FR2616701A1 - ROTARY TABLE FOR A VERTICAL MACHINE TOOL - Google Patents

Abstract

The present invention relates to the construction of machine tools. The table of a vertical machine tool has a tenon 2 mounted on a base 1 by means of a flange 14 pressurized into an annular bore made in said base. The spindle 3 is mounted by a bearing surface 6 on the guide 7 produced on the upper end surface of the tenon 2, cavities 10 being made on the lower end surface thereof. The cavities 5 and 10 are arranged opposite to each other. A clamping ring 9 is rigidly fixed on the lower end surface of the spindle 3 and mounted under the tenon 2 so as to cover the cavities 10. The table is advantageously used in vertical lathes and vertical grinding machines with rotary table.

Description

The present invention relates to the construction of machine tools and

  especially for object a rotary table

for a vertical machine tool.

  It is advantageous to use the present invention in vertical lathes or vertical grinders to

  rotary table in which the table is a primary unit

  cipal which carries the loads due to the forces, which receives the forces of cut and which determines the geometrical precision

  of a machine tool while simultaneously playing the role of a

  seems to be where the maximum amount of energy

  denies. The main problems that are not yet

  resolved and which prevent the application of hydro-

  in vertical machine tools.

  are: - maintaining a constant layer thickness

  working fluid when the temperature changes

  ture; the creation of a stable high rigidity of the layer of said liquid; - the elimination of the risk of clogging of the elements of the hydraulic system throughout the working period

of the table;

  - the creation of identical thicknesses (0.25 to 1.1%)

  layers of liquid in each cavity of the hy-

  drostats and the preservation of their identity and values during the period of use without adjustment or replacement of the elements of the system; - the reduction of the friction forces generated on the hydrostatic guides during the rotation of the

  which achieve important values and provoke

  important heat releases, which means that

  an increase in the power of the controls and

  the irrational consumption of electrical energy.

  We know a rotary table of a machine-

  vertical tool (SU - A - 700 321) which includes a post

  made integral with a base. A tray, equipped with

  hydrostatic circular systems, the cavities of which are

  on the base of the table, rests on

  tenon. The table is equipped with a mechanism ensuring a pre-

  tightening, with a floating clamping ring

  the plate against the bearing surface of the circular guides

  hydrostatic flows with a stress that does not depend on the loads applied to the plateau. The tables, made according to this design, require great efforts for the

  pre-tightening, which causes a deformation of the plate.

  In order to ensure the normal conditions for the work of a machine tool, the mechanism creates a pre-tightening by decreasing the range of the loads because the range of the loads will be: Pmax D = Pmin o: P ma is the maximum axial load, max

Pmin is the minimum axial load.

  Since the clamping force of the freely floating ring of the pre-clamping mechanism does not depend on

  the weight of the load, the minimum axial load

  ra: Pmin P + P min 1 2 o: P1 is the weight of the plate, P2 is the force applied to the compression ring, and the maximum axial load will be: p p + p max 3 + Pmin

  o: P is the weight of a blank to be mounted.

  Pmax P3 + Pmin D min = min Pmin Pmin For the load range D = 1.5, the pre-tightening is equal to the maximum double weight of a blank and the maximum axial load is equal to the maximum triple weight, which implies increase the lift of the hydrostatic guides three times by increasing their external dimensions for this purpose. As a result, liquid consumption and

the absorbed power increases.

  In addition, there are large losses of

  the expense of overcoming fluid friction in a liquid layer of hydrostatic guides. The power of losses is directly proportional to

  square of the linear speed of the guides while the chain

  their release as a result of the losses heats the guides and

  causes large thermal deformations, which is

  due to a decrease in the accuracy of the parameters. To reduce the deformations, refrigeration systems are used which cool the liquid brought into the cavities. However, even these measures do not eliminate the

  distortions that in the case of large developing powers

  the liquid, lying on the periphery of the guidelines

is warming up.

  Since the resultant force of the effort

  independent of the clamping of the tray is applied to its cen-

  the forces resulting from the cutting moment acting on the hydrostatic circular guides and the ring

  clamping forces are equal at the moment due to the cutting forces

  half of the diameter of the circular guides, the angular rigidity being proportional to the axial rigidity of the clamping ring. Therefore, to ensure a required rigidity, the diameter of the hydrostatic bearing guide is increased, which results in an increase in the linear speed of the guides and an increase in the temperature of heating. This limiting disadvantage

  the use of the table on vertical machine tools

  rotary table blocks operating at high speeds

  his. The roller bearing bearing mounted in said device does not provide high precision and radial rigidity at high cutting forces. To ensure high precision, it is essential to use

  precision manufactured by selective assembly of parts.

  A rotary table of a machine is also known.

  vertical chine-tool (US-A-3 871 721) having an angular post, fixed on a base in which is mounted a rotatable assembly with the possibility of rotating about the vertical axis and comprising a spindle and a plate and

  leaning vertically on the bearing surface on which

  are practiced cavities, separated from each other

  and together with the bearing surface forming a guiding

  Hydrostatic circular tread and a hydrostatic mechanism

  pre-tightening with a clamping ring and a system of

  conducted working fluid in said cavities. In this

  In this case, the rotary assembly is mounted in a radial radial bearing

  drostatic system and the working liquid supply system comprises throttling grooves made between the

  cavities on the bearing surface of the circular guide

  drostatic and in the clamping ring, these grooves

  grouped together, each connected to a tube of

  corresponding pillar connected to a pump. In addition,

  in this table, the clamping ring of the pre-

  tightening is carried out in the form of separate sectors which co-

  operate with gobs, which in turn act through a system of levers on the abutment surface of the

pre-tightening mechanism.

  In the table according to US-A-3 871 721, there is

  provided radial rigidity through the use of a

  hydrostatic abutment and the deformation of the plate due to pre-tightening forces has been eliminated because the clamping forces act on the base via

  of levers without acting on the board.

  However, by analogy with the table made according to the previous similar technical solution, this table is characterized by the need to apply

  important efforts for pre-tightening and leads to

  the power to overcome the fluid friction, and further increase the diameter of the hydrostatic bearing guide, which leads to an increase in the linear speed of said guides and an increase in the temperature of the heating. In addition, because the throttling grooves are connected in parallel with the capillary tubes and the tubes are connected in series with the

  pumps, it is impossible to ensure quantities of liquid

  of equal labor consumed in each cavity of a guiding

  corresponding hydrostatic head and it is therefore impossible to ensure equal thicknesses of the layers of

  liquid in each cavity of the guides.

  In this table, also means for controlling the temperature which varies as a result of the variation of the angular rotation speed of the machine are not provided.

  pin, which leads to a deteriorated accuracy of the para-

  geometric meters of the guides.

  The prestressing mechanism is of a construction

  complex, requires a lot of manpower for its

  brication, is difficult to adapt to a technology of

  brication and requires manual labor for scratching

  and adjusting the bearing surface of the hydrostatic guide

  as well as sets and pieces of this memoir. To control the accuracy of the realization of the geometrical parameters of the hydrostatic guides,

  complex special devices must be used.

  It was therefore proposed to develop a

  for a vertical machine tool in which the per-

  design of hydrostatic prestressing mechanism, hydrostatic guides and system

  of working liquid supply ensures improved accuracy.

  machining of blanks throughout the entire range of

  angular tesses, better rigidity of the table and a reduction of unproductive consumption of electrical energy. The problem thus posed is solved by means of a

  table of a vertical machine tool comprising an annular tenon

  fixed on a base and carrying a rotatably mounted assembly

  with the possibility of turning around the vertical axis

  carrying a pin and a tray and leaning vertically

  on a bearing surface on which cavities are provided.

  which are separated from each other and forming, jointly

  with the support surface, a circular hydraulic guidance

  static, and a hydrostatic prestressing mechanism, having a clamping ring, and a liquid supply system of

  in said cavities, characterized in that

  no is mounted on the base via a flange

  ring, made on one of its radial surfaces,

  due to the base and mounted to the press in a

  annular ring formed in the base, in that the spindle of the rotary assembly is mounted by the bearing surface on a hydrostatic guide provided on the upper surface of the

  on the underside of which are carved

  in front of the cavities of the hydro-

  static and form a hydrostatic mechanism of preser-

  ge, whose clamping ring is fixed rigidly to the underside of the pin and mounted above the pin so that it covers the cavities by the abutment surface

  provided on its underside, in that the surface of bu-

  the lower face of the post and the abutment surface of the clamping ring form, in this case, a single abutment surface of the hydrostatic pre-tightening mechanism, the cavities of which are placed in communication with the system

supply of working liquid.

  By mounting the tenon on the base by means of the flange which is rigidly connected to said base and mounted to the press in the annular bore, it ensures a high accuracy of the positioning of the spindle assembly in a given position as well as high angular rigidity

of the table.

  By relying on the bearing surface of the hydrostatic guide, formed on the upper face of the tenon, the spindle of the rotary assembly receives axial loads

Z66751

  resulting from the weight of a draft and the strength of the reaction

  tion due to the overturning torque generated during the

  pe, which eliminates the deformation of the plate by these forces by decreasing the jerks and thus increases the precision of

the usinage-.

  The fact that the cavities of the mechanism's guides

  pre-tightening are carried out with regard to the guiding cavities.

  hydrostatic dages and that they are arranged on top of

  lower end face contributes that the forces generated as a result of the clamping are transmitted to the body of the tenon in opposition to one another, which eliminates the

  forming bending moments which act on said

  no, and as regards the axial loads due to the weight of a

  mounted, they are received by the spindle, which eliminates

  me the deformation of the plate and improves the precision of the machining.

  The clamping ring, fixed rigidly to the sur-

  bottom end face of the spindle and rise above

  under the tenon so that the cavities, on its lower end surface, are covered, creates

  a prestressing effort that decreases inversely proportion-

  the weight of a blank, mounted on the plate, which reduces the pre-tightening force by twice and the deformation of the bearing planes of the spindle and the clamping ring that it can cause. In addition to the prestressing forces, the clamping ring fixed rigidly on the spindle absorbs the forces resulting from the overturning moments generated by the cutting forces, which increases at least twice the angular stiffness and, consequently, allows to obtain a high precision of the machining.

  Thanks to the fact that the pre-tightening efforts are

  minuted twice, it is possible to decrease by two

  the diameter of the hydrostatic support guide and

  thereby, by four times the losses of energy

  electricity. By decreasing the consumption of energy

  electrical energy, the heat release and

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  heat due to a decrease in the pre-

  geometric parameters of the hydrostatic guides

c.

  It is advantageous that the cavities of the hy-

  pre-tightening drost, the cavities of the hydrostatic circular guide and the support bearing cavities are

  in communication with the fluid supply system

  by means of a collector and a measuring device,

  in the form of known capillary tubes connected by

  their ends to the corresponding cavities and to the

  tor. In this case, additional tubes are mounted at the connection points on the capillary and connected tubes

  rigidly to said tubes and arranged coaxially therewith.

  The length of the capillary tubes is greater than at least

  200 times to their inner diameter.

  The connection of the circular pipe with the

  hydrostatic units, made using capillary tubes, manufactured with identical deviations of the inside diameter and the length mentioned above gives the possibility of obtaining

  high precision of the determination of the flow rates of working fluid

  in the cavities of the hydrostatic guides and the mecha-

  pre-tightening, which ensures, in turn, a thickness

  relatively equal layers of liquid in said cavities

  each of the hydrostatic guides.

  The complementary protective tubes arranged

  axially and with a clearance with respect to said capillary tubes

  They allow them to bend only to the value of the game. Then the two tubes bend together along the entire length. We eliminated the sections with a

  concentration of stresses, breaks in capillary tubes

  that is to say, it has ensured the reliability and

life length.

  In addition, according to the invention, hydrostatic guidance has been placed in the vicinity of the bearing surface.

  inside the tenon, a temperature control sensor

  ture that rises on said surface during rotation of the spindle. The sensor is connected to a known bridge measuring circuit and electrically connected via

  amplifiers to a compressor of a refrigerating chamber

  connected in series with the suction line of the

  pump of the working liquid supply system.

  The presence of the sensor with its connection, according to the aforementioned scheme, in the working liquid supply system ensures a constant thermal field of the table in the given range thanks to which connecting

  the refrigerating chamber in series on the suction line

  pump is offered the possibility to bring

  pump, the working fluid cooled proportionally

  the speed of the plate, the value of the cooling being established by the sensors, one of which

  located in the vicinity of the support surface of the hydro-

  static. This makes it possible to evacuate the heat released by

  thus a constant thermal field of the table. The constant thermal field ensures the suppression of the fall of the

  precision of the geometrical parameters of hydrostatic guides

  ticks. It is possible to make the support surface of the

  hydrostatic circular guidance in the form of a truncated cone

than.

  This achievement gives the possibility to all

  spindle to absorb axial and radial loads without support bearing, which can reduce the height of

  the table and thereby increase the necessary working space

  widening the range of typical dimensions of

  parts, in particular, to increase their height.

  It is also advantageous that the surface of bu-

  tee of the hydrostatic mechanism of the prestressing is carried out

in the form of a truncated cone.

  This gives the possibility of obtaining

  the tenon at the center of the hole equal to zero while being maximum at the point of attachment. The construction is close to a beam with equal resistance

  which gives the reaction forces of the guiding

  Hydrostatic circular tread and hydrostatic bearing 241670l pre-tightening mechanism to withstand axial loads

  and radial. This further reduces the

  of the table and thereby increase the workspace

  for an enlargement of the range of blanks to be machined.

  In order to simplify the technology of

  the accuracy and accuracy of the geometrical parameters of the guides, it is advantageous that the bearing surface of the hydrostatic circular guide and the surface

  of the hydrostatic prestressing mechanism are

rallèles.

  It is possible that cavities lying in

  the hydrostatic circular guidance and

  the hydrostatic head of the prestressing mechanism

identical.

  Equal forces resulting from the pressure created in said cavities are thus obtained by virtue of the fact that the surfaces of these cavities are equal and the pressure supplied is equal too. As a result, the bearing capacity of each of the aforementioned guide planes will be equivalent and can withstand the equivalent efforts of the reactions due to

at times of reversal.

  The axial dimension of the flange can be at least 4 times smaller than the axial dimension of the tenon itself. This ratio of axial dimensions mentioned above

  allows to obtain a cylindrical rigidity of the tenon, on the-

  the cavities of the hydrostatic guides, which are 60 times the rigidity of its flange, reduce the deformation of the hydrostatic guides, thus keeping the geometric dimensions of the

  hydrostatic guides at high loads.

  The invention will be better understood and other purposes, details and advantages thereof will become more apparent in the

  reading the following description of different modes

  only as non-binding examples.

  mitatives with reference to the accompanying nonlimiting drawings in which: - Figure 1 shows an overview of a table of a vertical machine tool, in longitudinal section; - Figure 2 is a section along the line II-II of Figure 1; os - Figure 3 shows an embodiment of the table, according to the invention; - Figure 4 schematically shows the working liquid supply system; - Figure 5 shows a capillary tube in longitudinal section on an enlarged scale; - Figure 6 shows the table claimed with bearing surfaces of the circular guide in the form of a truncated cone in longitudinal section; - Figure 7 is a section along the line VI- VI of Figure 6; FIG. 8 represents, in longitudinal section, the

  table of a vertical machine tool in which the surface

  this bearing of the circular guide and the abutment surface of the prestress mechanism are made in the form of a truncated cone; FIG. 9 is a section along the line VIII-VIII

of Figure 8.

  The table claimed for a vertical machine tool

  wedge comprises a base 1, an annular stud 2 fixed to said base, a rotatable spindle assembly, mounted with the possibility of rotating about the vertical axis "aa" and having a spindle 3, and a plate 4. The assembly of

  pin is supported vertically on the horizontal support surface

  zontal of the post 2 on which cavities are made

  5 (Figure 2) separated from each other and forming a joint

  with the support surface 6 (Figure 1), a cir-

  7. The table also includes a

  pre-tightening mechanism provided with a shim 8, a

  clamping ring 9, fixed rigidly on the surface of ex-

  lower end of the spindle 3 and disposed above the pin 2 so as to cover the cavities 10 guides of the prestressing mechanism. The cavities 10 are identical to the

  cavities 5 of the hydrostatic guide 7 and are arranged oppo-

  attached to them on the lower end surface of the

tenon 2.

  The abutment surface 11 of the lower end surface of the post 2 and the abutment surface 12 of the bushing

  9 form a single stop surface of the mechanism

* hydrostatic prestressing.

  The spindle is supported radially on a hy-

drostatic 13.

  The annular post 2 is provided with a flange 14,

  forcibly mounted in an annular bore made in the

  1. The axial dimension (b1) of the flange 14 is smaller

  four times at the axial dimension (b) of the post 2.

  It should be noted that the flange 14 is made, either on the radial outer surface, as shown in FIG.

  Figure 1, either on the radial inner surface, as

in figure 3.

  The system for supplying working liquid into the cavities 5, 10 (FIG. 3) of the guiding support surface

  Hydrostatic Circular and the Stop Surface of the Mechanism

  pre-tightening and in the support bearing cavities

  13 comprises a hydraulic reservoir 15 (FIG. 4), a pump

  pe 16 at low pressure, the output of which is connected to a pre-

  filter 17, a refrigerating chamber 18, connected in series with the suction line of the pump 19 discharging the working liquid. Through a prefilter

  and a fine filter 21, the output of said pump 19 is

  linked to a reduction valve 22 and then through

  a check valve 23 to a manifold 24.

  - Parallel to the collector 24, a connection was

  hydraulic accumulator 25, a relay 26 for controlling the

  pressure in the system and a pressure gauge 27.

  The collector 24 is connected to the cavities 5 and 10 to

  through the measuring device consisting of capillary tubes

  These tubes are connected by a known mode to the collector 24, to the corresponding cavities 5, 10 and to the cavities of the support bearing 13 (FIG. 1). In places o

  the tubes 28 (FIG. 5) are connected to the collector 24 (FIG.

  gure 3) and cavities 5 and 10 and the cavities of the

  13, complementary protective tubes 29 (FIG. 5) have been mounted which are arranged coaxially with the tubes 28 and are connected thereto rigidly. The length of each protective tube 29 exceeds its diameter 20 times and the length of

  each capillary tube 20 is greater than its integral diameter.

at least 200 times.

  The refrigerating chamber 18 (FIG. 4) has a compressor 30 which is electrically connected through the amplifiers 31 to a known bridge measurement circuit. This circuit comprises a temperature control sensor 32 which rises on the bearing surface 6 (FIG. 1) during the

  rotation of pin 3, a sensor 33 for measuring the temperature

  (Figure 4) in the assembly in which the clearance

  heat is zero, and a selector device 34 which

  poses an allowable limit of the variation of the thermal field

of the table.

  If it is necessary to provide a free space in the center of the table, it is possible to realize it according to the

mode shown in Figure 3.

  The bearing surface 6 (FIG. 1) of the circular guide

  hydrostatic and the abutment surface 11 of the hydro-

  static pretensioning are parallel.

  If it is necessary to reduce the height of the

  and other technological opportunities, it is necessary to

  aligns the bearing surface 6 (Figure 6, 7) in the form of a truncated cone, or both surfaces, the surface 6 and the surface

  11 (Figures 8, 9) are made in the form of a truncated cone.

  In case of realization of the surfaces in the form of a truncated cone,

  it is possible not to use the support bearing.

  The table works as follows.

  When the machine tool is engaged, the pumps 16

  19 are put into action and the working fluid is

  from the hydraulic reservoir 15 by the pump 16 at low

  pressure through the prefilter 17 in the refrigerating chamber

  than 18, connected in series with the suction line of the

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pump 19.

  The pump 19 delivers the working liquid via the

  pre-filter 20 and the fine filter 21. The working fluid par-

  comes through the check valve 23 into the manifold

  24 and the hydraulic accumulator 25 in the-

  a reserve of working fluid is created for the case of an interruption of the arrival of the working liquid because of a failure and is also carried out an attenuation of the pulsations of the pump. As soon as the pressure has reached

  prescribed value, the reduction valve 22 discharges a quantity

  excess of working fluid in the hy-

  15 and the pressure control relay 26 sends a signal which allows the rotation of the spindle 3. Using the pressure gauge 27, the value of the pressure which can

  be adjusted by the reduction valve 22.

  The working liquid is discharged under pressure through the capillary tubes 28 into the cavities 5 of the guide.

  ge of hydrostatic support, in the cavity 10 of the guide of bu-

  hydrostatic head of the pre-tightening mechanism and in the cavity of the hydrostatic bearing support 13. The capillary tubes acting as high-precision throttles dose the volumes of the liquid supplied into the cavities 5 by creating identical thicknesses of the layers of said liquid. following the entire perimeter of the hydrostatic support guide 7

  as well as in the cavities 10 of the abutment surface of the

  pre-tightening mechanism by also creating identical thicknesses

  ticks along the entire perimeter of the liquid layers of

  and in the hydrostatic support bearing 13. The pres-

  The liquid in the cavities 5 of the hydrostatic circular guides 7 raises the pin 3 together with the plate 4, fixed thereto. Through the clamping ring 9 and pin 3, the forces generated by the

  pressure, reigning in cavities 10 hydrostatic guides

  the pre-tightening mechanism, are transmitted to the

  These forces act on the pin 3 in opposition to each other without exerting any action on the plate 4. In this case, the

26 16? 7 1

  pin 3 takes the position with the imposed thicknesses of the

  layers of liquids: h is the thickness of the layer of

  quide in the prestressing mechanism and h1 is the thickness

  of the liquid layer in the circular water guides

  static. The values h and h! and the rigidity of their layers must be determined by the choice of the flow of liquid flowing through the cavities 5 and 10 while

  the forces imposed on the pre-tightening are regulated by the to-

  imposed ht = h + h1 that is ensured by choosing the thickness

  8. When a blank is placed on the plate 4, the vertical force resulting from its

  weight acts through pin 3 on the guides

  hydrostatic circular rods 7 and the pin descends under the effect of the chosen axial stiffness (imposed) of the liquid layer h1 together with the clamping ring 9 fixed thereto by decreasing the thickness of the layer h1 and increasing for this very reason, the same value, the thickness of the layer h. The increase in the thickness of the layer h as a result of the reduction in the hydraulic resistance causes a decrease in the pressure in the cavities 10 of the guides of the clamping mechanism by reducing the prestressing force.

  inversely proportional to the weight of the blank.

  This makes it possible to significantly increase the angular stiffness

  drawing of the table while at the same time decreasing the prestressing of a significant value (approximately twice). Under the action of the moment resulting from the cutting forces, the spindle

  3 bows. At this moment, the game decreases on one side of the guides.

  hydrostatic bearings 7 and on an opposite side of the guides of the

  tightening mechanism and increases on the other sides diamè-

  strongly opposed. This moment is then balanced by the moment of reaction of a couple of forces resulting from the liquid pressure which circulates through the cavities 5 of the circular guides 7, on the one hand, and the forces resulting from the pressure of liquid flowing at through the cavities

  of the clamping ring 5, on the other hand. The resulting strength

  aunt of each of these lies on the average diameter

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  said supports, that is to say, the forces resulting from the moment

  are equal to the quotient of the division of the moment sup-

  mentioned by the diameter of the circular guides 7. This

  provides the required angular stiffness for the diameter

  circular guides which is reduced by twice compared to the known table constructions, which

  increases at least two times the rotational angular velocity

  the spindle to an invariable heat clearance on the hydrostatic circular guides, or to reduce by four times the power spent on liquid friction

  in the liquid layer of hydrostatic bearings.

  The reaction forces of the circular guides act on the tenon and are transmitted through the body of the latter to the flange 14, permanently fixed in the base 1 because the cylindrical rigidity of the stud in which the guides are made is greater 60 times at the rigidity of the flange, the deformations of the guides 7 and 11 of the post 2

  at most 1/60 of the total deformities

  the flange 14. This makes it possible to keep the game imposed and, consequently, the high precision

  hydrostatic circular guides.

  During the operation of the pumping station, the

  vane pumps 19 (or piston pump) deliver the liquid

  in portions and creates a pulsating pressure in the system.

  tem. The hydraulic accumulator 25 partially attenuates the pulsation. This causes, in the feeding system,

  the vibration of all the elements and, in particular, the

  capillary tubes 28 chokes that break

  where they are connected to collector 24 and cavities 5, 10 at the points of the dangerous sections. The protective tubes 29 protect them against these breaks and

  in the case where the length of the protective tube 29 is greater than

  greater than 20 diameters they totally eliminate breaks

  possible. It is ensured by the fact that each of the tubes

  pillars 28 has the ability to bend at most a

  clearance between the protective tube 29 and its outer diameter.

  Then, the two tubes bend together, which is equivalent to a tree with equal resistance that bends

  regularly along the entire length and has no

  with a concentration of constraints.

  Before proceeding with the work, the limit chosen is imposed by using the selection device 34 made in the form of an adjustable resistor provided with a graduated scale of the limit of the variations of the thermal field. The

  selection device 34 is mounted on a control panel

  mand (not shown). The selection device 34, the temperature sensor 32 of the hydrostatic guide and the measurement sensor 33 of the temperature of the assembly o the

  heat is zero (they are made in

  thermoresistances), are connected to the electrical bridge measurement circuit which is connected so that if the temperature of the surface of the hydrostatic guide has exceeded the imposed limit a signal is sent and then amplified by the amplifiers 31 and sets running the compressor of

the refrigerating chamber.

  During the rotation of the plate 4, the liquid of the layer heats up as a result of the friction. The consumption

  absorbed energy for the heating of the liquid and di-

  exactly proportional to the square of the linear velocity.

  The working liquid bathes the surfaces of the guides

  hydrostatic circular washers 7 by heating them. As soon as the temperature of the hydrostatic circular guides 7 has exceeded the temperature of the assembly o the release of the

  heat is null, of a limit value imposed by the

  positive 34, the measuring bridge produces a signal. The amplifiers

  The amplifiers 31 amplify the signal and put the compressor 30 of the refrigerating chamber 18 into operation. While circulating through the refrigerating chamber, the working liquid is cooled and is sent by the pump 19. Then it reaches

  through the duct in the cavities 5 of the circular guide

hydrostatic water.

  The cooled liquid begins to cool the guides.

  Hydrostatic Circular Doses 7. Where their temperatu

  re decreased below the imposed limit, the signal of the

  measuring bridge disappears and the compressor 50 starts to

  Pos. This scheme makes it possible to bring the cooled working liquid into the cavities 5 and 10 and thus keep the thermal field of the table at a constant value in an imposed range and, ultimately, in the entire machine tool. This makes it possible to improve the precision of the machining of the blanks during the whole working period which

whatever the angular velocities.

  In the event of a breakdown and the termination of the

  page 19, the accumulated liquid in the hydraulic accumulator for the reserve continues to arrive in the cavities 5, 10 and the check valve 23 does not allow the working fluid

  return to the pumping station 19. If the pressure decreases

  naked below the imposed value the pressure relay 26

  disconnects the control from the table (not shown) and brakes

  do the plate 4, which eliminates the deterioration of the hydrostatic supports. This ensures reliability and a great

  service life of the machine tool.

  The operation of the tables made according to

  different modes with constructions different from

  bearing surfaces of the hydrostatic guides and

  stop of the pre-tightening mechanism is similar to the example de-

  written above, as shown in FIGS. 3, 6 to 8.

Claims (9)

  1. Rotary table for a vertical vertical machine   carrying an annular tenon (2) fixed on a base (1) and carrying   a rotary assembly rotatably mounted about the vertical axis   tical (a-a), having a pin (3) and a plate (4) and   leaning vertically on a support surface on which   are provided cavities (5) which are separated one of   the other and form with the support surface (6) a circumferential guide   hydrostatic wedge (7) and a pre-tightening hydrostatic mechanism, having a clamping ring (9), and a system   supply of working fluid into said cavities,   characterized in that the post (2) is mounted on the base (1) by means of an annular flange (14) made on one of its radial surfaces and integral with the base (1), said flange being mounted to the press by its outer surface in   an annular bore formed in the base, in that the broach   (3) of the rotary assembly is mounted by the   pui (6) on the hydrostatic guide (7) formed on the upper face of the tenon (2) on the lower surface of which are   practiced cavities (10) which are opposite   (5) of the hydrostatic guide (7) and form a mechanism   the clamping ring (9) is rigidly attached to the lower surface of the spindle (3) and mounted below the post (2) so that it covers the   cavities (10) by the abutment surface (11) on its inner surface   lower, in that the abutment surface (11) of the surface   tongue (2) and the abutment surface (12) of the base   clamping jig (9) form a solid abutment surface of the mech-   pre-tightening hydrostatic structure, whose cavities (10) are   connected to the working liquid supply system.   2. Table according to claim 1, characterized in that   the cavities (10) of the hydrostatic mechanism for preserving   rage and cavities (5) of hydrostatic circular guidance   (7) and the recesses of the support bearing (13) are   communication with the working fluid supply system.   means of a collector (24) and a metering device, constituting   killed by capillary tubes (28) connected by their extremities   corresponding cavities (5 and 10) and the collector   (24), complementary tubes (29) being mounted in   connection rights to the capillary tubes (28),   rigidly attached to these and arranged coaxially with those this.   3. Table according to claim 2, characterized in that the length of the capillary tubes (29) is at   less than 200 times larger than their inside diameter.   4. Table according to claim 1, characterized in that near the bearing surface (6) of the hydrostatic guide (7) inside the pin (2) is arranged a   temperature control sensor (32) rising on   surface during the rotation of the spindle (3), said cap-   connected to a bridge measuring circuit of one   known design electrically connected through amplifiers   (31) to a compressor (30) of the refrigerating chamber   (18) connected in series to a suction line   of the pump (19) of the working liquid supply system.   5. Table according to claim 1, characterized   in that the bearing surface (6) of the circular guide   drostatic (7) is formed as a truncated cone.   6. Table according to claims 1 and 5, characterized   in that the abutment surface (11) of the hinge mechanism   prestressing drost is made in the form of a cone truncated.   7. Table according to claim 1 or 5 and 6,   characterized in that the bearing surface (6) of the circumferential guide   hydrostatic wedge (7) and abutment surface (11, 12)   hydrostatic prestressing mechanism are parallel.   8. Table according to claim 7, characterized in that the cavities (5 and 10) disposed opposite those of the hydrostatic guide (7) and the hydrostatic mechanism.   pre-tightening are performed identical.   9. Table according to any one of the claims   characterized in that the axial dimension of the flange (14) is at least 4 times smaller than the dimension axial of the tenon (2) proper.