Chuck device

Abstract

To provide a chuck device equipped with a chip intrusion prevention mechanism.SOLUTION: A chuck device comprises: a chip intrusion prevention nozzle having, formed therein, one or more injection holes for injecting coolant into an inner diameter part of a workpiece gripped by chuck jaws, and a seal part which is fit circumferentially against the inner diameter part of the workpiece; a support block which slidably supports the chip intrusion prevention nozzle along a center line, and has one or more through holes formed therein for sending coolant to the injection holes of the chip intrusion prevention nozzle; and a flow path for supplying coolant to the through holes formed in the support block. The chip intrusion prevention nozzle and the support block are slidably engaged together to compose a closed space, and a total cross-sectional area of the through holes is formed to be greater than a total cross-sectional area of the injection holes so that the space changeable due to sliding of the chip intrusion prevention nozzle becomes a pressurized chamber.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a chuck device equipped with a chip intrusion prevention mechanism that prevents chips and the like from intruding to the back side of a workpiece. [Background technology]

[0002] In machine tools and the like, a chuck device is used as a component for setting the workpiece to be processed on the spindle. The workpiece held by the chuck device is rotated by driving the spindle device, and internal turning or other processing is performed using a cutting tool. Since chips are generated from the workpiece during various types of processing, the machine tool is provided with a coolant device. In other words, a component is provided for spraying coolant onto the processing location, which not only cools the processing location but also washes away the chips. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-192542 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if all the chips are washed away by the coolant, there is no problem, but chips and coolant may enter the back side of the workpiece, i.e., inside the chuck device. Therefore, the chuck device is provided with a chip intrusion prevention member that prevents chips from entering the back side of the workpiece. The chip intrusion prevention member is pressed against the workpiece to block the chips from entering the back side of the workpiece. A biasing member such as a coil spring is used to press the chip intrusion prevention member, as is also used in the above-mentioned Patent Document 1. However, a configuration using such a spring member may cause rust problems depending on the material because the coolant is used in the area. In addition, a small chuck device needs to have a space for installing the spring member, and assembly work in a narrow area is also difficult.

[0005] Therefore, in order to solve such problems, the present invention aims to provide a chuck device equipped with a chip intrusion prevention mechanism that prevents chips and the like from intruding to the back side of the workpiece. [Means for solving the problem]

[0006] The chuck device of the present invention grips a workpiece positioned on a seating member by the action of a chuck jaw, and includes a chip intrusion prevention nozzle having one or more injection holes for injecting coolant toward the inner diameter of the workpiece gripped by the chuck jaws and a seal portion formed to fit circumferentially against the inner diameter of the workpiece, a support block that slidably supports the chip intrusion prevention nozzle along a center line and has one or more through holes formed therein for sending coolant to the injection hole of the chip intrusion prevention nozzle, and a flow path for supplying coolant to the through holes formed in the support block, wherein the chip intrusion prevention nozzle and the support block are slidably fitted together to form a closed space, and the total cross-sectional area of ​​the through holes is formed larger than the total cross-sectional area of ​​the injection holes so that the space that changes due to the sliding of the chip intrusion prevention nozzle becomes a pressurized chamber. Effect of the Invention

[0007] According to the above-mentioned configuration, the workpiece positioned on the seating member is gripped by the action of the chuck jaws, and during machining, coolant is supplied to the through-holes formed in the support block, and the coolant is sprayed from the injection hole of the chip intrusion prevention nozzle to the inner diameter part of the workpiece. At this time, the coolant flows from the through-hole with the larger total cross-sectional area to the injection hole with the smaller total cross-sectional area, so that the pressure chamber located between them changes and the internal pressure increases, pushing the chip intrusion prevention nozzle and causing the seal part to come into circumferential contact with the inner diameter part of the workpiece, thereby preventing chips and the like from invading the back side of the workpiece. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a side view showing the internal structure of a machine tool equipped with a chuck device. [Diagram 2] FIG. 2 is a cross-sectional view showing one embodiment of a chuck device. [Diagram 3] FIG. 4 is an enlarged cross-sectional view showing a retracted state of a chip intrusion prevention mechanism of the chuck device. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a chip intrusion prevention mechanism of the chuck device in an intrusion prevention state. [Diagram 5] FIG. 11 is a cross-sectional view showing a modified example of the chip intrusion prevention mechanism of the chuck device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the chuck device according to the present invention will be described below with reference to the drawings. Fig. 1 is a side view showing the internal structure of a machine tool equipped with a chuck device of this embodiment. The machine tool 1 is mounted on a movable bed 14 equipped with wheels, and is configured to be movable in the front-rear direction (left-right direction in the drawing) along rails 131 laid on the upper surface of a base 13. Various devices such as a spindle device 2 are mounted on the movable bed 14, and the various devices of the machine tool 1 are automatically controlled by a control device 10 mounted on the rear of the machine body.

[0010] The spindle device 2 is configured with a spindle chuck 11 whose rotation is controlled, and rotates the gripped workpiece W by a spindle motor. The machine tool 1 is provided with a turret device 3 which selects one of a plurality of tools corresponding to the workpiece machining. The turret device 3 has a tool rest 12 to which a plurality of tools are attached, and selects and positions the tool to be used for machining by rotating and indexing. The drive devices which move the tool to the machining position of the workpiece W are a Z-axis drive device 5 which moves the tool in the Z-axis direction, which is the front-rear direction of the machine body, and an X-axis drive device 6 which moves the tool in the X-axis direction, which is the up-down direction of the machine body.

[0011] The machine tool 1 is also provided with a coolant system for handling the coolant used to wash away chips generated during workpiece machining and to cool the machining area. The coolant system has a coolant tank 15 arranged below the machining chamber where the workpiece is machined, and the coolant stored there is reused. A coolant pump 16 equipped with a strainer is installed in the coolant tank 15, and the coolant can be supplied to various locations via coolant piping 17.

[0012] In this machine tool 1, the workpiece W is gripped by the spindle chuck 11 through delivery to and from an automatic workpiece transporter (not shown), and is rotated by driving the spindle unit 2. In the turret unit 3, a tool to be used for machining the workpiece W is selected by rotation indexing. Then, the tool moves together with the turret unit 3 in the machining axis direction by driving the Z-axis drive unit 5 and the X-axis drive unit 6, and predetermined machining is performed by positioning the tool relative to the workpiece W. After machining of the workpiece W, the machined workpiece W is replaced with a new workpiece W in the spindle chuck 11, and the automatic machining of the workpiece W continues.

[0013] 2 is a cross-sectional view showing the chuck device of this embodiment. This chuck device 18 is incorporated in the machine tool 1 as the spindle chuck 11 of the spindle device 2. The spindle device 2 is configured such that a spindle 21 is rotatably provided inside a cylindrical headstock, and the chuck device 18 is integrated with the tip of the spindle 21. The spindle device 2 is provided with a spindle motor (not shown), which controls the rotation of the chuck device 18 integrated with the spindle 21. The spindle device 2 is also provided with a chuck cylinder (not shown), which is connected to a draw bar 23 inserted inside the spindle 21. Therefore, the chuck device 18 opens and closes the chuck jaws by the extension and contraction of the chuck cylinder.

[0014] In the chuck device 18, a transmission rod 24 is coaxially connected to the drawbar 23 and extends from the spindle 21 into the inside of a chuck body 25. The transmission rod 24 can reciprocate in the axial direction along the center line O of the device by the extension and contraction of a chuck cylinder, and an expanded diameter portion 241 is formed inside the chuck body 25 fixed to the spindle 21. A cylindrical operating member 26 is provided on the outside of the transmission rod 24 inside the chuck body 25. Although not shown in detail, the operating member 26 has an operating arm portion formed so as to extend in the outer diameter direction from a cylindrical portion that is slidable relative to the transmission rod 24, and a chuck mechanism that opens and closes the chuck jaws 27 is configured.

[0015] A spring box 28 is screwed onto the transmission rod 24 to form an integral unit, and a spring 29 that biases the operating member 26 is housed within the spring box 28. The operating member 26 is formed with a stepped portion so that the enlarged diameter portion 241 of the transmission rod 24 abuts against the drawbar 23. Therefore, when the chuck cylinder contracts to the left in the figure, the transmission rod 24 is pulled to the left in the figure against the biasing force of the spring 29, and the operating member 26 is hooked onto the enlarged diameter portion 241 and displaced in the same direction.

[0016] The chuck body 25 has a base block 31 fixed to the front side (right side in FIG. 2) of the chuck device 18. The base block 31 is formed with a central portion 311 on the center line O side and pedestal portions 312 that radiate from the central portion 311 and are provided at intervals of 120 degrees in the radial direction. Three chuck jaws 27 are provided on the chuck body 25 at intervals of 120 degrees in the circumferential direction so as to be located between each of the pedestal portions 312. The chuck jaws 27 grip the workpiece W from the outer diameter side, and are configured to swing in the direction indicated by the arrow by the operation of a chuck cylinder received from the transmission rod 24 via the operation member 26.

[0017] When viewed from the front side, the chuck device 18 has an annular seating member 32 fixed to a pedestal portion 312 of the base block 31 at a position overlapping with the chuck jaws 27. The seating member 32 has a front side formed with a plurality of convex portions that serve as a reference surface against which the workpiece W comes into contact, and a rear side formed with a groove portion for avoiding interference with the chuck jaws 27. The chuck device 18 of this embodiment is provided with a chip intrusion prevention mechanism in a central portion 311 of the base block 31 for preventing chips and the like from intruding into the rear side of the workpiece.

[0018] In the chip intrusion prevention mechanism, a support block 35 is fixed to the center portion 311 of the base block 31, and a chip intrusion prevention nozzle 36 is attached thereto so as to be displaceable in a direction along the center line O. The chip intrusion prevention nozzle 36 functions as a coolant injection nozzle as described later, and is also located at the front center of the chuck device 18 and functions as a chip intrusion prevention member that blocks the inner diameter portion Wa of the workpiece W gripped by the chuck jaws 27. Here, Figs. 3 and 4 are enlarged cross-sectional views showing the chip intrusion prevention mechanism, Fig. 3 shows the retracted state, and Fig. 4 shows the intrusion prevention state. The cylindrical support block 35 has recesses formed on both axial ends, one of which is a fixing recess 351 into which the central portion 311 of the base block 31, which has a circular convex shape, fits, and the other is a circular guide recess 352 into which the chip intrusion prevention nozzle 36 fits.

[0019] The chip intrusion prevention nozzle 36 has a convex guide portion 361 formed so as to slidably fit into the guide recess 352 of the support block 35, and a chip receiving portion 362 formed so as to extend from the guide portion 361. The chip receiving portion 362 corresponds to the shape of the workpiece W, and in this embodiment, it extends in a circular shape in a direction perpendicular to the center line O, and its peripheral portion protrudes so as to protrude in a direction parallel to the center line O. The protruding portion of the chip receiving portion 362 is parallel to the center line O along the inner diameter portion Wa of the workpiece W through which the outer surface is penetrated, and its acute-angled tip portion serves as a seal portion 365. The seal portion 365 is pressed against the workpiece W to be in close contact with the inner diameter portion Wa in a circumferential manner.

[0020] The chip intrusion prevention mechanism has a guide pin 37 fixed to the support block 35 so as to overlap with the center line O. The guide pin 37 has a male thread formed at its tip, and is fixed by screwing it into the female thread of the support block 35. The chip intrusion prevention nozzle 36 has a guide hole 366 that penetrates the center of the guide part 361, and the guide pin 37 is fixed while passing through the guide hole 366. The guide pin 37 has a head to prevent it from coming off, and the chip intrusion prevention nozzle 36 is assembled in a state where it can slide within a certain range of the guide part from the male thread to the head.

[0021] The chip intrusion prevention nozzle 36, which is displaceable while supported by the guide pin 37, is configured to be displaced toward the workpiece W, i.e., from the state shown in FIG. 3 to the state shown in FIG. 4, by the supply pressure of the coolant to be sprayed onto the machining portion of the workpiece W. As shown in FIG. 1, a coolant passage 51 for flowing coolant is formed in the center of the drawbar 23, and an air passage 52 for flowing air is formed at a position offset from the center. A coolant passage 53 and an air passage 54 are also formed in the transmission rod 24, which are connected to the coolant passage 51 and the air passage 52, respectively. The air passage 54 further communicates with the air passages of the base block 31 and the seating member 32, and air is blown out from a convex portion formed on the seating member 32 as a reference surface.

[0022] The coolant flow passage 53 of the transmission rod 24 is connected to a coolant flow passage formed by a through hole 56 formed in the center portion 311 of the base block 31, a through hole 58 formed in the support block 35, and spaces 55, 57 which are gaps between the respective members. A circular guide portion 361 formed in the chip intrusion prevention nozzle 36 is slidably fitted into a circular guide recess 352 formed in the support block 35. Due to this fitting, a space enclosed by the displaceable guide portion 361 is formed as a pressurizing chamber 59 in the guide recess 352.

[0023] In the chip intrusion prevention mechanism, the pressurizing chamber 59 is filled with coolant, and the supply pressure of the coolant acting therein presses the chip intrusion prevention nozzle 36 against the workpiece W. The chip intrusion prevention nozzle 36 is formed with two types of injection holes 61, 62, three of each type, as shown in the figure, which are alternately arranged at intervals of 60 degrees in the circumferential direction. Also, the support block 35 has three through holes 58 arranged at intervals of 120 degrees in the circumferential direction. Therefore, in order to apply pressure in the pressurizing chamber 59, the total cross-sectional area of ​​the three through holes 58 is formed to be larger than the total cross-sectional area of ​​the injection holes 61, 62.

[0024] 1, in the chuck device 18, the workpiece W is pressed against the seating member 32 from the front side, and the chuck jaws 27 swing to grip the workpiece W. At this time, the air ejected from the convex portion of the seating member 32 is suppressed to a certain extent by the workpiece W, and seating determination is performed by detecting air leakage. Then, coolant is supplied through the coolant flow paths 51, 53 when machining the workpiece W. The coolant flows through the spaces 55, 57 and through holes 56, 58 to the chip intrusion prevention nozzle 36, and is ejected from the ejection holes 61, 62 in the respective directions toward the inner diameter portion Wa side of the workpiece W.

[0025] The coolant pushed out from the coolant pump 16 to the coolant piping 17 flows through the flow passage at a predetermined pressure. When the coolant flows from the through hole 58 of the support block 35 to the injection holes 61, 62 of the chip intrusion prevention nozzle 36, the cross-sectional area of ​​the flow passage on the downstream side becomes smaller, and the fluid pressure of the coolant acts on the guide portion 361. Therefore, as shown in Fig. 4, the chip intrusion prevention nozzle 36 is pressed and the seal portion 365 of the chip receiving portion 362 is pressed circumferentially against the inner diameter portion Wa of the workpiece W. In this way, the seal portion 365 comes into close contact with the workpiece W, and the chip intrusion prevention nozzle 36 becomes like a lid, and the inner diameter portion Wa of the workpiece W that it penetrates is blocked.

[0026] Therefore, according to the chuck device 18 of this embodiment, when turning the inner diameter portion Wa of the workpiece W, coolant can be sprayed from the spray holes 61, 62 toward the processing portion, thereby cooling the cutting heat and washing away chips and the like. At that time, not all chips are discharged, and some chips invade the back side of the workpiece (left side of the drawing). However, since the chip intrusion prevention nozzle 36 blocks the penetrating inner diameter portion Wa of the workpiece W behind the processing portion, it is possible to prevent chips and the like from invading the back side of the workpiece W.

[0027] The chuck device 18 uses the pressure generated when the coolant is sprayed to operate the chip intrusion prevention nozzle 36, and therefore does not require the installation of a biasing member such as a spring, making it possible to simplify the assembly work. Furthermore, the chuck device 18 is designed to position the workpiece W during machining using the seating member 32. However, in a conventional structure in which the biasing force of a spring is always acting on the chip intrusion prevention nozzle 36, the biasing force acts as a force that hinders the positioning of the workpiece W. In this regard, in the present embodiment, no force that interferes with positioning, such as a spring, acts, and the pressure of the coolant can displace the chip intrusion prevention nozzle 36 after the workpiece W is gripped and positioned by the chuck jaws 27.

[0028] 5 is a cross-sectional view showing a modified example of the chip intrusion prevention mechanism of the chuck device. This chuck device is an inner diameter gripping collet chuck in which a draw bar 42 is incorporated in a collet chuck 41. The chip intrusion prevention mechanism in this chuck device has a support block 45 fixed in a convex shape to the tip of the draw bar 42, and a chip intrusion prevention nozzle 46 attached thereto so as to be displaceable in a direction along the center line O. The chip intrusion prevention nozzle 46 is formed with a cylindrical guide portion 461 (having a concave portion) that slidably fits into the cylindrical support block 45, and a chip receiving portion 462 that expands in the radial direction.

[0029] The chip receiving portion 462 spreads in a circular shape in a direction perpendicular to the center line O, and a taper is formed on the periphery to form a seal portion 465. The seal portion 465 is adapted to be pressed against the corner of the workpiece W to form a circumferentially tight fit. The chip intrusion prevention nozzle 46 is fixed to a support block 45 and supported by a guide pin 47 in a state in which it can be displaced within a certain range along the center line O. The columnar support block 45 and a cylindrical guide portion 461 are slidably fitted together, and the closed space within the guide portion 461 is configured as a pressurizing chamber 66.

[0030] Three through holes 65 are formed in the support block 35 at intervals of 120 degrees in the circumferential direction, and communicate with a coolant flow passage 63 formed in the center of the draw bar 42. Two types of injection holes 67, 68 are formed in the chip intrusion prevention nozzle 46, each of which is arranged alternately at intervals of 60 degrees in the circumferential direction. In this chip intrusion prevention mechanism, the pressurizing chamber 66 is filled with coolant, and the supply pressure of the coolant acting therein acts to press the chip intrusion prevention nozzle 46 against the workpiece W. For this reason, the total cross-sectional area of ​​the through holes 65 in the support block 45 is formed larger than the total cross-sectional area of ​​the injection holes 67, 68.

[0031] Next, when the inner diameter portion Wa of the workpiece W held by the collet chuck 41 is machined, coolant is sprayed from the spray holes 67, 68 toward the machining portion. At that time, since the flow path cross-sectional area of ​​the downstream spray holes 67, 68 of the coolant supplied to the pressurizing chamber 66 is smaller than that of the upstream through-hole 66, fluid pressure acts on the chip intrusion prevention nozzle 46, and the seal portion 465 of the chip receiving portion 462 is pressed circumferentially against the corner portion of the workpiece W. In this way, the seal portion 465 comes into close contact with the workpiece W, so that the chip intrusion prevention nozzle 46 becomes like a lid, and the inner diameter portion Wa of the workpiece W that has been penetrated is blocked.

[0032] Therefore, the chip intrusion prevention nozzle 46 blocks the penetrating inner diameter portion Wa of the workpiece W behind the machined portion, preventing chips and the like from intruding into the back side of the workpiece W. Also, there is no need to incorporate a biasing member such as a spring, simplifying the assembly work. Furthermore, since there is no spring, no force acts to hinder the positioning of the workpiece W, and the pressure of the coolant can displace the chip intrusion prevention nozzle 46 after the workpiece W is gripped and positioned by the collet chuck 41.

[0033] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the structure of the chuck device is not limited to the three-jaw chuck shown in FIG. 2 or the collet chuck shown in FIG. In addition, in the above embodiment, the sharp-angled tip and tapered surface of the chip intrusion prevention nozzle 36, 46 are used as the sealing portion 365, 465, but the shape is not specified as long as it has a structure that closely contacts the workpiece W side in a circumferential manner. [Explanation of symbols]

[0034] 18: chuck device 23: draw bar 24: transmission rod 25: chuck body 27: chuck jaws 31: base block 32: seating member 35: support block 36: chip intrusion prevention nozzle 58: through hole 59: pressure chamber 61, 62: injection holes

Claims

1. A chuck device that grips a workpiece positioned on a seating member by the operation of a chuck jaw, a chip intrusion prevention nozzle having one or more injection holes for injecting coolant toward an inner diameter portion of the workpiece gripped by the chuck jaws and a seal portion that fits closely around the inner diameter portion of the workpiece; a support block that supports the chip intrusion prevention nozzle so as to be slidable along a center line and has one or more through holes formed therein for feeding coolant to an injection hole of the chip intrusion prevention nozzle; a flow passage for supplying a coolant to a through hole formed in the support block; having a chuck device in which the chip intrusion prevention nozzle and the support block are slidably fitted together to form a closed space, and the total cross-sectional area of ​​the through holes is formed larger than the total cross-sectional area of ​​the injection holes so that the space that changes due to the sliding of the chip intrusion prevention nozzle becomes a pressurized chamber.

2. 2. The chuck device according to claim 1, wherein the chip intrusion prevention nozzle and the support block have a convex portion on one side and a concave portion on the other side that slidably fit together to define a space that serves as the pressurizing chamber, and the through hole and the injection hole are in communication with the space.

3. 3. The chuck device according to claim 2, wherein said chip intrusion prevention nozzle is slidably supported on a headed guide pin fixed to said support block.

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