APPARATUS FOR PLACING WIRE FASTENERS

Abstract

Disclosed is an apparatus for placing wire fasteners. The apparatus includes: a wire guide, a pivoting hook forming a section of the wire guide, a mechanical feeder of fastening wire, a blade for cutting the wire, a rotary twister, a single electric motor, a transmission mechanism having a wheel for sequential actuation of the hook and the blade, a first sensor of the angular position of the sequential actuation wheel, and an electronic circuit for controlling the electric motor connected to the first angular position sensor. The first angular position sensor is a continuously variable signal sensor that is sensitive to a rotation of the sequential actuation wheel over an angular range of 360 degrees. The apparatus can be used in the field of viticulture and arboriculture.

Claims

1. A tie placement apparatus, comprising: a wire guide for tie wire, extending between a wire inlet and a fixed guide end; a pivoting hook having one free hook end, where the hook forms a segment of the wire guide and pivots freely between an open position in which the free hook end is separated from the fixed guide end, and a closed position in which the free hook end is aligned with the fixed guide end; a mechanical tie wire feeder disposed upstream from the hook; a wire severing blade, where the blade is arranged downstream from the hook; a rotary twister with tie wire feeders arranged upstream and downstream from the hook, and downstream from the blade, where the feeders are configured for intercepting a tie wire in an alignment position of the rotary twister with the wire guide; an electric motor connected to a transmission mechanism comprising a sequential actuation wheel for the hook and the blade; a first angular position sensor of the sequential actuation wheel, configured for delivering a first continuously variable angular position signal over a 360 angular range of rotation of the sequential actuation wheel, where the first angular position sensor is associated with at least one among the sequential actuation wheel and the electric motor; an electronic command circuit for the electric motor connected to the first angular position sensor and receiving the first angular position signal from the angular position sensor, in order to drive the motor as a function of said first angular position signal.

2. The apparatus according to claim 1, wherein the first angular position sensor is a Hall effect sensor associated with at least one rotating magnet mounted on a shaft end of a shaft rotationally secured to at least one among the sequential actuation wheel and the electric motor.

3. The apparatus according to claim 1, wherein the electric motor is a permanent-magnet brushless three-phase synchronous motor, and wherein the first angular position sensor comprises a measurement circuit for at least one among a voltage and current of the phases of the motor, and a calculation unit configured for establishing the first angular position signal based on a measurement signal from the measurement circuit.

4. The apparatus according to claim 1, wherein the electronic command circuit for the electric motor comprises a memory for storing preset positions of the sequential access wheel associated with command phases of the motor.

5. The apparatus according to claim 1, further comprising, a second angular position sensor for the rotary twister, an electric motor associated with the rotary twister and an electronic command circuit for said electric motor associated with the rotary twister, where the electronic command circuit of said electric motor associated with the rotary twister is connected to the second angular position sensor and receives the second angular position signal from the second angular position sensor for driving of the motor depending on said second angular position sensor.

6. The apparatus according to claim 5, wherein the electric motor associated with the rotary twister is the electric motor connected to the transmission mechanism comprising the sequential actuation wheel and wherein the electronic command circuit of the electric motor associated with the rotary twister is the electronic command circuit connected to the first angular position sensor.

7. The apparatus according to claim 5, wherein, the electric motor associated with the rotary twister is a distinct electric motor from the electric motor connected to the transmission mechanism comprising the first sequential actuation wheel.

8. The apparatus according to claim 5, wherein, the second angular position sensor is a Hall effect sensor with continuously variable signal, sensitive to a rotation of a shaft rotationally secured with the twister.

9. The apparatus according to claim 5, wherein, the second angular position sensor is associated with two magnets mounted symmetrically on a support in a plane perpendicular to the shaft rotationally secured with the twister.

10. The apparatus according to claim 1, wherein the electronic command circuit of the electric motor connected to the transmission mechanism, respectively the electronic command circuit of the electric motor associated with the twister, is configured for at least one first stop phase of the rotation of the electric motor connected to the transmission mechanism, respectively the electric motor associated with the twister, during which the rotational speed is locked to the angular position of the sequential actuation wheel.

11. The apparatus according to claim 10, wherein the first stop phase is associated with the closed position of the hook.

12. The apparatus according to claim 10, wherein the advancing feeder for the tie wire comprises a feed roller and a presser roller, where the presser roller is able to move between a position close to the feed roller and a lifted position releasing a passage between the presser roller and the feed roller, and wherein a stop phase of the motor is associated with the raised position of the presser roller.

13. The apparatus according to claim 1, wherein the electronic command circuit of the electric motor connected to the transmission mechanism, respectively the electronic command circuit of the electric motor associated with the twister, is further configured for at least one second stop phase of the rotation of the electric motor connected to the transmission mechanism, respectively the electric motor associated with the twister, during which the rotational speed is locked to the angular position of the twister, where the second stop phase is associated with the position of alignment of the twister with the wire guide.

14. The apparatus according to claim 1, wherein the transmission mechanism comprises a freewheel coupling, coming selectively to engage with the sequential actuation wheel and the twister for opposite directions of rotation of the electric motor.

15. The apparatus according to claim 12, wherein the sequential actuation wheel is a gear wheel connected to the feed roller by a gear.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0107] FIG. 1 is a perspective of a tie placement apparatus conforming to the invention.

[0108] FIG. 2 shows the positioning of the apparatus from FIG. 1 around a branch before receiving a tie.

[0109] FIG. 3 is a view of the apparatus from FIG. 1 in which a front part of the housing and the electronic command circuit have been withdrawn.

[0110] FIG. 4 is a detailed perspective of the principal components of the tie placement apparatus and a transmission mechanism for the movement.

[0111] FIG. 5 is another perspective of components of the tie placement apparatus.

[0112] FIG. 6 is a diagram of rotational speed of an electric motor for the tie placement apparatus conforming to the invention giving a comparative example with the state-of-the-art and showing successive operations for the functioning of the apparatus from the invention during a tying cycle.

[0113] The figures are made at an arbitrary scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

[0114] In the following description, identical, similar or equivalent parts from different figures are labeled with the same reference signs in order to facilitate comparing one figure to another.

[0115] FIG. 1 is a perspective of the apparatus for placing ties. It has the shape of a tying gun 10 provided with a handgrip 12 and an actuation trigger 14. The handgrip 12 is secured to an apparatus body 16 provided with a tie placement head 18. The actuating handgrip is used to start a tie placement operation.

[0116] The tie placement head 18 has an end 19 forming a beak. An opposite end, at the rear of the handgrip 12, has an inlet 20 for tie wire. The inlet 20 for tie wire is an opening receiving a continuous tie wire, unwound from a tie wire coil, for example. The tie wire is not shown.

[0117] In a preferred embodiment, the apparatus body encloses a single electric motor 22 for the mechanical actuation of the tie placement head 18. The motor is suggested in broken line.

[0118] The motor is supplied with electric energy from a rechargeable battery 24 housed in the handgrip 12. The battery is also shown symbolically.

[0119] In the area of the beak 19 of the tie placement head 18, the presence of a twister 30 can be seen.

[0120] FIG. 2 shows the engagement of the beak 19 of the tie placement head 18 on a shoot R and training wire F to be secured by means of a tie. The tie is not shown.

[0121] In FIG. 3, a portion of the housing of the tie placement head 18 was withdrawn so as to show the main components.

[0122] The presence of the rotary twister 30, already visible in FIG. 1 can be seen. The twister is provided with two grasping arms. They constitute tie wire feeders 32 intended to grab and feed a tie wire which will be twisted. For simplification, the tie wire is not shown on the figure.

[0123] The presence of a hook 40 can be noted in the area of the twister. The hook is sheltered by a front part of the casing providing a beak 19 visible on FIGS. 1 and 2. The hook 40 is mounted pivoting on a pivot 42. It is shown in an open position allowing elements to be tied to be introduced under the beak of the tie placement head. In the closed position, shown in FIG. 4, the hook 40 encloses the beak.

[0124] A transmission mechanism for the movement 50 associated with the electric motor is used to transmit the movement from the motor to the twister 30. The movement of the motor is also transmitted to the hook 40, to an advancing feeder 44 for the tie wire, and to a blade 46 intended to cut the tie wire.

[0125] The transmission mechanism 50 is better seen in FIG. 4 which shows components of the mechanism in three dimensions in the position thereof in the tool. It comprises a drive pinion 52 for a longitudinal shaft 54 on which the twister 30 is mounted. The longitudinal shaft 54 is connected via the drive pinion 52 to an electric motor associated with the rotation of the twister.

[0126] In a preferred embodiment where the driving of the mechanical components of the apparatus is done by a single electric motor, the pinion 52 is connected to the longitudinal shaft 54 by the freewheel mechanism 56 with which to drive the longitudinal shaft 54 for only one direction of rotation of the motor. A rotation of the motor in a reverse rotation direction is free without driving the longitudinal shaft 54.

[0127] The transmission mechanism 50 further comprises a sequential actuation wheel 60 driven by an electric motor associated with the sequential actuation wheel.

[0128] In the preferred embodiment, where the driving of the mechanical members of the apparatus is done by a single electric motor, said wheel is also coupled to the motor by a freewheel mechanism 66. The freewheel mechanism 66 serves to drive the sequential actuation wheel only for rotation of the motor in a direction opposite to that driving the twister. A coupling gear wheel serves to couple the electric motor 22 to the sequential actuation wheel 60 and to the pinion 52 for driving the twister. The coupling wheel is not visible in FIG. 4. It appears in FIG. 5 with the reference 58.

[0129] The sequential actuation wheel 60 is a gear wheel serving to actuate the tie wire advancing feeder 44 by gear. The advancing feeder 44 comprises a feed roller 70 together with the presser roller 72. The feed roller 70 is provided with teeth intended to improve feeding of the tie wire. It is mounted on a shaft 91, rotationally secured to a gear wheel 74 continuously engaged with the sequential actuation wheel 60.

[0130] Further, the sequential actuation wheel 60 has a first cam forming roller 80 on the side thereof. During rotation thereof, the first cam forming roller 80 comes to actuate a lever 82, loaded by a spring 84 and actuating via a first link 86 the blade 46 for cutting the wire. The blade 46 is formed by a rotary guillotine intersecting the path of the tie wire. The guillotine is also provided with an actuating lever 88 with a pivot receiving the first link 86.

[0131] The first drive 86 passes above the shaft 91 bearing the feed roller 70 and bears the presser roller 72. The presser roller is mounted in free rotation around a shaft 78 secured to the link 86. Thus, the movement of the first link 86 serve successively to advance the tie wire by holding it on the feed rollers 70 by a pressure of the press or roller 72 and then separating the press or roller and pivoting the blade of the guillotine for cutting the tie wire. This position is retained for FIG. 4.

[0132] FIG. 5 shows another function of the sequential actuation wheel which is that of actuating the hook 40. It further shows actuation of the transmission mechanism 50 by the motor 22 and via the conical pinion 26 on the motor shaft engaging with the conical wheel 58. This corresponds to the preferred embodiment in which only one motor is associated with both the sequential actuation wheel and rotation of the twister.

[0133] A second, cam forming, roller 90 is mounted on the sequential actuation wheel 60 on the surface opposite the one receiving the first cam forming roller. The second cam forming roller 90 is intended to engage with a second lever 92. The movement of the second lever 92 is a rotation around the shaft 91. It is transmitted to a second link 96 connected to a lever 98 of the hook 40 via a pivot 42. The second link 96 is loaded by a spring 94.

[0134] The interaction of the second roller 90 with the second lever 92 serves to move the hook 40 from the closed position thereof, visible in FIG. 4, towards the open position thereof, visible in FIG. 5. When the second roller 90 leaves the second lever 92, the spring 94 returns the second link 96 into a rest position in which the hook is closed.

[0135] It can be seen in FIGS. 4 and 5 that the hook 40 is provided with a groove 41 which provides a guide section for the tie wire.

[0136] The path of the tie wire thus passes between the feed roller 70 and the presser roller 72, then passes in the guillotine forming the blade 46 for engaging in the groove 41 of the hook and reaching a fixed guide end 100 located in the extension of the free end 43 of the hook 40 behind the twister 30.

[0137] The set of components located in the tie wire pathin particular the mechanical feeder 44, the guillotine forming the blade 46, the groove 41 of the hook, the twister 30 and the fixed guide end 100make up a guide for a tie wire. The tie wire as such is an accessory of the apparatus and is not part of it. It is not shown. The twister 30 and in particular the prehensile arms, forming the feeder 32 of the twister 30, intercept the tie wire upstream from the hook, at the outlet of the guillotine 46 and downstream from the free end of the hook, before the fixed guide end 100.

[0138] A good interception of the tie wire is obtained by means of an appropriate angular positioning of the twister 30 shown in FIG. 4. This position is achieved because of the driving of the electric motor in which the speed thereof is locked to the angular position of the twister, in particular upon approaching the desired position.

[0139] The angular position of the twister is measured by means of the sensor 110 which constitutes the second angular position sensor in the meaning of the invention. The second angular position sensor is associated with two magnets 112 mounted on a support 114 rotationally secured with the twister 30 symmetrically about the longitudinal shaft 54 and in a plane perpendicular to the shaft. The second angular sensor 110 is preferably an analog sensor. It involves a Hall effect sensor or a magnetoresistance sensitive to variations of a magnetic field produced by each of the two magnets 112. The magnetic field is a maximum when one of the magnets 112 is closest to the sensor, but the sensor starts to deliver a signal upon the approach of a magnet, or reciprocally as it moves away. Thus, during one full turn of the shaft, the second angular position signal emitted by the irregular sensor 110 passes through two maxima respectively for the two magnets diametrically opposed about the longitudinal shaft 54. The maximum signal gives the precise position of the twister in rest position.

[0140] The signal passes continuously by a minimum when the two magnets are more than 20 away from the angular sensor 110. It is thus possible to anticipate the arrival of a magnet and consequently to reduce the speed of the motor so as to stop it at the moment when the magnet arrives opposite the sensor, without then overshooting the position thereof.

[0141] It is thus appropriate to note that it is possible in this condition to angularly anticipate during each full turn of the twister the arrival of two characteristic positions, since the twister must stop precisely at the end of the twisting cycle on one of these positions without the motor having been previously stopped for restarting at reduced speed towards the following position. Considering the number of twists to be made, the successive detection of the stop positions thus serves to progressively reduce the speed of the motor for just stopping precisely during the last turn in the stopped position of the twister.

[0142] The sensor 110 is connected to an electronic command circuit 120 of the motor 22 which makes use of the variations of the second angular position signal for locking the rotation speed of the motor and for driving a stop of the twister in a position aligned with the tie wire guide and in particular aligned with a portion of the guide made up by the hook 40. Stopping of the twister is preceded by phase of slowing during which the speed thereof decreases as the stop position is approached. One or more stop positions can be stored in a memory 121 of the electronic command circuit.

[0143] The electronic command circuit 120 of the motor 22 also receives a signal, as it happens the first angular position signal, from another sensor 130 which constitutes the first angular position sensor in the meaning of the invention. It can be seen schematically on FIG. 5.

[0144] The first angular position sensor 130 is preferably a sensor with one or preferably several Hall effect probes. For example, it involves a sensor of the type marketed by MPS under the catalog number MP9960.

[0145] The first angular position sensor 130 is associated with a magnet 132 mounted on a shaft 134 rotationally secured with the sequential actuation wheel 60. The magnet 132 has two magnetic poles North and South both positioned in a single plane perpendicular to the axis of the shaft 134. The shaft 134 in question is a shaft which receives the sequential actuation wheel and the coupling gear wheel 58 engaged with the drive motor.

[0146] The rotation of the shaft 134 and the magnet 132 with the sequential actuation wheel 60 creates a variable magnetic field near the first angular position sensor 130 which is converted by the first angular position sensor 130 into angular position data about the sequential actuation wheel. This signal is provided to the electronic command circuit 120 of the motor 22 in order to lock the speed of the motor to the angular position of the sequential actuation wheel and in order to cause shutdown phases of the motor when it is operated with one direction of rotation driving the sequential actuation wheel 60, including for positions distinct from those of the actuation of the cams 80 and 90.

[0147] In another embodiment, the first angular position sensor 130 may comprise a simple sensor, for example a Hall effect sensor associated with an indexing magnet for the sequential actuation wheel, indicating an angular reference position like for example the tying cycle start position. The signal for the reference angular position is then combined with a measurement 140 of the characteristics of the phases of the motor such as for example the voltage, giving an angular position relative to the sensor of the motor 22, where all of this is calculated with the reduction properties in a processor 160 of the electronic command circuit 120 in order to produce the first angular position signal. In this function, the processor 160 is also part of the first angular position sensor.

[0148] Two specific stop positions are in particular conceivable. It involves both one position, shown in FIG. 5, in which the hook 40 is at the farthest open position thereof, and also a position, shown in FIG. 4, in which the presser roller 72 is lifted from the feed rollers 70 in a movement participating in cutting the line.

[0149] The open position of the hook is an important position in which the elements to be attached can be inserted in the tie placement head 18.

[0150] The raised position of the roller is a position facilitating cleaning of the mechanical feeder 44 and, as needed, the replacement of the presser roller 72. It also serves to engage a tie wire in the advancing feeder 44 or to remove a tie wire from it that stayed caught.

[0151] The selection of stop and maintenance positions can be done by a command interface on the body of the placement apparatus visible for example in FIGS. 1 to 3, in particular with a MODE button which is used to select specific preestablished actions, leading to commands for the motor via the electronic command circuit thereof and establishing a rotation of the sequential actuation wheel into a preset position. The stop and maintenance position selection can also be coupled with a specific actuation of the trigger 14, for example maintaining pressure on this trigger for a predetermined time, for example for 2 seconds, longer than a normal actuation of the trigger.

[0152] The operation of the apparatus 10 for tie placement is again shown in FIG. 6 which gives the speed setting 200 for the rotation speed of the motor during a tie placement cycle as a solid line. For comparison, the setting 300 for the tie placement cycle in the state-of-the-art constituted by the apparatus described in the document EP 0,763,323 is indicated by a dotted line.

[0153] In the diagram, the rotation speed is indicated on the ordinate. Positive values indicate a rotation direction of the electric motor associated with the rotation of the sequential actuation wheel. Negative values indicate an opposite rotation direction of the electric motor causing the rotation of the twister. It involves a preferred embodiment with a single motor. In the case where several motors are used, and in particular a distinct motor for actuation of the rotary twister, the negative values represent the velocity setting for the electric motor associated with the twister.

[0154] The abscissa shows the time value over a full cycle starting from the moment when the operator actuates the trigger 14 to make a tie. It is understood that at the moment 0 the hook is open and that the elements to be tied can be inserted into the tied placement head.

[0155] In a first phase 202, the electric motor associated with the sequential actuation wheel is actuated. Advancing of the line and closure of the hook are thus actuated simultaneously. The sequential actuation wheel continues to advance the line until it arrives at the end of the fixed guide. The first cam, meaning the first roller 80, comes into contact with the associated lever 82, in order to proceed with cutting the line by actuating the guillotine 46 and then separates from the lever 82 in order to return the presser roller 72 into pressing on the line because of the restoring spring 84 before stopping the motor. In this first phase, the acceleration and deceleration slopes are small, while giving a rotation setting to the motor up to a speed level V20, for example of 9000 RPM. The apparatus is thus less mechanically stressed.

[0156] The first phase 202 corresponds to a first phase 302 in the apparatus from the state-of-the-art.

[0157] In a second phase 204, the electric motor associated with rotation of the twister is actuated. This corresponds to a change of the direction of rotation of the motor in the case of the preferred embodiment with a single motor. During this phase, the rotary twister is rotated and the sequential actuation wheel then remains in a fixed angular position. The twister makes the tie by making a tighter or looser twist according to the adjustment preferred by the user. The acceleration of the motor at the beginning of this phase serves to reach a rotation speed level V22, where the absolute value thereof is, for example, 10,000 RPM.

[0158] The second phase, corresponding to the actuation of the twister, comprises a progressive and slow slowing phase 206 of the motor. The beginning of the slowing phase 206 is calculated by the microprocessor based on the number of turns to make to account for final turns made at a progressively slower speed until stopping thereof in a position in which the twister is aligned with the tie wire guide. Because of the progressive reduction of the speed, the tie wire twister can then be precisely positioned in the predetermined position thereof directly on stopping of the motor.

[0159] The second phase 204 of the apparatus for tie placement from the invention can be compared to a second actuation phase 304 of the twister in the apparatus from the state-of-the-art.

[0160] It can be noted that the maximum rotation speed V22 of the motor during the second phase 204 of the apparatus from the invention is higher than the speed V12 of the motor in the apparatus from the state-of-the-art. On the other hand, the length of the second phase 204, including the slowing phase 206, is shorter than the second phase 304 in the apparatus from the state-of-the-art.

[0161] After the second phase 204, the electric motor associated with the sequential actuation wheel is activated a final time. In the preferred embodiment, this corresponds to the change of direction of rotation of the single motor. In this final phase 208, the sequential actuation wheel completes the rotation thereof over one full turn. In the final phase 208, the twister is stopped, and the hook 40 is brought back to the initial open position thereof by means of the second roller 90 acting on the lever 92 while actuating the tie wire feeder to have the wire pass through the twister and partially advance it into the hook. At the end of the cycle, the hook is completely raised and the motor stopped, ready for a new tying cycle.

[0162] As a comparison, an additional phase 310, preceding a stopping phase 308, can be noted for the tie gun from the state-of-the-art. The additional phase 310 corresponds to a re-indexing of the twister considering the rapid deceleration of the motor between the speed V12 at the moment of forming the twist and stopping thereof in the phase 304. This is due to the fact that the Hall effect sensor in the apparatus from the state-of-the-art gives a simple angular position pulse for the shaft of the twister at the moment when the twister reaches this position. Thus, during the shutdown of the motor, the twister is not precisely positioned considering the mechanical inertia thereof. The additional phase 310 thus is used to command the rotation of the twister with a speed V14 slower than the speed V12 at the time of the formation of the twist. The stop occurs upon detection of the next magnet. The rotational energy is thus much smaller and it is easier to precisely position the twister upon stopping the motor.

[0163] Since the motor for the tie gun from the state-of-the-art is, as already indicated, a direct-current motor, rotation speeds thereof are slower than a permanent-magnet three-phase synchronous motor and it is more difficult to manage the slow acceleration and deceleration slopes as shown by the phases 302, 304, 308 and 310 of the tying cycle for this apparatus. The speed levels V10, V12 and V14 are, for example and respectively, 7400, 6000 and 3500 RPM.

[0164] It can also be noted that in the state of-the-art the total length T1 of the cycle is of order 500 ms, but since it involves a direct-current motor it can vary according to values from 450 ms when the battery is fully charged to 550 ms when it is discharged but still allowing the execution of a tying cycle. It is longer than the total cycle length T2 obtained with the tie placement apparatus from the invention which is of order 400 ms. The use of both a permanent-magnet three-phase synchronous motor having a higher rotation speed capacity, locking of the speed thereof and the use of two sensors giving continuous angular positions of the main components serves, by anticipating the position thereof, to accelerate the average speed of the cycle while controlling the acceleration and deceleration phases of the motor. The operation is clearly faster but also easier on the mechanics, improving the life and reliability thereof. It can further be noted that the digital control of the motor is insensitive to the state of charge of the battery. Thus, the values of T1 are nearly identical whatever this charge status is.