JP3943451B2 - Wire electrical discharge machine using rotating mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a wire electric discharge machine for processing by generating a discharge phenomenon between a traveling wire electrode and a workpiece, and more particularly to a feed roller for feeding a wire electrode.
[0002]
[Prior art]
  The wire electric discharge machine is a machine that generates a discharge phenomenon between a wire electrode and a workpiece and cuts out the workpiece. Usually, the wire electric discharge machine is equipped with a wire electrode feeding device, continuously supplies the wire electrode during machining, and has a pair of upper and lower wire guides in the vicinity of the workpiece to position the wire electrode at a machining site of the workpiece. It is like that.
  As a conventional wire electrode feeding device, a technique disclosed in Japanese Patent Laid-Open No. 7-276146 is known. In this apparatus, as shown in FIG. 9, a roller housing 52 is provided in a lower wire guide 51, and a feed roller 54 that feeds a wire electrode 53 and changes the traveling direction is disposed therein. The shaft 55 of the feed roller 54 is rotatably supported by a bearing case 57 via a ball bearing 56.
[0003]
  The roller housing 52 has a first nozzle (not shown) for injecting the processing liquid toward the blades 59 of the feed roller 54, and a first nozzle for injecting the processing liquid toward the V-shaped guide groove 61 of the feed roller 54. 2 nozzles (not shown) are provided, and the feed roller 54 is driven in a state where the wire electrode 53 is pressed against the guide groove 61 by the spray pressure of the machining liquid, and the wire electrode 53 is introduced from the nozzle portion 63. It is designed to send out. Further, the bearing case 57 is sealed with an oil seal 65 and an O-ring 66, and the air 67 having an atmospheric pressure or higher is supplied to the sealed space, thereby increasing the pressure inside the bearing case 57 and preventing the machining liquid from entering, The ball bearing 56 can be protected from metal powder called rust and sludge.
[0004]
  In the conventional wire electrode feeding device of the wire electric discharge machine, the feed roller 54 is supported by using the ball bearing 56 as described above. On the other hand, in the wire electric discharge machine, the workpiece is processed in the machining liquid, and sludge generated by the electric discharge machining floats in the machining liquid. When such sludge enters the rolling surface of the ball bearing 56 together with the machining fluid, the rolling surface is damaged, preventing the roller from rotating and causing the wire to break. For this reason, as described above, the bearing case 57 is sealed with the oil seal 65 and the O-ring 66, and the air 67 at atmospheric pressure or higher is supplied into the sealed space to prevent the machining liquid from entering.
[0005]
[Problems to be solved by the invention]
  As described above, the wire electrode feeding device of the conventional wire electric discharge machine is provided with the oil seal 65, the air supply device, etc., and prevents the machining liquid from entering the bearing case 57, and the device is complicated and compact. There is a problem that it is difficult to make it expensive and expensive. Furthermore, the oil seal 65 is a rubber ring that closes the gap between the feed roller 54 and the shaft 55, but slides with the shaft 55, so that deterioration over time is inevitable.
[0006]
  The present invention has been made to solve the above problems, and is not affected by foreign matters such as sludge in the processing liquid in a rotating mechanism such as a feed roller used in the processing liquid. It is an object of the present invention to provide a structure that can be easily supported by a bearing with a simple structure and that suppresses deterioration over time. It is another object of the present invention to provide a structure of a wire electric discharge machine using such a rotation mechanism as a feed roller in a wire electrode feeding apparatus.The
[0007]
[Means for Solving the Problems]
  The rotation mechanism according to claim 1 of the present inventionA wire electric discharge machine using a wire electrode has a wire electrode feeding device, generates a discharge phenomenon between the traveling wire electrode and the workpiece, and injects the machining liquid onto the electric discharge machining portion of the workpiece. It is a wire electric discharge machine which processes the said to-be-processed object in a processing tank in connection. The wire electrode feeder includes a pair of upper and lower wire guides for guiding the wire electrode to an electric discharge machining portion of the workpiece, and a feed roller for changing the traveling direction of the wire electrode. The feed roller is constituted by a rotating mechanism that is supported by a hydrostatic bearing using a working fluid having the same composition as that of the processing liquid as a processing liquid and is jetted. The machining fluid supply source and the hydrostatic bearing working fluid supply source are the same. The
[0008]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 2,The pressure of the working fluid between the hydrostatic bearing and the feed roller is kept higher than the working fluid pressure in the working tank and the working fluid flowing out from the hydrostatic bearing is sealed in the working tank. It is what will be drained.
[0009]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 3, whereinA machining fluid tank serving as a supply source of the working fluid and the working fluid of the hydrostatic bearing is provided, and the machining fluid in the machining tank is cleaned and supplied to the machining fluid tank.
[0010]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 4,The fluid pumped from the working fluid tank serving as a supply source of the working fluid and the working fluid of the hydrostatic bearing is branched by a branching means having a flow rate adjusting function, and the working fluid of the working fluid and the hydrostatic bearing It is used for.
[0011]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 5 is any one of claims 1 to 4.The hydrostatic bearing is composed of a radial bearing that supports the rotating mechanism in the radial direction from the inside, and a thrust bearing that supports the rotating mechanism in the thrust direction from the side surface.
[0012]
  Claims related to this inventionA wire electric discharge machine using the rotating mechanism according to claim 6,The working fluid supply path of the radial bearing is branched to supply the working fluid to the thrust bearing.
[0013]
  Claims related to this inventionA wire electric discharge machine using the rotation mechanism according to claim 7,The thrust restriction is provided in the radial direction portion of the working fluid supply path of the thrust bearing.
[0014]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 8 according to any one of claims 5 to 7.A working fluid escape hole is provided between the radial bearing and the thrust bearing, and the working fluid flowing out from either the radial or thrust bearing flows out of the bearing without flowing into the other bearing. It is something to be made.
[0015]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 9 is any one of claims 5 to 8.The thrust bearing is configured by incorporating a thrust bearing partition wall that separates the adjacent thrust pocket into a ring-shaped recess that connects a plurality of thrust pockets provided in the thrust bearing body. To do.
[0016]
  Claims related to this inventionA wire electric discharge machine using the rotation mechanism according to claim 10, according to any one of claims 5 to 9.The radial bearing is provided with a plurality of radial pockets whose bottom surface is a flat surface formed by partially cutting a plurality of inner portions of the side surfaces of the side surfaces of the side surfaces of the cylindrical bearings. It is.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
  Embodiment 1 of the present invention will be described below with reference to the drawings.
  FIG. 1 is a schematic view showing a main part of a wire electric discharge machine according to Embodiment 1 of the present invention. In FIG. 1, 1 is a workpiece as a workpiece, 2 is a wire electrode for cutting out the workpiece 1 by generating an electric discharge phenomenon with the workpiece 1, and 3a and 3b are wire electrodes in the vicinity of the workpiece 1 from above and below. A pair of upper and lower pipes as a pair of wire guides for guiding and positioning 2 to an electric discharge machining part of the workpiece 1, 4 is a feed roller that feeds the wire electrode 2 and changes the traveling direction, and is supported by a hydrostatic bearing 5. Reference numerals 6 and 7 denote an upper nozzle and a lower nozzle for injecting a machining liquid from the upper side and the lower side, respectively. The lower block 10 is a lower arm that supports the lower block 9, and 11 is a processing liquid in the processing tank in which the above 1 to 10 are immersed, and a liquid having the same composition as the working fluid of the hydrostatic bearing 5, for example, deionized water It is.
[0018]
  Next, the operation will be described.
  The wire electrode 2 processes the workpiece 1 by generating a discharge phenomenon with the workpiece 1 while traveling from top to bottom. At this time, sludge is generated as processing waste and floats in the processing liquid 11.
  Each of the upper pipe 3a and the lower pipe 3b incorporates a diamond die therein, and the wire electrode 2 is pressed laterally against the diamond die. The power supply 8 that supplies power to the wire electrode 2 is pressed against the wire electrode 2 and applies tension to the wire electrode 2 to reliably press the wire electrode 2 against the diamond die inside the lower pipe 3b. As described above, the wire electrode 2 is pressed against the diamond die in the lateral direction, and the position within the horizontal plane is accurately maintained and guided to the electric discharge machining site.
[0019]
  The upper nozzle 6 and the lower nozzle 7 spray the machining liquid 11 on the electric discharge machining site,
The wire electrode 2 is cooled to prevent disconnection, and the sludge is blown off from the electric discharge machining site to prevent a short circuit between the wire electrode 2 and the workpiece 1, and the electric discharge machining proceeds stably.
  The feed roller 4 bends the traveling direction of the wire electrode 2 at a right angle so that the traveling direction of the wire electrode 2 is vertical to horizontal, and guides the wire electrode 2 to the wire recovery part (not shown) through the inside of the cylindrical lower arm 10. . The hydrostatic bearing 5 uses a liquid having the same composition as the working liquid 11 as a working fluid, sprays a pressurized working fluid toward the feed roller 4, and supports the feed roller 4 by the static pressure of the working fluid. The feed roller 4 can be smoothly rotated by forming a fluid film of the working fluid between them. The pressure of the working fluid between the hydrostatic bearing 5 and the feed roller 4 is kept higher than the pressure of the working fluid 11 in the working tank, and the working fluid flowing out from the hydrostatic bearing 5 is not sealed in the working tank. Let it flow out.
[0020]
  As described above, in this embodiment, since the feed roller 4 is supported by the working fluid of the hydrostatic bearing 5, the sliding resistance is extremely small, aging degradation can be remarkably suppressed, and the rotational resistance of the feed roller 4 is reduced. Since it can be made small, disconnection of the wire electrode 2 can be prevented. In addition, since the working fluid has the same composition as the working fluid 11, there is no problem even if the working fluid flowing out from the hydrostatic bearing 5 flows into the working tank, so that there is no problem between the hydrostatic bearing 5 and the feed roller 4. The pressure of the working fluid is kept higher than the pressure of the machining fluid 11 in the machining tank, and the working fluid is allowed to flow out from the static pressure bearing 5 into the machining tank, so that the sludge in the machining fluid is contained in the static pressure bearing 5. It was made to prevent intrusion.
For this reason, it is possible to easily prevent sludge from entering the hydrostatic bearing 5 with a simple apparatus configuration, and the feed roller 4 can be stably and reliably supported by the hydrostatic bearing 5 and can transport the wire electrode 2. .
[0021]
Embodiment 2. FIG.
  FIG. 2 shows an overall view of the wire electric discharge machine shown in the first embodiment.
  As shown in FIG. 2, the wire electrode 2 pulls the bobbin 20, pulleys 21 and 22 that change the direction of the wire electrode 2 fed out from the bobbin 20, upper and lower pipes 3 a and 3 b (not shown), the feed roller 4, and the wire electrode 2. The wire electrode 2 is transported by the wire electrode feeding device including the collection roller 23 and the collection box 24 of the used wire electrode 2 that has passed through the collection roller 23.
  In addition, the processing liquid (clean liquid) is pumped out by the clean liquid pump 26 from the clear liquid tank 25 as a processing liquid tank for storing the processing liquid (clean liquid), and the pumped processing liquid (clean liquid) is supplied at a flow rate. A branching device 27 having an adjusting function adjusts the flow rate to branch into three. The first machining liquid (clean liquid) branched by the branching device 27 is supplied as a working fluid to the hydrostatic bearing 5 that supports the feed roller 4 via the hydrostatic bearing pipe 28. The second and third processing liquids (clean liquids) branched by the branching device 27 are supplied to the upper nozzle 6 and the lower nozzle 7 via the upper nozzle pipe 29a and the lower nozzle pipe 29b, respectively. The machining fluid is sprayed from the upper side and the lower side to the electric discharge machining part.
  On the other hand, the processing liquid 11 in the processing tank 30 is recovered in the dirty liquid tank 32 via the recovery pipe 31.
The processing liquid (dirt liquid) is pumped out from the waste liquid tank 32 by the dirty liquid pump 33, and the pumped processing liquid (dirt liquid) is filtered and purified by the filter 34 to be processed liquid (clean liquid). The liquid is again stored in the clean liquid tank 25.
[0022]
  In this embodiment, the processing liquid in the clear liquid tank 25 is pumped out by a pump, is branched by a branching device 27 having a flow rate adjusting function, and is used as the working liquid and the working fluid of the hydrostatic bearing 5. For this reason, it is not necessary to use a separate supply device for the working fluid, and the number of pumps can be reduced, and the device configuration can be small, simple, and inexpensive.
[0023]
Embodiment 3 FIG.
  FIG. 3 is a view showing a detailed structure of the hydrostatic bearing 5. The right diagram in FIG. 3 (a) is a diagram for mainly explaining the radial bearing. The rotation axis of the feed roller 4 (dotted line: physically not present, but theoretically unique to the rotational motion of the feed roller 4. 2 is a cross-sectional view including the rotation axis determined by (2). Moreover, the right figure of FIG.3 (b) is sectional drawing mainly explaining a thrust bearing, and the left figure is a BB arrow line view of a right figure. FIG. 3A and FIG. 3B show a relationship in which the hydrostatic bearing 5 is rotated 45 degrees. For convenience, the feed roller 4 is omitted in the AA arrow view and the BB arrow view.
  In FIG. 3, 35 is a taper pipe joint for connecting a machining liquid pipe from the clean liquid pump 26 (see FIG. 2), 36 is a hydrostatic bearing body block for supporting the taper pipe joint 35, and 37 is this hydrostatic bearing body. A central pipe provided in the block 36, 38 is a radial branch pipe branched from the central pipe 37, 39 is a radial orifice which is a throttle means provided in the radial branch pipe 38, and 40 is a working fluid which becomes a working fluid. A radial pocket that reaches after passing through the radial orifice 39 is formed by being separated by a radial partition wall 40a, and the inside of the feed roller 4 faces the radial pocket 40. Reference numeral 41 denotes a set screw for pressing the radial orifice 39.
  Further, 42 is a thrust branch pipe branched from the central pipe 37, 43 is a thrust orifice which is a throttle means provided in the thrust branch pipe 42, and 44 is a working fluid which becomes a working fluid after reaching the thrust orifice 43. A plurality of thrust pockets are formed separated by a thrust partition wall 44 a, and the side surface of the feed roller 4 faces the thrust pocket 44.
Reference numeral 45 denotes a set screw for pressing the thrust orifice 43. 46 is an escape hole for allowing the machining fluid flowing out from the radial pocket 40 to escape to the outside of the hydrostatic bearing before entering the thrust pocket 44.
[0024]
  Next, the operation will be described.
  The working fluid that is the working fluid supplied to the hydrostatic bearing 5 is adjusted in flow rate and pressure by providing a throttle in the middle of the piping. The machining fluid that has passed through this squeezing enters a central pipe 37 disposed in the feed roller 4 via a tapered pipe joint 35. The machining fluid in the central pipe 37 flows into the radial branch pipe 38 and enters the radial pocket 40 through the radial orifice 39. The working fluid pressure in the radial pocket 40 is kept higher than the outside of the hydrostatic bearing, and the feed roller 4 is supported in the radial direction (radial direction) from the inside. Further, by appropriately setting the gap (bearing gap) between the feed roller 4 and the radial partition wall 40a and the diameter of the radial orifice 39, a radial force (radial force) that pulls back against the radial position fluctuation of the feed roller 4 is set. Is generated. That is, radial rigidity for the feed roller 4 is generated in the hydrostatic bearing 5.
[0025]
  Further, the machining fluid in the central pipe 37 also branches into the thrust branch pipe 42 and enters the thrust pocket 44 through the thrust orifice 43. The working fluid pressure in the thrust pocket 44 is kept higher than the outside of the hydrostatic bearing, and the feed roller 4 is supported in the thrust direction (axial direction) from the side surface. Further, by appropriately setting the gap (bearing gap) between the feed roller 4 and the thrust partition wall 44a and the diameter of the thrust orifice 43, a thrust force (axial force) that pulls back against the thrust direction position fluctuation of the feed roller 4 is set. Is generated. That is, a thrust rigidity for the feed roller 4 is generated in the hydrostatic bearing 5.
  Further, when the working fluid as the working fluid flowing out from the radial pocket 40 tries to flow into the thrust pocket 44, the working fluid flows out of the bearing through the escape hole 46 provided between the radial pocket 40 and the thrust pocket 44. It is guided and does not flow into the thrust pocket 44.
[0026]
  In this embodiment, since the hydrostatic bearing 5 is composed of a radial bearing and a thrust bearing and is supported by the hydrostatic bearing in both the radial direction and the thrust direction, the feed roller 4 is reliable only with the fluid film of the working fluid. Good and reliable support. For this reason, the feed roller 4 can be supported by the bearing with a configuration in which sliding resistance is extremely small and deterioration with age is remarkably suppressed. Further, since the rotational resistance of the feed roller 4 can be reduced, the wire electrode 2 can be prevented from being disconnected.
  Further, since the radial bearing is supported from the inside of the feed roller 4, the hydrostatic bearing 5 can be configured in a small size. Further, a central pipe 37 for supplying a machining fluid to the radial bearing is disposed in the feed roller 4, and the machining fluid in the central pipe 37 is branched into a radial branch pipe 38 and a thrust branch pipe 42, and a radial pocket 40, Since the supply is made to each of the thrust pockets 44, the piping system for supplying the machining liquid can be made compact. Furthermore, since the thrust orifice 43 is provided in the radial direction portion of the thrust branch pipe 38, the axial size can be further reduced, and the compact hydrostatic bearing 5 can be configured.
  Further, the clearance hole 46 is provided so that the machining fluid flowing out from the radial pocket 40 flows out of the bearing without flowing into the thrust pocket 44, thereby preventing interference between the radial bearing and the thrust bearing and stabilizing the bearing characteristics. Can be improved. Even when the bearing clearance of the thrust bearing is blocked by foreign matter or the like, the machining fluid in the radial pocket 40 flows out of the bearing through the escape hole 46, so that the reliability can be improved.
[0027]
Embodiment 4 FIG.
  FIG. 4 is a view showing a structure of another example of the hydrostatic bearing 5 shown in FIG.
  As shown in the figure, the thrust bearing has a plurality of ring-shaped depressions (this is formed by incorporating a plurality of thrust bearing partition walls 44a made of different parts at predetermined positions of the ring-shaped depression provided in the thrust bearing body. In this case, the four thrust pockets 40 are formed. The ring-shaped depression can be easily processed by using a lathe or the like, and a thrust bearing partition 44a, which is a separate part, can be easily incorporated to constitute a thrust bearing.
  Further, as shown in the drawing, the radial pocket 40 of the radial bearing has no recess, and one plane is configured as a radial pocket bottom surface 40b. As shown in the perspective view of FIG. 5, the inner portion of the side surface of the cylindrical radial bearing main body 36 with the both end portions 36 a left is partially cut out at a plurality of locations (in this case, four locations). The formed plane is defined as a radial pocket bottom surface 40b. The radial pocket 40 is configured with the both end portions 36a not to be scraped as radial gaps. Such a radial pocket 40 can be easily machined from a cylindrical radial bearing body 36 with a milling machine or the like.
[0028]
Embodiment 5 FIG.
  The detailed specifications of the hydrostatic bearing 5 are described below, particularly the bearing rigidity.
  As shown in the first embodiment, the wire electrode 2 is pressed against the diamond die in the lateral direction and positioned with an accuracy of about 1 μm in the lateral direction, for example. In the hydrostatic bearing 5, the feed roller 4 is supported by the fluid film of the working fluid, so that the position of the feed roller 4 varies depending on various conditions. 2 can be maintained at about 0.1 μm or less.
  In the hydrostatic bearing 5 shown in FIG. 3, there are four radial pockets 40 on the entire circumference, and only one of them is shown. If the pressure in the central tube 37 is ps, the pressure in the radial pocket 40 is po, the load (load capacity) supported by one radial pocket 40 is W, and the flow rate flowing out of the radial pocket 40 is Q, these are As shown by the following equation, it is proportional to the pressure difference p0-pa (pa is the ambient pressure and is substantially equal to the atmospheric pressure).
  W = Ae (po−pa), Q = K_Bh³(po−pa) / μ (1)
      h: Bearing clearance μ; Viscosity coefficient of working fluid (working fluid)
      Ae: Radial pocket effective area K_B; Flow rate characteristic coefficient
Ae, K above_BAre functions determined by the dimensions of the radial pocket 40, and are given as follows.
  Ae = E₁L₁(1 + ξ_E) (1 + ξ_L) / 4 (2)
  K_B= {(1 + ξ_E) / (1-ξ_L) φ + (1 + ξ_L) φ / (1-ξ_E)} / 6 ... (3)
Where ξ_E= E₀/ E₁  ξ_L= L₀/ L₁  φ = L₁/ E₁And E₀, E₁, L₀, L₁Is determined by the dimensions of the radial pocket 40 and the radial partition 40a, as shown in FIG. FIG. 5 is a diagram in which the radial pocket 40 and the radial partition wall 40a are projected onto a plane.
[0029]
  Further, the following relationship holds for the orifice (radial orifice 39).
  W = (ps−pa) Ae {(1 + 4H⁶)^(1/2)-1} / 2H⁶  .... (4)
here,
  H = {K_B ²(ps-pa) / μ²K_s ²}^(1/6)h (5)
  K_s= C_fπr_s ²(2 / ρ)^(1/2)  ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ （6）
    H: dimensionless gap r_sThe radius of the orifice
    c_f; Orifice flow coefficient ρ; Fluid density
  Expressing H that maximizes bearing rigidity ∂W / ∂h as a dimensionless optimum clearance H *, for example, it is described in page 162 of the revised Lubrication Handbook, edited by The Lubrication Society of Japan, published in Yokendo 1987. In the case of a journal bearing in which two of the four radial pockets are back-to-back, the dimensionless optimum clearance H * is
  H * = 1.03 (7)
It becomes.
  The dimensionless load capacity obtained by normalizing the load capacity W is set as W * and is expressed by the following equation.
  W * = W / {Ae (ps−pa)} (8)
  If the bearing rigidity obtained by partial differentiation of the dimensionless load capacity W * with the dimensionless gap H is expressed by dimensionless rigidity k *, the following equation is obtained.
  k * = 6H⁵・ {-(2H⁶+1) (1 + 4H⁶)^(1/2)+ 1 + 4H⁶} / {2H¹²(1 + 4H⁶)} (9)
[0030]
  Next, an example of the hydrostatic bearing 5 with specific numerical values will be shown.
  E₁= 20mm, L₁= 14 mm, ξ_E= Ξ_L= 0.65. At this time, φ = 0.7, the radial pocket effective area Ae and the flow characteristic coefficient K_BIs the following value:
  Ae = 190.58mm²
  K_B= 1.67
  Consider hydrostatic bearing specifications in which the bearing gap h is, for example, in the range of 16 to 30 μm.
  For example, the orifice 39 is set so that the bearing rigidity is maximized when h = 20 μm.
  Moreover, the dimensionless load capacity in the optimum gap is 0.59 according to the equations (4), (7), and (8).
[0031]
  At h = 16 μm, the dimensionless gap is
  H = 1.03 · (16/20) = 0.82
From Equation (9), k * = − 0.97, and from Equations (4) and (8), W * = 0.80. The displacement of the feed roller 4 due to the dimensionless load capacity 0.59 in the optimum gap is
  0.59 / k * = − 0.61
  Since 0.61 <0.82 (dimensionless gap H),
At h = 16 μm, the feed roller 4 is supported via the fluid film of the working fluid without contacting the hydrostatic bearing 5 with respect to the dimensionless load capacity of the optimum gap.
  At h = 20 μm, the bearing rigidity is set to be maximum at this time.
The dimensionless gap is
  H = 1.03
From Equation (9), k * = − 1.0.
The displacement of the feed roller 4 due to the dimensionless load capacity 0.59 in the optimum gap is
  0.59 / k * = − 0.59
  Since 0.59 <1.03 (dimensionless gap H),
At h = 20 μm, the feed roller 4 is supported through the fluid film of the working fluid without contacting the hydrostatic bearing 5 with respect to the dimensionless load capacity of the optimum gap.
[0032]
  At h = 30 μm, the dimensionless gap is
  H = 1.03 · (30/20) = 1.55
From Equation (9), k * = − 0.40.
The displacement of the feed roller 4 due to the dimensionless load capacity 0.59 in the optimum gap is
  0.59 / k * = − 1.48
  Since 1.48 <1.55 (dimensionless gap H),
At h = 30 μm, the feed roller 4 is supported through the fluid film of the working fluid without contacting the hydrostatic bearing 5 with respect to the dimensionless load capacity of the optimum gap.
[0033]
  To support a bearing gap h = 30 μm and a load W = 3 kgf, from equation (4):
  ps−pa = 2.68 kgf / cm²  It becomes.
When deionized water is used as the working fluid (working fluid), the viscosity coefficient μ of the working fluid is μ = 0.89 × 10.^-3Pa · s,
The value of the flow rate Q is as follows.
  Q = 0.468 liter / min
That is, since four radial pockets 40 are provided, the total flow rate is 1.872 liter / min.
  The radial orifice 39 is as follows.
  From equation (5), K_S= 2.365 × 10^-8(SI unit system)
Flow coefficient c_f= 0.603 using an orifice
Orifice radius r_s= 0.528 mm.
[0034]
  When the bearing clearance h decreases, the flow rate can be reduced. Therefore, when the bearing clearance h is in the range of 16 to 30 μm, the flow rate of the working fluid (working fluid) can be suppressed to 2 liters / min or less. It is easy to branch the machining fluid ejected from 7 and supply it to the hydrostatic bearing as a working fluid.
  Therefore, in the example of the hydrostatic bearing 5, when the bearing gap h is in the range of 16 to 30 μm, the feed roller 4 can be supported with reliability without contacting the hydrostatic bearing 5, and the working fluid (working fluid) The flow rate is also suppressed to 2 liters / min or less, and the machining fluid can be supplied with high reliability.
[0035]
Embodiment 6 FIG.
  Next, the characteristic measurement result of the hydrostatic bearing 5 incorporated in the wire electric discharge machine is shown in FIGS.
FIG. 7 shows the case where the bearing clearance of the radial bearing is 10.9 μm, and FIG. 8 shows the case where it is 28.2 μm.
In the figure, the vertical axis represents the height of the feed roller 4 (roller height), and the center position where the upper and lower gaps are equal is set to zero. The horizontal axis represents the flow rate of the working fluid (working fluid) supplied to the hydrostatic bearing 5, and the total flow rate supplied to the radial bearing and the thrust bearing. A wire electrode 2 is wound around the feed roller 4 and tension is applied to the wire electrode 2.
  When the flow rate is 0 and the tension (wire tension) of the wire electrode 2 is 0 kgf, the feed roller 4 is lowered by its own weight, and the roller height is lowered by the bearing gap. If the wire tension is 1-3kgf,
The feed roller 4 is lifted up by the wire electrode 2, and the roller height is increased by the bearing gap.
[0036]
  In FIG. 7, when the bearing clearance is 10.9 μm, the feed roller height is smaller than the bearing clearance and the fluid film is formed even with a wire tension of 3 kgf at a flow rate of 1 liter / min. It can be seen that the feed roller 4 is supported. In a range suitable for use, the support through the fluid film is easier as the flow rate is larger and the wire tension is smaller.
  In FIG. 8, when the bearing clearance is 28.2 μm, a fluid film is formed for a wire tension of 1 kgf at a flow rate of 1 liter / min and the feed roller 4 is supported, and at a flow rate of 2 liter / min for a wire tension of 2 kgf. It can be seen that a fluid film is formed and the feed roller 4 is supported. Since the flow rate here is the total flow rate supplied to the thrust bearing and the radial bearing, the supply flow rate to the radial bearing is, for example, 2 liters / min at a flow rate of 3 liters / min. From the roller height for the wire tension of 0 to 2 kgf at this time, the roller height for the wire tension of 3 kgf can be calculated to be about 15 μm. Further, since the bearing load is 1.41 times the wire tension, an actual gap of about 13.2 μm can be secured with respect to the bearing load of 4.5 kgf, and the feed roller 4 can be secured via this fluid film. Is supported. Thus, if the supply flow rate to the radial bearing is 2 liters / min, it can be confirmed that the feed roller 4 can be supported with high reliability without contacting the hydrostatic bearing even for a bearing load of 3 kgf.
[0037]
  In the above-described embodiment, the feed roller 4 used in the wire electric discharge machine has been described, in particular, the hydrostatic bearing that supports the feed roller 4. However, the feed roller 4 is not limited to the feed roller 4 used in the wire electric discharge machine. The present invention can also be applied to other rotating mechanisms that rotate, and the same effect can be obtained by supporting the rotating mechanism with a hydrostatic bearing that uses a working fluid having the same composition as the processing liquid.
[0038]
【The invention's effect】
  As described above, the rotating mechanism according to claim 1 according to the present invention.The wire electric discharge machine using
Provided with a wire electrode feeding device, causing a discharge phenomenon between the traveling wire electrode and the workpiece, and injecting the machining liquid onto the discharge machining portion of the workpiece in the machining tank This is a wire electric discharge machine for processing objects. The wire electrode feeder includes a pair of upper and lower wire guides for guiding the wire electrode to an electric discharge machining portion of the workpiece, and a feed roller for changing the traveling direction of the wire electrode. The feed roller is constituted by a rotating mechanism that is supported by a hydrostatic bearing using a working fluid having the same composition as that of the processing liquid as a processing liquid and is jetted. The working fluid supply source is the same as the working fluid supply source of the hydrostatic bearing. For this reason, there is no problem even if the working fluid flows out of the bearing, and the feed roller can be supported with high reliability by a hydrostatic bearing with a small, simple, and inexpensive structure, and the deterioration over time can be remarkably suppressed, and the wire electrode is disconnected. Can also be prevented. Further, since the supply source of the machining fluid to be injected is the same as the supply source of the working fluid of the hydrostatic bearing, the apparatus configuration of the wire electric discharge machine can be further simplified.
[0039]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 2,The pressure of the working fluid between the hydrostatic bearing and the feed roller is kept higher than the working fluid pressure in the working tank and the working fluid flowing out from the hydrostatic bearing is sealed in the working tank. Therefore, sludge can be easily prevented from entering the hydrostatic bearing with a simple and inexpensive device configuration, and the feed roller can be stably and reliably supported by the hydrostatic bearing.
[0040]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 3, whereinA working fluid tank is provided as a supply source of the working fluid and the working fluid of the hydrostatic bearing, and the working fluid in the working tank is cleaned and supplied to the working fluid tank. Therefore, efficient processing can be performed with a simple apparatus configuration.
[0041]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 4,The fluid pumped from the working fluid tank serving as a supply source of the working fluid and the working fluid of the hydrostatic bearing is branched by a branching means having a flow rate adjusting function, and the working fluid of the working fluid and the hydrostatic bearing Therefore, the device configuration is further small and simple.
[0042]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 5 is any one of claims 1 to 4.Since the hydrostatic bearing is composed of a radial bearing that supports the rotating mechanism in the radial direction from the inside and a thrust bearing that supports the rotating mechanism in the thrust direction from the side surface, the rotating mechanism is reliably supported only by the fluid film of the working fluid. Thus, a hydrostatic bearing having a small size and high reliability can be obtained.
[0043]
  Claims related to this inventionA wire electric discharge machine using the rotating mechanism according to claim 6,Since the working fluid supply path of the radial bearing is branched to supply the working fluid to the thrust bearing, the hydrostatic bearing can be further downsized.
[0044]
  Claims related to this inventionA wire electric discharge machine using the rotation mechanism according to claim 7,Since the thrust restriction is provided in the radial direction portion of the working fluid supply path of the thrust bearing, the axial size of the hydrostatic bearing can be reduced and further reduced in size.
[0045]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 8 according to any one of claims 5 to 7.A working fluid escape hole is provided between the radial bearing and the thrust bearing, and the working fluid flowing out from either the radial or thrust bearing flows out of the bearing without flowing into the other bearing. Therefore, interference between the radial bearing and the thrust bearing can be prevented, bearing characteristics can be stabilized, and reliability can be improved.
[0046]
  Claims related to this inventionThe wire electric discharge machine using the rotating mechanism according to claim 9 is any one of claims 5 to 8.The thrust bearing is configured by incorporating a thrust bearing partition wall that separates the adjacent thrust pocket into a ring-shaped recess that connects a plurality of thrust pockets provided in the thrust bearing body. Therefore, the thrust bearing can be simply and easily configured and can be easily manufactured.
[0047]
  Claims related to this inventionA wire electric discharge machine using the rotation mechanism according to claim 10, according to any one of claims 5 to 9.The radial bearing is provided with a plurality of radial pockets having a bottom surface formed on a side surface of the cylindrical radial bearing main body, by partially cutting a plurality of inner portions leaving both end portions of the side surface. A radial bearing can be simply and easily configured and can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a main part of a wire electric discharge machine according to Embodiment 1 of the present invention.
FIG. 2 is a schematic view showing an entire wire electric discharge machine according to a second embodiment of the present invention.
FIG. 3 is a sectional view and an arrow view showing a detailed structure of a hydrostatic bearing according to Embodiment 3 of the present invention.
FIG. 4 is a diagram illustrating the structure of a hydrostatic bearing according to Embodiment 4 of the present invention.
FIG. 5 is a perspective view showing a structure of a radial bearing according to a fourth embodiment of the present invention.
FIG. 6 is a diagram showing dimensions of a radial bearing according to a fifth embodiment of the present invention.
FIG. 7 is a diagram showing a characteristic measurement result of a hydrostatic bearing incorporated in a wire electric discharge machine according to Embodiment 6 of the present invention.
FIG. 8 is a diagram showing a result of measurement of characteristics of a hydrostatic bearing incorporated in a wire electric discharge machine according to Embodiment 6 of the present invention.
FIG. 9 is a side view and a partial cross-sectional view of a lower wire guide portion of a wire electrode feeding device in a conventional wire electric discharge machine.
[Explanation of symbols]
  1 Workpiece as workpiece, 2 wire electrode,
3a, 3b Upper and lower pipes as wire guides, 4 feed rollers, 5 hydrostatic bearings,
6, 7 Upper and lower nozzles, 11 machining fluid, 25 machining fluid (clean fluid) tank, 26 clear fluid pump,
27 branching device, 30 processing tank, 34 filter, 36 hydrostatic bearing body block,
37 Central pipe as working fluid supply path, 38 Radial branch pipe,
40 radial pocket, 40b bottom of radial pocket, 42 thrust branch pipe,
43 Thrust orifice as thrust throttle, 44 Thrust pocket,
44a Thrust bulkhead, 46 relief hole.

Claims (10)

Provided with a wire electrode feeding device, causing a discharge phenomenon between the traveling wire electrode and the workpiece, and injecting the machining liquid onto the discharge machining portion of the workpiece in the machining tank In a wire electric discharge machine for processing an object, the wire electrode feeding device includes a pair of upper and lower wire guides for guiding the wire electrode to an electric discharge machining part of the workpiece, and a feed roller for changing a traveling direction of the wire electrode The feed roller includes a rotating mechanism that is used in the processing liquid as the processing liquid and is supported by a hydrostatic bearing using a working fluid having the same composition as the processing liquid. A wire electric discharge machine using a rotating mechanism, characterized in that the working fluid supply source and the hydrostatic bearing working fluid supply source are the same. The pressure of the working fluid between the hydrostatic bearing and the feed roller is kept higher than the working fluid pressure in the working tank, and the working fluid flowing out from the hydrostatic bearing is not sealed in the working tank. The wire electric discharge machine using the rotating mechanism according to claim 1, wherein The working fluid and provided with a machining fluid tank comprising a source of hydraulic fluid in the hydrostatic bearing, claim 1 in the machining fluid tank and supplying by cleaning the working fluid of the machining tank or A wire electric discharge machine using the rotating mechanism according to 2 . The fluid pumped from the working fluid tank serving as a supply source of the working fluid and the working fluid of the hydrostatic bearing is branched by a branching means having a flow rate adjusting function, and the working fluid of the working fluid and the hydrostatic bearing The wire electric discharge machine using the rotation mechanism according to any one of claims 1 to 3, wherein the wire electric discharge machine is used. The said hydrostatic bearing is comprised by the radial bearing which supports the said rotation mechanism in the radial direction from an inner side, and the thrust bearing which supports the thrust direction from a side surface, The one in any one of Claims 1-4 characterized by the above-mentioned. Wire electrical discharge machine using a rotating mechanism. 6. The wire electric discharge machine using a rotating mechanism according to claim 5 , wherein the working fluid supply path of the radial bearing is branched to supply the working fluid to the thrust bearing . 7. A wire electric discharge machine using a rotating mechanism according to claim 6 , wherein a thrust throttle is provided in a radial direction portion of the working fluid supply path of the thrust bearing . A working fluid escape hole is provided between the radial bearing and the thrust bearing so that the working fluid flowing out from either the radial or thrust bearing flows out of the bearing without flowing into the other bearing. A wire electric discharge machine using the rotating mechanism according to any one of claims 5 to 7. The thrust bearing is configured by incorporating a thrust bearing partition wall that separates the adjacent thrust pocket into a ring-shaped recess that connects a plurality of thrust pockets provided in the thrust bearing body, and is configured as a separate part from the thrust bearing body. A wire electric discharge machine using the rotating mechanism according to any one of claims 5 to 8. The radial bearing is provided with a plurality of radial pockets on the side surface of the cylindrical radial bearing main body, the bottom surface of which is a plane formed by partially cutting a plurality of inner portions leaving both end portions of the side surface. A wire electric discharge machine using the rotating mechanism according to any one of claims 5 to 9.

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