SU1505724A1 - Clamping device - Google Patents

Abstract

The invention relates to welding, in particular, to equipment for securing products and can be used, for example, for centering and clamping parts during friction welding. The purpose of the invention is to simplify the design, improve the accuracy of the centering of parts and speed of the system. The device includes a housing 1, hydraulic cylinders 2 and 3 of the same diameter with single-rod pistons fixed in it, clamping blocks 8 and 9 connected to the piston rods, rods 11 and 12, which are fixed at one end to the piston rods, the other with movable electric elements sensors 15 and 16 linear displacement, the valve 19 with proportional electric control. The inlet of the latter is connected via a two-position four-line spool 17 with a pressure line, its two middle outlets are connected to rodless cavities of hydraulic cylinders, the other two exits - with a drain. The rod end of the hydraulic cylinders through the two-position four-line valve 17 is connected to the drain. The clamping pads 8 and 9 are rigidly connected to the moving elements of the electric sensors 15 and 16 linear displacements connected by electrical communication with the amplifier-adder 18, the control valve 19. When the control signal is applied to the spool 17, the pistons of the right and left cylinders begin to move to center. When the error signal on the speed ΔU, amplified in the amplifier-adder, appears, the valve 19 changes the flow rate of the fluid entering the rodless cavities of the right and left hydraulic cylinders to values equalizing the speeds of the pistons, respectively. When gripping the clamping pads, the error signal on the position ΔU redistributes the pressure in the rodless cavities of the right and left hydraulic cylinders so that counter forces on the piston rods are equalized, which ensures fixation of the part. When a control signal U _{y is} applied to the amplifier-adder _{, the} position of the clamped part can be changed. 1 il.

Description

25 1

7 2

15; j

(L

SP

about ate to

/ sixteen

I

pistons, clamping pads 8 and 9, connected to piston rods, rods 11 and 12, are connected at one end stationary with piston rods, the other with moving elements of electrical sensors 15 and 16 linear shuffles, the hydraulic distributor 19 with proportional electric control. The inlet of the latter is connected via a two-position four-line spool 17 with a pressure line, its two middle outlets are connected to rodless cavities of hydraulic cylinders, the other two exits - with a drain. The rod cavities of the hydraulic cylinders are connected via a two-position four-line valve 17 with a drain. The clamping pads 8 and 9 are rigidly connected to the moving elements of the electrical sensors 15 and 16 linear displacements connected by electrical connection with the amplifier-adder 18, controlled by their

by a hydraulic distributor 19. When a control signal is applied to the spool 17, the pistons of the right and left hydraulic cylinders begin to move towards the center. When a mismatch signal appears on the speed AL, amplified in the amplifier-adder, the valve 19 measures the flow of the fluid entering the rodless cavities of the right and left hydraulic cylinders to values equalizing the speeds of the pistons, respectively. When gripping the clamping pads, the error signal over the position or redistribution of pressure in the rodless cavities of the right and left hydraulic cylinders is such that counter forces on the piston rods are equalized, which ensures fixation of the part. When applying a control signal Uy to the amplifier-adder, the position of the clamped part can be changed. 1 il.

The invention relates to welding, in particular, to equipment for securing products, and can be used, for example, for centering and clamping parts during friction welding.

The purpose of the invention is to simplify the design, improve the accuracy of the centering of parts and speed of the system.

The drawing shows a diagram of the clamping device.

The device includes a housing 1, left 2 and right 3 hydraulic cylinders, fixed in housing 1 and having pistons 4 and 5 with rods 6 and 7, left 8 and right 9 clamping pads connected to rods 6 and 7, guiding 10 of the body in which clamping pads 8 and 9 are installed, rods 11 and 12, at one end fixedly connected to rods 6 and 7, and the other to moving elements 13 and 14 of electric sensors 15 and 16 linear displacements, two-position spool valve 17, electric amplifier-adder 18, hydraulic distributor 19 with proportional electric eskim control comprising chetyrehkromochny flow control valve 20 to the plunger 21 and the springs 22 and 23, control valve 24 soplo- type flap with a flap 25, the sensor 26 of the local feedback electrical communication, the pressure reducing valve 27 and the electromechanical transducer 28.

In this case, the inlet of the hydraulic distributor 19 is connected to the line of working fluid, the outlet b is connected to the rodless cavity of the left hydraulic cylinder, the outlet c is connected to the rodless cavity of the right hydraulic cylinder, and the outlets r and (- from the drain. The rod cavities of hydraulic cylinders 2 and 3 are connected through valve the drain, the amplifier-adder 18 - at the input with electrical connections with sensors 15 and 16 linear displacements, and at the output - with an electromechanical converter 28.

The device works as follows.

When a control signal is applied, the spool 17 is switched and simultaneously

The Q closes the electrical circuit connecting the amplifier-adder 18 to the electromechanical transducer 28. The working fluid enters the rodless cavities of the hydraulic cylinders 2 and 4, and partly to the drain. At the same time pistons 4 and 5

5 begin to move towards each other. The signals Ui and 1/2, coming from the sensors 15 and 16, are summed up in the amplifier-adder 18 with opposite signs, and the error signal of the remote control is amplified and supplied

 then to the electromechanical converter 28. When the speeds of movement of pistons 4 and 5 are equal, the error signal L (7 is equal to zero. When the speed of one of the pistons changes, for example, the speed of the left piston increases, the amplified signal

5 mismatch enters the electric-mechanical converter 28, which shifts the valve 25 of the control valve 24 nozzle-valve to the right by an amount proportional to the LU. As a result, a differential pressure appears in the control hydrolines of the distributor 20, which shifts the plunger 21 to the left, which increases the flow of working fluid into the rodless cavity of the right hydraulic cylinder and reduces the flow of the working fluid into the rodless cavity of the left hydraulic cylinder until

5 piston speeds 4 and 5 do not become

0

equal. In this way, an automatic leveling of the speed of movement of the pistons is started, starting from the moment of the start of movement.

If, when the part is gripped, the clamping pads 8 and 9, the forces on the pads are not equal to each other, the part-clamping pads system begins to shift towards the piston, the force on the rod is less. When the system is mixed in one direction or another, the position mismatch signal causes proportional mixing of the plunger 21 and redistribution of pressures in rodless cavities of the right 3 and left 2 hydraulic cylinders to the values equalized by their forces on the rods of the left and right pistons. Thus, in the proposed device, the forces are automatically equalized on the piston rods, which ensures rigid fixation of the clamped part without the presence of a pressure reducing valve, only when it is precisely installed in a predetermined position. This position may not coincide with the axis of rotation of the part and is determined by the magnitude of the control signal Uy.

When the control signal is removed, the cartridge 17 switches in the opposite direction. At the same time, the electrical connection between the amplifier-adder 18 and the electromechanical converter 28 is interrupted and the springs 22 and 23 set the plunger 21B to the neutral position. At the same time, the rod end cavities of the left and right hydraulic cylinders are connected through the spool 17 to the main, and the rodless cavities through the valve 19 are connected to the drain. The pistons return to their original position, and pads 8 and 9 release the part.

The accuracy of the centering of the parts to be welded is determined by the clamping rigidity, i.e. the difference in forces between the right and left clamping pads when the plunger 21 is in the neutral position.

A known method is used to analyze the error of the clamping force. To simplify the analysis, the radial clearance between the control valve body and the plunger is neglected, the edges are considered sharp, without curves, and the flow rate through all four channels is equal. The following designations are accepted: T is the difference between the technological forces acting on the right and left terminal blocks. in the direction of the left clamping block;

system speed; clamping pads — part; QI and Qs-costs of the working fluid through

biv hydrodistribution

V

body channels;

Qs and Q4 are the flow rates of the working fluid through the channels of the hydraulic distributor;

o

0

50

PH - nutritional pressure; PI and 2 - pressure in the working cavity of the (rodless) right and left hydraulic cylinders;

p is the density of the working fluid;

ji is the coefficient of discharge; f I and fa-area of the piston in the rodless cavity of the right and left guide .-., rotsilindrov;

 the ratio of the areas of the pistons - right and left hydraulic cylinders;

b is the length of the working window of the hydraulic distributor;

ho- initial opening of the control valve;

h is the mixing of the valve distributor from the middle position;

5 - misalignment of the clamping pads;

G-gear ratio between the clamping block and the hydraulic distributor plunger; the initial area of the working window;

the increment of the flow area due to the displacement of the spool from the neutral position.

5o D5

Consider the equation of the working fluid flow rates in rodless cavities of the right and left hydraulic cylinders:

afV Q3-Qi; ,

where, () (P

)

25 30

35

) o (S-AS), VI- (e-P

f

40

Q3 (S-A5) Q, (S + AS) | iV |

Summing up the left and right sides of the expenditure equations and expressing the result with respect to V, we get:

) VJ (5-А5) (d /, -f V / i) - (5 + A5) (V, + - V. Take into account the equation of static equilibrium of the piston

P, aF-P.

and the relationship between pressures P, + P, P

fair for a hydraulic drive with a four-edged flow spool for any values of V,

p, -i tp T.

 -1 +

R. (аР „F

After substitution of the expressions PI and P & equation for V and transformations

v (;, (i-twT 7 P F

n

X d / aG 1 + D1 + 7PGG Y 7 -P.

a + 1

V

The formula shows that the drive loses rigidity (/ (0) only if

 O if, i.e., at very large values of 7 () or small values of a (), which is practically unreal.

The proposed clamping device is simpler than the known

5, its hydraulic circuit does not contain a pressure reducing valve, while it provides a higher accuracy in centering one of the parts to be welded relative to a given axis, which is a consequence of an increase in the shear, its coefficient I n I l I gV / jjf 20 on an open control circuit,

consequently, the system performance also increases.

.. 2 и6 ,,, where / (for L // - Enter the dimensionless parameters:

 fiji r K-K / io P-nF

when used, the equation for V can be reduced to:

0 + 1 M + a. Allowing it relatively b, receive:

t l; H + Gl / a- (a + iW

VT + T + Vo Vl + f + Va-5 This expression determines the dependence of the following drive error on the piston speed and the load acting on it.

The considered drive during the working stroke. Works in two modes: the closure of the clamping pads () and the clamping of the part ().

Example. Determine the relative error of the drive. Technologically, usually the values lie in the range of 0.99-0.95.

Claims (1)

Invention Formula 25 A clamping device for centering and clamping parts during friction welding, comprising a housing with a guide, two mounted in the cylinder of a hydraulic cylinder with single piston pistons and fixed on the rods clamping pads located in the guide housing, a two-position four-line spool connecting the rod cavity one of the hydraulic cylinders with a drain; a synchronizer for displacing the pistons of the hydraulic cylinders. The value of the relative technological 5 in the form of a hydrodistributing body and the force g can theoretically vary within the limits of O-1. When determining the relative mismatch of a known device, the pressure loss of the clamp according to the principle of action is taken as 10%, i.e., 9. If we assume that the pressure loss on the clamp control and in this case equal to 10%, then to estimate the accuracy it is necessary to set the value, 1. Determine with proportional electric control, the inlet of which is connected to the main fluid line, one of the middle outlets with the rodless cavity of one hydraulic cylinder, and the two extreme outlets are connected to the drain, and the control system with two electric linear displacement sensors and an amplifier-adder, whose inputs are connected to electrical sensors, and the output is with the control mismatch of the actuator at 45 of the hydraulic distributor, while the mobile elements of the electrical sensors are rigidly connected to mnymi pads, characterized in that, in order to simplify the design, improve accuracy tsentriroa 0, 95 and 1: T l / a-T .. 1; - 07. yi + 74-Va- vani details and speed of the system. The microns are taken and (1 and a absolute) the input of the hydrodistributor is connected to the master mismatch calculated by the formula: through the two-position four-line spool, the rodless cavity of the second hydraulic cylinder is connected to the second middle outlet of the hydraulic distributor, and the rod cavities of the hydraulic cylinders are connected to each other.   1.05 microns. The result indicates a high rigidity of the drive. In the general case, the stiffness of the drive can be assessed in the dT d8 case is determined by the formula: The K –– gauge, which is considered for d / a – G 1 + D1 + 7PGG TH 7 –P. a + 1 Invention Formula 25 A clamping device for centering and clamping parts during friction welding, comprising a housing with a guide, two mounted in the cylinder of a hydraulic cylinder with single piston pistons and fixed on the rods clamping pads located in the guide housing, a two-position four-line spool connecting the rod cavity one of the hydraulic cylinders with a drain; a synchronizer for displacing the pistons of the hydraulic cylinders. implemented in the form of hydraulic distribution with proportional electric control, the inlet of which is connected to the main fluid line, one of the middle outlets with the rodless cavity of one hydraulic cylinder, and the two extreme outlets are connected to the drain, and the control system with two electric linear displacement sensors and an amplifier-adder, whose inputs are connected to electric sensors, and the output is controlled by a control valve through a two-position four-line valve, the rodless cavity of the second hydraulic cylinder is connected to the second average hydraulic output redelitel, and the rod end of the hydraulic cylinders are interconnected.