SEWING MACHINE WITH ELECTRONIC GEARDESCRIPTION OF THE INVENTION.
The present invention is directed to a sewing machine that uses positional information signals to electronically engage the movement of the needle to the movement of the coil. A precise timing adjustment is needed between the movement of the needle and the movement of the bobbin on a sewing machine. In order to link the movement of the needle to that of the bobbin, conventional sewing machines use mechanical links, gears, drive shafts, time bands, and other mechanisms, to mechanically connect and mechanically say to engage the coil to the needle. An arm is used to place the needle on top of the coil, with the links between the needle and coil guided through the arm. A single motor is typically used to drive both the needle and the coil by means of the mechanical gear that connects them together. Several disadvantages result from the mechanical link between the needle and the coil; the speed of the sewing machine is limited by the inertia and friction caused by the mechanical links. These mechanical links require constant lubrication, the operation suffers in a system that employs so many moving parts; additional energy is needed to accelerate and decelerate the mass of the bonds. As a result, greater heat dissipation is required to prevent overheating; the noise levels increase, as a result of these moving mechanical parts. Finally, the ergonomic disadvantages associated with the mechanical linkage of the needle and spool, reduce the versatility of the sewing machine by limiting the mobility and placement of the sewing head (needle and spool). Attempts have been made to physically separate the needle and coil, and to use separate electric motors to synchronize the needle with the coil. In U.S. Patent 3,515,080 Ramsey, presents a sewing machine having physically separate separate needle and coil drive units, which are to be synchronized. Step motors are presented as drive units and each one "is connected and works electrically synchronously and in unison". However, Ramsey does not have a system or mechanism to electronically link the needle to the coil. Ramsey presents with some detail, a control system to move the needle and coil laterally in the XY plane, and to rotate them around the Z axis, but there is little or no presentation of how the needle and coil are driven or controlled for sewing ( this is how the up and down movement of the needle is controlled and the rotation of the coil is controlled coil coupling and hooking the thread that is being carried by the needle). The prior art provides an inflexible approach to coordinate the movements of the needle and spool during sewing. Whenever a needle type is changed or the thickness of the material changes or the coil is changed to a loop, one of the sewing parameters has changed. The machines of the prior art can not automatically adjust to those changed parameters; instead, prior art machines employ a physically separate needle and coil that must be readjusted manually to operate within the new parameters.
The object of the present invention is to eliminate the difficulties presented by the prior art by electronically joining or meshing the movement of the needle to that of the coil, using position information. In doing so, the present invention seeks to eliminate any mechanical connection between needle and spool, thereby improving efficiency, reliability and versatility. Another object of the present is to reduce or eliminate the intervention of the user when a parameter of the sewing mode is changed. Another object of the present is to improve safety by controlling the rotation movement of the motor continuously. Another object, is to provide the ergonomic advantage that the head is capable of mounting where needed, so that it faces the material and provides the capacity for multiple applications of the head. With respect to the above objects and others, the present invention provides an apparatus for sewing a yarn through a material. The sewing apparatus has a plurality of sewing parts, which move in a sewing movement through a range or range of sewing positions to sew a thread in the material. Servomotors are connected to the parts they sew to produce the sewing movement. The monitors continuously monitor the sewing positions of the moving parts and produce guide signals corresponding to the sewing positions. Means of data acquisition and control, receive the signals from the monitor and produce commands for each servomotor to allow the electronic gearing of the sewing parts, so that they move with cencertación among themselves; a user interface connected to the data acquisition and control means allows the user to select stitch templates stored in the electronic memory, and to set various other sewing parameters. A means to disconnect all servomotors is provided in case the moment of rotation in any of the servomotors exceeds predetermined limits; A manual wheel is also provided to allow a manual mode in the electronic gear movement of the sewing parts. In a preferred embodiment, this invention provides a sewing apparatus having a needle and bobbin mechanically separated in its driving parts for sewing fabric. The sewing machine includes a servo motor connected to a coil to form a coil assembly. The needle and coil assemblies combine to form a sewing head where each assembly is functionally located on opposite sides of the fabric when sewing. A needle monitor produces signals corresponding to the positions of the needle, and a monitor The coil produces signals corresponding to the positions of the coil. A controller receives the signals from the corresponding monitors and produces commands for the needle and coil, thus allowing an electronic gear of the coil to the needle. the monitor signals are produced by encoders attached to the servo motor. A user interface connected to the digital controller allows the user to electronically store, and subsequently select from the electronic storage, templates or stitch patterns and other parameters for sewing. It also provides a means for a two-dimensional movement of the fabric between the stitches, to cushion on the other hand the movements of pulling the machine and to offer a uniform tight stitch, each movement of the fabric consumes the maximum amount of time available between the stitches. Multiple head applications are made possible by the invention. The multiple sewing heads are connected to the controller so that the needle and coil of each individual head are electronically geared. In another preferred embodiment of the invention, a method is provided for electronically engaging a plurality of sewing parts in a sewing machine wherein the machine has at least one needle and one coil. The first step of this method requires designing one of the parts electronically engaged as master or principal. The second step requires designing all other parts as slaves. The third step requires initializing all electronically engaged parts to a home position. The fourth step is to control the positions of all electronically engaged parts. The fifth step requires the commanded movement of the slave parts as a function of the controlled position of the main part. The position control of the sewing parts allows a multivibrator alternative of the main part and the slaves if one of the parts Slaves is unable to follow the main one. Another preferred embodiment of this invention provides a sewing apparatus having a sewing needle for sewing a thread through a material. A needle motor moves the needle through a series of positions in a reciprocal movement to sew the thread. in the material. A needle pulse is connected to the needle motor to give power to the needle motor. A manual wheel allows manual control of the position of the needle in its series of positions, by means of a control on the wheel. The wheel monitor controls or verifies the position of the wheel and produces a signal corresponding to the movement of the wheel. A controller responds to the monitoring signal of the 5 wheel, controlling the needle motor to move the needle in its range of reciprocal movement in response to the movement of the wheel.In the drawings, equal reference figures 10 are used for the equal parts, thus indicating the same or similar elements: Figure 1 is a diagram of a two-needle band loop in an electronic gear sewing machine; Figure 2 is a general illustration of the apparatus of".. the invention; ~~ Figure 3 is a somewhat isometric view of the X-Y table to which the servo motors are fixed; Figure 4 is a functional block diagram of the frame of the sewing machine with the attached servo motors; Figure 5 is a functional block diagram of the feedback and command structure of a two-needle, two-needle, loop-type sewing machine with electronic gear; Figure 6A is a block functional diagram of the feedback and command structure of a five-hole, five-needle, button-hole, electronic gear sewing machine; Figure 6b is a block diagram of a needle / bobbin head for the buttonhole sewing machine of Figure 6A; Figure 6C is a somewhat isometric view of the heads for the sewing machine of the button hole of Figure 6A; DETAILED DESCRIPTION OF THE PREFERRED MODE In accordance with a preferred embodiment of the present invention as shown in Figures 1 and 2, the hardware configuration for an electronically geared two-band loop stitch sewing machine 10 is illustrated . The stitching can be done by the electronic gear of the needles 22 and 24 that have a hook to catch the thread during sewing to create a closing stitch. Alternatively, a linker replaces the bobbin and hook to create a chain stitch . (For simplicity a coil with a hook or a linker will be called hereafter coil simply). There are no mechanical synchronizing links or rods connecting the needles 12 and 14 to the coils 22 and 24. the elimination of the mass associated with the axes of drive and mechanical links allows the sewing machine 10 to quickly reach the maximum speed due to the lower inertia, thus eliminating many of the problems associated with the acceleration and deceleration of the sewing machine 10. the advantages achieved by the elimination of those moving parts include greater safety, reduced heat and noise levels, and lower energy consumption. Still referring to FIGS. 1 and 2, the two needles 12 and 14 are rigidly connected by a needle bar 16 so that they move in unison. The needle bar 16 connects to a flywheel 18 by means of a shaft 20. The flywheel 18 is driven by the servo motor 26. By joining the needle bar shaft 20 to a flywheel 18 at a point displaced from the center of the flywheel, a vertical sewing movement of the needles 12 and 14 when the servo motor of the needle 26 rotates the flywheel 18. Each of the coils 22 and 24 is driven by the servo motors 28 and 30. And each of which operates at twice the speed of the servo motor. needle 26. On one side of each of the needles 12 and 14 have a pneumatically driven foot 32 and 34 for stopping the fabric 90 in the guide 36 when sewing. Each leg 32 and 34 is moved vertically by a pneumatic cylinder 38 and 40 during the sewing process. When the legs 32 and 34 are actuated, the fabric is stopped firmly between the legs 32 and 34 and the guide 36 to provide a uniform stitch and allowing a two-dimensional movement of the fabric 90 during sewing. When the stitch is complete, the trimmers 60 and 62 are driven by the pneumatic cylinders 42 and 44, cutting the coil and needle threads. Following the reference to figures 1 and 2, the cloth 90, when held in place by the action of the leg cylinders 38 and 40, moves in a direction of the X axis and in a direction of the Y axis. in relation to needles 12 and 14, which remain stationary in the X-Y plane. This X-Y movement allows the sewing machine 10 to sew a variety of stitch patterns. The two leg cylinders 38 and 40, the two legs 12 and 14 and the guide 36 are rigidly connected to a clamp 46. the clamp 46 is rigidly connected to a table XY 48 so that the movement of the XY table induces a movement same on the legs 12 and 14, on the leg cylinders 38 and 40, and on the guide 36. As shown in figures 1 and 3, the movement of the XY table 48 is controlled by two servo motors. An X axis servo motor controls movement along the X axis by rotating a translation screw 54 attached to the 48 XY table. A Y axis servo motor 52 controls movement along the Y axis by rotating a translating screw 56 attached to the Y axis servo motor 52, thereby allowing unobstructed movement of the translational screw 56 of the Y axis along the X axis. Figure 4 illustrates the frame 96 of the sewing machine with the servo motor needle 26 and the coil servomotors 28 and 30 already installed. The coils 22 and 24 are shown connected to their respective servo motors 28 and 30. The verification of the position of the sewing parts allows an electronic gearbox of the movements of the parts for sewing.These are parts that are required to be moved exactly during sewing operations, including needles 12 and 14 and coils 22 and 24. An example of a part not shown in figures 1 and 2 is an electronic thread taker. nico A conventional thread tensioner 27 is used in the preferred embodiment in place of an electronic wire taker. Although the preferred embodiment uses rotary servomotors for the needles 12 and 14, the coils 22 and 24, and the X-Y table, it is understood that linear servo motors may also be used. The position control can be done by any effective position signaling method. In the preferred embodiment as shown in Figure 5, each of the servomotors is equipped with an encoder 110, 112, 114, 116 and 118 to control the position of the servomotor load. The position information of the encoder is of the incremental type. This can generally be considered as a series of pulses. Where each pulse represents a specific amount of angular movement about the servomotor axis. For example, an encoder that has a resolution of one pulse per degree of motion around the servomotor axis, would give 360 pulses for each complete revolution of the servomotor. The rotation of the servomotor equals a specific position of the load so that 150 pulses from the home or starting position of the needle encoder equals 114, for example, so that the needles 12 and 14 are placed one inch above the fabric 90. In an alternative mode, absolute position information is provided from the reference around the servomotor shaft so that instead of a series of pulses, the encoder emits a signal corresponding to 100 degrees when the servo motor has moved 100 degrees from the reference.The absolute position information can also be easily determined from the incremental position information. Referring still to Figure 5, each servo motor 26, 28, 30, 50 and 52 is connected to a drive servo 120, 122, 124, and 128 (as illustrated) to provide excitation to the servo motor. The movement commands for each of the servomotors 26, 28, 30, 50, and 52 are generated by a motion controller 104 and then passed to the servo drives 120-128 via an interface 130. This 130 is either a guide of digital data or is direct hardware link between the motion controller 104 and the servo drives 120-128 and the pneumatic pressure feed 132. The movement commands in the preferred embodiment are in the form of analog voltages, but it is understood that also digital commands can be used. Each command or movement order uses a curve profiling to eliminate the thrust of the machine, and instructs the corresponding servo drive to provide a specific amount of current to the servo motor. The motion controller 104 knows how far each servo motor 26, 28, 30, 50, and 52 should move in each given period of time, thus periodically adjusting the analog voltage level for each movement command to prevent an excess or lack of servomotor travel. For example, to move the coil 22 an analog motion command corresponding to the desired movement of the coil 22 is generated by the controller 104 and sent to the impeller 120 of the coil I. The analog motion command is received by the coil driver 120 and used to provide an electric current for the excitation of servo motor 28 of coil I. The encoder 110 controls the position of servo motor 28 and outputs this to position controller 104. This receives digital position information from coil driver 120. and uses it for two purposes, first the information of the encoder 110 is used by the controller 104 as feedback to determine if the servomotor 28 has traveled the stretch it should have traveled. If the ordered motion differs from that performed at a predetermined distance, then the controller 104 increases or decreases the voltage level of the analog motion command to increase or decrease the speed of the servomotor 28. Secondly, the encoder information is used by the controller 104 for limiting the moment of rotation in the servo motor 28. This limiter of the rotational movement prevents the motion controller 104 from increasing the analog voltage movement command beyond a predetermined limit, limiting the maximum amount of current that it has to feed the servo motor. In an alternate mode, the encoder 110 by its position information is used by the coil driver 120 to feed back and allow comparison of the commanded movement with the realized movement. In this alternative mode, the coil driver 120 adjusts itself to servo motor 28 to correct any excess or lack of travel In the preferred embodiment, AC servomotors are used for coil servomotors 28 and 30 and needle servo motor 26, and DC servo motors are used for X axes and Y. The servo drives 120, 122, and 124 for each of the AC servomotors are preferably YESKAWA servo drives. The servo drives for each of the DC servomotors are preferably servo drives C0MPUM0T0R OEM670X The encoders 110, 112, and 114 for each of the CA 26-30 motors are preferably magnetic encoders, such as SONYMAGNESCALE INC. Magnetic Encoder RE90B-2048C. The encoder position signals 110-114 are guided through the servo drives 120-124 to the interface 130 for use by the motion controller 104 in calculating the movement commands. The X axis servo motor 50 and the Y axis 52 motor are preferably DC servomotors. The servo drives 126 and 128 for each of these DC servomotors are preferably OEM670X COMPUTER OVER servo drives. The encoders 116 and 118 for each of the DC servo motors 40 and 52 are preferably optical encoders such as COMPUTER OPTICAL PRODUCTS, INC CM350-1000 -L.E1 encoder 116 and 11 118 send their position signals that are brought directly to the motion controller 104. The position information of the encoder is used by the controller 104 as feedback control of the servomotor. Still referring to Figure 5, the motion controller 104, which is part of a computer 102, and its associated software can be considered as a plurality of movement command axes, so that a command axis is established for each servo motor and its corresponding driver. For example, a command shaft is established for the needle driver 124, the needle servo motor 26, and the needle servomotor encoder 114. A separate command shaft is established for the bobbin driver 120., the servo motor 28 of the coil 1, and the encoder 110 of the same coil. Each movement command axis calculates the movement commands as a function of the encoder position information from all servomotors 28, 30, 32, 50, and 52. Motion commands provide the 120-128 impellers with related information with the desired movement of the servo motors 26, 28, 30, 50 and 52, and each command of movement and movement resulting from the servo motor can be seen generally as a pulse due to its relatively short duration. More rapid stitch operations require a shorter duration and higher frequency movement commands, the motion controller 104 is programmed to control the position of the servomotors 26, 28, 30 50 and 52 by generating movement commands corresponding to the frequency and current of those pulses to be supplied to servomotors. In the preferred embodiment, PC Bus Motion Controllers cards such as GALIL DMC-1000 cards that have eight motion control axes per card with multiple card synchronization are used within the computer 102. Each axis of the motion controller 104 generates an appropriate movement command for its corresponding servomotor and driver. The control by the motion controller 104 of the encoders 110-118 allows the electronic gearing of the coils 22 and 24 and of the needles 12 and 14. The encoder 110-118 in its control is used, for example, to designate one of the servomotors as master with the other servomotors enslaved to the master. For example, in the preferred embodiment, the coil servomotors 28 and 30 are enslaved to the needle servomotor 26, which is the master, so that each enslaved control shaft controls the needle servomotor encoder 114 and generates the appropriate movement command for the concerted movement of the slave motors with the needle servomotor 26. In an alternative mode, any of the servomotors may be the master. If information is provided via encoders 110-114, which indicates one of the slave servomotors is unable to keep up with the master servomotor, and is behind the master, with, for example 50 encoding pulses or more, the controller of movement 104 will cause the master servomotor to slow down. This effectively multivibrators the identities of the servomotors and the slave servomotor suddenly becomes the master servomotor. In the alternative embodiment, the servomotor of the X axis 50 and the axis 52 of the Y axis are enslaved to the needle servomotor 26 in such a way that the movement of the XY table 48 is as slow as possible. In other words, when the needles 12 and 14 move upwards and release the fabric 90, the table XY 48 will begin to move, and the speed of that table 48 is calculated to achieve the desired XY axis movement at the known time required for the needle to be moved. Lift to the extreme part of your path and return to the point where you must again penetrate the fabric 90. Consuming the maximum length of time between the stitches in order to move the table 48 XY otherwise cushions the pushing movements of the machine and reduces or eliminates the problems associated with acceleration and deceleration, thus allowing the sewing machine 10 to reach the stitch or seam shape as smooth and tight as possible. In the preferred embodiment, the XY table begins its movement When the needle encoder 114 has an output of 2800 pulses from the home or split position with the needles 12 and 14 rising to a height that is approximately one quarter of an inch (0.62 cm) above the plane of the trouser guide 36, and the XY table completes its movement when the needle encoder 114 has an output or emission of 4000 pulses from the home position and the needles again lower a position about a quarter of an inch above the plane of the pants guide 36. As an alternative to the master-slave arrangement of the preferred modality, the electronic gear can generate movement commands without reference to a master. Each controller axis receives positional encoder information based on the positions of all the parts that they sew. If the said information indicates that one of the servomotors is unable to keep pace with the others and is behind the others, for example, 50 coding pulses or more, then the servomotor left behind is designated as master of all the others control axes and these are enslaved to keep the gearbox electronic gear. Therefore an alternative mode is presented where a slave-slave arrangement does not exist until there is a delay in one of the servomotors. Each encoder 110-118 is equipped with a reference position indicator, allowing the movement controller 104 to command each servomotor 26, 28, 30, 50, and 52 to find a reference point and then move to home or origin point This home position is used to start the sewing machine 10 and start sewing operations. The encoders 110-118 sense the movement from the home position and produce signals corresponding to such movements. The start (move the servomotors to the home position) and the selection of the stitch template is performed using the user of an interface 100, for example a screen monitor per touch. A software package for the user, such as Visual Basic, is used to generate interface screens. The stitch templates are stored in an electronic storage, including the hard disk of the computer 102 and other magnetic media, RAM and ROM, and selected by the user by the touch screen monitor 100. A wheel is shown in FIG. hand or steering wheel11 which is similar in function to the steering wheel of a conventional sewing machine. The flywheel 11 becomes operable after being selected from the touch screen monitor 100. As illustrated in FIG. 5, an encoder 140 is connected to the flywheel 11 to provide to the movement controller 104 with handwheel movement signals. Alternatively, a servomotor can be connected to the handwheel 11. Once the handwheel has been selected, all the sewing parts become slaves to the handwheel, so that the movement signals of the handwheel they dictate all the movement commands that are sent by the motion controller 104 Therefore the flywheel 11 gives the ability to use a manual mode, but an electronically geared movement of all the parts that sew and are with an electronic gear. The computer 102, in addition to allowing the operation of the electronic gear of the parts that sew also allows a great variety of other automated functions., One that allows the computer 102, is the limitation of the moment of rotation to improve the security. The computer 102 calculates and controls or checks the current that is required per pulse for each servo motor. When, for example, the needles 12 and 14 are passing through a heavy cloth 90, more current is required per pulse to the servo motor of the needle. (to have more torque) to maintain the desired speed of operation, this is the need for more moment of the servo motor 26 increases. Likewise, if the needle tries to pass through a finger, more current will be required to maintain the selected speed of operation. By a manual application by the user the interface 102 has a set time limit. This limit is continuously compared to the need of the moment of the servo motor. When a finger is struck by a needle 12 or 14, or when another obstruction causes an excessive amount of the required moment, the computer 102 turns off the sewing machine 10, preventing further damage to the finger or other obstacle, instead of ordering the servo motor 26 that provides more moment of rotation above the established limit. This also prevents self-destruction of the sewing machine 10. The shutdown by the moment limit of the sewing machine 10 for blocking is a two step process. Firstly a Current limit defined by the user prevents the computer from commanding a level in excess of the defined limit. The limit will vary depending on the thickness and the resistive properties of the material being sewn. For thin materials, a low limit is set. For thicker materials a higher limit. Once the current limit is reached, the computer will maintain the current at that level until the encoder with its information indicates that the blocked servo motor is being left behind by say, 50 pulses or more. At this point, the master and slave motors identify with their multivibrators whether the locked servo motor is a slave. If it is that master motor, there is no multivibrator. If the blocked servomotor continues to be left behind, for example by another 50 or more pulses, even though the maximum current is being ordered, then the computer turns off the sewing machine 10 .
Another function performed by the computer 102 is the control of the real time of production and maintenance of the sewing machine 10. The computer controls the amount of time that the sewing machine has worked 10,1 at the speed at which it operates, and the energy required for a period of time.This feature allows an automated maintenance sequence of the sewing machine 10. The components are modularized to improve maintenance.For example the coils 22 and 24 shown in figure 3 can be easily removed and replaced with linkers. The versatility of the electronic gear on needles 12 and 14 to coils 22 and 24 allows the user to make parameter changes without having to manually reset other parameters of the machine. The electronic gear allows automatic adjustment to new sewing parameters. There are innumerable variations for the application of electronic gear to sewing operations due to the elimination of conventional sewing links, for example the interior seams of the denim trousers. This type of machine typically requires a short throat to maintain high speeds, the electronic gear allows the operation with high speed of even long-throat sewing machines, since there are no mechanical links or drive axes to slow the operation. Another application of the present invention is a button hole sewing machine for sewing multiple button holes simultaneously. Figure 6A shows a high level block diagram for the configuration of a buttonhole sewing machine, which makes it in five holes. A computer 202 coordinates the electronic gearing of the coil heads 204, 206,208,210 and 212 of five holes that are spaced, center to center, by sufficiently small distances to allow simultaneous seaming of the button holes, this is from approximately 6.25 to 10 cm. As shown in Figure 6B, each needle coil head 204-212 comprises at least one needle 220 and one driver 226 with a corresponding servomotor 22, coder 224 and driver 226 and one coil 230 with a servo motor 232, coder 234 and driver 236. The needle servo motor 22, the encoder 224 and the needle 220 form a needle assembly 228. The coil motor 232, the encoder 234 and the coil 230 form a coil assembly 238. As illustrated in FIG. 6C illustrates , the needle assembly 228 and the spool assembly 238 of each sewing head 204-212 that are structurally fixed in opposite manner from each other so that the needle assembly 228 of each head is positioned on the opposite side of the fabric 250 that its corresponding coil assembly 238 when sewing. The electronic gear of each of the heads 204-212 is made possible by the use of the position information provided for example by encoders attached to the servo motors, as described previously.
The needle of each head 204-212 is electronically geared to the coil of the same head. Although not necessary, electronic gearing between the needles and coils of all heads 204-212 is also preferred. Multiple spindle applications of the present invention are made possible because the needle and coil are physically free from each other. This physical separation allows the coil heads 204-212 to move in three dimensions when sewing, allowing sewing operations in three dimensions. Now, instead of bringing the fabric to the sewing machine, the present invention allows to carry the sew the fabricIt is contemplated and evident to the technicians, by the above description and the appended drawings that there are multiple possible variations in the embodiments of the invention, without departing from the spirit and scope of the present invention.