JP2950914B2 - Free-form surface polishing method and polishing apparatus using polishing film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a free-form surface polishing method and a polishing apparatus using a polishing film, and development of a polishing method and apparatus capable of automatically performing polishing using a machine tool such as an NC control machining center similar to shape processing. With the goal.

[Prior art]

The general processing steps currently used for creating a free-form surface include shape processing and polishing processing (smoothing processing + mirror finishing). In this creation process, with regard to shape processing, the development and spread of NC machine tools and tools (carbide ball end mills, cermet ball end mills, etc.) will increase the automation and cost of machining, excluding problems such as programming. Efficiency seems to be making steady progress. On the other hand, subsequent polishing is still a bottleneck. In other words, in the current trend of automation and unmanned factories being rapidly promoted, automation and unmanned polishing is technically difficult only in this polishing process, so it is unavoidable that the grinding wheel, stick whetstone, file, polishing cloth It has to rely on hand finishing with paper, etc., and is still a very labor-intensive field. However, in recent years, due to a remarkable increase in labor costs and an increase in demand for free-form surface machining, there has been a strong demand from the die industry for:-reduction of machining time-reduction of machining cost-improvement of machining accuracy. ing. This is an opportunity to further raise interest in mechanization and automation of recent polishing processes.

[Problems to be solved by the invention]

Therefore, the present invention has also started to develop a free-form surface polishing method and apparatus satisfying the following conditions, aiming at the mechanization and automation of this polishing. In other words, (1) whether it is not possible to attach the machine tool used for shape processing such as a machining center to the spindle, (2) whether polishing following shape processing can be performed with the same NC program, (3) motherhood principle Whether a pressure cutting method with excellent polishing can be performed even on a machine tool for shape processing based on JIS, (4) As a polishing tool, a "polishing film" that exhibits stable polishing performance is used (5) Whether the polishing tool can be given an efficient motion for improving the roughness of the finished surface and the polishing efficiency.

[Means for Solving the Problems]

As a result, as a free-form surface polishing method using a polishing film, the polishing film wound in a roll is sequentially fed and supplied to a contact wheel made of an elastic spherical body that simultaneously gives both a vibration motion and a rotation motion on the polishing surface, and the polishing is performed. Adopting a free-form surface polishing method using a polishing film, characterized by selecting a combination of contact wheels having different types of film and hardness of elastic spherical body, and polishing with an attachment having a shank that can be mounted on a milling chuck. As a device used for concrete implementation thereof, a shank (1) attachable to a milling chuck at a base, a contact wheel (10) made of an elastic spherical body at a tip, and an attachment body (20) therebetween are the same. And a contact wheel (1
0) a pressing force adjusting device and a vibrating device, and a winding device comprising a feeding spool (9) and a winding spool (11) of a polishing film (8) to be sequentially supplied to the contact wheel. And developed a free-form surface polishing machine. The polishing film used here is a wrapping tape used for ultra-precision polishing of electronic parts and precision mechanical parts, and a polyester film (polyethylene terephthalate reinforced biaxially stretched) is used as a base material (backing). (PET) film is used, and its thickness is generally 25 to 75 μm. The abrasive grains applied to the polishing film are extremely fine abrasive grains with an average grain diameter of several tens of microns to sub-micron, and the shape is different from that for general grinding wheels (blocky type close to spherical). What is called a standing prism shape is used. As the type of abrasive grains, green carborundum (G
C), white alundum (WA), chromium oxide (K),
There are iron oxide (M), artificial diamond (SD), and the like, and these are finished on the base material by electrostatic coating or roller coating to form a polished film. A contact wheel for abutting and polishing the above-mentioned polishing film on a surface to be polished has an outer periphery serving as an elastic resilient body, and is preferably made of urethane rubber excellent in abrasion resistance, aging resistance and oil resistance. The hardness of the urethane rubber is set according to the required characteristics of polishing. Usually, those having H _S = 40 to 70 are used. The rotational movement of the polished surface is given by attaching the entire attachment to the milling chuck, and the oscillating movement gives fine vibration exceeding 10,000 cycles / min by the eccentric cam provided on the attachment, giving an amplitude in the range of 0 to 4 mm. Can be. In order to continuously supply a new surface to the polishing surface according to the degree of wear, the polishing film incorporates a winding device including a feed spool and a take-up spool of the polishing film in the attachment. The shank (1) and the attachment body (20) serve as a pressing force adjusting device for the polished surface.
The connecting portion (14) is provided with a spring (15) and a double nut (16) to adjust the pressing force against the surface to be polished so as to improve the followability to the curved surface.

[Action]

The operation of the free-form surface polishing method and apparatus using the polishing film of the present invention is as follows. (1) The used abrasive film that has clogged
A new polishing film surface is always fed from the pay-out spool to the machined part after being taken up by the take-up spool. 1) When using a grindstone, dressing is necessary because clogging occurs. Does not require dressing. 2) Since there is no need for dressing, operation of the present polishing apparatus does not require skill. 3) Since the sharpness of the abrasive grains does not change immediately before and immediately after the dressing as in a grindstone, a finished surface of stable quality can always be obtained. (2) Since the pressing pressure is low, heat generation is small, and a work-affected layer is hardly generated on the surface of the workpiece. (3) Since the film index speed can be adjusted stepwise and the number of vibrations of the polishing film can be adjusted steplessly, the optimum polishing conditions for the workpiece can be set. (4) By changing the hardness of the contact wheel, a forced cutting method or a pressure cutting method can be used.
Further, adjustment of the pressing force (cutting amount) is also easy. (5) Both dry and wet types can be used. (6) Since the polishing attachment can be mounted on, for example, a milling chuck of a grinding machine tool, a polishing finishing step can be set as an extension of the processing step, and the processing can be fully automated by an automatic tool changer (ATC).

【Example】

Hereinafter, embodiments of the method of the present invention will be described in detail along with examples of apparatuses. First, an example of a polishing apparatus will be described with reference to the drawings. FIG. 1 is a front view of an attachment attached to a tool shank, and FIG. 2 is a side view of the attachment body. A flange (2) is attached to a shank (1) that can be mounted on the milling chuck via a ball bearing, and the flange (2) is fixed to the machine side by a detent (3). In addition, a copper plate ring is bonded to the groove of the bakelite electrode (4), which is fastened to the shank (1) by a hexagon nut, with an epoxy resin. The carbon brush in (5) is pressed by the spring. The current input from here is
The polishing film is supplied to a winding motor (6) and a vibration motor (7). The take-up motor (6) for the polishing film has an input voltage A.C of 100 V and a rotation speed of 1 rpm, and the vibration motor (7) has a DC of 9 to 15 V and a speed of 6,500 to 14,000 rpm. The polishing film (8) was in the form of a tape having a width of 15 mm. Here, a micro-finishing film (ECF) and a wrapping film (RCF) manufactured by Sumitomo 3M Limited were used.
These are sent out from a delivery spool (9), and the contact surface with the surface to be polished is backed up by a urethane / rubber contact wheel (10) forming an elastic spherical body, and vibration is given by a vibration motor (7). After being wound, it is wound on a winding spool (11) driven from a winding motor (6) via a bevel gear and a spur gear. In this apparatus, both the bevel gear and the spur gear have the same number of teeth, but by changing the combination of these numbers of teeth, several types of film index speeds can be obtained. The vibration is provided by the eccentric cam, but since the vibration frequency exceeds 10,000 cycles / min, attention must be paid to the loss of the motor torque due to the wear and friction of the sliding part. Therefore, the eccentric cam reduces friction by lubricating oil, and the vibrating part is a slide bearing (1
3) The adoption of (linear motion bearing) enables smooth movement against the pressing force on the workpiece. The vibration can be continuously adjusted between 0 and 4 mm by using a double eccentric cam. The connection (14) between the attachment body (20) and the shank (1) of the device is composed of a spring (15) and a double nut (1).
6) The pressing force against the workpiece is adjusted by the pressing force adjusting device consisting of (1) and the followability to the curved surface is improved. Next, a polishing method performed using the present apparatus will be described. The present method is characterized in that polishing is performed by mounting a polishing apparatus to be used on a cutting machine based on the motherhood principle as a kind of tool unit having a function of a selection principle. Another feature is that while many curved surface polishers use a stick whetstone, a polishing means called a polishing film is employed. In addition, while continuously supplying the polishing film to a contact wheel made of an elastic spherical body that has been simultaneously subjected to vibration motion and rotational motion, free-form surface polishing is performed by a machining center that can be numerically controlled so that an appropriate contact pressure is always provided by a new polishing surface. It is characterized by doing. The polishing motion in the present invention has both a vibration motion and a rotational motion in the polishing film, and such a motion is similar to the processing principle of super-finishing, so that the same effect as super-finishing can be expected. The direction of the vibration to be applied to the polishing film is to make it always perpendicular to the cutting streaks generated by the pre-processed surface and to prevent the streaks of the grindstone from overlapping. Therefore, a large number of abrasive grains cut the surface with fine streaks without directivity. This vibration is not always applied to the grindstone, but may be applied to the workpiece or to both the grindstone and the workpiece. The feature of super-finishing is that a very good finished surface can be obtained in a short time. Needless to say, honing or lapping can provide a surface as smooth as super-finishing, but the polishing efficiency is far from the method capable of super-finishing. As is apparent from the above-described apparatus, the rotating motion is mounted on a milling chuck such as a machining center, so that the contact wheel made of an elastic spherical body comes into rotational contact with the surface to be processed on a vertical axis orthogonal to the rotation axis. The vibration is always given in the axial direction of the contact wheel. Here, when one abrasive grain on the polishing film is simultaneously subjected to the vibration motion and the rotation motion in polishing the processing surface having the inclination angle θ between the polishing surface and the rotation axis, the trajectory viewed from the vertical direction is obtained by computer simulation. 3 to 5. Here, r is the eccentricity of the vibration amplitude, and m is the rotation ratio. FIG. 3 shows a trajectory in which θ = 0 °, that is, a case where the workpiece is not tilted and is rotating about a vertical axis with respect to the surface, and is reciprocating radially from the center while reciprocating. FIG. 4 shows the case where the contact is made at an inclination of θ = 10 °, and FIG. 5 shows the case where the rotation ratio m is further increased to 30 which is three times. From this, it can be seen that when the rotation ratio m is increased, the cross hatch is increased and the intersection angle is also increased, so that a highly efficient and highly accurate finished surface can be obtained. Further, such a cross hatch is very effective for finishing a free-form surface because it is close to polishing work by a human hand. In order to cover a wide range of required polishing roughness and polishing rate, the present method copes with the use of the polishing film composed of various kinds of abrasive grains as described above and the change of the rubber hardness of the elastic spherical surface of the contact wheel. ing. Further, it is mounted on a machining center so that the pressing force of the contact wheel can be controlled. It is possible to use the forced cutting method using NC machine tools or the single-shape or multi-axis self-shaping constant-pressure polishing (pressure cutting method) by copying.

【The invention's effect】

According to the method and apparatus of the present invention, not only a conventional grinding machine, but a general-purpose NC milling machine, NC drilling machine or machining center for shaping can be used for polishing, and as an extension of shaping, a polishing tool such as ATC is used. It is now possible to perform polishing with the same NC program as for shape processing while leaving the clamp of the workpiece unchanged. In addition, the use of a polishing film enables unprecedented finish polishing and cleaning polishing of a free-form surface to be performed unattended, contributing to automation of the polishing process and labor saving.

[Brief description of the drawings]

FIG. 1 is a front view of an attachment in which the apparatus is mounted on a tool shank, and FIG. 2 is a side view of the attachment body. FIGS. 3 to 5 are locus diagrams of one abrasive grain on the polishing film obtained by computer simulation. (1) Shank, (2) Flange (3) Flange detent, (4) Electrode (5) Terminal, (6) Film winding motor (7) Vibration motor, (8) Polishing film (9) Feeding spool, (10) Contact wheel (11) Take-up spool, (13) Slide bearing (14) Connection, (15) Spring (16) Double nut, (20) Attachment body

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) B24B 1/04 B24B 21/12 B24B 21/14 B24B 19/00

Claims (3)

(57) [Claims] 1. A polishing film wound in a roll is sequentially fed to a contact wheel made of an elastic spherical body which simultaneously gives both a vibration motion and a rotary motion on a polishing surface, and is supplied thereto. A free-form surface polishing method using a polishing film, wherein a combination of contact wheels having different hardnesses is selected, and polishing is performed using an attachment having a shank that can be mounted on a milling chuck. 2. A shank (1) attachable to a milling chuck at a base, a contact wheel (10) made of an elastic spherical body at a tip, and an attachment body (20) therebetween.
Are arranged on the same axis, and the main body includes a pressing force adjusting device and a vibration device for a contact wheel (10), and a feeding spool (9) and a take-up spool of a polishing film (8) sequentially supplied to the contact wheel. A free-form surface polishing apparatus comprising: a winding device comprising (11). 3. The free-form surface polishing apparatus according to claim 2, wherein the pressing force adjusting device is a spring (15) and a double nut (16) provided at a connecting portion (14) between the shank (1) and the attachment body (20). .