WO2022252303A1

WO2022252303A1 - Fixture and method for workpiece positioning and machining method for optical element

Info

Publication number: WO2022252303A1
Application number: PCT/CN2021/101185
Authority: WO
Inventors: 王伟; 陈曦; 周响; 秦琳玲; 倪颖; 郭培基
Original assignee: 苏州大学
Priority date: 2021-05-31
Filing date: 2021-06-21
Publication date: 2022-12-08
Also published as: CN113198697A; CN113198697B

Abstract

The present invention relates to the technical field of optics. Disclosed are a fixture and method for workpiece positioning and a machining method of an optical element. The fixture for workpiece positioning comprises: an adhering area, an isolating area, and a reference positioning area; the adhering area and the reference positioning area are spaced apart by the isolating area; the reference positioning area is provided with a reference plane for positioning; the adhering area is provided with a recess used for accommodating a hot melt adhesive; the isolating area is provided with an isolating recess used for accommodating the hot melt adhesive overflowing from the adhering area; a plane to be adhered on a workpiece is in surface contact with a reference plane on the reference positioning area, and the plane to be adhered on the workpiece is adhered and connected to the adhering area by means of the hot melt adhesive. The reference plane is tightly attached to the plane to be adhered of the workpiece, thereby preventing clamping unequal-thickness errors caused by uneven thickness of an adhesive layer during adhering; use of the isolating area prevents the hot melt adhesive from contaminating the reference positioning area; since the adhesive layer is thick, a longer time is required for curing, thereby effectively preventing deformation of the fixture from being transmitted to the workpiece.

Description

Fixture and method for workpiece positioning and processing method of optical element

technical field

The invention belongs to the field of optical technology, and relates to a workpiece positioning fixture and a positioning method.

Background technique

The most widely used material in optical processing is glass material, which is brittle and easy to break. When machining glass materials, mechanical hard clamping methods such as three-jaw and self-centering chucks are easy to cause glass breakage, and it is easy to cause internal stress deformation of glass materials during clamping.

Aiming at the problem of glass material being brittle and easy to break, in the prior art, parallel metal plates are widely used for protection during clamping, the glass is glued to the parallel metal plates, and the metal plate at the bottom is clamped during clamping to realize the clamping of the workpiece. The clamping force during clamping causes the deformation of the metal plate to be transmitted to the glass workpiece.

The traditional gluing method is to apply hot melt adhesive between the datum surface and the workpiece. After gluing, the restoration of the datum surface will cause stress and deformation in the workpiece after the workpiece cools down. The base layer covers the reference plane. When the workpiece is positioned on the reference plane, the reference plane cannot be in direct contact with the workpiece, but is filled with a layer of hot melt adhesive layer; the adhesive layer is difficult to be very uniform, even if there are differences Uniformity will lead to changes in the positioning of the workpiece. The hot melt adhesive cools quickly during the gluing process, and the thicker the adhesive layer becomes more viscous during the cooling process, so the thinner the adhesive layer in the prior art, the more conducive to improving the adhesive strength. layer uniformity. A thin adhesive layer is easy to improve the uniformity of the adhesive layer and is more conducive to making the workpiece reference plane parallel to the parallel metal plate, but at the cost of sacrificing part of the adhesive force.

technical problem

The technical problems to be solved are: the uneven thickness of the adhesive layer will cause the reference plane of the workpiece to be non-perpendicular to the machining spindle; the clamping force will cause stress inside the workpiece and cause deformation.

technical solution

A fixture for workpiece positioning. A workpiece to be positioned is provided with a plane to be glued, including: a gluing area, an isolation area, and a reference positioning area. The gluing area and the reference positioning area are separated by the isolation area. The positioning area is provided with a reference plane for positioning, and the gluing area is provided with a groove for accommodating hot melt adhesive; the isolation area is provided with an isolation groove for accommodating hot melt adhesive overflowing from the gluing area; The matching mode of the reference plane on the reference positioning area is surface contact, and the glued area and the plane to be glued on the workpiece are connected by hot-melt glue. Preferably, the level of the glued area is at least 0.5mm higher than the level of the isolation area, and the reference plane of the reference positioning area is 0.3~0.4mm higher than the level of the glued area.

When the above-mentioned fixture for workpiece positioning is in use, S1. Install and fix the fixture on the machine tool workbench, smooth the datum plane of the datum positioning area with light knife technology, and the datum plane to be flattened is perpendicular to the spindle of the machine tool; S2. Heating The jig for workpiece positioning, and apply the heated and melted hot melt adhesive in the groove of the gluing area, place the heated workpiece to be positioned on the jig for workpiece positioning, and apply pressure to the workpiece to be positioned so that the datum The reference plane set on the positioning area is in contact with the plane to be glued on the workpiece to be positioned; the hot melt adhesive melted in the gluing area adheres to the workpiece to be positioned, and the excess hot melt adhesive flows into the isolation groove in the isolation area during positioning , after cooling, the workpiece can be clamped; after S3 is processed, the glued area is heated, only the workpiece is removed, and the fixture is still installed and fixed on the machine table; if repeated positioning is required, repeat S2 steps to achieve alignment Workpiece clamping.

Beneficial effect

Since the hot melt adhesive is only applied on the gluing area during the clamping process, the reference plane of the reference positioning area can be closely attached to the gluing plane of the workpiece to be positioned, which can effectively prevent uneven clamping caused by uneven thickness of the glue layer during gluing. Equal thickness error, and due to the setting of the isolation area, it can effectively prevent the hot melt glue from contaminating the reference plane of the reference positioning area during clamping. The plane of the workpiece to be glued after being clamped by the technical solution is perpendicular to the main shaft of the machine tool, which greatly improves the positioning accuracy of the workpiece in the Z direction (the main shaft direction). In addition, the temperature of the fixture rises when it is clamped, causing the reference plane to slightly expand along the Z direction. Since the reference plane of the reference positioning area of the fixture is higher than the level of the glued area, the deformation of the reference positioning area in the Z direction after heating Greater than the deformation of the gluing area; the datum plane is in contact with the workpiece during gluing, and after cooling down, the datum plane shrinks and returns to the original shape, and the contact between the datum plane and the workpiece is out of contact; the glue layer between the gluing area and the workpiece is gradually cooling Slow curing during the process, because the glue layer is thick, the time required for curing is long, which effectively avoids the transmission of the deformation of the fixture to the workpiece. In the traditional gluing method, the uniformity of the adhesive layer is more difficult to control when the adhesive layer is thicker. However, this technical solution has the reference plane positioning through the reference positioning area. By increasing the thickness of the adhesive layer in the gluing area, it solves the problem of workpiece reference plane and processing caused by uneven adhesive layer. The non-vertical problem of the main shaft also solves the problem of stress deformation of the workpiece caused by the thermal deformation of the hot-melt adhesive fixture. When the workpiece needs to be repeatedly clamped, the S2 step can be repeated to realize the clamping of the workpiece. Since the reference plane for positioning when the workpiece is repeatedly clamped is the reference plane of the reference positioning area, the reset accuracy of the Z axis is high. For those who need to accurately control the thickness of the workpiece In some cases, the Z coordinate of the reference plane can be used as the reference zero point. By measuring the Z coordinate of the center of the workpiece end face, the center thickness can be obtained from the coordinate difference between the Z coordinate and the Z coordinate of the reference plane. The fixture of this solution is first fixed and clamped on the machine tool turntable when in use, and the glued area on the deformed fixture is glued to fix the workpiece, and the fixture is still fixed on the machine tool turntable after processing, so the clamping force of the fixture will not be transmitted to the artifact.

Due to the cooperation between the positioning outer cone and the auxiliary positioning block during the clamping process, the reset positioning accuracy in the X direction and the Y direction is further improved. For the optical elements of rotationally symmetrical workpieces, this method can effectively reduce the eccentricity caused by the eccentricity and inclination of the optical axis of the workpiece.

Description of drawings

Figure 1. Schematic diagram of top view of Fixture Example 1 for workpiece positioning.

Fig. 2. Schematic cross-sectional view of fixture example 1 for workpiece positioning.

Figure 3. Schematic cross-sectional view of a fixture for workpiece positioning with a heating circuit.

Figure 4. Schematic top view of a fixture for workpiece positioning with air holes.

Figure 5. Schematic cross-sectional view of the workpiece to be positioned by gluing the fixture for workpiece positioning with a hot melt adhesive container.

Figure 6. Schematic top view of fixture example 2 for workpiece positioning.

Fig. 7. Schematic diagram of the sectional view of the glued workpiece to be positioned in Example 2 of the fixture for workpiece positioning.

Fig. 8. Schematic cross-sectional view of a fixture for workpiece positioning with an inner cone locating surface.

Figure 9. Schematic diagram of the cross-sectional structure of the auxiliary positioning block.

Figure 10. Schematic diagram of the assembly of the inner cone positioning surface and the auxiliary positioning block.

Figure 11. Schematic diagram of the glued body between the workpiece and the positioning outer cone.

In the figure: 1. Inner gluing area, 2. Inner isolation groove, 3. Datum positioning ring, 4. Outer isolation groove, 5. Outer gluing area, 6. Heating circuit, 7. Air guide hole, 8. Hot melt adhesive, 9 , workpiece to be positioned, 10, positioning outer cone, 11 positioning flange surface, 12, inner cone positioning surface, 13, auxiliary positioning block, 14, locking device, 15, hot melt adhesive container, 16, hot melt adhesive conduit.

Embodiments of the present invention

Embodiment one: as shown in Fig. 1 and Fig. 2, a kind of fixture that is used for workpiece positioning, the workpiece 9 to be positioned is provided with the plane to be glued, and the plane to be glued is the datum plane of the workpiece to be positioned; It includes: a gluing area, an isolation area, and a reference positioning area. The gluing area and the reference positioning area are separated by the isolation area. The reference positioning area is provided with a reference plane for positioning, and the gluing area is provided with a Groove for melted glue; the isolation area is provided with an isolation groove for accommodating the hot melt adhesive overflowing from the gluing area; the plane to be glued on the workpiece and the reference plane on the reference positioning area are matched in surface contact, and the gluing area and the surface of the workpiece The plane to be glued is set to be glued and connected by hot melt adhesive 8; the glued area is the inner glued area 1, the isolation area is the inner isolation groove 2, and the reference positioning area is the reference positioning ring 3; the end face of the reference positioning ring is ring-shaped The reference plane, the inner gluing area is set inside the annular reference plane, and the inner gluing area is recessed inward to form a groove for accommodating hot melt adhesive; the inner isolation groove is set between the reference positioning ring and the inner gluing area between, and the inner isolation groove is inwardly recessed into an annular groove.

The optimization scheme based on the above scheme is: configure the heating circuit in the fixture, as shown in Figure 3, the schematic diagram of the cross-sectional view of the fixture for workpiece positioning with the heating circuit configured, after the heating circuit 6 is powered on, place an appropriate amount of solid hot melt adhesive in the gluing area Particles, after being fully melted, press the workpiece to be glued on the reference positioning area, the hot melt adhesive will be glued to the bottom of the workpiece, and the excess glue will flow into the inner isolation groove to prevent the hot melt adhesive from polluting the reference positioning area. Disconnect the heating circuit, and the workpiece can be glued on the fixture after cooling. This method effectively improves the clamping efficiency. The hot melt adhesive can be melted in a few seconds after the heating circuit is energized, and the workpiece can be fixed on the fixture after cooling after gluing the workpiece. The reference positioning area of the fixture is perpendicular to the spindle of the machine tool, and there is no hot-melt adhesive layer between the bottom of the workpiece and the reference positioning area, which effectively solves the problem of inclination of the workpiece positioning surface caused by the uneven thickness of the adhesive layer, so that the upper surface of the workpiece can be processed. positioning accuracy. For example, when processing the parallelism of the upper and lower end faces of the workpiece, use this fixture to glue one end face arbitrarily, and process the other end face plane. After the other end face plane is processed, press the processed end face plane on the reference positioning area, and fix it with hot melt glue. Finally, process the other end face, which can effectively reduce parallelism and perpendicularity errors.

An optimization scheme is shown in Figure 4, a fixture for workpiece positioning is also provided with an air guide hole 7, the air guide hole is used to balance the air pressure in the isolation area and the environment, one end of the air guide hole is arranged in the isolation area, The other end is connected to outside air. If there is no such air guide hole, a closed space may be formed in the isolation groove during gluing, which is not conducive to the flow of hot melt adhesive. When the workpiece is glued, the air in the heated isolation area of the workpiece is thin. After cooling down, the air pressure in the isolation area may be lower than the external ambient air pressure, resulting in negative pressure. When processing high-precision workpieces, it is easy to generate deformation inside the workpiece. For example, when processing optical aspheric or spherical surfaces, negative pressure It is easy to generate stress in the workpiece, resulting in the stress recovery of the workpiece removed from the fixture after the processing is completed, resulting in out-of-tolerance processing surface shape. Setting air guide holes can effectively solve the problem of negative pressure in the isolation area.

Another optimization scheme, as shown in FIG. 5 , is also provided with a hot melt adhesive container 15 and a hot melt adhesive conduit 16 , one end of the hot melt adhesive conduit communicates with the hot melt adhesive container, and the other end communicates with the gluing area. Set up a hot-melt adhesive container, after the heating circuit is energized, the hot-melt adhesive in the hot-melt adhesive container flows into the gluing area through the hot-melt adhesive conduit, after the processing is completed, the hot-melt adhesive in the gluing area melts after the heating circuit is energized, and can The glue conduit returns the hot melt adhesive to the hot melt container. The hot melt container can be configured as a metal syringe.

Embodiment two: a kind of fixture for workpiece positioning on the basis of embodiment one, as shown in Figure 6, is also provided with outer isolation groove 4, outer gluing zone 5; Outer gluing zone is arranged on the outside of described annular datum plane, The outer gluing area is inwardly recessed to form a groove for accommodating hot melt adhesive; the outer isolation groove is arranged between the reference positioning ring and the outer gluing area, and the outer isolation groove is inwardly recessed to form an annular groove.

When the fixture is in use, as shown in Figure 7, the inner gluing area can be used to complete the gluing for workpieces with small diameters; but the outer gluing area can be used for large-diameter workpieces; for large-diameter workpieces that require large gluing force, the The inner gluing area and the outer gluing area jointly complete the gluing and fixing.

A fixture for workpiece positioning based on Embodiment 1 and Embodiment 2 can be used in a machine tool workbench or other equipment that requires accurate horizontal (or vertical) positioning. The workbench of traditional machine tools is mostly equipped with multi-standard T-shaped slots or threaded holes or self-centering chuck structure, and the positioning is realized by pressing the plate or clamping the workpiece. Using the reference positioning area of this technical solution and the workpiece for The direct contact between the glued datum surfaces can obtain a higher positioning posture; the clamping method of only applying hot melt adhesive on the glued area can effectively reduce the stress of the workpiece.

Embodiment three: a kind of fixture for workpiece positioning, as shown in Figure 8 and Figure 9, is also provided with positioning outer cone 10, positioning flange surface 11, auxiliary positioning block 13, inner cone positioning surface 12, locking device 14. The positioning outer cone is set at the bottom of the fixture for workpiece positioning, and the central axis of the positioning outer cone is perpendicular to the reference plane of the reference positioning area; the positioning flange surface is located at the bottom of the fixture for workpiece positioning At the bottom, the positioning flange surface is perpendicular to the central axis of the positioning outer cone; the auxiliary positioning block is provided with an inner cone positioning surface that cooperates with the positioning outer cone, and the center of the end surface of the auxiliary positioning block and the inner cone positioning surface The axis is vertical; after the positioning outer cone is matched with the auxiliary positioning block, as shown in Figure 10, the positioning surface of the inner cone is tangent to the positioning outer cone, and the positioning flange surface is tangent to the end face of the auxiliary positioning block; the locking device is set on the auxiliary positioning block Upper, used for locking and positioning the outer cone and auxiliary positioning block.

The steps for positioning the fixture are as follows: S1. Install the fixture for workpiece positioning on the machine tool table, and after the positioning outer cone and the auxiliary positioning block are matched, the locking device locks the positioning outer cone and the auxiliary positioning block ; Smooth the datum plane of the datum positioning area with the light knife process, and the datum plane to be flattened is perpendicular to the main shaft of the machine tool; S2. Apply the heated and melted hot melt adhesive in the groove of the gluing area, and place the heated workpiece to be positioned On the fixture used for workpiece positioning, apply pressure to the workpiece to be positioned so that the reference plane set on the reference positioning area is in contact with the plane to be glued on the workpiece to be positioned; the melted hot melt adhesive in the gluing area adheres to the On the workpiece, the excess hot melt glue flows into the isolation groove of the isolation area. After cooling, the plane to be glued on the workpiece to be positioned and the glued area are fixedly connected by hot melt adhesive; S3. After processing, loosen The locking device unlocks the positioning outer cone and the auxiliary positioning block, and removes the workpiece and the positioning outer cone glued body as shown in Figure 11; if repeated positioning is required, after the workpiece and the positioning outer cone glued body are matched with the auxiliary positioning block, lock them The device locks and positions the outer cone and the auxiliary positioning block to realize the reset and clamping of the workpiece. Using the positioning outer cone 10, the positioning flange surface 11, the auxiliary positioning block 13, and the inner cone positioning surface 12 to cooperate with each other can achieve high-precision repeat positioning accuracy, not only can restore the positioning coordinates of the Z axis, but also can restore the X and Y axes. Coordinates, realize self-centering when restoring.

For example, the method of processing an optical element using this jig is as follows.

According to a processing method of an optical element according to the above-mentioned fixture usage method, the first end surface of the optical element is a reference plane, and the second end surface is one of a plane, a convex surface, and a concave surface. First, any end surface of the optical element blank is clamped on the The reference positioning area of the fixture used for workpiece positioning described above, after clamping, the other end face of the optical element is milled into a plane, and the optical element is removed by heating the glued area; after the plane shape meets the requirements, the processed plane is used as the optical The reference plane of the component is glued to the glued area. After the second end face is processed, the shape of the optical element is processed by edging process; Measure, if the surface shape meets the requirements, heat the optical element and the positioning outer cone to remove the workpiece, and obtain the optical element mirror body; if it is found that the second end surface shape error exceeds the tolerance, then the optical element and the positioning outer cone are glued together Assemble it on the auxiliary positioning block again, and perform compensation processing until the detection surface shape meets the requirements and remove the optical element. This processing method can effectively solve the eccentricity error caused by the unevenness of the workpiece reference surface, and can also effectively solve the eccentricity error when the optical axis of the workpiece deviates from the geometric center. It can also precisely control the thickness of the center of the workpiece with the datum plane as the reference zero point.

Claims

A fixture for workpiece positioning. A plane to be glued is arranged on the workpiece to be positioned, and is characterized in that it includes: a gluing area, an isolation area, and a reference positioning area; the gluing area and the reference positioning area are separated by the isolation area Open, the reference positioning area is provided with a reference plane for positioning, the gluing area is provided with a groove for accommodating hot melt adhesive; the isolation area is provided with an isolation groove for accommodating hot melt adhesive overflowing from the gluing area; The gluing plane and the datum plane on the datum positioning area cooperate in surface contact, and the gluing area and the plane to be glued on the workpiece are connected by hot-melt glue.
A fixture for workpiece positioning according to claim 1, characterized in that: a heating circuit is also provided, and the heating circuit is used for heating the glued area.
A fixture for workpiece positioning according to claim 1, characterized in that: an air guide hole is also provided, one end of the air guide hole is set in the isolation area, and the other end is connected to the outside air.
A fixture for workpiece positioning according to claim 1, wherein the gluing area is an inner gluing area, the isolation area is an inner isolation groove, and the reference positioning area is a reference positioning ring; the reference positioning The end face of the ring is an annular reference plane, the inner gluing area is set inside the annular reference plane, and the inner gluing area is recessed inward to form a groove for accommodating hot melt adhesive; the inner isolation groove is set at the reference position Between the ring and the inner gluing area, and the inner isolation groove is recessed inward to form an annular groove.
A fixture for workpiece positioning according to claim 4, characterized in that: an outer isolation groove and an outer gluing area are also provided; the outer gluing area is set outside the annular reference plane, and the outer gluing area is formed by inward depression A groove for accommodating hot melt adhesive; the outer isolation groove is arranged between the reference positioning ring and the outer gluing area, and the outer isolation groove is recessed inward to form an annular groove.
A fixture for workpiece positioning according to claim 1, characterized in that: it is also provided with a positioning outer cone, a positioning flange surface, an auxiliary positioning block, an inner cone positioning surface, and a locking device; the positioning outer cone It is arranged at the bottom of the fixture for workpiece positioning, and the central axis of the positioning outer cone is perpendicular to the reference plane of the reference positioning area; the positioning flange surface is located at the bottom of the fixture for workpiece positioning, and the positioning flange surface and The central axis of the positioning outer cone is vertical; the auxiliary positioning block is provided with an inner cone positioning surface that cooperates with the positioning outer cone, and the end face of the auxiliary positioning block is perpendicular to the central axis of the inner cone positioning surface; the positioning outer cone and After the auxiliary positioning block is matched, the positioning surface of the inner cone is tangent to the positioning outer cone, and the positioning flange surface is tangent to the end face of the auxiliary positioning block; the locking device is arranged on the auxiliary positioning block to lock the positioning outer cone and the auxiliary positioning piece.
A machine tool workbench, characterized in that the machine tool workbench is configured as the fixture for workpiece positioning according to any one of claims 1 to 6.
A method for workpiece positioning, characterized in that: using the fixture for workpiece positioning according to claim 1 to perform positioning, comprising the following steps:

S1. The described fixture for workpiece positioning is installed on the machine tool workbench, and the datum plane of the datum positioning area is smoothed with light knife technology, and the datum plane by smoothing is perpendicular to the main shaft of the machine tool;

S2. Apply the heated and melted hot melt adhesive to the groove in the gluing area, place the heated workpiece to be positioned on the fixture for workpiece positioning, and apply pressure to the workpiece to be positioned so that the benchmark set on the reference positioning area The plane is in contact with the plane to be glued on the workpiece to be positioned; the melted hot melt adhesive in the gluing area adheres to the workpiece to be positioned, and the excess hot melt glue flows into the isolation groove in the isolation area. After cooling, the workpiece to be positioned The plane to be glued and the glued area set on the top are fixedly connected by hot melt glue;

S3. After processing, heat the glued area to remove the workpiece; if repeated positioning is required, repeat the step S2 to realize the reset and clamping of the workpiece.
A method for workpiece positioning, characterized in that: using the fixture for workpiece positioning according to claim 6 to perform positioning, comprising the following steps:

S1. Install the fixture used for workpiece positioning on the machine tool workbench, after the positioning outer cone cooperates with the auxiliary positioning block, the locking device locks the positioning outer cone and the auxiliary positioning block; The datum plane is flat, and the datum plane to be flattened is perpendicular to the spindle of the machine tool;

S2. Apply the heated and melted hot melt adhesive to the groove in the gluing area, place the heated workpiece to be positioned on the fixture for workpiece positioning, and apply pressure to the workpiece to be positioned so that the benchmark set on the reference positioning area The plane is in contact with the plane to be glued on the workpiece to be positioned; the melted hot melt adhesive in the gluing area adheres to the workpiece to be positioned, and the excess hot melt glue flows into the isolation groove in the isolation area. After cooling, the workpiece to be positioned The plane to be glued and the glued area set on the top are fixedly connected by hot melt glue;

S3. After processing, loosen the locking device to unlock the positioning outer cone and the auxiliary positioning block, and remove the workpiece and the positioning outer cone glued body; if repeated positioning is required, after the workpiece and the positioning outer cone glued body are matched with the auxiliary positioning block, The locking device locks and positions the outer cone and the auxiliary positioning block to realize the reset and clamping of the workpiece.
A processing method for an optical element, wherein the first end surface of the optical element is a reference plane, and the second end surface is one of a plane, a convex surface, and a concave surface, and it is characterized in that: firstly, any end surface of the optical element blank is clamped in claim 6 In the reference positioning area of the fixture used for workpiece positioning, after clamping, the other end face of the optical element is milled and processed into a plane, and the optical element is removed by heating the glued area; after the plane shape meets the requirements, the processed plane is used as the The reference plane of the optical element is glued to the glued area. After the second end face is processed, the shape of the optical element is processed by edging process; Carry out measurement, if the surface shape meets the requirements, heat the optical element and the positioning outer cone to remove the workpiece, and obtain the optical element mirror body; The fit is assembled on the auxiliary positioning block again, and compensation processing is performed until the detection surface shape meets the requirements, and the optical element is removed.