High-performance fixed abrasive small tool for shaping and polishing free-form surface and preparation method of high-performance fixed abrasive small tool

Abstract

The invention discloses a high-performance fixed abrasive small tool for shaping and polishing a free-form surface and a preparation method of the high-performance fixed abrasive small tool. The tool is characterized by comprising a grinding and polishing layer, a cloth base body layer, an elastic base body layer, a rigid base body layer and a rotating shaft, the grinding and polishing layer is a curved surface prepared by uniformly mixing, hot-pressing and curing aggregate diamond abrasive particles and swelling resin, and bulge structures are uniformly distributed on the surface of the grinding and polishing layer; the structure of the elastic base body layer is spherical crown-shaped; the rigid base body layer is of a disc-shaped structure; the rotating shaft is a stainless steel cylindrical rod. The fixed abrasive tool is simple in preparation process, ideal in removal function, stable in machining performance, high in self-finishing capacity, high in removal efficiency, good in conformity and capable of being attached to a free-form surface to achieve high-efficiency and low-damage shaping and polishing.

Description

Technical Field

[0001] The present invention relates to an ultra-precision machining technology, in particular to a modification and polishing technology for free-form surfaces, and specifically to a high-performance fixed-abrasive small tool for free-form surface modification and polishing and a preparation method thereof. Background Art

[0002] Complex free-form surface parts mostly use difficult-to-machine materials with high strength and high hardness, such as nickel-based superalloys, titanium alloys, optical glasses, and composite materials, etc., to meet the usage requirements in extreme environments, and occupy a core position in modern high-end manufacturing fields such as aerospace, energy and power, and medical engineering. The modification and polishing of free-form surfaces play a key role in improving surface quality, optimizing fluid performance, enhancing fatigue life, and improving assembly accuracy. The small tool modification and polishing technology is a deterministic polishing technology based on computer-controlled optical surface forming technology. By preset algorithms and programs, the small tool is controlled to move on the workpiece surface at a predetermined speed and trajectory for local material removal to meet the surface shape accuracy requirements of the workpiece. The removal function of the small tool polishing is a key factor affecting machining accuracy and machining efficiency. At present, the removal functions of existing free-form surface modification and polishing small tools are unstable, there are edge effects, and they cannot completely match the aspheric surface, which will cause subsurface damage and high-frequency errors during the machining process.

[0003] Chinese Patent CN103465162B proposes a fixed-abrasive polishing head and a polishing method thereof, which uses a disc-shaped fixed-abrasive polishing head substrate to precisely polish optical aspheric elements with different shapes and sizes, and obtains better surface shape accuracy. Chinese Patent CN108081070B proposes a numerical control small tool polishing assisted atmospheric plasma processing method. By combining the atmospheric plasma processing method and flexible small tool grinding and polishing, the correction of the surface shape and surface roughness of optical elements can be realized, and the processing of large-aperture optical elements with multiple surface shapes can be achieved. Chinese Patent CN107160242A proposes a processing method for controlling the full-band error of aspheric elements. The airbag polishing technology is used to quickly conformally polish and brighten the aspheric elements, and the flexible asphalt small tool is used to evenly polish the aspheric elements to remove the medium and high-frequency errors brought by conformal polishing, effectively improving the final full-band accuracy of processing large-aperture aspheric elements. At present, most of the existing free-form surface modification and polishing small tools are applied to optical aspheric elements, the processing objects are limited, multiple processes are required to complete the single processing of free-form surface workpieces, the processing efficiency is low, the removal function is not ideal, and the processing requirements of high efficiency, high conformability and low damage cannot be met simultaneously. Summary of the Invention

[0004] The object of the present invention is to address the problems that existing free-form surface dressing and polishing tools are mostly applied to optical aspherical elements, with limited machining objects, requiring multiple processes to complete the single machining of free-form surface workpieces, resulting in low machining efficiency, unsatisfactory removal functions, and inability to meet the machining requirements of high efficiency, high conformability, and low damage simultaneously. A high-performance fixed abrasive tool for free-form surface dressing and polishing is designed, and a corresponding preparation method is provided. It uses aggregated diamond and a matrix material with swelling characteristics to prepare a fixed abrasive pad, which has strong self-trimming ability, can conform to the workpiece surface, has good stability of the removal function, realizes the integration of dressing and polishing, improves machining efficiency, and has excellent machining accuracy.

[0005] One of the technical solutions of the present invention is:

[0006] A high-performance fixed abrasive tool for free-form surface dressing and polishing, the lapping and polishing tool sequentially includes a lapping and polishing layer 1, a cloth matrix layer 2, an elastic matrix layer 3, a rigid matrix layer 4, and a rotating shaft 5 from top to bottom; the lapping and polishing layer 1 is a curved surface obtained by uniformly mixing aggregated diamond abrasive grains and a resin with swelling characteristics and hot pressing and curing, and convex structures are uniformly distributed on the surface for liquid storage and chip removal; the cloth matrix layer 2 is one of fiberglass cloth, polyester cloth, nylon cloth, and non-woven fabric; the elastic matrix layer 3 is one of polyurethane foam, EVA foam, epoxy resin, phenolic resin, and polyurethane rubber, and its structure is spherical crown-shaped; the rigid matrix layer 4 is one of stainless steel and carbon fiber reinforced composite material, and its structure is disc-shaped; the rotating shaft 5 is a stainless steel cylindrical rod.

[0007] The lapping and polishing layer 1 is hot pressed and cured on the cloth matrix layer 2, the cloth matrix layer 2 is connected to the elastic matrix layer 3 through a first bonding layer 6, the elastic matrix layer 3 is connected to the rigid matrix layer 4 through a second bonding layer 7, and the rigid matrix layer 4 is fixedly connected to the rotating shaft 5 through threads.

[0008] The thickness of the lapping and polishing layer 1 is 0.4 - 2 mm, and the convex structure is one or a combination of a circle, an annulus, a triangle, a rectangle, a regular pentagon, and a regular hexagon, with a height of 0.5 - 3 mm.

[0009] The spherical crown diameter of the elastic matrix layer 3 is 10 - 70 mm, and the spherical crown height is 3 - 30 mm.

[0010] The disc diameter of the rigid matrix layer 4 is 10 - 70 mm, and the disc height is 5 - 50 mm.

[0011] The cylindrical rod diameter of the rotating shaft 5 is 2 - 20 mm, and the cylindrical rod length is 40 - 120 mm.

[0012] The first bonding layer 6 and the second bonding layer 7 are one or a combination of nylon fasteners, AB epoxy resin glue, and crystal glue.

[0013] The described grinding and polishing layer 1 is prepared by uniformly mixing aggregated diamond abrasives and a resin with swelling properties, and then heating and curing.

[0014] The second technical solution of the present invention is:

[0015] A preparation method of a high-performance fixed abrasive small tool for free-form surface modification and polishing, characterized by comprising the following steps:

[0016] Step 1: Design a mold with a groove 10 according to the spherical crown shape and the convex structure of the grinding and polishing layer 1. The mold is a three-piece split mold. The lower left piece 12 and the lower right piece 11 are curved surfaces including the groove 10 structure, and the upper piece 9 is a smooth curved surface structure. The three-piece structure is accurately positioned by a positioning pin 13;

[0017] Step 2: Configure abrasive grains and matrix raw materials that meet the requirements of grinding and polishing processing;

[0018] Step 3: Spray a release agent and evenly apply the raw materials into the groove 10 of the mold and compact them. Cover the cloth matrix layer 2 and press the upper piece 9 of the mold. Heat and pressurize to cure the grinding and polishing layer on the cloth matrix layer;

[0019] Step 4: Connect the cloth matrix layer 2 and the elastic matrix layer 3 through a first bonding layer 6, connect the elastic matrix layer 3 and the rigid matrix layer 4 through a second bonding layer 7, and fix and connect the rigid matrix layer 4 and the rotating shaft 5 through a thread 8 to obtain a fixed abrasive small tool;

[0020] A draft angle is reserved at the groove 10 of the mold for easy demolding.

[0021] The beneficial effects of the present invention are:

[0022] The fixed abrasive tool of the present invention uses aggregated diamond abrasives and a resin with swelling properties to be uniformly mixed and heated and cured to obtain a fixed abrasive polishing pad. The polishing pad has excellent self-trimming characteristics, effectively inhibits subsurface damage while ensuring processing accuracy, and improves processing quality.

[0023] The fixed abrasive tool of the present invention uses a spherical crown-shaped elastic matrix layer, which has a yielding property and undergoes a certain deformation when subjected to polishing pressure to adapt to the changes in the surface shape of various complex free-form surface parts, realizing flexible adaptive polishing.

[0024] The fixed abrasive tool of the present invention uses a three-piece split mold to prepare a fixed abrasive pad. A diagonal guide post and a draft angle are designed at the groove structure of the lower left piece and the lower right piece for easy demolding.

[0025] The removal function of the fixed abrasive tool of the present invention is stable, and it can realize the integration of modification and polishing, improving processing efficiency and processing accuracy. Brief Description of the Drawings

[0026] Figure 1 This is an overall sectional view of the fixed abrasive tool of the present invention.

[0027] Figure 2 This is a schematic structural view of the fixed abrasive tool of the present invention.

[0028] Figure 3 This is a schematic view of a three-piece split mold for the fixed abrasive pad of the present invention.

[0029] The specific markings in the figure are as follows: 1 - grinding and polishing layer; 2 - cloth substrate layer; 3 - elastic substrate layer; 4 - rigid substrate layer; 5 - rotating shaft; 6 - first bonding layer; 7 - second bonding layer; 8 - screw hole; 9 - upper sheet mold; 10 - groove; 11 - lower right sheet mold; 12 - lower left sheet mold; 13 - positioning pin. Detailed Description of the Invention

[0030] The present invention will be further described below in conjunction with the drawings and embodiments.

[0031] As Figure 1 , 2 shown.

[0032] A high-performance fixed abrasive small tool for free-form surface modification and polishing is composed of a grinding and polishing layer 1, a cloth substrate layer 2, an elastic substrate layer 3, a rigid substrate layer 4, and a rotating shaft 5. As Figure 1 , the grinding and polishing layer 1 is a curved surface obtained by uniformly mixing aggregate diamond abrasives and a resin with swelling characteristics and hot-pressing and curing. The surface is uniformly distributed with convex structures for liquid storage and chip removal; the cloth substrate layer 2 is one of fiberglass cloth, polyester cloth, nylon cloth, and non-woven fabric; the elastic substrate layer 3 is one of polyurethane foam, EVA foam, epoxy resin, phenolic resin, and polyurethane rubber, and the structure is spherical crown-shaped, as Figure 2 ; the rigid substrate layer 4 is one of stainless steel and carbon fiber reinforced composite materials, and the structure is disc-shaped; the rotating shaft 5 is a stainless steel cylindrical rod.

[0033] The above solution uses uniformly mixed aggregate diamond abrasives and a resin with swelling characteristics, and prepares a fixed abrasive polishing pad by heating and curing. The polishing pad has excellent self-trimming characteristics, effectively inhibits subsurface damage while ensuring processing accuracy, and improves processing quality; uses a spherical crown-shaped elastic substrate layer with a yielding characteristic, which deforms to a certain extent when subjected to polishing pressure to adapt to the changes in the surface shape of various complex free-form surface parts and realizes flexible adaptive polishing.

[0034] As Figure 1 , 2As shown, the grinding and polishing layer 1 of the present invention is hot-pressed and cured on the cloth base layer 2, the cloth base layer 2 is connected to the elastic base layer 3 via a first bonding layer 6, the elastic base layer 3 is connected to the rigid base layer 4 via a second bonding layer 7, and the rigid base layer 4 is fixedly connected to the rotating shaft 5 via a thread 8.

[0035] The most ideal dimensions of each part obtained by repeated experiments are as follows:

[0036] The grinding and polishing layer 1 has a thickness of 0.4-2 mm, and the protrusion structure is one of a circle, annular, triangular, rectangular, regular pentagon, regular hexagon or a combination thereof, and has a height of 0.5-3 mm.

[0037] The spherical cap diameter of the elastic base layer 3 is 10-70 mm, and the spherical cap height is 3-30 mm; the disc diameter of the rigid base layer 4 is 10-70 mm, and the disc height is 5-50 mm; the cylindrical rod diameter of the rotating shaft 5 is 2-20 mm, and the cylindrical rod length is 40-120 mm.

[0038] The first adhesive layer 6 and the second adhesive layer 7 are one of nylon hook and loop, AB epoxy resin glue or crystal glue or a combination thereof.

[0039] The fixed abrasive tool of the present invention has a stable removal function, can realize the integration of shaping and polishing, and improves the processing efficiency and processing accuracy.

[0040] Embodiment 2.

[0041] like Figure 3 shown.

[0042] A method for manufacturing a high-performance fixed abrasive small tool for free-form surface modification and polishing, the method comprising the following steps:

[0043] Step 1: Design a mold with a groove 10 according to the shape of the spherical crown and the convex structure of the grinding and polishing layer 1, such as Figure 3 As shown, the mold is a three-piece split mold, the lower left piece 12 and the lower right piece 11 are curved surfaces including a groove 10 structure, the upper piece 9 is a smooth curved surface structure, and the three-piece structure is accurately positioned by a positioning pin 13;

[0044] Step 2: Prepare abrasive grains and matrix materials that meet the requirements of grinding and polishing;

[0045] Step 3: spray the release agent and evenly apply the raw material to the groove 10 of the mold and compact it, cover the cloth base layer 2 and then press the upper sheet 9 mold, heat and press to solidify the grinding and polishing layer on the cloth base layer;

[0046] Step 4: Connect the cloth matrix layer 2 and the elastic matrix layer 3 through the first bonding layer 6, connect the elastic matrix layer 3 and the rigid matrix layer 4 through the second bonding layer 7, and fixedly connect the rigid matrix layer 4 and the rotating shaft 5 through the thread 8 to obtain a consolidated abrasive tool.

[0047] The consolidated abrasive tool of the present invention uses a three-piece split mold to prepare a consolidated abrasive pad, and a draft angle is designed at the groove structure of the lower left piece and the lower right piece to facilitate demolding.

[0048] The consolidated abrasive tool of this application is suitable for the modification and polishing of free-form surfaces, and can also be used for the grinding and polishing of other similar workpieces. The following will illustrate the specific application of the consolidated abrasive tool of this application with several examples.

[0049] Example 1.

[0050] Apply the high-performance consolidated abrasive tool for free-form surface modification and polishing provided by the present invention to the processing requirements of TC4 titanium alloy workpieces. Select diamond with a particle size of 20-30 microns and a swelling property resin, mix them evenly in proportion and pour them into the mold. Cover the abrasive with a non-woven fabric with a thickness of 0.5 mm, cover the upper mold tightly, and heat and pressurize to cure to obtain a consolidated abrasive layer.

[0051] Bond the above-prepared consolidated abrasive layer to a polyurethane foam spherical crown elastic matrix layer with a diameter of 60 mm and a spherical crown height of 25 mm with resin glue, then bond the elastic matrix layer to a rigid matrix layer with a diameter of 60 mm and a height of 20 mm with crystal glue, and tightly connect a rotating shaft with a diameter of 2 mm and a length of 100 mm to the rigid matrix layer to make a consolidated abrasive tool. Conduct a TC4 titanium alloy free-form surface workpiece modification and polishing test on an ABB robot platform. The grinding and polishing pressure is 0.032 MPa, the electric spindle speed is 500 rpm, the polishing liquid is deionized water, the polishing liquid flow rate is 100 ml / min, the surface roughness Ra of the workpiece before grinding and polishing is 900 nm, and after 5 minutes of grinding and polishing, it is detected that the surface roughness Ra of the workpiece drops to 197.3 nm.

[0052] Change the above grinding and polishing pressure to 0.024 MPa, and under the condition that other conditions and parameters remain unchanged, after grinding and polishing for 5 minutes, the surface roughness Ra of the workpiece drops to 168.5 nm.

[0053] Example 2.

[0054] Apply the high-performance consolidated abrasive tool for free-form surface modification and polishing provided by the present invention to the processing requirements of fused silica glass free-form surface workpieces. Select diamond with a particle size of 10-20 microns and a swelling property resin, mix them evenly in proportion and pour them into the mold. Cover the abrasive with a non-woven fabric with a thickness of 0.8 mm, cover the upper mold tightly, and heat and pressurize to cure to obtain a consolidated abrasive layer.

[0055] The prepared consolidated abrasive layer is bonded to a polyurethane resin spherical crown elastic matrix layer with a diameter of 50 mm and a spherical crown height of 20 mm using resin glue. Then, the elastic matrix layer is bonded to a rigid matrix layer with a diameter of 50 mm and a height of 15 mm using AB epoxy resin glue. A rotating shaft with a diameter of 3 mm and a length of 80 mm is tightly connected to the rigid matrix layer to make a consolidated abrasive tool. A free-form surface workpiece trimming and polishing test of fused silica glass is carried out on an ABB robot platform. The polishing pressure is 0.038 MPa, the speed of the electric spindle is 500 rpm, the polishing liquid is deionized water, the flow rate of the polishing liquid is 100 ml / min. Before polishing, the surface roughness Ra of the workpiece is 176 nm. After 5 minutes of polishing and detection, the surface roughness Ra of the workpiece drops to 56.3 nm.

[0056] When the above polishing pressure is changed to 0.026 MPa and other conditions and parameters remain unchanged, after 5 minutes of polishing, the surface roughness Ra of the workpiece drops to 44.2 nm.

[0057] Example 3.

[0058] Apply the high-performance consolidated abrasive small tool for free-form surface trimming and polishing provided by the present invention to the processing requirements of a free-form surface of spinel. Select diamond with a particle size of 5 - 7 microns and a swelling property resin, mix them evenly in proportion and pour them into a mold. Cover the abrasive with a non-woven fabric with a thickness of 0.3 mm, cover the upper mold tightly, and cure by heating and pressurization to obtain a consolidated abrasive layer.

[0059] The prepared consolidated abrasive layer is bonded to an EA foam spherical crown elastic matrix layer with a diameter of 40 mm and a spherical crown height of 15 mm using resin glue. Then, the elastic matrix layer is bonded to a rigid matrix layer with a diameter of 40 mm and a height of 15 mm using nylon fasteners. A rotating shaft with a diameter of 2 mm and a length of 120 mm is tightly connected to the rigid matrix layer to make a consolidated abrasive tool. A free-form surface workpiece trimming and polishing test of fused silica glass is carried out on an ABB robot platform. The polishing pressure is 0.016 MPa, the speed of the electric spindle is 500 rpm, the polishing liquid is deionized water, the flow rate of the polishing liquid is 100 ml / min. Before polishing, the surface roughness Ra of the workpiece is 57 nm. After 5 minutes of polishing and detection, the surface roughness Ra of the workpiece drops to 22.7 nm.

[0060] When the above polishing pressure is changed to 0.010 MPa and other conditions and parameters remain unchanged, after 5 minutes of polishing, the surface roughness Ra of the workpiece drops to 13.1 nm.

[0061] The above are only the preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

[0062] The parts not involved in the present invention are the same as or can be implemented by the prior art.

Claims

1. A high-performance fixed abrasive small tool for free-form surface dressing and polishing, characterized in that The lapping and polishing tool sequentially includes a lapping and polishing layer (1), a cloth matrix layer (2), an elastic matrix layer (3), a rigid matrix layer (4), and a rotating shaft (5) from top to bottom; the lapping and polishing layer (1) is a curved surface obtained by uniformly mixing and hot-pressing and curing aggregate diamond abrasives and a swelling property resin, and the surface is uniformly distributed with convex structures for storing liquid and discharging chips; the cloth matrix layer (2) is one of fiberglass cloth, polyester cloth, nylon cloth, and non-woven fabric; the elastic matrix layer (3) is one of polyurethane foam, EVA foam, epoxy resin, phenolic resin, and polyurethane rubber, and the structure is spherical crown-shaped; the rigid matrix layer (4) is one of stainless steel and carbon fiber reinforced composite material, and the structure is disc-shaped; the rotating shaft (5) is a stainless steel cylindrical rod.

2. The high-performance fixed abrasive tool for free-form surface dressing and polishing according to claim 1, characterized in that: The lapping and polishing layer (1) is hot-pressed and cured on the cloth matrix layer (2), the cloth matrix layer (2) is connected to the elastic matrix layer (3) through a first bonding layer (6), the elastic matrix layer (3) is connected to the rigid matrix layer (4) through a second bonding layer (7), and the rigid matrix layer (4) is fixedly connected to the rotating shaft (5) through threads.

3. The high-performance fixed abrasive small tool for free-form surface dressing and polishing according to claim 1, characterized in that, The thickness of the lapping and polishing layer (1) is 0.4 - 2 mm, and the convex structure is one or a combination of a circle, an annulus, a triangle, a rectangle, a regular pentagon, and a regular hexagon, and the height is 0.5 - 3 mm.

4. The high-performance fixed abrasive small tool for free-form surface dressing and polishing according to claim 1, wherein The spherical crown diameter of the elastic matrix layer (3) is 10 - 70 mm, and the spherical crown height is 3 - 30 mm.

5. The high-performance fixed abrasive tool for free-form surface dressing and polishing according to claim 1, wherein The disc diameter of the rigid matrix layer (4) is 10 - 70 mm, and the disc height is 5 - 50 mm.

6. The high-performance fixed abrasive tool for free-form surface dressing and polishing according to claim 1, wherein The cylindrical rod diameter of the rotating shaft (5) is 2 - 20 mm, and the cylindrical rod length is 40 - 120 mm.

7. The high-performance fixed abrasive tool for free-form surface dressing and polishing according to claim 2, characterized in that, The first bonding layer (6) and the second bonding layer (7) are one or a combination of nylon fasteners, AB epoxy resin glue, and crystal glue.

8. A preparation method of a high-performance fixed abrasive small tool for free-form surface dressing and polishing as described in claims 1 to 7, characterized in that, It includes the following steps: Step 1, design a mold with grooves (10) according to the spherical crown shape and the convex structure of the lapping and polishing layer (1). The mold is a three-piece split mold. The lower left piece (12) and the lower right piece (11) include curved surfaces with groove (10) structures, and the upper piece (9) is a smooth curved surface structure. The three-piece structure is accurately positioned through a positioning pin (13); Step 2, configure abrasive grains and matrix raw materials that meet the requirements of lapping and polishing processing; Step 3, spray a release agent and evenly apply the raw materials into the grooves of the mold (8) and compact them. Cover the cloth matrix layer (2) and press the upper piece (9) of the mold. Heat and pressurize to cure the lapping and polishing layer on the cloth matrix layer; Step 4, connect the cloth matrix layer (2) to the elastic matrix layer (3) through the first bonding layer (6), connect the elastic matrix layer (3) to the rigid matrix layer (4) through the second bonding layer (7), and fixedly connect the rigid matrix layer (4) to the rotating shaft (5) through threads (8) to obtain a consolidated abrasive small tool.

9. The preparation method according to claim 8, characterized in that, A draft angle is reserved at the groove (10) for easy demolding.

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