will be seen that at the outset, the twisting head 20 has been moved forwardly toward the knot wheel plate 10 from its position illustrated in FIG. 1 so that the tapered forward end 23 is positioned over the outer margin of the plate 10 with the outer margin received in the slot 24 and with the transverse openings 25 in the tapered forward end 23 aligned with one of the peripheral holes 14 in the knot wheel plate 10. One of the wire bundles 15 has been inserted through the respective aligned openings 25 and a peripheral hole 14, so that end portions or legs of approximately equal length (such legs being referred to as lengthsherein) extend outward on opposite sides of the knot wheel plate 10.

At view B the twisting head 20 has been retracted in an axial direction away from the knot wheel plate 10 a distance of 13/16 inch so as to bend the bundle 15 to form a bight and also so that the bifurcations of the twisting head 20 have cleared the edge of the plate.

At view C the twisting head 20 after having f rst been axially retracted, has been rotated in the direction shown while continuing a slight axial retraction to overlay the legs of the wire bundle 15 and start the formation of a knot.

At view D the twisting head has been retracted axially an additional axial increment without additional rotation so that the total axial retraction is 1 1/64 inches.

At view E the twisting head has been rotated an additional 180 while continuing a small axial retraction so that a full 360 intertwisting of the legs has been accomplished.

At view F the twisting head has been retracted axially an additional axial increment so that the total axial retraction has been 1 15/64 inches.

At view G the twisting head has been rotated an angle of 180 while continuing a small axial retraction so that the total twisting accomplished has been 1% turns or 540.

Views H through M illustrate the remaining steps taken to complete the sequential intertwisting of the legs of the bundle 15.

At view N the twistinghead 20 has been retracted past the ends of the bristles to free the bundle 15 from the twisting head 20 and complete the formation of the knot.

These steps are illustrated graphically in FIG. 3. The sequential twisting thus described produces improved knots which reduce the occurrence and extent of long bristle fracture and afford increased bristle wear and effectiveness. In the preferred embodiment of the method of the invention the sequential steps are so performed as to provide a progressively increasing lead for the intertwisted bristle legs so that the knot is tightest adjacent the knot wheel plate 10. Because of the progressively increasing lead the knot has less tendency to unwind when the bristle ends are released from the twisting head 20.

The improved bristle end form is illustrated in FIG. 4 which shows a knot wheel brush A formed according to the method of the invention. The brush A has bristle bundles l5 bent to form a bight 30 and with the resulting legs intertwisted to form a knot 31. The twisted legs have a generally helical form in the knot and the helices have a progressively increasing lead from the edge of the plate toward their outer ends. The outer ends have a relatively uniform radial extension because the knot has not experienced any substantial unwinding after the legs were intertwisted.

FIG. 5 illustrates a prior art knot wheel brush B wherein the bristle ends of each leg of the respective wire bundles fan outwardly to a greater degree than in brushes constructed according to the present invention. (The relative amount of fanning is exaggerated for purposes of illustration). This is caused by the partial unwinding of the bristles after twisting to form a knot. This, in turn, is caused by the fact that the knot helices of the prior art brush B have a generally uniform lead.

FIGS. 6 through 10 illustrate a machine embodying the present invention for forming knot wheel brushes of the .type shown in FIG. 4 and which is especially adapted for the practice of the method of the present invention. The machine comprises an indexing assembly C adapted to position and index a knot wheel plate 10, and a twisting head drive assembly D adapted to provide the axial and rotary drive for the twisting head 20.

The indexing assembly C is mounted for horizontal adjustment in a direction-perpendicular to the indexing head 11 on a main frame 40 that supports a pair of vertically spaced horizontal guide rods 41. A carriage 42 is slidably mounted for horizontal travel on the rods 41 so as to provide for proper lateral positioning of a knot wheel plate 10 carried on the indexing head 11. The adjustment is accomplished by means of an adjusting screw 43 which is joumaled in the main frame 40 and which drives an adjusting nut 44 secured to the carriage 42.

The indexing head 11 is of compound construction and includes a center shaft 45 (FIG. 8) having a forward end that receives a knot wheel plate 10, and an annular groove in its forward end that receives a lock ring 46 to secure a knot wheel plate 10 on the head.

The center shaft 45 is received within a pair of axially aligned bushings including a forward bushing 47 and a rear bushing 48, the bushings being threadedly secured to one another to form a single unit. The

bushings

47 and 48 are in turn received in a bearing sleeve 49 that is joumaled in a bearing unit 50. The bearing sleeve 49 has a conical taper at its forward end that is adapted to receive a corresponding conically tapered part of the forward bushing 47 to provide a taper lock when the

bushings

47, 48 and sleeve 49 are assembled.

The center shaft 45 has a threaded rearward end that receives a locking nut 52 with a control wheel 53 secured thereto. The nut 52 bears against the rearward end of the bearing sleeve 49 so that by tightening down the nut 52 against the bearing sleeve 49 the lock ring 46 firmly clamps a knot wheel plate 10 in place against the front face of the forward bushing 47.

A drive gear 54 secured to the rearward end of the bearing sleeve 49 (FIGS. 7 and 8), meshes with another gear 55 mounted on a shaft 56 joumaled in the carriage 42. The shaft 56 also carries a helical gear 57 that meshes with another helical gear 58 on the output shaft of an electro-hydraulic stepping motor 59 which may be for example of the type sold commercially under the trade designation FANUC Pulse Motor No. 56 555. The control system for the stepping motor 59 can thus be used to drive the motor through a predetermined angular distance to index a knot wheel plate 10 through the angle necessary to properly position the plate to a new bundle receiving position after completion of each twisting operation.

The twisting head drive assembly D comprises a frame 60 that supports a forward bearing unit 61 in which the spindle 22 is slidably joumaled. The spindle 22 has a splined rearward end length 62 with a sleeve 63 with matching internal splines slidably received thereon, the sleeve 63 being joumaled in a rear bearing unit 64 also supported on the frame 60. The sleeve 63 has a pinion 65 secured thereto by a lock nut 66. The pinion 65 is driven by the output gear 67 of an electrohydraulic stepping motor 69 that serves to turn the spindle 22 through an accurately controlled predetermined angular distance in response to control pulses fed to the stepping motor 69 by a control system to be described below.

The controlled axial movement of the twisting head 20 during its twisting operation in accordance with the present invention is accomplished by means of a ball nut assembly 70 best illustrated in FIGS. 8 and 9. The ball nut assembly 70 cooperates with the spindle 22 which has a helical groove 71 formed in a portion of its cylindrical surface to provide a race for steel drive balls 72. The balls 72 are seated in hemispherical seats within a ball nut 73 so that rotation of the ball nut 73 when the spindle is held against free rotation by the engagement of the pinion 65 with the gear 67, causes axial movement of the spindle 22 unless the pinion 65 is driven at the same rotational speed as the ball nut 73. With this arrangement both axial and rotational movement of the spindle 22 can be accomplished at the same time.

The ball nut assembly 70 has a housing 74 that is slidably supported at its ends on

horizontal guide rods

75 and 76 mounted in

brackets

77 and 78 on the frame 60. A keyed shaft 80 slidably extending through the ball nut housing 74 is joumaled in the

brackets

77 and 78 between the

rods

75 and 76. A pinion 81 is keyed to the shaft 80 and is free to slide axially along the shaft 80 with the ball nut housing 73. The pinion 8 1 has a hear ing sleeve 82 joumaled in the ball nut housing 73, and meshes with a ball nut gear 84 that also has a bearing sleeve 85 joumaled in the ball nut housing 74. The

bearing sleeve 85 is threaded onto the ball nut 73 so that the nut isturned by the gear 84. The shaft 80 extends through the bracket 78 and has a pinion 87 mounted on its rearwardly extending end. The pinion 87 meshes with the output gear 88 of an electrohydraulic stepping motor 89. Both of the

electrohydraulic stepping motors

69 and 89 may be, for example, of the type commercially available under the trade designation FANUC Pulse Motor No. 3-555.

Secured to the bottom of the ball nut housing 74 is a rack 91 that is engaged by a pinion 92 mounted on a shaft 93 journaled in bearing blocks 94 and 95 on the frame 60 (FIG. 9). A shaft gear 96 mounted on left hand end of the shaft 93 as viewed in FIG. 9, meshes with the output gear 97 of a drive motor 98. The motor 98 is used only to adjust the position of the twisting head 20 before and after the twisting operation of the head 20 is performed. It is not used during the twisting operation. The motor 98 may be, for example, a three phase plugging reversing electric motor commercially available from Louis Allis Chalmers Corporation. This type of motor will make one revolution and reverse one revolution and then plug to a stop for one half second.

OPERATION The construction of a knot wheel brush such as the brush A of FIG. 4, using the machine of FIGS. 6 to 10, in accordance with the method of the invention begins by mounting a knot wheel plate 10 on the indexing head 11. This is accomplished merely by placing the plate on the center shaft 45 with one face against the end face of the forward bushing 47, and then inserting the lock ring 46 in the annular slot on the center shaft 45. The wheel 53 is then turned to tighten the lock ring 46 against the plate 10 so that the plate is tightly held between the lock ring 46 and the forward bushing 47.

The apertures 14 in the knot wheel plate 10 are positioned in a predetermined initial angular position using a locating device for example that has been made for the specific size and form of the plate. The motor 98 is then operated to move the carriage 70 along with the spindle 22 and twisting head until the bifurcations of the twisting head 20 receive the knot wheel plate 10 therebetween with the transverse holes of the twisting head 20' aligned with an aperture 14 in the knot wheel plate 10. The motor 98 is stopped when the desired position has been reached and is not normally operated again until the construction of a brush has been completed.

It will be noted that before the positioning of the twisting head 20 to the position shown in FIGS. 6 through 9 (as well as in FIG. 2 (A)), the spindle is moved by the ball nut assembly 70 to its maximum forward extension relative to the assembly 70. This is accomplished by operating the electro-hydraulic stepping motor as viewed in FIG. 9 until the spindle 22 has moved relative to the nut 73 to approximately the position illustrated in FIG. 8.

With the holes 25 in the twisting head 20 thus aligned with an aperture 14 in the knot wheel plate 10, a bundle of wire bristles 15 is inserted horizontally through the respective holes 25 and aperture 14 as illustrated in FIG. 2 (A). The feeding of the wire bundles may be accomplished using precut cartridge loaded filaments or in any other fashion as will be apparent to persons of ordinary skill.

To begin the forming of the wire bundle 15 the electrohydraulic stepping motor 89 is operated to turn the ball nut 73 in a clockwise direction as viewed in FIG. 9 to retract the spindle 22 and twisting head 20 a predetermined axial distance. The resulting bight formed in the wire bundle is illustrated in FIG. 2 (B).

After the twisting head 20 has been retracted the predetermined axial distance so that the bifurcations clear the edge of the plate 10, the electro-hydraulic stepping motor 69 is operated together with the motor 89 to turn the spindle 22 through a predetermined angle which in the operation illustrated is 180, and at a rotational speed just slightly less than the speed of the ball nut 73 so that the axial movement of the spindle will be substantially reduced during the twisting movement. According to the preferred embodiment it is desired that some axial retraction be continued during the turning of the spindle 22 and twisting of the respective wire bundle 15 so that rotational speed of the spindle 22 in response to the drive from the motor 69 is geared in such a way as to be slightly slower than the speed of the ball nut 73. The speed differential will result in some axial retraction but at a reduced rate as compared with the initial rate of spindle retraction. The speed of the two stepping

motors

69 and 89 however, is preferably exactly the same. The procedure is then repeated with the electro-hydraulic stepping motor 89 being operated continuously and the electro-hydraulic motor 69 being operated intermittently to provide the alternating axial movement and rotary or turning movement of the spindle accompanied by a small axial retraction but at a reduced rate.

It will be noted that during this portion of the knot wheel construction procedure the housing 74 remains stationary relative to the

horizontal guide rods

75 and 76. The total axial travel of the twisting head 20 in the operation illustrated is 3% inches while the total angular movement is 180. After the desired twisting has been accomplished the retraction is continued until the bristle ends have passed entirely through the holes 25 in the twisting head 20 after which the electro-

hydraulic stepping motors

69 and 89 are operated to turn the twisting head 20 another 90 so that it is at a new starting position relative to the plate 10.

The knot wheel plate 10 is then indexed to a new angular position .using the electro-hydraulic stepping motor 59 while at the same time, the electro-hydraulic stepping motor 89 is operated in a reverse direction to move the twisting head 20 forward again to its maximum forward extension and with its transverse holes 25 aligned with an aperture 14 for starting a new twisting operation. A new bundle 15 is then inserted in the manner described above and the twisting operation re peated until the desired number of bundles 15 have been secured to the knot wheel plate 10. The knot wheel plate 10 is then removed from the indexing head 11 and a new plate mounted in position.

CONTROL SYSTEM FIG. 11 shows in diagrammatic form a numerical control system for the machine of FIGS. 6 through 10. The system controls the operation of the

electrohydraulic stepping motors

59, 69 and 89 through, for example, the illustrative series of operational steps described above and illustrated in FIGS. 2 and 3. The system uses information storage means such as a I060ll 0481 punched tape containing control information for making a specific knot wheel brush. The tape is normally advanced continuously through a tape reader 101 that may use for example a light beam detector to complete intermittently a signal producing circuit. In the embodiment shown, four parallel channels ofinformation are punched into the tape.

The resulting signals for each channel in the form of electrical pulses are fed to a motor control unit 102 which may be for example, the unit commercially available under the trade designation ICON 410 from ICOR Corporation of 156 6th Street, Cambridge, Massachusetts. The control unit 102 includes four

pulse amplifiers

103, 104, 105 and 106 which are adapted to amplify the signal pulses from the tape reader 101 to produce electrical driving pulses of the proper voltage and amperage for driving the respective stepping motors.

As to the ind exing stepping motor 59 it is desirable that the amount of shaft rotation for each driving pulse from the respective pulse amplifier 106 be small enough that a difference of one indexing pulse affords an extremely small increase or decrease in the angular movement of the indexing head 11 during the indexing cycle. This capacity for vernier adjustment of the angular indexing movement is necessary in order to accommodate knot wheel plates of different size and different number of peripheral apertures. Accordingly the number of pulses required to turn the indexing head 11 through one full 360 turn should be fairly large and is preferably divisible by as many integers as possible.

It will be noted that the

gears

54, 55, 57 and 58 provide a reduction of 16 between the shaft of the motor 59 and the indexing head 11 so that the motor 59 will turn through three times the angle that the indexing head 11 will turn through in response to each driving pulse. Accordingly if 50 pulses are required to rotate the stepping motor 59 through one full turn (i.e., 7.2 of rotation per pulse) then 150 pulses will turn the indexing head through one full 360 turn (i.e., 2.4 of rotation per pulse). Thus the angular movement of the indexing head may be easily adjusted to provide for knot wheel plates having for example 10, 15,25 or knots. For example if a plate is to have 25 circumferentially spaced knots then the number of pulses punched into the tape for one indexing cycle would be 150 divided by 25 or six pulses.

The spindle stepping motor 69 and ball nut stepping motor 89 are preferably rotated through equal angles in response to each pulse from their

respective pulse amplifiers

103 and 105. This greatly simplifies the preparation of control punch tapes. As to the spindle stepping motor 69, 300 pulses are required to turn the motor through one full'3 60 turn. Since the gear 65 will turn through twice the angle of the gear 67 in response to one pulse, the spindle 22 will require 150 pulses for one full 360 turn. Thus if the spindle turns through 810 (i.e., 2 /4 turns) during the twisting operation this will require a total of 338 pulses.

The ball nut motor 89 also requires 300 pulses for one full 360 turn and since the ball nut 73 will be turned through slightly more than twice the angle thatthe motor 89 will be turned by one pulse, less than 150 pulses are required to turn the ball nut one full turn. The pitch of the helices 71 in the spindle is such that one full revolution of the ball nut will move the spindle in an axial direction 1% inches.

Since the ball nut 73 must move the spindle both backward and forward it is necessary that the control pulses for reversing the ball nut (i.e., extending the spindle) be provided on a separate channel to a separate pulse amplifier 104 and that the respective driving pulses be delivered to the reversing terminal of the ball nut motor 89.

It will be seen that if an equal number of pulses are fed to the

motors

69 and 89 simultaneously, the ball nut 73 will turn in the same direction and at a slightly faster rate than the spindle 22 so that a small axial movement will result. The

gears

87 and 88 provide the small speed differential between the ball nut 73 and the spindle 22 in response to an equal number of pulses fed at the same rate, in order to continue some retraction movement of the spindle during its rotation. This speed differential may be increased by increasing the number of teeth on the gear 88 or reducing the number of teeth on the gear 87 so that even though the

motors

69 and 89 operate at the same speed the ball nut will turn slightly faster than the spindle 22 and thus provide the small axial retraction of the spindle 22 during rotation.

It will be noted that during those steps of the operation wherein a purely axial movement of the spindle is required, only the motor 89 will be suppliedwith driving pulses. These pulses are supplied continuously at the same rate through the twisting operation. During those steps where rotation is desired, a group of driving pulses are fed (corresponding to the angular movement desired) to the stepping motor 69.

Table l below represents the control information, i.e., the number of pulses punched in each of the four parallel channels in a punched tape in order to control the machine during the sequences illustrated in FIGS. 2 and 3. In this instance the pulses are fed at a rate of 2,000 pulses per second and since a total of 815 pulses are required during a complete twisting and indexing cycle the total time required will be 0.4 seconds. However, after completion of the twisting and the subsequent indexing of the knot wheel plate 10 to a new angular position it is desirable to have a delay of at least 9% second for inserting a new bristle bundle into the twisting head 20 and the respective apertures in the knot wheel plate 10. Accordingly, the total time required for knotting each bundle would be about 0.9 seconds. Thus a plate with 18 knots would require 16 seconds to manufacture (i.e., 225 brushes per hour).

While the method and machine of the invention have been shown and described with respect to specific embodiments thereof this is intended for the purpose of illustration rather than limitation and other embodi ments and modifications will be apparent to those skilled in the art upon a reading of the specification. Accordingly, the patent is not to be limited in any manner that is inconsistent with the extent to which the progress in the art has been advanced by the invention.

1 claim:

1. A method for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material .comprising the steps of:

anchoring an end portion of each length to fix the respective end portions relative to one another;

l060l l 0482 slidably holding the lengths intermediate the respective anchored end portions and the free ends thereof in a rotatable twisting element that locates the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of said twisting element;

moving said twisting element axially away from said anchored end portions and linearly along said lengths a predetermined distance;

thereafter rotating said twisting element through a predetermined angle to intertwist said lengths in their respective spans between said anchored end portions and said twisting element, and

repeating the two steps next above until said lengths are intertwisted a predetermined number of turns.

2. A method as defined in claim 1 wherein the predetermined angle through which said twisting element is rotated becomes progressively smaller relative to the next preceding axial movement of said twisting head, with each successive rotating step.

3. A method for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material comprising the steps of:

anchoring an end portion of each length with a stationary anchoring element to fix the respective end portions relative to one another; slidably holding the lengths intermediate the respective anchored end portions and the free ends thereof in a rotatable twisting element that locates the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of said twisting element;

moving said twisting element axially away from said anchoring element and linearly along said lengths a predetermined distance;

thereafter rotating said twisting element through a predetermined angle to intertwist said lengths in their respective spans between said anchoring element and said twisting element; repeating the two steps next above until said lengths are intertwisted a predetermined number of turns; moving said twisting element axially away from said anchoring element an additionsl axial distance until the free ends of said lengths are released from said twisting element; rotating said twisting element through an additional angular increment to a predetermined starting attitude, and

moving said twisting element axially toward said anchoring element to a new starting position.

4. A method for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material comprising the steps of:

anchoring an end portion of each length with a stationary anchoring element to fix the respective end portions relative to one another;

slidably holding the lengths intermediate the respective anchored end portions and the free ends thereof in a rotatable twisting element that locates the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of said twisting element; generating a group of electrical driving pulses; moving said twisting element axially away from said anchoring element and linearly along said lengths a predetermined distance in response to each of said pulses so that the total distance moved is determined by the number of said pulses in said group;

thereafter generating a second group of electrical driving pulses;

rotating said twisting element through a predetermined angular increment in response to each of said pulses of said second group so that the cumulative angle through which said twisting element is rotated is determined by the number of pulses in said second group;

repeating the four steps next above until said lengths are intertwisted a predetermined number of turns.

5. The method of constructing a rotary knot wheel brush which includes a knot wheel plate having a plurality of apertures spaced about its periphery and a plurality of bristle knots each consisting of an elongated bundle of bristle material bent intermediate its ends to form two leg portions which are helically intertwisted, and a bight portion which loops through one of said apertures, in a machine having a twisting element with a central axis and a bifurcated end portion having opposed openings in its furcations transverse to said axis, said twisting element being mounted for linear move ment along said axis between an extended position and a retracted position and for'rotation about said axis, means mounting said knot wheel plate with its peripheral edge located between said furcations when said twisting element is in said rest position, and for rotary indexing movement between a plurality of discrete bristle receiving positions characterized by alignment of one of said plate apertures will said openings in said twisting element comprising the steps of:

feeding an elongated bristle bundle endwise through one of said plate apertures and aligned openings in said twisting element; generating a group of driving pulses; moving said twisting element axially away from said plate a predetermined distance along said nose axis in response to each of said pulses to bend said bundle to form a bight and then alternately; generating a second group of driving pulses; rotating said twisting element about said axis a predetermined angular distance in response to each of the pulses of said second group, and

thereafter repeating in alternating relation said axial and rotary movement of said twisting head until said bundle is intertwisted a predetermined number of turns to form a knot.

6. A method as defined in claim 5 including the additional steps of generating another group of driving pulses representative of the desired angular indexing movement for rotating said plate to the location of the next adjacent knot and rotating said plate in response to said other group of pulses.

7. A method as defined in claim 6 including the additional steps of generating still another group of driving pulses representative of the axial movement of said twisting headnecessary to return said head from its retracted position following the completion of said twisting to its extended position and moving said twisting head forward in response to said pulses of said group.

l060ll 0483 8. In a machine for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material and including means for anchoring an end portion of each length to fix the respective end portions relative to one another-and a rotatable twisting element for slidably holding the lengths intermediate the respective end portions and the free ends thereof and for locating the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of the twisting element, the improvement which comprises:

means for moving said twisting element axially away from said anchored end portions at spaced time intervals in progressive increments of predetermined axial length while said twisting element is held against rotation, and

means for rotating said twisting element through angular increments of predetermined angular size in alternating relation with said axial increments, each increment occurring between two sequential steps of the axial movement thereof, whereby said lengths are intertwisted progressively along a length span thereof by the alternating turning movement of said twisting element.

9. A machine as defined in claim 6 wherein said means for moving said twisting element axially comprises a stepping motor operatively connected to said twisting element for moving said twisting element axially in response to stepped rotation thereof and a programmed source of driving pulses to turn said stepping motor through a predetermined angle in response to each pulse.

10. A machine as defined in claim 6 wherein said means for rotating said twisting head comprises a stepping motor operatively connected to said twisting head and a programmed source of driving pulse to turn said stepping motor through a predetermined angle in response to each pulse.

11. In a machine for making rotary wire knot wheel brushes and including an indexing head for holding an apertured knot wheel plate and means for indexing the head through a discrete angle about its axis, a spindle means mounting said spindle for rotation and for linear movement along its axis of rotation, a twisting head carried by said spindle and means for feeding bundles of wire bristles laterally through the twisting head and through an aperture in said knot wheel plate, the improvement which comprises:

a first stepping motor operatively connected to said spindle for moving said spindle axially between an extended bundle receiving position and a retracted position;

a second stepping motor operatively connected to said spindle for rotating said spindle, and

a programmed source of driving pulses for said respective stepping motors for alternating moving said spindle axially in stepped increments and for rotating said spindle between said axial movement to twist said wire bundle to form a knot securing said bundle to said knot wheel plate.

12. A machine as defined in claim 11 including a third stepping motor for indexing said knot wheel plate and wherein said programmed source of electrical driving pulses includes means for generating groups of pulses representative of the desired angular indexin movement for said knot wheel plate to operate sai third stepping motor.

l060ll 0484

Claims

1. A method for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material comprising the steps of: anchoring an end portion of each length to fix the respective end portions relative to one another; slidably holding the lengths intermediate the respective anchored end portions and the free ends thereof in a rotatable twisting element that locates the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of said twisting element; moving said twisting element axially away from said anchored end portions and linearly along said lengths a predetermined distance; thereafter rotating said twisting element through a predetermined angle to intertwist said lengths in their respective spans between said anchored end portions and said twisting element, and repeating the two steps next above until said lengths are intertwisted a predetermined number of turns.

3. A method for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material comprising the steps of: anchoring an end portion of each length with a stationary anchoring element to fix the respective end portions relative to one another; slidably holding the lengths intermediate the respective anchored end portions and the free ends thereof in a rotatable twisting element that locates the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of said twisting element; moving said twisting element axially away from said anchoring element and linearly along said lengths a predetermined distance; thereafter rotating said twisting element through a predetermined angle to intertwist said lengths in their respective spans between said anchoring element and said twisting element; repeating the two steps next above until said lengths are intertwisted a predetermined number of turns; moving said twisting element axially away from said anchoring element an additionsl axial distance until the free ends of said lengths are released from said twisting element; rotating said twisting element through an additional angular increment to a predetermined starting attitude, and moving said twisting element axially toward said anchoring element to a new starting position.

4. A method for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material comprising the steps of: anchoring an end portion of each length with a stationary anchoring element to fix the respective end portions relative to one another; slidably holding the lengths intermediate the respective anchored end portions and the free ends thereof in a rotatable twisting element that locates the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of said twisting element; generating a group of electrical driving pulses; moving said twisting element axially away from said anchoring element and linearly along said lengths a predetermined distance in response to each of said pulses so that the total distance moved is determined by the number of said pulses in said group; thereafter generating a second group of electrical driving pulses; rotating said twisting element through a predetermined angular increment in response to each of said pulses of said second group so that the cumulative angle through which said twisting element is rotated is determined by the number of pulses in said second group; repeating the four steps next above until said lengths are intertwisted a predetermined number of turns.

5. The method of constructing a rotary knot wheel brush which includes a knot wheel plate having a plurality of apertures spaced about its periphery and a plurality of bristle knots each consisting of an elongated bundle of bristle material bent intermediate its ends to form two leg portions which are helically intertwisted, and a bight portion which loops through one of said apertures, in a machine having a twisting element with a central axis and a bifurcated end portion having opposed openings in its furcations transverse to said axis, said twisting element being mounted for linear movement along said axis between an extended position and a retracted position and for rotation about said axis, means mounting said knot wheel plate with its peripheral edge located between said furcations when said twisting element is in said rest position, and for rotary indexing movement between a plurality of discrete bristle receiving positions characterized by alignment of one of said plate apertures will said openings in said twisting element comprising the steps of: feeding an elongated bristle bundle endwise through one of said plate apertures and aligned openings in said twisting element; generating a group of driving pulses; moving said twisting element axially away from said plate a predetermined distance along said nose axis in response to each of said pulses to bend said bundle to form a bight and then alternately; generating a second group of driving pulses; rotating said tWisting element about said axis a predetermined angular distance in response to each of the pulses of said second group, and thereafter repeating in alternating relation said axial and rotary movement of said twisting head until said bundle is intertwisted a predetermined number of turns to form a knot.

7. A method as defined in claim 6 including the additional steps of generating still another group of driving pulses representative of the axial movement of said twisting head necessary to return said head from its retracted position following the completion of said twisting to its extended position and moving said twisting head forward in response to said pulses of said group.

8. In a machine for intertwisting a plurality of lengths of relatively stiff, deformable filamentary material and including means for anchoring an end portion of each length to fix the respective end portions relative to one another and a rotatable twisting element for slidably holding the lengths intermediate the respective end portions and the free ends thereof and for locating the slidably held portions of the lengths in fixed relation to one another and symmetrically spaced about the axis of rotation of the twisting element, the improvement which comprises: means for moving said twisting element axially away from said anchored end portions at spaced time intervals in progressive increments of predetermined axial length while said twisting element is held against rotation, and means for rotating said twisting element through angular increments of predetermined angular size in alternating relation with said axial increments, each increment occurring between two sequential steps of the axial movement thereof, whereby said lengths are intertwisted progressively along a length span thereof by the alternating turning movement of said twisting element.

11. In a machine for making rotary wire knot wheel brushes and including an indexing head for holding an apertured knot wheel plate and means for indexing the head through a discrete angle about its axis, a spindle means mounting said spindle for rotation and for linear movement along its axis of rotation, a twisting head carried by said spindle and means for feeding bundles of wire bristles laterally through the twisting head and through an aperture in said knot wheel plate, the improvement which comprises: a first stepping motor operatively connected to said spindle for moving said spindle axially between an extended bundle receiving position and a retracted position; a second stepping motor operatively connected to said spindle for rotating said spindle, and a programmed source of driving pulses for said respective stepping motors for alternating moving said spindle axially in stepped increments and for rotating said spindle between said axial movement to twist said wire bundle to form a knot securing said bundle to said knot wheel plate.

12. A machine as defined in claim 11 including a third stepping motor for indexing said knot wheel plate and wherein said proGrammed source of electrical driving pulses includes means for generating groups of pulses representative of the desired angular indexing movement for said knot wheel plate to operate said third stepping motor.