JP2849092B2 - Balance mechanism of the body - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balance mechanism against an unbalanced load of a machine tool or the like having a headstock that can turn in a vertical plane.

2. Description of the Related Art In FIG. 7 to FIG. 9, a conventional headstock 101 capable of turning in a vertical plane is provided as a balance mechanism against an offset load of a turning headstock such as a milling machine provided at the tip of a ram 102 capable of moving in the Y-axis direction. In the prior art, a weight 104 equivalent to an eccentric load was attached to the turning shaft 103 to achieve balance. Further, both ends of the rack shaft 106 meshing with the pinion 105 fitted on the turning shaft 103 are
It was pressed by 7 and balanced by the reaction force of the spring.

Problems to be Solved by the Invention Among the former described in the prior art, when the eccentric load is large, the weight 104 becomes large and there is a problem in design such as a mounting place. In the latter case, the relationship between the turning angle θ of the headstock 101 and the eccentric load draws a sine curve as shown in FIG. 10, but the reaction force due to the spring 107 shows linearity. However, when the turning angle θ exceeds 90 °, the difference rapidly increases, so that it cannot be used above 90 °.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide a balance mechanism that can accurately balance over the entire turning angle. .

Means for Solving the Problems In order to achieve the above object, a balance mechanism according to the present invention provides a machine tool having a revolving body that can pivot in a vertical plane; Two cylinders having pistons at both ends of a rack provided on a pivot shaft and having two ends as pistons, detection means for detecting a rotation angle of the revolving body, and a rotation direction determined by an output of the detection means, the two rotation directions are determined. Means for selecting a flow path to the cylinder;
Means for controlling so as to supply to the selected cylinder an oil pressure which is a reaction force against an eccentric load generated according to the turning angle of the turning body by the output of the detecting means.

When the revolving body (spindle head) is turned by the driving means, the turning angle is output from the detector to the classification circuit and the arithmetic circuit. In the separation circuit, for example, as soon as the spindle head at the vertical position (0 °) starts turning clockwise, it sends a signal to the solenoid valve control circuit, and this signal causes the solenoid valve control circuit to energize one of the solenoids, The solenoid valve is switched so that the pressurized fluid can be supplied to the fluid pressure cylinder with the head tilted. At the same time, the arithmetic circuit calculates a numerical value corresponding to the unbalanced load of the spindle head that changes depending on the turning angle, and outputs it to the pressure control circuit. In response to this, the pressure control circuit adjusts the supply pressure by adjusting the supply voltage to the proportional electromagnetic relief valve so that the supply pressure to the hydraulic cylinder is proportional to the numerical value.
The reaction force corresponding to the unbalanced load on the headstock is obtained by the thrust of the piston generated by the supply pressure adjusted in this manner.

Embodiment An embodiment will be described with reference to the drawings. 1 to 6, a column 2 having a slide guide surface 2a in a vertical direction (Z axis) on a base 1 in a known NC milling machine.
The knee 3 is provided on the slide guide surface 2a so as to be movable and positioned by NC control, and the table 4 is moved by NC control on the slide guide surface in the X-axis direction cut out on the upper surface of the knee 3. It is placed so that it can be positioned. Further, on the upper surface of the column 2, a slide guide surface in the Y-axis direction is cut, and the ram 5 is movably mounted on the slide guide surface.
It is moved and positioned via a ball screw 7 by an NC servo motor 6. A spindle head 8 is provided at the tip of the ram 5 so as to be pivotable about a pivot axis in the Y-axis direction described later.
On the spindle head, a spindle 9 perpendicular to the turning shaft is supported by a plurality of bearings (not shown).

A bearing housing 10 is fitted in a hole 5a formed in the tip of the ram, and a turning shaft 12 that is rotatably supported by a plurality of bearings 11 in the bearing housing is fixed to a headstock body 13. A gear 14 is fitted to the turning source shaft 12, and the gear 14
14 meshes with a gear 16 fitted to the intermediate shaft 15,
A worm wheel 17 is fitted to 15. A gear 21 is engaged with a gear 19 fitted on an output shaft 18a of a servo motor 18 fixed to the ram 5 via a back gear 20.
The gear 21 is a worm meshed with the worm wheel 17.
22 is fitted on a worm shaft 23 engraved. In this way, the headstock 8 is turned and positioned by the servomotor 18 under NC control.

The headstock body 13 has a boss 13 integrated concentrically with the turning shaft 12.
a is provided, the boss portion 13a is freely inserted into the hole 5b of the ram 5, and a clamp ring 25 having a tapered hole 25a at the tip is fixed concentrically. A piston 27 is fitted around the outer periphery of the bearing housing 10 to form a hydraulic cylinder 26. The piston 27 is moved by pressure oil supplied to oil passages 28 and 29. The tip of the piston 27 is formed in a taper 27a that is inserted into the tapered hole 25a,
Taper when piston moves to the right due to pressure oil sent to oil passage 28
27a and the tapered hole 25a come into contact and the headstock body 13 is pulled in through the clamp ring 25, and the left end surface of the boss portion 13a and the tip surface 5c of the ram are pressed against each other, and at the same time, the taper 27a of the piston 27 is in the tapered hole 25a. The inner diameter of the tapered portion is reduced by being pressed, and the headstock 8 is clamped by being fitted to the outer periphery 10a of the bearing housing 10.

A rotating shaft 30 is rotatably supported by a plurality of bearings in holes 5d and 5e formed concentrically with the hole 5a at the rear end of the ram 5, and a spline shaft portion 30a at the tip of the rotating shaft is connected to the rotating shaft. 12
In the spline hole 12a. And ram 5
Is connected to the rear end of the turning shaft 30 via a connecting shaft 31. The detector 32 is connected to the turning angle θ of the headstock 8.
Is detected and output to a classification circuit 49 and an arithmetic circuit 51 described later. Further, a pinion 34 is fitted to the rear end of the turning shaft 30, and a rack meshed with the pinion 34.
Pistons 36 and 37 are fixed to both ends of 35. The pistons 36 and 37 are concentrically and symmetrically fitted into hydraulic cylinders 38 and 39 fixed to the ram. The pressurized oil supplied to the cylinders 38 and 39 is supplied from a hydraulic pump (not shown) after a source pressure P supplied through a pipe 42 is adjusted by a proportional electromagnetic relief valve 43 provided in the pipe 42. The valve is switched by a three-position solenoid valve 44 and supplied to one of the cylinders through one of the conduits 45 or 46.

The control circuit of the relief valve 43 and the solenoid valve 44 for switching the pressure oil supplied to the cylinders 38 and 39 and adjusting the pressure is the sixth circuit.
As shown in the block diagram, the turning angle θ of the headstock 8 output by the detector 32 is input to a separation circuit 49, where the turning angle θ is 0 ° (headstock vertical position) or 180 °.
° (headstock inverted position) and outputs a signal to the solenoid valve control circuit 50. In the solenoid valve control circuit, the solenoid SOL1 is used up to a turning angle of 0 ° to 180 °, and 180 ° to 360 °
Up to °, the solenoid SOL2 is energized to switch the solenoid valve 44.

Further, in the arithmetic circuit 51, the headstock 8 which varies depending on the turning angle θ
Is output to the pressure control circuit 52. In the calculation of the output numerical value in the arithmetic circuit 51, for example, the maximum torque T generated by the unbalanced load of the headstock is the product (WL) of the distance L from the turning center to the headstock center of gravity a and the weight W of the headstock center of gravity. And the maximum torque T is 90 ° or 27 °
At 0 °, the actual torque that changes with the turning angle θ is T
sin θ. On the other hand, cylinders 38 and 39
Is determined by the product (Fl) of the distance l from the center of rotation to the center of the cylinder and the thrust F of the cylinder, and the thrust F is determined by the cylinder area and the supply pressure. Can be obtained by calculation. In response to the output signal of the arithmetic circuit, the pressure control circuit 52 applies a voltage to the proportional electromagnetic relief valve 43 so as to adjust the source pressure P to a pressure proportional to the input numerical value, and sends an exciting current. The pressure oil whose pressure has been adjusted in this manner is supplied to one of the cylinders 38 and 39 via the electromagnetic valve 44.

Note that the cylinders 38 and 39 and the pistons 36 and 37 are not limited to the linear type as in this embodiment, and it is needless to say that a rotary actuator or the like can be used.

Further, the fluid pressure is not limited to the hydraulic pressure, and it goes without saying that compressed air or the like can be used.

Effects Since the present invention is configured as described above, the following effects can be obtained.

Detects the turning angle of the headstock, switches the fluid pressure supplied to the two hydraulic cylinders and adjusts the pressure based on the turning angle, and engages with a pinion fitted to the turning shaft via a piston via a piston. To give a reaction force to
Accurate balance can be achieved over 360 °, turning positioning of the headstock is facilitated, and positioning accuracy is improved, and machining accuracy when performing machining while turning the headstock is improved.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a turning mechanism of a spindle head and a balance mechanism of the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, FIG. FIG. 5 is a cutaway view showing a spindle head turning drive unit, FIG. 5 is a side view of a milling machine having a turning headstock, FIG. 6 is a block diagram and a hydraulic circuit diagram of a control circuit, and FIGS. FIG. 9 is a sectional view taken along the line AA of FIG. 8, and FIG. 10 is a graph for explaining the prior art. 8. Headstock (revolving body), 49 ... Separation circuit 12 ... Revolving axis, 30 ... Revolving axis 32 ... Detector 38, 39 ... Hydraulic cylinder 49 ... Separation circuit 50 ... Solenoid valve control circuit 51 ... Arithmetic circuit, 52 ... Pressure control circuit θ: Swing angle

Claims (1)

(57) [Claims] 1. A machine tool having a revolving body (8) that can pivot in a vertical plane, a drive means for revolving the revolving body, and both ends of a rack meshing with a pinion provided on a revolving shaft of the revolving body. Two cylinders serving as pistons, detecting means for detecting a turning angle (θ) of the revolving body, means for determining a turning direction based on an output of the detecting means and selecting a flow path to the two cylinders Means for controlling the supply of hydraulic pressure, which is a reaction force to an eccentric load generated in accordance with the swing angle of the swing body by the output of the detection means, to the selected cylinder. Balance mechanism.