CN108032123A - A kind of ball head core shaft rigid grasp frock - Google Patents

Abstract

The invention belongs to the technical field of precision machining. The invention provides a rigid clamping tool for a ball head mandrel, including: a cone seat, a connecting sleeve, a steel ball cage, a steel ball, a machine tool dynamic top, a ball head mandrel, an adjusting screw, a sealing ring, a piston, and a return spring , Swivel seat. Utilizing the wedge angle between the inner cone surface of the cone seat and the ball head mandrel, the high-precision steel ball moving in the axial direction produces a radial displacement component to realize the rigid clamping of the ball head mandrel; the radial installation of the cone seat The position is adjustable, so that the inner cone surface of the cone seat is coaxial with the rotation axis of the machine tool's dynamic center; the contact between the steel ball and the inner cone surface of the cone seat and the ball head spindle is point contact, and the impurities in the cutting fluid are difficult to enter the contact area to make the parts Wear and tear; Under the action of hydraulic pressure, three working state structures of the ball head mandrel, namely loosening, semi-clamping and full clamping, can be realized. Compared with the traditional elastic clamping tooling, the present invention has the advantages of simple structure, low processing cost, high positioning accuracy and long service life, and has good market application prospect and popularization value.

Description

A rigid clamping tool for a ball head mandrel

technical field

The invention belongs to the technical field of precision machining, and relates to a rigid clamping tool for a ball head mandrel for a machine tool.

Background technique

The mandrel is a common type of part in the field of mechanical processing. When in use, the center hole of the mandrel is used as the reference to realize the positioning of the mandrel. For the mandrel with the requirement of rotation angle accuracy, such as the gear machining mandrel, the relative rotation between the mandrel and the moving center of the machine tool is not allowed during the machining process. It is difficult to realize the rigid connection between the mandrel and the moving center of the machine tool only by the friction between the tapered surface of the center hole of the mandrel and the moving center of the machine tool. In order to increase the rigidity of the connection between the mandrel and the moving center of the machine tool, an additional clamping tool is required. For low-speed or intermittent fixed-angle indexing, an ordinary non-axisymmetric manual clamping device can be used; for continuous rotation and medium-high speed rotation, an axisymmetric clamping device is required to reduce the movement. The impact of balance on machining accuracy.

The collet is a very commonly used axisymmetric clamping tool, which can be automatically clamped manually, hydraulically or pneumatically. With the improvement of machine tool automation, it is necessary to control the working state of the chuck through the CNC program during the workpiece clamping process, and switch between loosening, half clamping and full clamping. At this time, it is convenient to use hydraulic or pneumatic drive to realize automatic clamping. Clamp.

For the existing collets, in order to achieve high-precision clamping and positioning, the axis of the flexible flap of the collet is required to be completely consistent with the axis of the dynamic center of the machine tool, and the cone of the inner hole and outer diameter of the flexible flap of the collet is required. The face has high roundness and coaxiality requirements. Therefore, the manufacturing cost of high-precision collets is relatively high. In addition, the flexible petal of the existing collet has multiple (more than 3) grooves in the radial direction, so as to facilitate radial deformation, so as to realize the clamping of the ball head mandrel. However, after the deformation of the flexible flap, the inner and outer tapered surfaces have become non-circular surfaces, and the clamping of the ball head mandrel has also become multi-regional clamping. In addition, there is a line or surface contact between the flexible valve and the inner cone surface of the cone seat used for the limit, and the grinding debris or sand particles during the processing are easy to enter this area, causing the wear of the cone seat and the flexible valve, and affecting the positioning of the collet accuracy and service life. Therefore, the flexible valve in the existing collet is a vulnerable part and needs to be replaced regularly. In addition, the processing technology of the flexible flap in the existing collet is complicated, requiring high processing precision, resulting in high processing cost and use cost.

Contents of the invention

In order to solve the problems of high use cost, difficult processing and difficult to ensure positioning accuracy existing in the existing collet, the present invention provides a tool that adopts steel balls to realize the rigid clamping of the ball head mandrel.

The specific technical solutions are:

A rigid clamping tool for a ball-end mandrel, including: a cone seat, a connecting sleeve, a steel ball cage, a steel ball, a machine tool dynamic top, a ball-end mandrel, an adjusting screw, a sealing ring, a piston, a return spring, and a rotary seat; The steel ball cage is located on the upper part of the connecting sleeve, both of which are located in the cone seat, the ball head mandrel is in contact with the steel balls in the steel ball cage, and the dynamic top of the machine tool passes through the connecting sleeve and the steel ball cage is inserted into the ball head mandrel;

The cone seat is a revolving body structure, the upper part of the inner wall of the cone seat is distributed radially along the circumference with more than two drain holes A, the middle part is equipped with 2 to 3 sealing rings, and the lower part is radially distributed along the circumference with more than four adjustment tights. Fixed threaded holes; three or more countersunk holes and more than three return spring limit platforms are evenly distributed along the circumference of the cone seat base platform; the inner hole at the upper end of the cone seat is provided with an inner cone surface; the cone seat is connected to the rotary seat through the connecting screw B Fixed, the inner tapered surface at the upper end exerts force on the ball mandrel through the steel ball to realize the clamping of the ball mandrel;

The connecting sleeve is a hollow inverted T-shaped rotary body, and more than three connecting holes are evenly distributed along the circumference on the base platform of the rotary body, and the number of spring holes equal to the connecting holes is arranged alternately and evenly distributed with the connecting holes; the lower part of the outer wall of the connecting sleeve is evenly arranged along the circumference Inverted cone surface corresponding to the position of the connecting hole; two or more drain holes B are evenly arranged along the circumference on the upper part of the connecting sleeve wall; connecting internal threads are provided from the top of the inner wall of the connecting sleeve to the top of the draining hole B; the thrust surface on the top of the connecting sleeve; The sleeve is connected with the piston through the connection hole through the connecting screw A; the return spring passes through the spring hole of the connection sleeve and is limited between the return spring limit platform of the cone seat and the piston;

The lower end of the steel ball cage is connected with the connecting sleeve by threads through the external thread, the upper end of the steel ball cage is a conical structure with equal wall thickness, the wall thickness is smaller than the diameter of the steel ball, and the inner and outer cone angles are equal to the cone angle of the inner cone surface of the cone ; More than four ball chambers with an inner diameter greater than the diameter of the high-precision ball are evenly arranged along the circumferential wall. The diameter of the edge of the ball chamber near the inner cone surface is smaller than the diameter of the steel ball to prevent the steel ball from falling out of the steel ball cage; the upper end of the steel ball cage A card slot is provided for disassembly and installation of the steel ball cage; a ball slot is provided on the lower side of the ball chamber to ensure that the maximum diameter of the steel ball touches the thrust surface of the connecting sleeve. The depth of the thread is controlled so that after the steel ball cage is connected with the connecting sleeve, the steel ball can move freely in a small range in the axial and radial directions in the ball chamber. Steel balls can be replaced in batches after wear.

Further, the contact position between the above-mentioned steel ball and the spherical surface of the ball spindle is higher than the maximum diameter of the ball spindle in the horizontal direction; the tangent of the contact position between the steel ball and the spherical surface of the ball spindle and the inner The taper forms a wedge angle.

Further, an annular chip groove is provided on the upper end surface of the piston.

Further, the above-mentioned cone seat and connecting sleeve are made of hardened steel with a hardness not lower than HRC60; the steel ball cage is made of wear-resistant brass.

The beneficial effect of the present invention is that a ball-end mandrel rigid clamping tool has been invented, which is characterized in that: using the wedge angle between the inner cone surface of the cone seat and the ball-end mandrel, the axially moving steel ball produces a The radial displacement component realizes the rigid clamping of the ball head mandrel; the radial installation position of the cone seat is adjustable, and through adjustment, the inner cone surface of the cone seat is coaxial with the rotation axis of the moving center of the machine tool; the steel ball and The contact between the inner cone surface of the cone seat and the ball-end mandrel is a point contact, and impurities in the cutting fluid are difficult to enter the contact area and cause parts wear; under the action of hydraulic pressure, the ball-end mandrel can be loosened, half-clamped and fully clamped Tight structure of three working states. Compared with the traditional elastic clamping tool, the rigid clamping tool of the ball head mandrel provided by the present invention has the advantages of simple structure, low processing cost, high positioning accuracy, long service life, etc., and has good market application prospect and promotion value.

Description of drawings

Figure 1 Sectional view of the rigid clamping tooling of the ball head mandrel.

Figure 2 Outline drawing of the rigid clamping tooling for the ball head mandrel.

Figure 3 Assembly of steel ball cage and connecting sleeve.

Figure 4 cone seat.

Figure 5 Connection sleeve.

Figure 6 Steel ball cage.

In the figure: 1 taper seat; 1-1 taper seat connecting countersunk hole; 1-2 drain hole A; 1-3 reference taper surface; 1-4 taper seat adjustment threaded hole; 2 connecting sleeve; 2-1 connecting hole ;2-2 spring hole; 2-3 inverted cone surface; 2-4 thrust surface; 2-5 connection internal thread; 2-6 drain hole B; 3 steel ball cage; -2 ball groove; 3-3 ball chamber; 3-4 card slot; 3-5 outer cone surface of steel ball cage; 3-6 inner cone surface of steel ball cage; 4 steel balls; 5 machine tool dynamic top; 6 balls Head spindle; 7 adjusting screw; 8 connecting screw A; 9 connecting screw B; 10 sealing ring; 11 piston; 11-1 chip groove; 12 return spring; 13 rotary seat.

Detailed ways

(1) The structure of a ball head mandrel rigid clamping tooling

A ball head mandrel rigid clamping tool, its structure includes: cone seat 1, connecting sleeve 2, steel ball cage 3, steel ball 4, machine tool dynamic top 5, ball head mandrel 6, adjusting screw 7, connecting screw A8, connecting screw B9, sealing ring 10, piston 11, return spring 12, rotary seat 13, etc.

Cone seat 1 is a revolving body structure, and the cone seat is radially processed with multiple drain holes A1-2, 2 to 3 sealing rings, 4 uniformly distributed tightening threaded holes 1-4, and uniformly distributed multiple screw holes. A countersunk hole 1-1, return spring limit table and other structures, the inner hole of the upper end of the cone seat 1 is processed with a high-precision cone surface 1-3, and the vertical error of the axis relative to the bottom surface of the cone seat is not more than 2 μm; the cone seat 1 1 is fixed to the slewing seat 13 through the connecting screw B9, and the inner tapered surface 1-3 at the upper end applies force to the ball-end mandrel 6 through the high-precision steel 4 balls to realize the clamping of the ball-end mandrel 6 .

The connecting sleeve 2 is a hollow T-shaped rotary body, on which 4 uniformly distributed connecting holes 2-1, 4 uniformly distributed spring holes 2-2 and 4 uniformly distributed inverted cone surfaces 2-3, and a plurality of uniformly distributed The cloth discharge hole B2-6, connecting internal thread 2-5, thrust surface 2-6 and other structures; the orientation of the inverted cone surface 2-3 is consistent with the orientation of the connecting hole, and staggered with the orientation of the spring hole 2-2; The cone angle of the inverted cone surface 2-3 is 10°-15°; the flatness error of the thrust surface 2-4 is less than 0.5 μm, and the end surface deflection of the thrust surface 2-4 relative to the rotary axis of the machine tool dynamic top 5 after installation The error is less than 1 μm; the connecting sleeve 2 is connected to the piston 11 through a screw connection 8; the return spring 12 passes through the spring hole 2-2 of the connecting sleeve and is limited between the cone seat 1 and the piston 11;

The steel ball cage 3 and the connecting sleeve 2 are connected together by threads, and a ball chamber 3-3 with a diameter greater than 0.1-0.2mm of the high-precision ball is processed on it, and the upper end is a conical structure with equal wall thickness, and the wall thickness is smaller than that of the steel ball. 0.8 ~ 1.2mm, the cone angle of the inner and outer cone surfaces 3-6 and 3-5 is equal to the cone angle of the inner cone surface 1-3 of the cone seat; the outer diameter of the ball chamber 3-3 near the inner cone surface is smaller than the diameter of the steel ball 4, Prevent the steel ball 4 from falling out of the steel ball cage 3; the card slot 3-4 on the steel ball cage 3 is used for the disassembly and installation of the steel ball cage 3; there is a ball groove 3-2 under the ball chamber, which is convenient The maximum diameter of the steel ball 4 can touch the thrust surface 2-4 of the connecting sleeve 2; the depth of the thread is controlled so that after the steel ball cage 3 is connected with the connecting sleeve 2, the steel ball 4 can axially and Free movement in a small radial range;

The upper end of the piston 11 is processed with an annular chip groove 11-1 with a semicircular cross-section; it is convenient for depositing impurities such as sand grains and iron filings in the cutting fluid during the machining process. Impurities in the chip pocket 11-1 need to be cleaned regularly.

The steel ball 4 is made of GCr15 steel balls with the same batch of precision above G5 to ensure that the intergranular diameter difference of the steel balls is not more than 0.2 μm; the steel ball 4 needs to be replaced in batches after wear;

The above-mentioned cone seat 1 and connecting sleeve 2 are made of hardened steel material, the hardness is not lower than HRC60; the steel ball cage is made of wear-resistant brass material to prevent the wear of the steel ball 4;

The contact position between the spherical surface of the ball head mandrel 6 and the steel ball 4 is higher than the maximum diameter of the ball head mandrel in the horizontal direction; the radial component of the force of the steel ball 4 on the ball head mandrel 6 is used to clamp the ball head The radial component of the mandrel makes the ball mandrel 6 press on the machine tool dynamic center 5 of the machine tool, increasing the contact stiffness between the ball mandrel 6 and the machine tool dynamic center 5, thereby enhancing the clamping effect of the ball mandrel 6.

The tangent of the contact position between the spherical surface of the ball head mandrel 6 and the steel ball 4 forms a wedge angle with the inner cone surface 1-3 of the cone seat, thereby ensuring that the force on the ball head mandrel 6 is consistent with the hydraulic pressure of the piston 11. The force and its axial displacement are directly proportional.

(2) Installation and adjustment of the rigid clamping tooling of the ball head mandrel

(1) First, fix the connecting sleeve 2 to the piston 11 through the connecting screw A8.

(2) Then measure the deflection of the thrust surface 2-4 of the connecting sleeve relative to the axis of rotation of the moving center 55 of the machine tool. If the installation position of the connecting sleeve relative to the piston cannot be adjusted, the thrust surface 2-4 of the connecting sleeve can The yaw error of the rotation axis of 5 is less than 1 μm, and it is necessary to grind the thrust surface 2-4 or its mounting surface of the connecting sleeve until the design requirement is met.

(3) Then assemble the steel ball cage 3 with the connecting sleeve 2 through threaded connection, then insert the high-precision steel 4 into the ball chamber 3-3 of the steel ball cage, and place it on the periphery of the ball chamber 3-3 Apply a little grease to prevent the steel ball 4 from falling out;

(4) Cone seat 1 is finally installed;

First put the piston return spring 12 into the spring hole 2-2 of the connecting sleeve, and apply a little grease to the sealing ring 10 and put it into the sealing ring of the cone seat;

Then align the orientation of the adjustment threaded hole of the cone seat 1 with the orientation of the reverse conical surface 2-3 of the connecting sleeve, and connect the cone seat 1 to the rotary seat 11 through the connecting screw B9, and at this time, the cone seat connecting screw B9 does not need to be tightened;

Then adjust the radial position of the cone seat 1, take the axis of rotation of the machine center 5 as a reference, measure the radial runout error of the cone seat 1 through the steel ball 4 in contact with the inner cone surface 1-3 of the cone seat, and use the four adjustment screws 7 , adjust the radial position of the cone seat 1 until there is no obvious eccentric error of the cone seat 1;

Finally, evenly tighten the connecting screws B9 between the cone seat 1 and the slewing seat 13, and then loosen the four adjusting screws 7 to prevent the set screws 7 from interfering with the connecting sleeve 2 moving up and down.

(3) Operation of the rigid clamping tooling of the ball head mandrel

The ball head mandrel rigid 6 clamping tool is similar to the traditional elastic clamping tool, and has three working states of loosening, half clamping and full clamping. The three states of the rigid clamping tool of the ball head mandrel are controlled by the hydraulic pressure of the hydraulic system. In the relaxed state, when the pressure of the hydraulic system is 0Mpa, the piston 11 is at the top under the action of the return spring 12, the steel ball 4 is in a free state, and the ball head mandrel 6 is not subject to any force from the rigid clamping tool;

In the semi-clamped state, the pressure of the hydraulic system is about 1Mpa, the piston 11 moves up, pushes the steel ball 4 to move axially, and the return spring 12 compresses; at the same time, the steel ball 1 is in the cone seat inner cone surface at a wedge angle of 1-3 The radial displacement is generated under the action, and the steel ball 4 is pushed to clamp the ball head mandrel 6; the steel ball 4 bears the pressure from the connecting sleeve thrust surface 2-4, the inner cone 1-3 surface of the cone seat and the ball head mandrel 6 The force acting on the spherical surface is in a state of force balance.

In the fully clamped state, the pressure of the hydraulic system is about 2Mpa, the piston 11 moves up slightly, and the steel ball 4 bears pressure from the thrust surface 2-4 of the connecting sleeve, the inner cone surface 1-3 of the cone seat and the ball head mandrel. The forces on the 6 spherical surfaces all increase and are in a state of force balance. The ball-end mandrel 6 also bears a large force from the steel ball 4, so that the connection rigidity between the ball-end mandrel 6 and the dynamic center 5 of the machine tool is further increased.

During the use of the rigid clamping tooling of the ball mandrel 6, the cutting fluid will enter the interior of the tooling through the gap between the cone seat 1, the steel ball cage 2 and the ball mandrel 6, and lubricate the gap between the connecting sleeve 2 and the cone seat 1. Between the sealing ring 10, the excess cutting fluid flows out through the drain holes 2-6 and 1-2 in the connecting sleeve and the taper seat.

When replacing the rigid precision steel ball 4, the cone seat 1 needs to be removed, and after replacing the steel ball 4, readjust the radial position of the cone seat according to step (4) in the embodiment (2).

Claims (5)

1. A kind of 1. ball head core shaft rigid grasp frock, it is characterised in that including：Cone seat, connector sleeve, ball retainer, steel ball, machine Bed moves top, ball head core shaft, adjusting screw, sealing ring, piston, resetting spring, revolving bed；Ball retainer is located on connector sleeve Portion, all in cone seat, ball head core shaft is contacted with the steel ball in ball retainer for the two, and lathe moves top through connector sleeve, steel Ball retainer is inserted into ball head core shaft；

   Cone seat is rotary structure, and cone seat upper inside wall is radially uniformly distributed along the circumference more than two leakage opening A, middle part equipped with 2~3 A sealing ring, lower part are radially uniformly distributed along the circumference more than four adjustment tightening threaded holes；Cone seat base platform is uniformly distributed along the circumference The counter sink of more than three and the resetting spring limiting stand of more than three；Cone seat upper end endoporus is equipped with inner conical surface；Cone seat passes through company Meet screw B to fix with revolving bed, the inner conical surface of upper end applies pressure to ball head core shaft by steel ball, realizes the clamping of ball head core shaft；

   Connector sleeve is hollow inverted T shaped revolving body, and be uniformly distributed along the circumference more than three connecting holes and connecting hole on revolving body base platform The quantity that alternating is uniformly arranged is equal to the spring eye of connecting hole；Connector sleeve outer wall lower part is circumferentially evenly arranged and connecting hole position Put corresponding inverted cone surface；Connector sleeve wall top is circumferentially evenly arranged more than two leakage opening B；At the top of connector sleeve inner wall extremely Connection internal thread is opened up above leakage opening B；It is thrust surface at the top of connector sleeve；Connector sleeve by attachment screw A through connecting hole with Piston connects；Resetting spring is through the spring eye of connector sleeve and spacing the resetting spring limiting stand and piston of cone seat；

   Ball retainer lower end is connected through a screw thread for external screw thread with connector sleeve, and ball retainer upper end is the taper knot for waiting wall thickness Structure, wall thickness are less than the diameter of steel ball, its interior outside cone angle is equal to the cone angle of cone seat inner conical surface；Circumferentially wall be evenly arranged four with Upper internal diameter is more than the ball room of high-precise ball diameter, and ball room is less than steel ball size close to the edge diameter of inner conical surface, prevent steel ball from Dropped out in ball retainer；Ball retainer upper end sets card slot to be used for removing and installing for ball retainer；Ball room downside Ball groove is opened up, ensures that steel ball maximum gauge touches the thrust surface of connector sleeve.
2. 2. ball head core shaft rigid grasp frock according to claim 1, it is characterised in that above-mentioned steel ball and ball head core shaft Maximum gauge of the contact position of spherical higher than the horizontal direction of ball head core shaft；Steel ball contact with the spherical of ball head core shaft The tangent line of position and the inner conical surface of cone seat form the angle of wedge.
3. 3. ball head core shaft rigid grasp frock according to claim 1 or 2, it is characterised in that piston upper surface is equipped with ring Shape chip pocket.
4. 4. ball head core shaft rigid grasp frock according to claim 1 or 2, it is characterised in that above-mentioned cone seat and connection Set selects hardened steel material, and hardness is not less than HRC60；Ball retainer selects wear-resisting brass material.
5. 5. ball head core shaft rigid grasp frock according to claim 3, it is characterised in that above-mentioned cone seat and connector sleeve choosing With hardened steel material, hardness is not less than HRC60；Ball retainer selects wear-resisting brass material.