The present invention relates to a reinforcing bar binding machine, particularly relates to a reinforcing bar binding machine constituted to adjust a length of a binding wire by pulling back the binding wire after winding the binding wire around a reinforcing bar.
There is known a reinforcing bar binding machine having a binding wire feed-mechanism for feeding out a binding wire and hanging the binding wire around a reinforcing bar and a binding wire twist mechanism for twisting the binding wire wound around the reinforcing bar to bind for carrying out binding operation of 1 cycle by successively executing binding ire binding operation and binding wire twisting operation by trigger operation. Further, as disclosed in, for example, JP-A-08-034406 (claim 2, paragraph No. 0022, paragraph No. 0055), there is proposed a reinforcing bar binding machine for pulling back a binding wire after binding wire feed operation, bringing a loop of the binding wire into close contact with a reinforcing bar to start twisting operation. According to the reinforcing bar binding machine, by pulling back the binding wire, a line length thereof is adjusted in accordance with a diameter of the reinforcing bar to thereby promote finishing and also save to reduce an amount of consuming the binding wire.
In the case of constituting the reinforcing bar binding machine such that the binding wire is pulled back after the binding wire feeding operation and the twisting operation is started in a state of bringing the binding wire into close contact with the reinforcing bar, setting of a pull back tension poses a problem. When a feeding force of the binding line feed mechanism is weak, time is taken in pulling back the binding wire or the binding wire cannot be pulled back. Further, when the feeding force is conversely excessively large, there is a concern of cutting the binding line.
As a means for preventing such a drawback from being brought about, it is conceivable to provide electric control means for setting a motor torque to a degree of being sufficient for pulling back the binding wire and stopping a motor by detecting an increase in a drive current by a rapid increase in a pull back resistance in finishing to pull back the binding wire. However, a flexibility of the binding wire significantly differs by a kind of the binding wire or an environmental condition of an outside air temperature or the like and a width of varying the pull back resistance is wide and therefore, a width of changing the current is not constant, a peak value of the current in stopping the binding wire is significantly varied also by a remaining capacity of a power source battery and therefore, it is difficult to control to stop the motor stably without being influenced by these factors. Further, when there is constructed a constitution of setting a threshold value of the current of stopping the motor at each time for pertinently pulling back the binding wire, the operation becomes complicated and practical performance is deteriorated. Further, there also poses a problem that cost is increased by providing a control circuit including a current detecting circuit or the like.
Hence, there poses a technical problem to be resolved in order to stably pull back a binding wire regardless of a kind of the binding wire, and an external condition, a voltage of a battery or the like and it is an object of the invention to resolve the above-described problem.
The invention is proposed to achieve the above-described object. There is provided a reinforcing bar binding machine comprising a binding wire feed mechanism for feeding out a binding wire to wind around a reinforcing bar, a binding wire grasp mechanism of grasping and twisting the winding wire wound around the reinforcing bar, a binding wire pull back function of pulling back a loop of the binding wire wound around the reinforcing bar to be brought into close contact with the reinforcing bar and thereafter twisting the binding wire, control means for reversely rotating a drive system of the binding wire feed mechanism by a constant number in pulling back the binding wire, and means for permitting to slip the drive system for restricting a pull back tension exerted to the binding wire to be equal to or smaller than a limit value of cutting the binding wire.
Further, there is provided the reinforcing bar binding machine constituting the binding wire feed mechanism by bringing a driven sheave into elastic contact with a main drive sheave and constituted such that when a pull back tension exerted to the binding wire pinched between the pair of sheaves exceeds a certain value, the sheaves are idly rotated to restrict the pull back tension exerted to the binding wire.
Further, there is provided the reinforcing bar binding machine constituting the binding wire feed mechanism by bringing the driven sheave into elastic contact with the main drive sheave, interposing a torque limiter of a friction clutch or a ball clutch to a drive system of the binding wire feed mechanism and constituted such that when a pull back tension exerted to the binding wire pinched between the pair of sheaves exceeds a certain value, the main drive sheave and the driven sheave are stopped to restrict the pull back tension exerted to the binding wire.
Further, in notations in the drawings, numeral 1 designates a reinforcing bar binding machine, numeral 3 designates a binding wire clamp mechanism, numeral 4 designates a binding wire feed mechanism, numeral 6 designates a magazine, numeral 7 designates a nose, numeral 8 designates a center clamp plate, numeral 9 designates a right clamp plate, numeral 10 designates a left clamp plate, numeral 11 designates a cutter devise, numeral 13 designates a main drive gear having a V groove, numeral 14 designates a driven gear having a V groove, numeral 15 designates s feed motor, numeral 16 designates a reduction gear mechanism, numeral 17 designates a lever, numeral 18 designates a compression coil spring, numeral 19 designates a binding wire guide, numeral 23 designates a gear for feeding, numeral 24 designates a torque limiter, notation W designates a binding wire, notation S designates s reinforcing bar.
Although an embodiment of the invention will be described in details in reference to the drawings as follows, for convenience of explanation, first, an outline of a total constitution of a reinforcing bar binding machine will be explained.
When a lower end portion of the lever 17 is pressed to a center side (left side of
As described above, in 1 cycle operation of the reinforcing bar binding machine 1, respective steps of feeding the biding wire, clamping the front end of the binding wire loop, pulling back the binding wire, clamping the rear end of the binding wire loop, cutting the binding wire and twisting the binding wire are successively executed by a control of a control portion of a microprocessor or the like. The aspect of the invention resides numbers of reversely rotating the feed motor 15 and the main drive gear 13 having the V groove of the binding wire feed mechanism 4, in the step of pulling back the binding wire, are set to values sufficient for completely pulling back the binding wire, in any conditions. Further, a principal point thereof resides in that the control pressure of the main drive gear 13 having the V groove and the driven gear 14 having the V groove is set in consideration of a strength of the binding wire. When two pieces of the gears 13, 14 having the V grooves are rotated in a state of forcibly stopping the binding wire, the binding wire is prevented from being cut by slipping the gears 13, 14 having the V grooves and the biding wire.
Successively, the binding wire W is pulled back by reversely driving to rotate the main drive gear 13 having the V groove and the driven gear 14 having the V groove of the binding wire feed mechanism 4, the feed motor 15 is driven to rotate reversely up to a previously set rotational number by the control portion and the binding wire W is wound around the reinforcing bar S as shown by
Successively, after cutting the binding wire W by driving to rotate an outer side ring portion of the cutter devise 11, the left clamp plate 10 is closed by the cam mechanism and the rear end of the binding wire is clamped by the center clamp plate 8 and the left clamp plate 10, a total of the biding wire clamp mechanism 3 is driven to rotate and the reinforcing bar S is bound by twisting an end portion of the loop of the binding wire W as shown by
Further, in place of the constitution of setting the contact pressure of the main drive gear 13 having the V groove and the driven gear 14 having the V groove to permit to slip the binding wire W, as shown by
Further, the invention is not limited to the above-described embodiment but can variously modified further in the technical range of the invention and the invention can naturally cover the modifications.
As has been explained above, according to the reinforcing bar binding machine of the invention, the binding wire feed mechanism is driven to rotate reversely by the constant rotational number in the step of pulling back the binding wire, when pulling back is finished before finishing the pulling back step, the drive system is reversely rotated by slipping relative to the binding wire and therefore, the binding wire can completely be pulled back regardless of the boldness or the number of pieces of the reinforcing bars, the kind of the binding wire, the external condition, the voltage of the battery or the like and there is not a concern of cutting the binding wire, which archives an effect in stabilizing a binding function.
Number | Date | Country | Kind |
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2002-312185 | Oct 2002 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP03/12029 | 9/19/2003 | WO | 4/8/2005 |