JPH0551412B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for shaping a workpiece into a desired shape by changing the relative position of the wire electrode and the workpiece while applying current between the wire electrode and the workpiece. The present invention relates to a wire electrical discharge machining apparatus that performs machining, and particularly relates to a wire electrical discharge machining apparatus equipped with a mechanism for suppressing tension fluctuations in a wire electrode.

[Prior Art] FIG. 3 is a schematic diagram showing, for example, a wire path of a wire electrical discharge machining apparatus equipped with a conventional mechanism for suppressing tension fluctuations in a wire electrode.

In the figure, 10 is a wire electrode, 12 is a wire bobbin around which the wire electrode 10 is wound, and 14a to 14
d is the first to fourth idlers that guide the wire electrode 10, and 18 is the wire electrode 1 consumed during processing.
20 is a capstan roller directly connected to the wire collection motor 18;
21 is a spring, 22 is a pinch roller pressed against the capstan roller 20 by the spring 21, 24 is a brake roller that applies main tension to the wire electrode 10, 26 is a brake that drives the brake roller 24, and 27 and 27a are wires. first and second power supply parts that supply processing voltage to the electrode 10; 28 is an initial tension brake that provides initial tension to the wire electrode 10; 30 is a mounting shaft that supports the wire bobbin;
32 is a workpiece, 34 is a processing power supply device, 36 and 38 are upper and lower wire guides for guiding the wire electrode 10 at the upper and lower parts of the workpiece 32, and 40
and 42 are upper and lower nozzles for spouting machining fluid during machining.

In addition, 100 is a wire collection mechanism part which is comprised by the wire collection motor 18, the capstan roller 20, the spring 21, and the pinch roller 22, and is for running the wire electrode 10 at a desired speed.

Moreover, 200 is a wire bobbin attachment part, which is constituted by the wire bobbin 12, the brake 28 for initial tension, and the attachment shaft 30.

Next, the operation of the wire electrical discharge machining apparatus having a mechanism for suppressing tension fluctuation of the wire electrode 10 configured as described above will be explained.

The wire electrode 10 is unwound from the wire bobbin 12, and is passed from the first idler 14a to the brake roller 2.
4 → second idler 14b → third idler 14
c→first power feeding section 27→upper wire guide 36→
The wire is stretched along the route of workpiece 32 → lower wire guide 38 → second power supply section 27 a → fourth idler 14 d → wire recovery mechanism section 100.

Then, as the wire collection motor 18 of the wire collection mechanism section 100 operates, the capstan roller 20 and the pinch roller 22 rotate, and the wire electrode 10 held by the capstan roller 20 and the pinch roller 22 is transferred to the wire bobbin 12. The wire electrode 10 that is continuously fed from the machine and consumed by electrical discharge during machining is collected in a collection box (not shown).

Next, machining power is supplied from the machining power supply device 34 to the wire electrode 10 and the workpiece 32 via the first and second power supply parts 27, 27a, and electric discharge occurs. X- (not shown)
The Y table operates to cut the workpiece 32 into a desired shape.

Note that the wire electrode 10 during machining is
A tension that is the sum of the values set by the brake 24 and the initial tension brake 28 is acting.

Here, when an unbalanced load exists on the wire bobbin 12, the initial tension brake 28 generates a constant braking force, and as the wire bobbin 12 rotates, the unbalanced load position moves. An angular velocity change occurs in the wire bobbin 12, which appears as a tension fluctuation in the wire electrode 10 stretched between the wire bobbin 12 and the wire collection mechanism section 100.

Further, as the wire electrode 10 wound around the wire bobbin 12 is fed, the winding diameter of the wire bobbin 12 decreases, and accordingly, the tension F acting on the wire electrode 10 is F= T/R However, T: Motor torque R: Since it is determined by the wire bobbin radius, it changes gradually in the direction of increase.
Therefore, the rotation speed of the wire bobbin 12 increases and the tension of the wire electrode 10 changes.

[Problems to be Solved by the Invention] Since the conventional wire electric discharge machining apparatus is configured as described above, even if the wire collection motor 18 rotates at a constant speed and winds up the wire electrode 10, the unbalanced load on the wire bobbin 12 remains. Therefore, the angular velocity of the wire bobbin 12 is large when the unbalanced load position rotates from above to below, and conversely becomes small when it rotates from below to above. Therefore, due to this change in angular velocity, the wire bobbin 12 and the wire collection mechanism section 10
Tension fluctuations occur in the wire electrode 10 stretched between the two ends. This tension fluctuation causes a change in the amplitude of the wire electrode 10 during machining, resulting in a decrease in machining accuracy, the occurrence of vertical streaks, and surface roughness on the machined surface.
This caused a decline in quality, etc., and hindered the improvement of precision in wire electrical discharge machining equipment.

Moreover, when the tension fluctuation of the wire electrode 10 becomes abnormally large, wire breakage occurs, resulting in a decrease in the operating rate of the wire electric discharge machining apparatus.

Furthermore, the winding diameter decreases due to consumption of the wire electrode 10 wound around the wire bobbin 12, and accordingly, the tension acting on the wire electrode 10 changes in the direction of increasing, resulting in poor machined surface quality at the beginning and end of machining. There were some problems, such as the inconsistency.

Therefore, this invention was made to solve the above problems, and eliminates the tension fluctuation of the wire electrode,
The object of the present invention is to provide a wire electrical discharge machining device that has high machining accuracy and high operation rate by applying an appropriate tension corresponding to the rotation speed of the wire bobbin.

[Means for Solving the Problems] A wire electrical discharge machining apparatus according to the present invention has a rotating shaft having a mounting portion that supports a wire bobbin formed by winding a wire electrode, and a rotating shaft that is coupled in the rotational direction to move the wire in the axial direction. A sliding shaft having an engaging portion that freely moves the rotating shaft and an end of the sliding shaft in a viscous fluid sealed in a container, and a viscous fluid coupling that establishes a coupling relationship between the rotating shaft and the end of the sliding shaft by the viscous fluid. and a braking force adjustment means that engages with the engaging portion of the sliding shaft and moves in the axial direction by coupling in the rotation direction, and rotation speed detection means that detects the rotation speed of the rotation shaft. The output of the braking force adjusting means is adjusted based on the output of the braking force adjusting means.

[Function] In the present invention, a rotating shaft having a mounting portion that supports a wire bobbin formed by winding a wire electrode is freely movable in the axial direction by coupling in the rotational direction via the viscous fluid coupling portion. The rotation speed of the rotating shaft is detected by a rotation speed detection means, the output of the rotation speed detection means is obtained, and the rotation speed of the rotating shaft is detected by a rotation speed detection means. The output of the braking force adjusting means is adjusted by varying the coupling relationship.

[Example] Hereinafter, a wire electrical discharge machining apparatus according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram showing a mechanism for suppressing tension fluctuations of a wire electrode in a wire electric discharge machining apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an uneven load on a wire bobbin. In addition, in the drawings, the same reference numerals and symbols as those in the conventional example indicate the same or corresponding components, and in particular,
Here, only the wire bobbin mounting portion 200, which is different from the conventional example, will be explained.

In FIG. 1, 50 is a mounting nut for fixing the wire bobbin 12 to the mounting shaft 30, 51 is a guide member for positioning when fixing the wire bobbin 12 to the mounting shaft 30, 52 is a bearing for the mounting shaft 30, and 54 is a mounting shaft This nut is screwed onto a guide member 51 attached to the housing 30 and rotatably supports the mounting shaft 30 with respect to the housing 56. Also,
Reference numeral 60 denotes a viscous fluid (for example, silicone oil) as a damping material, which is sealed in the container 61 . 62 is a rotating shaft, 63 is a bearing, 64 is a bearing 63
A coupling 66 directly connects the rotary shaft 62 rotatably supported by the mounting shaft 30 to the rotary shaft 62 via the viscous fluid 60, and
A sliding shaft 68 having a male thread cut at the end connects the sliding shaft 66 held by a liner bearing 72 to the sliding shaft 66 via a nut 70 having a female thread cut inside.
74 and 76 are first and second O-rings that prevent the viscous fluid 60 from leaking outside, and 78 is a pulse motor that moves the sliding shaft 66 in the axial direction without rotating it. It is a rotation speed detection means for detecting the rotation speed.

Note that 300 constitutes a viscous fluid coupling portion in which the ends of the rotating shaft 62 and the sliding shaft 66 are connected by the viscous fluid 60 in the viscous fluid 60 sealed in the container 61 . Further, 400 constitutes a braking force adjusting means that engages with the engaging portion of the sliding shaft 66 and moves in the axial direction by coupling in the rotational direction to vary the coupling relationship of the viscous fluid coupling portion 300. .

Next, the operation of the wire electrical discharge machining apparatus having a mechanism for suppressing tension fluctuations in the wire electrode 10 of this embodiment configured as described above will be described.

After the wire electrode 10 is unwound from the wire bobbin 12 and consumed by electric discharge during machining, it is collected in a collection box (not shown) through a wire feeding path, and a machining voltage is supplied from a machining power supply device 34 and an X- (not shown) Each process in which the Y table operates and machining is performed is the same as that of the conventional apparatus shown in FIG. 3, and therefore a description thereof will be omitted.

Now, when feeding the wire electrode 10, due to the eccentricity of the weight of the wire bobbin 12, the wire bobbin 1
2, when an instantaneous rotational speed fluctuation occurs, the braking force adjustment means 400 operates as described below.

That is, as shown in FIG. 2a, the wire bobbin 1
The center of the mounting hole of No. 2 is eccentric to the position of symbol B, shifted by symbol e from symbol A representing the true center,
Assuming that the wire bobbin 12 rotates to the left, if the unbalanced load position of the wire bobbin 12 moves from above to below as shown in FIG. As the angular velocity of the rotating shaft 62 attached to the rotating shaft 62 tends to increase, the braking coefficient of the viscous fluid 60 interposed between the rotating shaft 62 and the sliding shaft 66 increases, and the braking force on the rotating shaft 62 increases. It works to reduce the angular velocity. vice versa,
As the unbalanced load position moves from below to above as shown in FIG. It works so as not to reduce the angular velocity.

Therefore, the angular velocity fluctuation per rotation of the wire bobbin 12 becomes extremely low, and the wire electrode 10
The tension fluctuation can be made extremely small.

Moreover, as the wire electrode 10 is consumed by processing and the winding diameter of the wire bobbin 12 becomes smaller, the number of revolutions of the wire bobbin 12 gradually increases, and the tension of the wire electrode 10 also changes. Therefore, in order to obtain a constant tension regardless of the rotation speed of the wire bobbin 12 even if the rotation speed of the wire bobbin 12 increases, the braking coefficient of the braking force adjustment means 400 is set to an appropriate value in accordance with the rotation speed of the wire bobbin 12. It is necessary to change to . In such a case, after the rotation speed of the wire bobbin 12 is detected and processed by the rotation speed detection means 78, in order to obtain an appropriate braking coefficient corresponding to the rotation speed of the wire bobbin 12,
The viscous fluid coupling section 3 obtains a coupling relationship in the viscous fluid 60 sealed in the container 61 by driving the pulse motor 68 by the output from the control means 600.
By controlling the distance between the rotating shaft 62 and the sliding shaft 66 at 00, the rotational shaft 62 and the sliding shaft 66
The volume of the viscous fluid 60 interposed between the wire electrodes 10 and 10 is controlled so that the tension of the wire electrode 10 is always constant.

Furthermore, when changing the feeding speed or tension of the wire electrode 10 depending on processing conditions, the command value can be changed by instructing the control means 600 to a desired feeding speed or tension of the wire electrode 10. After being processed by the control means 600, the output drives the pulse motor 68 to set and maintain an arbitrary tension value corresponding to the command value, similar to the operation described above.

Note that in the above embodiment, the sliding shaft 66 held by the liner bearing 72 is connected to the sliding shaft 66 without rotating the sliding shaft 66 via the nut 70.
A pulse motor 68 is used as a means for moving in the direction, but this is a DC motor with a position detector.
Similar operation can be expected by using a servo motor, an AC servo motor with a position detector, an air cylinder, or a hydraulic cylinder.

In the above embodiment, a viscous fluid 60 interposed between the rotating shaft 62 and the sliding shaft 66 is used as a means for controlling the tension of the wire electrode 10 to always be constant.
However, by controlling the temperature of the viscous fluid 60 and changing its viscosity, the tension can be kept constant even if the braking coefficient is changed.

[Effects of the Invention] As described above, according to the wire electrical discharge machining apparatus of the present invention, a rotating shaft having a mounting portion that supports a wire bobbin formed by winding a wire electrode in a viscous fluid enclosed in a container; For a viscous fluid coupling part that obtains a coupling relationship of a sliding shaft, which has an engaging part that allows free movement in the axial direction by coupling in the rotational direction,
Since the output of the rotation speed detection means for detecting the rotation speed of the rotating shaft is obtained and the coupling relationship of the viscous fluid coupling portion is varied by the control means, the viscous fluid is Since the braking force is applied by the friction of In addition to obtaining a smooth surface, it is also possible to prevent wire electrode breakage due to amplitude fluctuations, and maintain a high operating rate. Furthermore,
Since the braking force can be adjusted by the braking force adjusting means, the optimum braking force can be applied to the rotational speed of the wire bobbin or the set tension of the wire electrode, which has the effect of enabling highly accurate machining.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing a mechanism for suppressing tension fluctuation of a wire electrode in a wire electric discharge machining apparatus according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing an unbalanced load on a wire bobbin, and Fig. 3 is a diagram showing a conventional wire electric discharge machining device. FIG. 2 is a schematic diagram showing a wire path of a wire electrical discharge machining apparatus equipped with a mechanism for suppressing fluctuations in tension of an electrode. In the figure, 10: wire electrode, 12: wire bobbin, 60: viscous fluid, 61: container, 62:
Rotating shaft, 66: Sliding shaft, 78: Rotation speed detection means,
300: Viscous fluid coupling portion, 400: Braking force adjustment means, 600: Braking means. In addition, in the figures, the same reference numerals and symbols indicate the same or equivalent parts.

Claims (1)

[Claims] 1. The relative position of the wire electrode and the workpiece is changed while applying current between the wire electrode and the workpiece, and the workpiece is processed into a desired shape, and the A wire electrical discharge machining device that collects the wire electrode at a constant speed, the wire electrode being rotatably coupled to a rotating shaft having a mounting portion that supports a wire bobbin formed by winding the wire electrode, so as to be freely movable in the axial direction. a sliding shaft having an engaging portion; a viscous fluid coupling portion that connects the rotating shaft and the end of the sliding shaft with the viscous fluid in a viscous fluid sealed in a container; a braking force adjusting means that engages with an engaging portion of a sliding shaft and moves in the axial direction by coupling in a rotational direction to vary the coupling relationship of the viscous fluid coupling portion; and detecting the rotation speed of the rotating shaft. A wire electric discharge machining apparatus comprising: a rotation speed detection means for detecting the rotation speed; and a control means for obtaining the output of the rotation speed detection means and adjusting the output of the braking force adjustment means.