RU105606U1 - DEVICE FOR COMPENSATION OF MUTUAL MOVEMENTS OF THE AXIS OF THE TOOL AND THE PROCESSED HOLE ON THE COORDINATING AND BORING MACHINE WITH A HORIZONTAL SPINDLE LOCATION - Google Patents

Abstract

 A device for compensating the mutual displacements of the tool axes and the machined hole on a coordinate boring machine with a horizontal spindle arrangement, which contains three supports designed to install a machined case blank, one of which is made in the form of a hydraulic jack located in the maximum proximity to the machine stand, electro-hydraulic converter, station hydraulic pressure and electronic levels for evaluating the mutual angular displacements of the tool axes and the bore hole from bending strain of the machine bed installed on the workpiece and the machine stand, characterized in that the second of the three supports, located in the closest proximity to the stand, is also made in the form of a hydraulic jack, and additional electronic levels are installed on the machined case blank and the machine stand to evaluate the mutual angular displacements of the tool axes and the bored hole from torsion deformation of the machine bed.

Description

The utility model relates to the field of mechanical engineering, mainly to high-precision machine tool industry, and can be used in precision machine tools for boring and milling groups with a horizontal spindle arrangement.

In the patent [1], a method for improving the accuracy of the machine by spatial control of the position of the bed with the table and the machined case blank relative to the foundation is presented. Management is carried out using four hydraulic jacks installed around the perimeter of the bed. The disadvantage of this method is the significant influence of contact deformations at the joints of the subsystems "bed-table", "table-workpiece", affecting the accuracy of processing.

A device for stabilizing the power deformations of the bed [2], containing the additional support of the machine, made in the form of a hydraulic jack, installed under the greatest deflection of the frame and containing a programmable logic controller that controls the force of the hydraulic jack, preventing the appearance of bending deformations of the frame. The disadvantage of this device is the frequent occurrence of control errors due to various disturbing influences, which can be temperature deformations, wear of mating surfaces, elastic deformations due to an increase in cutting forces and mass of the workpiece. This, in turn, leads to repeated readjustments, complication and cost of maintenance of technological equipment.

A device for compensating mutual angular movements of the tool axes and the bored hole [3], consisting of a hydraulic jack, an electro-hydraulic converter and a hydraulic pressure station. In this device, instead of one of the three supports on which the machined case blank is based on the table, a hydraulic jack is introduced, and to assess the mutual angular movements of the tool axes and the bored hole, electronic levels are installed that are installed on the machined case blank and the machine rack, respectively. The disadvantage of this device is only a partial compensation for the occurring power strains, that is, it only compensates for bending strains of the machine bed. It should be noted that when processing a workpiece, the machine bed experiences not only bending deformation, but also torsion.

The main task to which the claimed utility model is directed is to compensate for the mutual displacements of the tool axes and the machined hole caused by torsion deformations of the bed, thereby increasing the accuracy of the machining of the holes.

This problem is achieved due to the fact that in the proposed device for compensating the mutual displacements of the tool axes and the machined hole on a coordinate boring machine with a horizontal spindle arrangement, the mutual displacement of the tool axes and the machined hole is controlled by two hydraulic jacks installed instead of two of the three minimum necessary supports. These supports, on which the processed case blank is based on the table, are placed in the maximum proximity to the rack. To assess the mutual displacements of the tool axes and the bored hole from the torsion deformations of the bed, additional electronic levels are set on the body of the workpiece and the machine rack, respectively.

Figure 1 shows a General view of the coordinate boring machine with a horizontal spindle, equipped with a device for compensating the mutual movements of the axes of the tool and the bored hole. The machine consists of a bed 1, mounted on three rigid supports 2, 3 and 4 relative to the foundation. A rack 5 moves along the bed guides in the direction of the OZ axis, with a spindle head 6 processing a case blank 7 on the machine, which is mounted on the table 8 of the machine. A headstock containing a spindle assembly with a fixed cutting tool 9 (boring bar) is moved in the direction of the OY axis by means of an electric motor 10 (M). The housing blank is installed on the mounting support 11 and two hydraulic jacks 12, 13 of the proposed device. The device contains a hydraulic control system for hydraulic jacks, consisting of a hydraulic station 14, electro-hydraulic converters 15 and 16, electric signal amplifiers 17 and 18. The device also includes electronic levels 20, 21, 22, 23. The position of the rack 5 along the OZ axis on the rails bed 1 is controlled by a displacement sensor 24, the signal of which is supplied to the CNC system 19 (CNC).

The electronic level 20 on the rack determines the angle of inclination α ₁ due to deformation of the bend of the bed, and level 21 on the workpiece to be processed determines the angle of inclination of the workpiece α ₂ . In turn, the electronic level 22 on the rack and the electronic level 23 on the workpiece to be processed determines the angle of inclination of the latter φ ₁ , due to torsion deformation of the bed. Analog or digital outputs from the levels are connected to the CNC system of the machine.

Figure 2, b presents a diagram of the installation of fixing the body blanks on the machine table. The workpiece on the side of the mounting support 11 is secured by a gripper 26 with a bolt to the machine groove 27 with the nut 28 and the washer 29. The base surface of the body blank is mounted on the jack pushers 30 and secured with studs 31 with nuts 32 and washers 33. The lower ends of the studs are screwed into threaded holes of the pushers, which are fixedly connected to the rigid centers 34.

The hydraulic jack (figure 2, a) consists of a base 35, which, with the help of four holes evenly spaced around the circumference, is attached to the T-shaped grooves of the table. On the persistent thread of the base 35 is screwed into the housing 36, which allows you to adjust the spatial position of the workpiece. Through the fitting 37 into the housing of the hydraulic jack 36 is supplied a working fluid, the pressure of which is regulated in the electro-hydraulic Converter. Using an elastic membrane 38, the variable pressure in the hydraulic jack translates the rigid center 34 and accordingly moves the front edge of the workpiece relative to the mounting support 11. The cover 39 is screwed to the housing 36 using fixing screws, presses the tightly elastic membrane and creates a tight connection.

Figure 3 shows the geometry of the displacements of the top of the cutting tool and the axis of the hole due to bending and torsion deformation of the machine bed. During the movement of the rack towards the workpiece, the bed experiences bending and torsion deformations, which lead to a loss of machining accuracy on the machine. The reason for this is the mutual deviation of the tool axes and the bored hole, due to the angular movements of the spindle assembly and the workpiece.

Figure 4 shows the structural diagrams of compensation for deviations from the parallelism of the axes and vertical correction of the axis of the tool, which presents the following notation:

U _in1 , U _in2 - input signal (input state);

U _o1 , U _o2 - output signal (state at the output);

U ₁ , U ₂ - control action;

UE ₁ (20 figure 1) - electronic level mounted on a rack, fixing the bending deformation of the bed;

UE ₂ (21 figure 1) - electronic level mounted on the workpiece, fixing the bending deformation of the bed;

UE ₃ (22 figure 1) - electronic level, mounted on a rack, fixing the torsion strain of the bed;

UE ₄ (23 figure 1) is the electronic level mounted on the workpiece, fixing the torsion strain of the bed;

α ₁ - the angle of inclination of the axis of the tool, due to bending deformations of the bed;

α ₂ - the angle of inclination of the axis of the bored hole, due to bending deformations of the frame;

φ ₁ - the angle of inclination of the axis of the bored hole, due to torsion deformation of the bed;

φ ₂ - the angle of inclination of the axis of the tool, due to bending deformations of the bed;

CNC - CNC system;

U is an amplifier;

EGP - electro-hydraulic converter;

DG - hydraulic jack;

ОУ - control object (case blank);

DP - displacement sensor;

M - electric motor for moving the headstock on the rack rails along the OY axis;

ШУ - spindle unit.

When installing the workpiece, the machine bed experiences torsional deformation due to the uneven distribution of the weight of the workpiece, due to which the axis of the machined hole is shifted by an angle φ ₁ (Fig. 3, b). At the same time, when moving the rack along the guides of the bed, the latter begins to bend to a greater extent as it moves away from the standard support of the machine 4 (Fig. 1). These movements correspond to the input signals marked on the structural diagrams of figure 4, a and figure 4, b. The input signal or the directional movement of the rack produces bending deformations of the bed, which, in combination with the twisting of the bed, unequally reflect on the angular displacements of the body blank as well as the rack itself. Thus, the electronic levels when exposed to derivatives of the input signal determine the magnitude of the angular displacements. When applying the input signal to level 20, the angle of inclination of the stand and, accordingly, the axis of the tool α ₁ is determined, when applying the input signal to levels 21 and 23, the angle of inclination and the displacement of the workpiece and, accordingly, the axis of the bored hole α ₂ and φ _{1 are} determined. The total displacement of the axis of the machined hole and the axis of the tool is presented in figure 3, b.

The angle α ₁ will be positive, since it is formed during the angular movement of the counter counterclockwise, the angle α ₂ will be negative, since it is formed during the angular movement of the workpiece clockwise. The nature of the angle φ ₁ will depend on the installation of the workpiece on the machine. The values of all angles are fed to a comparator, which in practice should be implemented in the NC program, and on a block diagram made out as a separate element. The data obtained is processed, so the sum corresponds to the difference between the two angles α ₁ and α ₂ , which is then fed to one of the inputs of the CNC system, and the difference between the zero offset mark and the angle φ ₁ , to the second input. It should be noted that the probability of the tilt of the rack as it moves relative to the supports 2 and 3, is also taken into account. The signal from the electronic level 23 is fixed and the input signal U _{I2 is} adjusted based on the received data. The angle of inclination of the rack φ ₂ we take equal to zero, due to its significant compensation due to the dead weight of the rack. In the CNC system, the required stroke value of the pusher of each hydraulic jack will be determined in order to rotate or tilt the workpiece at angles α ₁ + α ₂ and φ ₁ + φ ₂ . The stroke of the pusher is calculated by the angle of rotation and the offset value of the workpiece and the known distances taken in the projection along the OZ and OX axis between the mounting support of the workpiece 11 and the hydraulic jacks 12 and 13. This distance must be entered into the CNC memory before processing as a constant for each individual workpiece . Further, the stroke values of each pusher, converted into an electrical signal, are taken from the CNC output and fed to the inputs of the amplifiers, which, amplifying these signals, feed them to the inputs of the electro-hydraulic converters. Electro-hydraulic converters convert the electrical signal into a proportional pressure of the working fluid, which is the control action at the inlet of the hydraulic jacks. Hydraulic jacks when changing the pressure at the outlet of the converters; any of the supporting edges of the body blank is displaced, which causes it to rotate or shift relative to the mounting supports 11 by the angles α ₁ + α ₂ and φ ₁ + φ ₂ .

At the output of the structural diagram, the housing blank changes its relative position and, accordingly, the tilt angles α ₂ and φ ₁ , which are fed back to the electronic levels 21 and 23 as a perturbation. In this case, the initial input signal from the movement of the rack and bed is no longer taken into account at the input of these levels. Since the position of the workpiece was changed by the control action, and we consider the operation of the device at each specific point in time in which the movement of the rack and bed have some final value. In this case, the input signal is stored at the input of the electronic level 20 and has a constant value until the subsequent discrete movement of the rack.

At electronic levels 21 and 23, perturbations are determined, i.e. angles α ₂ and φ ₁ , which are then fed to the comparison device. If the angle α ₂ is not equal to the angle α ₁ , and the angle φ _{1 is} not equal to zero (or the angle (φ ₂ ), then the angle difference will be converted again into the control action of the hydraulic jacks until the equality conditions are satisfied.

Figure 4, b shows the structural diagram of the vertical correction of the axis of the tool relative to the axis of the bore hole. The diagram shows that the input signal, represented by discrete movement of the rack, is supplied in addition to electronic levels to the input of the displacement sensor, which converts the linear displacement of the rack into an electrical signal. The amount of movement measured by the sensor corresponds to the distance between the initial position of the stand and the position in which the mutual angular movements of the tool axes and the hole appear.

The output signals from the electronic levels (α ₁ and α ₂ ) and the displacement sensor are fed to the inputs of the CNC system, which converts the electrical signals into binary code data. Then, based on these data, the vertical correction value is calculated. Part of the data for the calculation must be defined in the control program as variable data, for example, the coordinates of the cutting tool. The rest of the data necessary for the calculation should be entered at the beginning of the processing of each individual case stock (overall dimensions of the workpiece).

The calculated vertical correction value is converted into an electrical signal of a certain power or frequency depending on the type of motor used. The electric motor moves the spindle assembly along the displaced axis OY 'by the amount of vertical correction y' _cor necessary to ensure that the axis of the tool coincides with the continuation of the axis of the bore hole.

Thus, when installing on the machine bed of a body blank of various weights, as well as when moving the rack on the bed, the parallelism of the axes of the tool and the boring hole is automatically stabilized and the axis of the tool is vertically corrected relative to the axis of the hole. The proposed device can significantly reduce the effect of elastic force deformations of bending and torsion of the bed on the accuracy of processing.

INFORMATION SOURCES

1. Pat. 3807034 United States, IPC B23Q 11/00; G05B 19/404. Method of truing up heavy workpieces on the table of a metal-cutting machine and such table for carrying said method into effect / Semen Pevzner, Viktor Koire 1974.

2. Pat. 74839 of the Russian Federation, IPC V23V 25/06. The device for stabilization of force bending deformations of the bed of a horizontal boring machine / Gorshkov B.M., Krasnov S.V., Samokhina N.S., Lysak P.M., Vyunov A.V., Zagrebin K.V. Bull. No. 20, 2007.

3. Pat. 85389 RF, IPC B23Q 23/00. A device for compensating mutual angular movements of the tool axes and the bored hole / Samokhina N.S., Gorshkov B.M., Denisenko A.F., Trubacheva S.I., Marshanskaya O.V., Zagrebin K.V. Bull. No. 22, 2009.

Claims (1)

A device for compensating the mutual displacements of the tool axes and the machined hole on a coordinate boring machine with a horizontal spindle arrangement, which contains three supports designed to install a machined case blank, one of which is made in the form of a hydraulic jack located in the maximum proximity to the machine stand, electro-hydraulic converter, station hydraulic pressure and electronic levels for evaluating the mutual angular displacements of the tool axes and the bore hole from bending strain of the machine bed installed on the workpiece and the machine stand, characterized in that the second of the three supports, located in the closest proximity to the stand, is also made in the form of a hydraulic jack, and additional electronic levels are installed on the machined case blank and the machine stand to evaluate the mutual angular displacements of the tool axes and the bored hole from torsion deformation of the machine bed.