JPH07276146A - Wire feeding device in wire electric discharge machine - Google Patents

Abstract

PURPOSE:To give a large rotating force to a feed rover with the pressure of a working liquid ejected on the feed roller, and prevent the working liquid from entering a bearing case. CONSTITUTION:In a lower wire head 31 to guide a wire electrode 1 in cooperation with an upper wire head at an electric discharge part, a plurality of blades 43 are provided on the side of a feed rover 37 to guide the wire electrode 1 by a guide groove 42 formed in the circumferential surface, and the working liquid is ejected on the blades 43 to increase the rotating force of the feed roller 37. An air feeding tube 55 to feed the air whose pressure is above the atmospheric pressure is connected to a bearing case to prevent the working liquid from entering the bearing case 41 from a roller housing 38 even when an oil seal 51 is deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire feed device in a wire electric discharge machine for machining a work by generating an electric discharge phenomenon between a wire electrode and a work.

[0002]

2. Description of the Related Art A wire electric discharge machine is a machine tool that cuts out a workpiece such as cemented carbide or hardened steel by generating an electric discharge phenomenon between a wire electrode and a workpiece. When starting, the wire electrode must be pre-inserted through the start hole drilled in the workpiece and the wire electrode must always be supplied during wire electrical discharge machining. Further, when the machining of the workpiece is completed and the machining of another workpiece is started, the wire electrode is once cut to insert the wire electrode into the start hole of the other workpiece, and the wire electrode is broken. In any case, the damaged wire electrode tip must be cut and removed. Then, the wire electric discharge machine includes an automatic wire supply device having an automatic wire supply mechanism for sending out a wire electrode, a wire cutting mechanism for cutting the wire electrode, and a wire electrode removal mechanism.

As shown in FIG. 7, an automatic wire feeding device generally feeds the wire electrode 1 fed from a source bobbin 60 to an electric discharge machining portion A, and therefore, a large number of direction changing rollers 61, tension rollers 62, and brake rollers. 6
3, a wire electrode supply system including a drawing roller 64, a winding roller 65, and the like. Also, electric discharge machining area A
In, the wire electrode 1 is restrained and guided by the upper wire head 66 and the lower wire head 67. That is, the upper wire head 66 and the lower wire head 67 can guide the wire electrode 1 so that the guide position does not shift even during taper processing.

By the way, the conventional lower wire head has a structure as shown in FIGS. The lower wire head 67 includes a nozzle holder 68 having a nozzle into which the wire electrode 1 is inserted, and the wire electrode 1 for restraining the wire electrode 1.
, A die guide holder 69 provided with a die guide for preventing positional deviation, a power supply holder 70 provided with a power supply for supplying electric power to the wire electrode 1, a roller housing 72 provided with a feed roller 71 for guiding the wire electrode 1, Ball bearing 7 for rotatably supporting the feed roller shaft 73
4 is housed in a bearing case 75 and the like. Further, the lower wire head 67 is used for the water jet nozzle 7
6 and 77, the feed roller 71 receives a rotational force by the pressure of the working liquid jetted from the water jet nozzles 76 and 77 toward the guide groove 79 of the feed roller 71, and the wire electrode 1 is fed to the feed electrode 71. It is pressed against the guide groove 79 of 71. By the rotating force of the feed roller 71, the wire electrode 1
Is sent out from the lower wire head 67. Further, in order to prevent the working fluid sprayed toward the peripheral surface of the feed roller 71 from entering the bearing case 75 from the roller housing 72, the roller housing 72 and the bearing case 7 are prevented.
5, an oil seal 78 is provided between the bearing case 75 and the feed roller shaft 73.

[0005]

As described above, in the conventional lower wire head 67, when the wire electrode 1 is fed, the working liquid is jetted toward the guide groove 79 of the feed roller 71 in the traveling direction of the wire electrode 1. While the feed roller 71 was rotated by the pressure of the working liquid and the wire electrode 1 was sent out by the working liquid, it was not sufficiently effective to send out the wire electrode 1. As the feed roller 71, one having a flat side surface has been conventionally used as shown in FIG. 9, but it has been a problem to strengthen the rotational force by utilizing the pressure of the working liquid.

Further, in the conventional lower wire head 67, an oil seal 78 is provided between the bearing case 75 and the feed roller shaft 73 to prevent the working fluid from entering the bearing case 75. When the oil seal 78 deteriorates or is damaged, the working liquid having a high pressure easily enters the bearing case 75 through the oil seal 78, and there is a problem that the bearing 74 becomes rusted and cannot rotate. Further, due to deterioration or damage of the oil seal 78, not only the machining liquid,
By the sludge entering the bearing case 75,
The bearing 74 sometimes stopped rotating. Since such a problem is considered to be caused by the pressure inside the roller housing 72 being considerably higher than the pressure inside the bearing case 75, it was a problem to reduce the pressure difference between the two.

The object of the present invention is to solve the above problems,
A wire in a wire electric discharge machine that applies a large rotational force to the feed roller by the pressure of the fluid jetted toward the feed roller, promotes the feeding of the wire electrode, and effectively prevents the machining fluid from entering the bearing case. It is to provide a feeder.

[0008]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention relates to a lower wire head that cooperates with an upper wire head that guides a wire electrode to an electric discharge machining site for a workpiece, and a guide groove that is arranged in a roller housing provided in the lower wire head and that guides the wire electrode. And a bearing for rotatably supporting the feed roller, a bearing case in which the bearing is arranged, an oil seal for preventing machining fluid from entering the bearing case, and the inside of the bearing case. The present invention relates to a wire feeding device in a wire electric discharge machine, which comprises a gas supply device that feeds gas at atmospheric pressure or higher.

Further, the wire feeding device in this wire electric discharge machine has a rotational force strengthening means for injecting a fluid toward the feeding roller to give a rotational force to the feeding roller.

Alternatively, the present invention is directed to a lower wire head that cooperates with an upper wire head that guides the wire electrode to an electric discharge machining site for a workpiece, and is disposed in a roller housing provided in the lower wire head and guides the wire electrode. Feed roller having a guide groove on its peripheral surface, a bearing for rotatably supporting the feed roller, a bearing case in which the bearing is arranged, an oil seal for preventing machining fluid from entering the bearing case, and the feed The present invention relates to a wire feeding device in a wire electric discharge machine, comprising a rotational force enhancing means for ejecting a fluid toward a roller to give a rotational force to the feed roller. Further, the wire feeding device in this wire electric discharge machine is provided with a gas supply device for feeding a gas at atmospheric pressure or higher to the bearing case.

Further, in the wire feeding device of this wire electric discharge machine, the rotating force enhancing means is provided with a plurality of blades provided at intervals on the side surface of the feeding roller in the circumferential direction, and a fluid toward the blades. It has a spray nozzle for spraying.

Alternatively, in the wire feeding device of this wire electric discharge machine, the rotating force strengthening means comprises a plurality of recesses provided at intervals in the circumferential direction of the side surface of the feeding roller,
And a fluid ejecting means for ejecting a fluid toward the recess.

[0013]

Since the wire feeding device in the wire electric discharge machine according to the present invention is constructed as described above, it works as follows. That is, since the wire feeding device in this wire electric discharge machine is configured to feed a gas at atmospheric pressure or higher, such as air, into the bearing case, the pressure in the bearing case increases, so that the bearing case is fed from the feed roller side. It is possible to prevent the working fluid from entering the inside.

Further, the wire feeding device in this wire electric discharge machine is provided with a plurality of blades on the side surface of the feeding roller,
Since the working fluid is ejected toward the blades, the feed roller can obtain a large rotational force by receiving the working fluid ejection pressure.

Further, the wire feeding device in this wire electric discharge machine is provided with a plurality of concave portions on the side surface of the feeding roller,
Since the working fluid is ejected toward the concave portion,
When the recess receives the jetting pressure of the working liquid, the feed roller can obtain a large rotational force.

[0016]

Embodiments of the lower wire head of the wire electric discharge machine according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic front view showing a wire electric discharge machine to which a lower wire head according to the present invention is applied, and FIG. 2 is a schematic front view showing a state in which wire electrodes are supplied by the wire electric discharge machine shown in FIG.

This wire electric discharge machine is, for example, for performing a wire electric discharge machining on a workpiece 8 into a predetermined machining shape by a wire electrode 1, and an automatic wire feeding is performed to a head 10 constituting the wire electric discharge machine. A device is provided. Further, the workpiece 8 is fixed by a clamp 22 on a work table 21 mounted on a cross slide operated by a servo motor with a servo function. A support body 9 which constitutes an automatic wire feeder is attached to an upper portion of a head 10 of the wire electric discharge machine, and a support body 23 to which an upper wire head 6 is attached and a feed pipe 5 are attached to a lower portion of the head 10. Also, a support 24 to which a roller 18 for guiding the wire electrode 1 and the like is attached is fixed. A pair of guide rods 3 is arranged between the support body 9 and the support 24. A holder 20 is attached to these guide rods 3 so as to be slidable in the vertical direction.

A supply pipe 5 for guiding the wire electrode 1 is fixed to the holding body 20 with a set screw 25 or the like.
A thread guide 12, a pair of annealing rollers 4 provided with power supply pins 17, and a pipe holder 13 are attached. The pair of annealing rollers 4 sandwich the wire electrode 1 fed through the thread guide 12 attached to the holding body 20 and sandwich the wire electrode 1, the start hole 26 punched in the workpiece 8, and the workpiece 8 are discharged. Processing slit 27 which is a thin processing slit described later formed by processing.
(See FIG. 2). Further, the annealing roller 4 is provided with a power supply pin 17 for supplying a current to the wire electrode 1 through the annealing roller 4. A direction changing roller 7 and a felt brake roller 11 are attached to the support body 9, and the wire electrode 1 is applied with a predetermined tension applied to the wire electrode 1.
Are fed into the supply pipe 5. A slide rail 14 is fixed to the support 24 attached to the head 10 in order to smooth the sliding movement of the supply pipe 5. In the support 24, the slide rail 14
A cutter 16 is installed in the vicinity of the lower side of the cutter.

The cutter 16 cuts the wire electrode 1 so as to adjust the tip of the wire electrode 1 in order to prepare a good wire electrode end. That is, the cutter 16
Usually, the tip of the wire electrode 1 is inserted into the start hole 26 to perform electric discharge machining of a predetermined machining shape on the workpiece 8 and then the wire electrode 1 is cut, and then the tip of the wire electrode 1 is newly added to another start hole. No. 26 or the start hole 26 of another workpiece, the wire electrode 1 has a function of adjusting the tip of the wire electrode 1. In addition to the above functions, the cutter 16 inserts or re-inserts into the machining slit 27 so that the wire electrode 1 can be directly inserted into the machining slit 27 formed in the workpiece 8 by wire electric discharge machining to be described later. In the case of performing the above, it also functions to cut and remove the end of the wire electrode 1 in order to arrange the end of the wire electrode 1.

In the support 24 fixed to the head 10, a feed pin 17 and a pair of common rollers 15 for guiding the wire electrode 1 and a roller 1 are provided below the cutter 16.
8 etc. are arranged. Further, when the roller 18 that guides the wire electrode 1 and the tip of the supply pipe 5 descend to the support 23 that is close to the lower surface of the support 24 and fixed to the head 10 (see FIG. 2). A pipe stopper 19 and an upper wire head 6 are attached to prevent excessive lowering. Although not shown in detail, the upper wire head 6 incorporates the wire delivery port 6A, the die guide, the jet nozzle, the electron feeder, the electron feeder presser, and the like, as in the conventional case. Further, the wire electric discharge machine is provided with a lower wire head 31 facing the upper wire head 6, and the wire electrode 1 is pulled out to the downstream side of the lower wire head 31 to tension the wire electrode 1. A pair of pull-out rollers 32 are provided. The lower wire head 31 has a wire electrode 1
A sensor 28 for detecting that the wire is inserted into the lower wire head 31 is provided. This sensor 28 has the lower wire head 3 even though the tip of the wire electrode 1 is inserted into the start hole 26 or the processing slit 27.
When it is not inserted into 1, the supply failure detection signal is transmitted to the controller.

Further, the support 24 fixed to the head 10 is provided with a wire tip detecting sensor 29 downstream of the cutter 16 and upstream of the upper wire head 6. The wire tip detection sensor 29 detects that the tip of the wire electrode 1 is located on the wire tip detection sensor 29 in a non-contact state and sends a detection signal to the controller. If the wire electrode 1 is broken, the work piece 8
In order to insert and connect the tip of the wire electrode 1 into the start hole 26 or the processing slit 27, it is generally necessary to cut the wire electrode 1 once and adjust the tip. At that time, if the waste of the wire electrode 1 is to be minimized,
It is desirable to cut only the damaged tip of the wire electrode 1 with the cutter 16, and for that purpose, the wire electrode 1 needs to be wound up. However, when winding the wire electrode 1, how much the wire electrode 1 is wound depends on the situation at that time, so the wire tip detection sensor 29 plays an important role. That is, the wire electrode 1
The length of the wire electrode 1 that needs to be wound differs depending on whether the wire electrode 1 is broken or when the wire electrode 1 is broken, and even if the wire is broken, the length of the wire electrode 1 to be wound depends on where the wire is broken. Different.
Therefore, the wire electric discharge machine has a wire tip detection sensor 29, and the wire tip detection sensor 29 is configured to detect the tip of the wire electrode 1.

Further, a waste wire clamp 30 as a wire discharging means is installed on the support 24 between the cutter 16 and the wire end detection sensor 29. Although the structure of the waste wire clamp 30 is not shown in detail in the drawing, the waste wire clamp 30 does not include a clamp portion that clamps or releases the end portion of the cut wire electrode 1 (adsorption or release by an electromagnet). It has a rod having a clamp part at one end and a piston provided at the other end of the rod to reciprocate in the cylinder by supplying or discharging hydraulic pressure in the cylinder. There is. Stroke of piston is eliminated after cutting wire electrode 1
Since the length of the consumed wire electrode 1 is longer than that of the consumed wire electrode 1, the end of the cut wire electrode 1 is clamped by the clamp part and the wire electrode 1 is pulled out in the horizontal direction, so that the consumed wire electrode 1 is discharged to the waste box. Can be done. If the length of the portion of the wire electrode 1 to be cut and eliminated is set to be short, the waste wire clamp can be made small.

Also in the wire electric discharge machine shown in FIG.
It has a wire electrode supply system as shown in FIG. This wire electric discharge machine has a motor that can drive the source bobbin 60 around which the wire electrode 1 is wound in both forward and reverse directions. By driving the motor in the reverse direction, the unwound wire electrode 1 can be wound up. . This motor is driven to wind up the wire electrode 1 when the wire electrode 1 is broken or when a wire head supply failure occurs. In this wire electrode supply system, from the direction changing roller 2 located downstream of the brake roller, the wire electrode 1 is changed to the direction changing roller 7 and the felt brake roller 1.
1, the thread guide 12, the pair of annealing rollers 4, the supply pipe 5, the pair of common rollers 15, and the guide roller 18 in order, and is fed to the upper wire head 6 and reaches the electric discharge machining site A with the workpiece 8. Further, the wire electrode 1 further includes the electric discharge machining part A and the lower wire head 31.
Through the draw-out roller 32, for example, a winding roller 65 as shown in FIG.

Further, the wire electrode 1 is connected to the start hole 26.
In order to insert the wire electrode 1 into a hole such as a start hole, the wire electrode 1 can be smoothly inserted.
When the wire electrode 1 is passed through the pair of common rollers 15, the wire electrode 1 is once sandwiched between the annealing roller 4 and the common roller 15, and then the power feeding pin 17 provided on the annealing roller 4 and the power feeding pin provided on the common roller 15. A voltage is applied between the wire electrode 17 and the wire electrode 1, and a current is passed through the wire electrode 1 between them to perform an annealing treatment on the wire electrode 1. By this annealing treatment, the wire electrode 1 is twisted, strained or the like, that is, internal stress is eliminated and softened, and the wire electrode 1 straightly extends and is easily inserted into the start hole 26 or the processing slit 27 smoothly.

In FIG. 1, in the wire electric discharge machine, the holder 20 is moved upward along the guide rod 3 and the lower end of the supply pipe 5 is positioned above the cutter 16 attached to the support 24. The status is shown. In this state,
Conventional wire electric discharge machining, that is, wire electric discharge machining for cutting a workpiece into a predetermined shape is performed. Further, in this state, after the wire electric discharge machining or after the wire electrode 1 is broken, the tip portion of the wire electrode 1 is cut and removed. Further, in FIG. 2, in the wire electric discharge machine, the holding body 20 is moved downward along the guide rod 3 and the lower end portion of the supply pipe 5 is positioned on the upper surface of the pipe stopper 19 attached to the support body 24. The status is shown. When the wire electrode 1 is broken during electric discharge machining for cutting out the workpiece 8 into a predetermined shape, the supply pipe 5 is moved to the position shown in FIG. The wire electrode 1 is passed through the processing slit 27.

3 and 4 are views showing a first embodiment of the lower wire head according to the present invention, FIG. 3 is a front view of the lower wire head, and FIG. 4 is a side sectional view of the lower wire head. . The lower wire head 31 includes a nozzle holder 34 that includes a nozzle into which the wire electrode 1 is inserted, a die guide holder 35 that includes a die guide that restrains the wire electrode 1 and prevents the wire electrode 1 from being displaced, and the wire electrode 1 A power supply holder 36 having a power supply for supplying electric power, a roller housing 38 having a feed roller 37 for guiding the wire electrode 1, and a bearing having a ball bearing 40 rotatably supporting a shaft 39 of the feed roller 37. It is composed of a case 41 and the like.

The feed roller 37 has a V-shaped guide groove 4 on its peripheral surface.
2 is formed, and the wire electrode 1 is guided by the guide groove 42. The guide groove 42 is mirror-finished. Six blades 43 are radially attached to one side surface of the feed roller 37, and a shaft 39 is attached to the other side surface of the feed roller 37. The number of blades is not limited to six. The feed roller 37 is housed in a roller housing 38.

A bearing case 41 is provided adjacent to the roller housing 38, and the shaft 39 of the feed roller 37 extends into the bearing case 41. The shaft 39 of the feed roller 37 is rotatably supported by the bearing case 41 by two ball bearings 40, 40 provided in the bearing case 41. An outer collar 44 is provided between the ball bearings 40, 40, and the outer collar 44 is formed with an outer peripheral groove 45 and a plurality of radial holes 46.

A working liquid supply pipe 47 for supplying a working liquid is attached to the roller housing 38. The working liquid supply pipe 47 is branched into two and communicates with two water jet nozzles 48 and 49, respectively. There is. The tip of the first water jet nozzle 48 faces the blade 43 of the feed roller 37, and the second water jet nozzle 49 faces the guide groove 42 of the feed roller 37. The pressure of the working liquid jetted from the first water jet nozzle 48 toward the blades 43 of the feed roller 37 gives a large rotational force to the feed roller 37, and the working liquid jetted from the second water jet nozzle 49. The wire electrode 1 is pressed against the guide groove 42 of the feed roller 37 by the pressure. Then, the wire electrode 1 inserted from the nozzle holder 34 is sent by the rotational force of the sending roller 37 and sent out from the outlet 31A of the lower wire head 31.

The roller housing 38 is closed by a cover 50 so that the machining fluid jetted from the water jet nozzles 48 and 49 does not leak outside. In addition, the working fluid and sludge sprayed toward the blades 43 and the guide grooves 42 of the feed roller 37 are discharged from the roller housing 38 to the bearing case 4.
In order to prevent the intrusion into the housing 1, the roller housing 38 and the bearing case 41, that is, the bearing case 4
An oil seal 51 is provided between 1 and the shaft 39 of the feed roller 37.

The bearing case 41 has an oil seal 51 whose one end face is provided between the bearing case 41 and the roller housing 38.
Since the other end surface is closed by the bearing cover 53 via the O-ring 52, a sealed space, that is, a bearing chamber is formed in the bearing case 41. Air above atmospheric pressure is supplied from the air supply device (gas supply device) 54 to the bearing chamber which is the sealed space. That is, the air supply pipe 55 that constitutes a part of the air supply device 54 has an air outlet 55A whose outer collar 44 is provided between the two ball bearings 40, 40.
Of the bearing case 41 so as to face the outer peripheral groove 45 of the
Is attached to. Thus bearing case 4
Bearing case 4 by supplying air above atmospheric pressure into 1
Since the pressure in 1 is increased, even if the oil seal 51 is deteriorated or damaged, there is a problem that the working fluid enters the bearing case 41 from the oil seal 51 and rusts the bearing 40. Disappear.

In the lower wire head 31 shown in FIG. 4, the air supply pipe 55 has an air outlet 55A provided between the two ball bearings 40, 40.
4 so that the bearing case 4 faces the outer peripheral groove 45.
However, the air supply pipe 55 may be attached at another place. For example, the air supply pipe 55 may be attached to the center of the bearing cover 53. In that case, the air outlet 55A of the air supply pipe 55 is connected to the feed roller 3
7 towards the end of the shaft 39.

FIGS. 5 and 6 are views showing another embodiment of the wire feeding device in the wire electric discharge machine according to the present invention. This embodiment is the same as the above embodiment except that the construction of the feeding roller is different. Is. 5 is a front view of the feed roller, and FIG. 6 is a sectional view taken along line BB of FIG.
Six concave portions 56 are formed on the side surface of the feed roller 37. The recessed portion 56 has a pressure receiving surface 57 that receives the pressure of the working liquid jetted from the first water jet nozzle 48, and the pressure receiving surface 57 is radially arranged in the front in the rotation direction of the feed roller 37. Since the recessed portion 56 that has received the jetting of the processing liquid exerts a function as an impeller, the feed roller 37 can obtain a large rotational force as compared with the conventional feed roller shown in FIGS. 8 and 9.

[0034]

Since the wire feeding device in the wire electric discharge machine according to the present invention is configured as described above, it has the following effects. That is, since the wire feeding device in this wire electric discharge machine can keep the pressure in the bearing case high by feeding a gas of atmospheric pressure or more into the bearing case, it is possible to reduce the pressure between the roller housing and the bearing case, that is, Even if the oil seal provided between the bearing case and the shaft of the feed roller deteriorates or is damaged, machining fluid and sludge are less likely to enter the bearing case through the oil seal. Therefore, the risk that the bearing will rust or stop rotating will be extremely small, and the wire head having a long life can be provided.

Alternatively, the wire feeding device in this wire electric discharge machine is provided with a plurality of blades on the side surface of the feeding roller and ejects the fluid toward these blades. Alternatively, the wire feeding device in the wire electric discharge machine is configured to provide a plurality of concave portions on the side surface of the feeding roller and eject the fluid toward the concave portions. Therefore, in any case, the feed roller can receive a large rotational force from the ejected fluid. Therefore, the wire electrode inserted into the lower wire head can be delivered reliably and smoothly.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a wire electric discharge machine equipped with a wire feeding device according to the present invention.

FIG. 2 is a schematic front view showing an automatic wire supply process in the wire electric discharge machine of FIG.

FIG. 3 is a front view showing an embodiment of a wire feeding device in the wire electric discharge machine according to the present invention.

4 is a side view and a partial cross-sectional view of the lower wire head of FIG.

FIG. 5 is a side view of a feed roller showing another embodiment of the wire feed device in the wire electric discharge machine according to the present invention.

6 is a cross-sectional view taken along the line BB of FIG.

FIG. 7 is a schematic front view showing a wire electrode supply system in the wire electric discharge machine.

FIG. 8 is a front view showing a conventional lower wire head.

9 is a partial cross-sectional view of the lower wire head of FIG.

[Explanation of symbols]

 A Electric discharge machining part 1 Wire electrode 6 Upper wire head 31 Lower wire head 37 Feed roller 38 Roller housing 40 Ball bearing (bearing) 41 Bearing case 42 Guide groove 43 Blades 48, 49 Injection nozzle 51 Oil seal 54 Air supply device 56 Recess

Claims (6)

[Claims] 1. A lower wire head that cooperates with an upper wire head that guides a wire electrode to an electric discharge machining site for a workpiece, and a guide groove that is disposed in a roller housing provided in the lower wire head and that guides the wire electrode. A feed roller provided on the peripheral surface, a bearing for rotatably supporting the feed roller, a bearing case in which the bearing is arranged, an oil seal for preventing machining fluid from entering the bearing case, and a large inside the bearing case. A wire feeding device in a wire electric discharge machine, comprising a gas supply device for feeding a gas at atmospheric pressure or higher. 2. The wire in the wire electric discharge machine according to claim 1, further comprising a rotating force strengthening means for injecting a fluid toward the feed roller to give a rotating force to the feed roller. Feeder. 3. A lower wire head that cooperates with an upper wire head that guides a wire electrode to an electric discharge machining site for a workpiece, and a guide groove that is disposed in a roller housing provided in the lower wire head and that guides the wire electrode. A feed roller provided on the peripheral surface, a bearing for rotatably supporting the feed roller, a bearing case in which the bearing is arranged, an oil seal for preventing machining fluid from entering the bearing case, and the feed roller. A wire feeding device in a wire electric discharge machine, comprising a rotational force enhancing means for ejecting a fluid to apply a rotational force to the feed roller. 4. The wire feeding device in a wire electric discharge machine according to claim 3, wherein a gas supply device for feeding a gas at atmospheric pressure or higher is provided in the bearing case. 5. The rotating force enhancing means includes a plurality of blades provided at circumferentially spaced sides of the feed roller, and an injection nozzle for ejecting a fluid toward the blades. A wire feeding device in the wire electric discharge machine according to claim 2. 6. The rotating force strengthening means includes a plurality of recesses provided in a circumferential direction of a side surface of the feed roller and spaced apart from each other, and a fluid ejecting means for ejecting a fluid toward the recesses. The wire feeding device in the wire electric discharge machine according to claim 2 or 3.