BACKGROUND OF THE INVENTION

Field of the Invention The present invention relates to woven, endless ti reinforcement belts.

In recent years, endless- oven tire reinforcement belts have been shown to provide a number of advantages ove breaker belts of more conventional construction. According to the preferred method of production, these endless belts are woven from coated continuous reinforcement material by laying it in an ordered zig-zag pattern on the surface of a forming drum or other endless weaving surface.

It is an advantage of production that the woven belts are rapidly formed. Unfortunately, however, if it is desired to switch from production of reinforcement belts of one width to another, or one cord angle to another, or one thickness to another, it has been necessary in practice to make a number of adjustments to the weaving apparatus. Thes adjustments may be necessary, not just for a single pro¬ duction run, but also for each belt woven. Some of these adjustments may be mechanically complex and cumbersome, such that it is not economically feasible in a production setting to weave such belts. This problem is particularly acute if it is desired to weave a production series of single belts comprising multiple belt portions having different widths, thicknesses, or cord angles within each single belt.

It would be desirable to have a method and apparatus that would simplify the production of woven, endless tire reinforcement belts and provide flexibility in enabling rapid, economical changes in belt parameters such as width, thickness, and cord angle.

Discussion of the Prior Art

Tire reinforcement belt winding machines are known in the prior art. For example. United States Patent No. 3,748,203 to Green shows in FIG. 1 thereof a schematic illus- tration of one form of apparatus for producing an endless reinforcement. In the ^, 203 patent, the guides are inter¬ connected by a cable and pulley arrangement. The drum and guides are driven by a motor. The guides are arranged through suitable mechanical linkage to reciprocate across drum surface transversely to the direction of rotation of the drum. A gear train includes a suitable arrangement of gears to control the movement of the guides with respect to the drum so that the strips are laid on the drum surface in a predetermined pattern. The disadvantages of the '203 patent include the limitations imposed by the gear train. If it is desired to weave belts or belt portions having different predetermined patterns, such as differing cord angles, it is necessary to change the gearing ratios, such as for example by physically changing the gears. This is time consuming as well as cumber some and can be prohibitively so where it is desirable to weave different patterns for each single tire reinforcement belt produced. Also, no provision is made in the '203 patent for producing belts where the two guides lay down strips having different cord angles that may differ from belt por¬ tion ^' to belt portion within a single belt.

United States Patent No. 4,600,456 to Oswald-also shows a method and apparatus for forming woven endless tire reinforcing belts wherein the drive for the drum is a first electric motor and the drive for the weaving heads is a second electric motor. The relative speeds of the motors are

synchronized by a phase lock loop controller and associate circuitry or other suitable servomotor control system. Th phase lock loop controller will preferably be of the high gain, high accuracy type and can be set to a desired ratio speeds for the two motors by suitable means such as a digi thumbwheel switch. In the preferred embodiment, the speed the motor for the weaving heads will be monitored by an encoder which provides a reference signal to the phase loc loop controller. The speed of the drum drive motor will b monitored by an encoder, which also provides a feedback signal to the controller. The corrected drum drive speed then provided to the motor by the controller. The guide means are arranged to function in mirrored relationship to one another. The disadvantages of the '456 apparatus and method include the limitations that no provisions are made for producing belts wherein the cord angles may differ from bel portion to belt portion. For example, no provisions are ma in the '456 patent for weaving the type of improved belts disclosed in copending application serial number 929,602, filed November 12, 1986, such as where a reinforcing belt i disclosed including a first belt portion having a first wid W^ and cord angle A^ with a second belt portion having a second, narrower width W ₂ and a cord angle A ₂ woven onto the radially outward side of the first belt portion.

SUMMARY OF THE INVENTION Apparatus is provided for weaving a woven endless tire reinforcing belt on an endless surface in a zig-zag pattern. The apparatus comprises input means for receiving information defining the zig-zag pattern, means for storing the information, central computer control means for reading the stored information and controlling the weaving of the belt as defined by the information, at least one endless weaving surface, means for continuously rotating the weavin surface under computer control, at least one reinforcement

guide means for supplying cord reinforcement to the weaving surface, and at least one means for reciprocating the guide means under computer control. The computer controls the rotating means and the reciprocating means to reciprocate the guide means in timed relationship to the rotation of the weaving surface to effect the laying of said cord reinforce¬ ment on said surface in said zig-zag pattern in accordance with said information.

It is an object of the present invention to provide a programmable apparatus and method for forming endless tire reinforcing belts.

It is an object of the present invention to provide apparatus for forming endless tire reinforcing belts wherein the width of the belts woven can be readily changed from one belt portion to another.

It is a further object of the present invention to provide apparatus and a method for forming endless tire reinforcing belts wherein the cord angle of the belts woven can be readily changed from one belt portion to another. It is a further object of the present invention to provide apparatus and a method for forming endless tire reinforcing belts wherein the thickness, or ply, of the belts woven can be readily changed from one belt portion to another. Further attendant objects and advantages of the present invention shall become apparent from the following brief description of the drawings in light of the detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of one preferred em¬ bodiment of the present invention;

F-CG. 2 is a block diagram of the apparatus of the FIG. 1;

FIG. 3 is a flow chart depicting the method of the present invention using the apparatus of FIG. 1? and

FIG. 4 is a schematic representation of one desir¬ able zig-zag pattern for tire reinforcement belts that can woven with the apparatus and method of the present inventio

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The schematic diagram of FIG. 1 read in conjunctio with the block diagram of FIG. 2 best illustrates a first preferred embodiment of the present invention.

FIG. 1 schematically represents a preferred appara tus according to the present invention in operation during the early stages of formation of an endless tire reinforcin belt. As shown, the apparatus includes a flexible endless belt 22, which may be.a multiple ply belt of reinforced rubber or of stainless steel having a thickness of from abou 0.032 to 0.035 inches. The outer surface 24 of the endless flexible belt 22 comprises an endless weaving surface upon which the coated continuous cord reinforcement strips 18 and 18' are laid to form the reinforcing belt. The inner surfac of the endless flexible belt 22 may have means such as a "V shaped projection (not shown) to mate with a complimentary notch in support members to assure tracking.

To support the endless weaving surface carried on the flexible endless belt 22, means comprising a plurality o support members, here shown as cylindrical members 26 and 28 are provided. If desired, a greater number of support mem- bers can be provided. All of the support members are rotat- able about spaced parallel axes, here shown as defined by th centers of shafts 30 and 32. Due to the buildup of tension during winding, means should be provided for securely lockin the shafts at the desired spacing. According to the embodi- ent shown in FIG.l, the support member 26 is the driven member with support member 28 being driven by it due to the endless flexible belt 22 being tensioned thereover during operation.

Member 26 is driven by means operatively engaged with shaft 30 to cause rotation in the direction shown by th arrow and movement of the belt being formed in a generally

left-to-right direction in the drawing. Suitable drive mean preferably including a servomotor 31, appropriate gearing, and a phase lock loop or other servomotor control system, as will be explained in more detail below, are provided. Any suitable means for rotating the weaving surface can be used, so long as the rotating means such as for example servomotor 31 is responsive to control signals to rotate the weaving surface at a controlled angular velocity.

It is understood that a weaving drum means may be substituted for the weaving belt of FIG. 1. By way of example only, such a weaving drum apparatus is disclosed in United States Patent No. 3,706,623 to Klein or United States Patent No. 3,761,340, also to Klein. The use of a weaving belt or drum is a design choice that is not part of the present invention.

The embodiment shown in FIG. 1 is capable of laying two coated continuous cord reinforcement strips on the end¬ less weaving surface 24 simultaneously. This is currently the preferred mode of operation, however, the same principles apply regardless of the number of cord reinforcement strips employed, whether it be one or a greater plurality.

Each of the strips, 18 and 18' are supplied to the endless weaving surface 24 by independent reinforcement guide means shown generally as 38 and 38'. Because each of these means functions in the same manner, except that one is the mirror image of the other, the operation of only reinforce¬ ment guide means 38 will be described in detail. The like parts on the other means will be the same with like parts performing like functions having the reference number dis- tinguished in the drawing by the use of prime numbers.

Both of these reinforcement guide means 38 and 38' can be simply and effectively moved in the requisite timed relationship to the movement of the weaving surface by oper¬ able engagement through suitable gearing with a traverse motor 37, which is synchronized with drum drive 31 for the endless weaving surface. Traverse motor 37 can be any suitable means for reciprocating the guide means and is

preferably a servomotor. Drum drive 31 is also preferably servomotor. This engagement is schematically indicated in the drawing of FIG. 1.

Traverse motor 37 operates cam drive 64 through pulley arrangement 66. Cam drive 64 converts the rotationa output of motor 37 to reciprocational motion by conventiona means not forming part of the present invention. Recipro¬ cational motion is output on arms 67 and 67' . This reciprocational motion is transmitted to weaving heads 38 a 38' by pump rods 69 and 69'. Weaving heads 38 and 38' are operatively connected to guide members 68 and 68'. United States Patent No. 4,061,524 to Tolan describes such an arrangement as would be suitable for the present invention. The relative speeds of motors 31 and 37 are syn- chronized by phase lock loop controller 33 and associated circuitry or other suitable servomotor control system. The phase lock loop controller will preferably be of the high gain, high accuracy type and can be set to a desired ratio speeds for the two motors by signals issuing from the pro- gram able logic controller. The speed or angular velocity o motor 31 will be monitored by encoder 36 which provides a reference signal, or angular velocity feedback signal, to th control means such as phase lock loop controller 33.

The speed or angular velocity of motor 37 will be monitored by encoder 35 which provides a reciprocation feed¬ back signal to the control means such as controller 33. The angular velocity of the motor 37 is directly related to the speed of reciprocation of the guide means or weaving heads 3 and 38'. By controlling this angular velocity, the reciproc tion speed can be controlled, thereby controlling the cord angle at which the reinforced strips are laid on the weaving surface.

Computer means compares the weaving surface angular velocity feedback signal and the reciprocation feedback signal with information A _n defining the desired cord angle. Any corrected reciprocation speed if necessary is then provided to motor 37 by the controller 33.

In operation, an individual coated continuous rein¬ forcement strip 18 is fed between counter-rotating rollers 42 and 44, which are operable to lay the strip under pressure against endless weaving surface 24. The movement of the reinforcement guide means 38 and

38' back and forth in a direction generally transverse to the direction.of movement of the endless weaving surface 24 is achieved by moving guide means 38 and 38' back and forth on traverse rods 68 and 68' as driven by pump rods 69 and 69'. It can be most easily seen from strips 18 and 18' positioned on weaving surface 22 in FIG. 1 that the width of the belt portion woven by guide means 38, referred to for convenience only as the right-hand weaving head and denoted by the distance indicated as 39 in FIG. 1, corresponds to the amplitude of reciprocation of guide means 38. That is, the greater the distance of travel permitted for traverse rod 68, the greater will be the amplitude of reciprocation and there¬ fore the width of the belt portion woven by weaving head or guide means 38. The width of the belt portion woven by guide means 38' is a mirror image of that portion woven by guide means 38.

A preferred apparatus for adjusting the amplitude of reciprocation of the weaving heads or other guide means is disclosed in United States Patent No. 4,061,524 to Tolan, which patent is entitled Adjustable Traverse Tire Belt Winding Apparatus.

The additional improvement of the present invention includes stepper motor 41 and associated mechanical linkage operatively connected to the screw and nut assembly 70 and 72 to cause cam drive 64 to be moved with respect to traverse rods 68 and 68'. As described in the '524 patent, the dis¬ tance that the traverse rods move in each stroke between reversals will therefore be changed.

The stepper motor arrangement of the present inven- tion provides a means of controlling the amplitude of recipro¬ cation of guide means 38 by signals sent to stepper motor 41. Guide means 38' is in mirrored relationship thereto.

Stepper motor 41 is operatively connected to a central com puter control means, such as the programmable logic con¬ troller 100, which controls the state of stepper motor 41 weave a belt portion as defined by data inputs to the logi controller. This is explained in further detail hereinaft Because of the flexibility afforded by the arrang ment of the. resent invention, a single tire reinforcing b can be woven to include a irst belt portion of width ₁ with a second belt portion of W ₂ woven on the radially out ward side thereof. The second belt portion ₂ can also have a cord angle different from the first belt portion simply by changing the speed of traverse motor 37 relative drum drive 31 under computer control. Such a reinforcing belt is depicted schematically in FIG. 4. The details and advantages thereof are disclosed in copending application serial number 929,602.

Stepper motor 41, which can also be any other suit able means ^' for adjusting the amplitude of reciprocation, is responsive to control signals to weave a belt portion of width W _χ , thereafter a belt portion of width W ₂ , and so on up to a belt portion of width _n .

The zig-zag pattern on the coated continuous cord reinforcement strip within the endless tire reinforcing bel being formed is achieved by timing the movement of reinforc ment guide means 38 and 38' with the movement of the endles weaving surface 24, as described above. The cord reinforce ment is applied to the endless weaving surface in a zig-zag pattern, being positioned across the surface from one side the other. The angle of the cord reinforcement strip to th edges of the belt is reversed and the lengths of the cord reinforcement between reversals are interleaved with length disposed at an opposite angle along at least one line subst tially parallel to and intermediate the edges of the belt.

For one especially preferred embodiment, the param ters of the belt are related according to empirical relatio ships, which are generally described in the following manne

C • an • A _ EPI - C - D ' sin A - _GR 2 - W P - M ± 1 wherein C is the circumference of the reinforcing belt, A is the smaller angle between the cord reinforcement and the edge of the reinforcing belt, W is the width of the reinforcing belt measured perpendicular to the edges, EPI is the number of cord reinforcements per inch measured perpendicular to the cord lengths, P is an integer and equal to one plus the total number of interleaving lines parallel to and intermediate the edges of the reinforcing belt, M and D are two integers having no common factor and which render P'M- ¹ an integer

D with D being less than P, and D and P have no common factor.

GR is the number of repeating cycles of the cord reinforce¬ ment edge and back to the same edge for each circumference of the reinforcing belt. This is, however, at best an approxi- mation and does not hold true for all desired patterns when wound on the apparatus of the invention. There are several factors which make mathematical predictability difficult with this apparatus. Among these are, the changing effective radius and effective velocity of the forming surface. How- ever, with the formula as a guide, the desired pattern can be obtained reproducibly through limited trial and error.

FIG. 2 shows a block diagram of the present inven¬ tion. Programmable logic controller 100, comprising at least one central processing unit, provides central computer con- trol means for controlling the weaving of the belt in accord¬ ance with parameter data input through thumbwheel switch 102. The programmable logic controller (PLC) 100 then outputs con¬ trol signals to stepper motor 41 for controlling the belt portion widths as set forth above. in addition to issuing signals to stepper motor 41 for controlling the belt widths, PLC 100 also controls the system for synchronizing the weaving surface movement with the transverse reciprocation of the guide means or weaving heads 38 and 38'. This timing system is indicated generally by the components encompassed by dotted line 108 and includes

-li¬ the main components of drum drive 31, weaving head drive or traverse motor 37, and phase lock loop system 33. Encoder 3 provides rotational feedback information from drum drive 31 to the phase lock loop system 33. Encoder 35 provides reci procational feedback information to phase lock loop system for the weaving heads. Encoder 124 is operatively connecte to the weaving head drive for providing traverse counting feedback information back to PLC 100.

Thumbwheel switches 102 as shown in FIG. 2, and al as shown in conjunction with the controller 100 in FIG. 1, are for receiving data defining the belt pattern in terms o belt widths, belt cord angles, and belt plies or thicknesses Controller 100 in conjunction with switches 102 includes means for reading and storing appropriate inputs that are representative of the zig-zag pattern, such as W _n , A _n , R _n , and GR _n as described in detail below. The values of the parameters W _n , A _n , R _jj , and GR _n are chosen by the tire designer and are not considered part of the present invention. The different belt patterns that may be desired may be requested of the apparatus of the present invention by th appropriate inputs to the thumbwheel switches 102. Any give belt may be made up of n belt portions 1,2, ... ,n-l,n, wherei the nth belt portion is woven on the radially outward side o the (n-l)th portion.

For example, it may be desirable to weave a rein¬ forcement belt wherein the radially inward belt portion is o width V^_ and cord angle A^ _^ and thereafter a second belt portion of width ₂ and cord angle A is superposed on the radially outward side of the first belt portion. Such a belt and the advantages thereof are described in copending application serial number 929,602, which is hereby incor¬ porated by reference. Theoretically, additional nth belt portions could be woven to form a belt comprising 1,2,..., n-l,n portions radially superposed, each having its own width. Accordingly, the thumbwheel switches are preferably

adapted to receive information specifying the width _1# W ₂ , ... W _n _ ₁ , _n of the successive belt portions.

In addition to the belt parameters _n for the nth portion, any belt to be woven is also characterized by the cord angle A. The cord angle A is defined as the smaller angle between the cord or strip reinforcement and the edge of the reinforcing belt. The cord angle A is determined by the timed relationship between the rotation of the weaving drum as compared to the rate of reciprocation of guide means 38 and 38' on the other hand. The faster the drum rotates in relationship to the reciprocations, the smaller is the cord angle A, and vice versa.

The cord angle A can also be expressed in terms of a gear ratio R, in that a specific gear ratio corresponds to a given cord angle. The "gear ratio" literally describes the gear ratio needed in a mechanical, gear driven system such as that of the ^, 203 patent to achieve a certain cord angle. The PLC 100 and the phase lock loop system 33 are preferably capable of taking the gear ratio information and 'converting it to information for controlling the rotation and reciproca¬ tion to achieve the desired cord angle A.

It may also be desirable to change the gear ratio R for each belt portion 1,2, ...,n-l,n making up a specific belt. Accordingly, it is necessary to specify R _lr R ₂ ,...,

In addition to belt parameters _lf W ₂ , .. • - ^w _n _ι _. W _n and R ₁ ,R ₂ , . • • ,R _n _ι,R _n/ it is also desirable to specify the thickness or number of plies for the various belt portions. The preferred way of doing this is to specify the number of traverses GR. A traverse is defined as one com¬ plete cycle of reciprocation for a weaving head such as guide means 38. The number of traverses will establish how many plies are woven, in particular whether the belt or belt portion will be a one, two, three, or more ply belt. The number of traverses GR necessary to weave a belt of a given ply is generally known in the art and is not part of the present invention.

The number of traverses is counted by encoder 74, which is operatively connected by suitable linkage to pulle 76 of cam drive 64. Encoder 74, which can be any suitable counting means, counts the number of reciprocations of the weaving heads. Encoder 74 is operatively connected to con¬ troller 100, which continuously compares the number of trav ses actually woven with the number of desired traverses GR _n for the nth belt portion. The controller 100 generates con trol signals to stepper motor 41 and also to drum drive 31 and traverse motor 37 through phase lock loop system 33 to begin the weaving of the nth belt portion after the (n-l)th belt portion has been woven.

Just as the different belt portions 1,2, ... ,n-l,n may have varying widths and cord angles, so may the differen portions have different plies or thicknesses indicated by

The programmable logic controller 100 reads the thumbwheel switch settings and stores the data GR _j ,.,^, and _n . PLC 100 preferably comprises a programmable miσro- computer chip set.

The PLC 100 as described more fully in detail below can then generate control signals representative of W _n to stepper motor 41. The PLC 100 also generates control signal representative of R _j ^ to the timing system 108, in parti- cular the phase lock loop system 33. The phase lock loop system 33 may itself have a computer control timing means fo further generating control signals to the traverse motor 37 and drum drive 31 as described in more detail below. These signals are preferably digital pulses, although other signal waveforms can be used as a matter of design choice. The PLC 100 can also generate START and STOP signals to drum drive 3 and weaving head drive 37.

The phase lock loop system 33 can be any suitable control system that accomplishes the timing or synchroni- zation function as already described above with respect to FIG. 1. In a particularly preferred embodiment, system 33 includes a computer control timing means, such as a central

processing unit 78, for controlling traverse motor 37 and drum drive 31 in the appropriate timed relationship. This computer control timing means is under the further control of programmable logic controller 100, in that controller 100 directs unit 78 how to control the timed relationship.

The PLC 100 receives signals representative of the number of traverses counted by encoder 124. When the number of traverses counted corresponds to the desired number of traverses for a particular thickness or ply, then the PLC 100 issues control signals for changing the belt parameters for a second belt portion, or if the belt is completed, a STOP signal to the drum drive 31 and also a STOP signal to the weaving head drive 37.

The apparatus of the present invention may be more clearly understood in conjunction with the flow chart shown in FIG. 3.

Box 130 represents the routine power up stage, where the appropriate power supplies for the motors and control circuitry are energized. After the PLC 100 and associated circuitry has been energized, PLC 100 reads and stores the various belt para¬ meters from the thumbwheel switches 102 for the first belt portion as indicated by box 132 in FIG. 3. The parameters for the belt to be woven will include the number of traverses GR _j _ the cord angle, perhaps expressed in terms of the gear ratio R _1# for the weaving head; and the belt width ^ These parameters for the first belt portion are stored in an appropriate memory.

This process is also completed for the second belt portion by reading and storing the parameters GR ₂ , R ₂ , and ₂ at box 134. This process may be completed for all n belt portions if there are more than two such portions.

Controller 100 in conjunction with phase lock loop system 33 generates control signals to weave belt portion 1, or the first belt portion, in accordance with parameters ^GR 1' ^w l' ^{and A} l* Thereafter, the (n-l)th belt portions

are woven up through the nth portion, the nth portion being on the radially outward side of the (n-l)th portion.

The system is initialized at box 136. That is, th motors 31, 37, and 41 are properly set to their beginning or initial state and the PLC 100 is likewise initialized.

After initialization, PLC 100 at box 138 generates an output signal to stepper motor-41 for adjusting the ampli tude of reciprocation to weave a belt of width W ₁ . This signal is preferably in the form of a series of discrete pulses. Stepper motor 41 responds by driving ball screw 72. Ball screw nut 70 in turn responds by traveling along screw 72 and carrying with it cam drive 64. Output arms 67 and 67 from cam drive 64 therefore may engage pump rods 69 and 69 ^■ at different points along their length to result in differen amplitudes of reciprocation for guide means or weaving heads 38 and 38'.

When the stepper motor 41 is properly set for W _1# the drum drive 31 is activated (box 140) and the endless weaving surface is rotated past the weaving heads 38 and 38'. As shown at box 142 an output signal is transmitted to the traverse motor 37 to provide shaft rotation at a pred termined angular velocity V-^ necessary to operate or reci¬ procate the weaving heads to weave the first belt portion having a gear ratio R^, which may also correspond to a particular cord angle A ₁ as explained above. This output signal may be in the form of a series of discrete digital pulses or an analog signal or a combination of the two, depending upon the particular control system and associated circuitry used. The specific circuitry used is a design choice not forming a part of the present invention.

A feedback signal is read back from traverse motor 37 (box 144) through encoder 35 or other suitable feedback means from which can be determined the angular velocity of the motor 37. The drum drive speed is monitored through encoder 36. Accordingly, it is determined by an appropriate comparison means whether the angular velocity of motor 37 is that velocity necessary to weave a belt portion having a gear

ratio R _η _ (box 146) . If the angular velocity is not correct for weaving the first belt portion with gear ratio R-L, a modified signal is sent to motor 37 until the necessary angu¬ lar velocity is achieved (boxes 148 and 150) . The angular velocity is continuously monitored while the traverse motor is operated to weave the first belt portion, and modified signals are sent to the motor 37 as necessary (boxes 152 and 154) .

The number of traverses are counted through encoder 124 operatively connected to the weaving head drive (box 156) . When the number of traverses counted is equal to GR- _{, /} which is the number of desired traverses for the first belt portion, then the apparatus has completed weaving the first belt portion and now proceeds to weave the next belt portion (boxes 158, 160, and 162).

The basic steps for weaving the first belt portion are then repeated, except with the parameter W ₂ , R ₂ , and GR ₂ for the second belt portion.

An output signal is generated for the stepper motor for adjusting the amplitude of reciprocation to weave a belt of width W ₂ (box 162).

An output signal is also sent to motor 37 for the angular velocity V ₂ , perhaps different from the first belt portion, to operate the weaving heads to weave a second belt portion of ratio R ₂ (box 164) . The angular velocity feed¬ back signal from motor 37 is compared and the control signal thereto is corrected if necessary (boxes 166, 168, 170, and 172) .

The motors 37 and 31 are thereafter substantially continuously operated, while the angular velocity of motor 37 is monitored and corrections made as necessary, until the proper number of traverses GR ₂ have been counted and the second belt portion is completed (boxes 174, 176, 178, and 180) . Although it is not described in FIG. 3, it is under¬ stood that this process can be carried out for up to N belt portions.

Once the belt has been completed through all n portions, the weaving operation is stopped and the belt is doffed or removed from the weaving surface (boxes 182 - 184) It should be understood that various changes and modifications to the preferred embodiments described above will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention, and it is there¬ fore intended that such changes and modifications be covered by the following claims.