KR850000589Y1 - Strip casting apparatus - Google Patents

Abstract

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Description

Amorphous metal strip casting machine

Figure 1 is an elevational view of a partial cross section illustrating a traditional apparatus used for continuous casting of strip material.

2 is a cross-sectional view of the nozzle of the present invention.

3 is a perspective view of a curved piece forming the nozzle of the present invention.

4 is an enlarged sectional view through the hole passage of the indictment shown in FIGS. 2 and 3;

5 is an enlarged cross-sectional view through a hole passage of another form of prosecution of the present invention.

6 is a cross-sectional view of a hole passage of another embodiment of the present invention.

Figure 7 is an enlarged cross-sectional view illustrating another hole passage in the prosecution of the present invention.

8 is an enlarged cross-sectional view illustrating another hole passage in the prosecution of the present invention.

The present invention relates to the casting of strip materials at high speed quenching and high production rates, and more particularly to the apparatus for high speed casting of thin metal strip materials.

Compared with the conventional rolling or reducing operation, there are various advantages and economics in producing a thin metal strip material by the present casting apparatus. The fact that strip casting should be carried out under rapid quenching to produce amorphous material makes more sense. However, there are many difficulties in the successful development of strip casting apparatus because there are many strip casting parameters that need to be adjusted in order to make casting strips of acceptable quality and uniform composition and structure.

General methods for casting thin metal materials, such as steel sheets, foils, strips and ribbons, were already developed in the 1900's, for example US Pat. Nos. 905,758 and 993,904 which pour molten material onto a moving cooling surface. The method of stretching and curing into a continuous thin strip on the bed was suggested. These documents describe a method of making strip material by rotating molten metal and pouring it onto a circumferential surface of a copper drum or disk that is cooled with liquid. Despite the earlier methods, successful strip casting did not take place in the early 20th century.

Recently, methods for producing continuous products such as metal wires and strips from molten metals have been described in US Pat. Nos. 3,522,836 and 3,605,863, which describe the convex meniscus of molten material: cohesion upon contact with liquids and containers. By the contact of the curved contact) and the surface of the heat extraction surface, such as a water-cooled drum, runs into a passage parallel to the exit hole and in contact with the mini-cus of molten metal, and continuously extracts the molten material from the ministers so that it is a uniform continuous product. Make The above-described method is called a melt drag method because the heat extraction surface running through the mini-cus of molten metal in the nozzle hole has an effect on the flow rate of molten metal through the nozzle.

More recently, strip casting development focuses on relatively limited refining in the metal strip casting field, for example US Pat. No. 4,141,571 describes groove structures in metal strip casting nozzles. U. S. Patent No. 4,077, 462 relates to the installation of a special structure for a housing fixed on the circumferential surface of a cooling roll used in strip casting.

There are many other rapid quenching methods known in the art, for example, a melt preparation method for producing metal filaments by cooling the melt microfluid in a glass flight or cooling block. The crucible melt extraction method described in US Pat. No. 3,838,185 is also known, the droplet melt extraction method is claimed in US Pat. No. 3,896,203 and the thin plate cooling method is described in US Pat. No. 3,297,436. However, it has been found very difficult to produce a uniform thin steel sheet or strip by a rapid quenching method. There are many factors such as affecting casting temperature and pressure, secondary surface cooling rate, coating on the casting surface, and product thickness, quality and reproducibility of the rapid casting strip material.

Despite the relatively long history and recent developments in the field of strip casting, strip casting is currently not widely practiced industrially, which requires various improvements, modifications and innovations to enable industrial manipulation in the strip casting sector. Indicates. In particular, molten metal tundish structures, nozzle hole sizes and dimensions, space from the casting surface, speed at which the casting surface moves, cooling rates, and metals to achieve the uniformity and consistency required for successful industrial production of casting strips. Appropriate relationships between variable factors, such as temperature and infusion rate, require more accurate matching and correlation. In particular, it has been found that the nozzle size and their jig relationship for the casting surface on which the strip material is to be cast is inadequate for obtaining a uniform strip casting when using various casting parameters.

Accordingly, there is a need for a new refinement for casting a wide range of thin strip materials that can eliminate the disadvantages of conventional structures. Such a device should be more accurate and efficient than the structure invented in the prior art and be reproducible, uniform and consistent in strip casting.

The present invention provides a new improved apparatus for continuous casting of metal strip material. Such a device consisted of a nozzle comprising a tundish and a curved element, wherein the inlet hole had a uniform cross-sectional dimension through its longitudinal extension. On the nozzle outer surface, a cold casting surface that is movable through the nozzle in a direction perpendicular to the longitudinal axis of the hole passage is movable. The first and second sides of the prosecution are hole passages through which molten metal is injected into the casting surface.

An advantage of the present invention is to provide a strip casting apparatus capable of continuously casting metal strips of uniform dimension and uniform quality through length. Another advantage of the present invention is to provide a strip casting apparatus having a nozzle structure that can effectively and quickly cast a metal strip material with minimal metal turbulence during casting.

It is an object of the present invention to provide a strip casting apparatus capable of successfully reproducing a strip casting operation.

Another object of the present invention is to provide a strip casting apparatus that can rapidly quench the prepared strip to effectively produce the amorphous strip. However, the continuous casting of the crystalline material also belongs to the present invention.

It is a further object of the present invention to provide a design and the required dimensions, in particular a nozzle structure, for the rapid and continuous casting of uniform and homogeneous metal strip materials. These and other materials and advantages will become more apparent from the following description with reference to the accompanying drawings.

Referring to the drawings, FIG. 1 illustrates an apparatus for casting a metal strip material 10 according to the present invention.

The apparatus includes a drum, wheel, belt, etc., for casting the strip 10. In a suitable embodiment, the continuous strip 10 is cast on an annular drum or a smooth outer circumferential surface 14 as shown in FIG. Arrangements other than annular may also be used, for example a wheel having a smooth cutting cone surface (not shown). Also generally used as casting machines is a belt that can rotate through the distributor passage. Regardless of the arrangement used, the casting surface 14 should be cooled to below the solids and temperature of the metal to be cast and at least as wide as the strip to be cast.

In a preferred embodiment, the casting element 12 comprises a water-cooled precipitate hardened copper alloy wheel comprising about 98% copper and inverse 2% chromium. Copper and copper alloys are suitable because of their high thermal conductivity and wear resistance, but can be used only or in combination with beryllium-copper alloys, steel, bronze, aluminum, aluminum alloys or other materials. For example, a multi-piece wheel with a circumferential sleeve of molybdenum or other material is used. Cooling may be accomplished using media other than water, but traditionally water is selected because of its low cost and ease of use.

In the operation of the strip casting apparatus of the present invention, the surface 14 of the casting wheel 12 absorbs heat generated by contact with the molten metal at the initial casting point 16, and this heat is a dynamic wheel during each rotation of the wheel. Evangelized into The initial casting point 16 refers to the position on the casting surface 14 where the molten metal 20 flowing out of the tundish 22 contacts the casting surface 14. Cooling by heat conduction may be achieved by directing a sufficient amount through an internal passage located near the circumference of the casting wheel 12 of water or directing the cooling medium directly to the mill surface of the casting surface. A refrigeration method may be used to accelerate or reduce the cooling rate or to effectively effect the expansion or contraction of the wheel during strip casting.

When using drums, wheels or belts for casting, the casting surface is generally smooth and symmetrical to ensure maximum uniformity in strip casting. For example, in some strip casting operations, the distance between the outer circumferential casting surface 14 and the face defined by the hole passage of the nozzle for injecting molten material onto the casting surface 14 should not have an error from the desired distance during the casting operation. This distance is hereinafter referred to as the prescribed distance or distance. When casting a uniform slip material, the spacing must be kept constant throughout the entire casting operation.

If casting is carried out on a rotating body 12, such as a drum or wheel, the rotating body 12 must be carefully manufactured so that the rotation does not deviate during operation in order to provide uniformity to the strip casting. Drums or wheels that deviate by more than 0.020 inches have unstable dimensions that are unacceptable for any strip casting operation unless corrected or corrected during operation. It has been found that the elimination of problems related to weld porosity as well as tolerance of allowances can be achieved by fabricating wheels or drums from a single slab of cold rolled copper alloy. However, other materials may be used, including the coating of the sleeve, as described above.

The molten material 20 to be cast in the device is held in a crucible 22 or tundish equipped with a nozzle 24. Although not required, the nozzle is located at the bottom of the tundish 22 as shown in FIG. 1 and the nozzle includes a curved element 24 within the tundish 22 as described above. Curved elements 24 located at the bottom of the tundish 22 are best shown in tundish 22, shown in perspective views in FIGS. 2 and 3. As shown in the figure, the hole passage 30 is located at the center of the nozzle prosthesis 24, and the center of the hole toro or groove provides uniformity when equalizing the pressure of the molten metal acting on it during the casting operation. It was kept to be possible. However, the grooves can also be placed away from the center as needed.

The longitudinal extension of the aperture 30 is equal to the width of the strip to be cast. There is no restriction on the longitudinal extension of the hole passage, and a passage of 36 inches or more in the curved element is included in the present invention. The molten metal was made to flow evenly through the hole passage 30 in the curved element 24 of the present invention in order to make a uniform and excellent strip material. In other embodiments, strips of varying widths may be produced by cutting a plurality of holes 30 aligned with the longitudinal extension of the longitudinal extension in the curved element 24 forming the nozzle of the tundish 22 as opposed to a single hole 30. Can be prepared.

Regardless of the size of the hole passage 30, the cross sectional dimension of each passage 30 must be uniform through the longitudinal extension to produce a strip with uniform dimensions. In the operation of the strip casting apparatus of the present invention, it operates through the hole passage 30 in a direction perpendicular to the longitudinal axis of the passage 30 of the cooled casting surface 14.

As shown in FIG. 4, the hole passage 30 is defined between the first side portion 32 and the second side portion 34 of the curved element 24. The first side portion 32 is located on the downstream side of the hole passage 30 with respect to the direction of movement of the casting surface 14 indicated by the arrow in FIG. The first side portion 32 has a flat inner surface 36 and an outer lip protruding surface 38 is disposed facing the casting surface 14. In the position downstream from the hole passage 30, as in 40, the outer leaf projection surface 38 is replaced to form the leaf projection 24. As shown in FIG. The second side portion 34 is located on an upstream side of the hole passage 30 with respect to the moving direction of the casting surface 14 indicated by the arrow in Fig. 4. The second side portion 34 is a flat inner surface 49. This inner surface faces smoothly with the inner surface 36 of the first side portion 32 at the outer surface of the hole passage 30 with respect to the direction of the metal flowing from the tundish 22 through the passage 30. The bottom face 48 of the second side face 34 is disposed facing the casting face 14.

In a suitable embodiment, the outer leaf protruding surface 38 of the first side portion 32 and the portion of the bottom surface 48 of the second side portion 34 are in full parallel with the casting surface 14 running below. When using drums, wheels and curved elements 24 that can be enclosed, complete parallelism is achieved by placing sandpaper against the casting surface 14 together with the frictional side of the sandpaper facing the curved element 24. Can be. The outer leaf of the first side part 32 by actuating in close contact with the casting surface 14 having sandpaper disposed between the curved elements 24 and simultaneously operating the casting surface 14 and sandpaper passing through the nozzle 24. The protruding surface 38 and the low surface 48 of the second side face 34 are polished completely parallel to the casting surface 14 by the friction surface of the sandpaper, even on the most difficult nozzles, even with round or other curved casting surfaces. The equilibrium can be achieved and it has been found that 400 or 600 grits sandpaper is suitable for equilibrating by this process.

By keeping at least a portion of the outer leaf protruding surface 38 completely parallel to the casting surface 14, the prescribed distance or spacing h between the outer leaf protruding surface 38 and the casting surface 14 is reduced to the entirety of the projection 42. Maintained throughout the length. In order to successfully cast the strip material, the spacing h between the outer leaf protruding face 38 and the casting face 14 should be kept below 0.120 inches. In particular, this spacing h is kept below 0.080 inches and spacing h below 0.010 inches is suitable for casting any alloy into a thin strip. It also shows that the spacing h between the low surface 48 of the second side portion 34 is not critical. More preferred for the second side portion 34 is that its inner surface 46 extends toward the casting surface 14 while being parallel to the inner surface 36 of the first side portion 32 in the outer surface portion of the hole passage 30. The molten metal is allowed to flow safely through the casting surface 14 through the passage 30 in the curved element 24. Thus, the lower surface 48 of the second side portion 34 is spaced within about 0.002 inches from the casting surface 14 as shown in FIG. 7 or the lower surface 48 is shown in FIG. The curved inclination was achieved while falling from the hole in the casting surface 14 direction. In some cases, the spacing h between the bottom surface 48 and the casting surface 14 of the second side portion 34 is limited at the nozzle to prevent backflow of molten metal during casting.

In another embodiment shown in FIG. 5, the inner surface 36 of the first side portion 32 extends to the outer leaf protruding surface 38 through the curved surface 50 as opposed to 90 ° engagement in FIG. 4. . This elongated corner surface 50 assists in the manufacture of certain grades of strip material. In particular, the elongated corner surface 50 minimizes turbulence of molten metal during strip casting, thereby providing more uniform manufacturing results. In addition, the sharp edges between the inner surface 36 and the outer leaf protruding surface 38 are subject to various pressures and flows that create stress conditions for curved elements 24 made of a material, in which case cracking, cracking or abrasion during casting By destroying the equilibrium strip casting conditions. The rounded surface 50 can minimize adverse effects such as turbulence on the flow of metal through the curved elements 24 including the nozzles of the tundish 22.

In order to minimize turbulence during strip casting through the present invention, the inner surface portion of the hole passage 30 became narrower from top to bottom. As shown in the figure, the first side portion 32 and the second side portion 34 have their inner surfaces cut into a V-shaped or rounder U-shape to form an initial funnel-like structure, thereby maximizing the uniformity of metal flow. Minimize irregularities and turbulence during strip casting.

Another suitable arrangement for minimizing turbulence of molten metal during strip casting is to arrange the curved elements 24 at an angle at which the metal is injected in the same direction as the casting surface 14, which is the inner surface of the hole passage 30. By arranging (36) and (46) at an angle of 90 degrees or less, in particular an angle of 45 degrees, towards the casting surface 14. The molten metal flowing by this arrangement does not cause a severe change in flow rate as experienced when the hole passage 30 is arranged to inject molten metal perpendicular to the casting surface 14. Crucible 22 is made of a material having a high degree of insulation. If the thermal insulation is insufficient to keep the molten material at a relatively constant temperature, an auxiliary heater such as an induction coil or a resistance element such as a wire should be provided in or around the crucible 22.

Conventional crucible materials are thermal insulation made from fibrillated kaolin, naturally occurring high purity alumina-silica clay, which may be commercially available as a Kaoul HS board. However, other materials, including graphite, alumina-graphite, quartz, clay-graphite, boron nitride, silicon nitride, silicon carbide, boron carbide, alumina, zirconia or mixtures thereof, for continuous operation and casting alloys with higher melting temperatures. Can be used to make a crucible 22 or a curved piece 24. These materials can also be reinforced, for example by impregnating fibrous kaolin with a silica gel or the like.

The hole passage 30 of the curved element 24 remains open and its arrangement must remain stable through the strip casting operation. The hole passage 30 should not be corroded or blocked during strip casting where the corrosion or blockage is impeded by the primary purpose of maintaining uniformity in the casting and minimizing turbulence of the metal flow in the tundish 22. In this state, the insulating material cannot maintain their stability over a long casting period. In order to solve this problem, the side portions 32 and 34 forming the hole passages 30 of the curved elements 24 have a long period of time. It shall consist of a material that is capable of maintaining its structural stability and intact during exposure to molten metal melts. This material takes the form of a single semi-circulatory bed 24 together with the recess 30 as shown in FIG. The curved elements 24 include a pair of facing inserts in the crucible 22 to form grooves 30 therebetween, as shown in FIG. In a suitable embodiment, the hole passage 30 in the single curved element 24 is ultrasonically delivered to accurately create the desired groove dimensions. The curved element 24 may be quartz, graphite, clay-graphite, boron nitride, alumina graphite, Made of durable materials for silicon carbide, stabilized zirconia silicate, zirconia, magnesia, alumina or other similar molten metal. Such curved elements 24 are installed in the crucible 22 either mechanically or using various refractory cements.

The drive system of the present invention and the housing for the drum, wheel or other casting surface 14 should be rigid to allow rotation to occur without structural instability causing the drum to slip or vibrate.

In particular, care should be taken to avoid resonances to the casting surface 14 at operating speeds. The casting surface 14 may be operated at a surface speed of 200 ft / min-10,000 ft / min. When using a drum 8 feet in circumference, the drum speed is calculated to be 25-1250 rpm. A three-horsepower, variable-dynamic braking motor is mounted as the drive system for the 2-inch thick and 8-foot circumferential copper alloy casting drum.

In one embodiment, the rough surface 14 on the wheel or drum of the subject innovation should be smooth. In some applications, such as for producing amorphous materials, products with improved uniformity can be obtained when finished with the circumferential surface 14 of the casting drum 12 loaded with 400-grit abrasive paper, especially 600-grit abrasive paper. It was found possible.

In a suitable embodiment as illustrated in FIG. 2, the crucible 22 consists of an insulating board, such as a Khao HS HS board, and the curved elements 24 as shown in FIG. 3 are materials that are durable against molten metal. It is made of phosphorus clay-graphite and placed in the wall of the crucible 22. The bore furnace 30 in the clay-graphite 24 is ultrasonically cut. The first side portion 32 and the second side portion 34 of the curved element 24 form a hole passage or groove 30 therebetween. A suitable example of a curved element 24 made of quartz or non-corrosive material, which is a high durability for molten metal having a width of 1.5 inches, is bent to an appropriate radius as shown in the figure. The curved element 24 also includes cast boron nitride. The desired grooves forming the hole passages 30 in the curved elements 24 are precisely cut by an ultrasonic drill. As best described in FIGS. 2, 3 and 4, curved elements 24 consisted of semi-cyclic rings of material resistant to molten metal. In this embodiment, the insert is crucible as ultrasonically drilled into a grooved clay graphite insheet material having a width of 0.010-0.080 inches between the parallel inner surfaces 36 and 46, as shown in FIG. It is established in (22). The outer circumferential surface of the curved element nozzle can be deformed to help mount the curved element 24 in the wall of the crucible 22.

A suitable hole passage 30 in the curved element 24 of the inventive device is shown in an enlarged cross sectional view of FIG. In one embodiment of the apparatus the dimensions shown in FIG. 4 have the following appropriate limits.

Dimension Design Moderate Limits Moderate Limits

a Bottom at least 0. 001 inches 0. 25-0. 50 inches

b Width of the hole passage 0. 010-0. 080 inches 0.025-0. 035 inches

c External leaf protrusion length 0. 01-0. 16 inches 0.02-0.06 inches

d Relief distance at least 0.01 inches at least 0.04 inches

In the manufacture of amorphous strip material, the width b of the hole passage 30 has traditionally been 0.010-0. 040 inches. In the production of crystalline strip material such as stainless steel, the width b of the hole passage 30 should be as large as 0.080 inch if the thick strip is to be manufactured uniformly according to the present invention.

The dimension representing the cross-sectional thickness of the curved element 24, e, f representing the width at which the upper end of the hole passage 30 is relieved, and g representing the depth at which the upper end of the hole passage 30 is relief, are somewhat arbitrary. . The purpose of the relief at the top of the hole passage 30, indicated by dimensions f and g in FIG. 4, is to eliminate the blockage of molten metal in the hole.

By relieving the sharp edge of the nozzle in the casting direction, turbulence of molten metal during the strip casting can be minimized or avoided. Like the curved edge surface 50 shown in FIG. 5, the edge relief can be made by fabricating a curved element 24 of erosion material, such as a Kaoul HS board, which provides natural erosion as a result of the strip casting operation. Turbulence can also be avoided by completely rounding the corners 50 of the protrusion 42 on the first side 32 of the curved element 24, as shown in FIG. 5 during or after fabrication.

In operation of the device of the present invention, the molten metal is transferred to the heated crucible 22. A heater, such as an induction coil of a resistance wire, is installed in the crucible 22 to maintain the desired constant molten metal temperature. Molten metal may also be poured into a direct preheated crucible. The preheating temperature prevents freezing or clogging of the hole passage 30 during the initial casting operation, and then raises the temperature of the flowing metal sufficiently to form the crucible 22 and the nozzle passage 30 in the curved element 24 forming the nozzle. Do not block through the flow. In some cases, the curved elements 24 are externally heated during the casting operation. The metal injected into the crucible 22 may be overheated to a limit temperature without adversely affecting the flow of metal through the orifice passage 30.

The metallized head height in the tundish 22 should be kept below 10 inches on the hole passage 30 so that a relatively constant head pressure is maintained in the hole passage 30 through the casting operation. This can be accomplished by initially pouring the molten metal 20 into the crucible 22 to the desired height and then adjusting the addition rate of the molten metal 20 to maintain the desired metallurgical head. The rate of addition of molten metal to the crucible 22 coincides with the rate at which metal flows out of the hole passage 30 into the casting surface 14 to form the strip material 10. Maintaining the metal at a constant height in the crucible 22 maintains the molten metal flow pressure through the hole passage 30 so that the casting operation or the strip material 10 does not adversely affect the quality. An externally applied pressure may be used to adjust this pressure in the hole passage 30.

304 type stainless steel is cast using a tundish or crucible 22 similar to that shown in FIG. 1 made of a Tendish Blister, sold under the trade name Garnex. The hole passage 30 at the base of the crucible has a width of 0.081 in. And a width of 1.3 in. And the distance or spacing between the outer leaf protrusion 38 and the casting face 14 is 0.02-0. . It is 04 inches. When the water-cooled copper alloy drum maintains the rotational speed at 930 ft / min, molten metal is poured into the crucible 22 at a temperature of about 2900 ° F. as measured by pyrometer. The entire casting operation maintains a head height of 6 inches and the fabricated strip is 0,006-0. It was 008 inches thick and exhibited good toughness and ductility in casting.

During casting of the strip material, the tendency of the strip 10 to adhere to the casting surface 14 for a sufficient distance of several feet or more from the initial casting point 16 was observed, which caused the strip material 10 to rotate in the casting drum or wheel 12. If impregnated during full rotation of the bed, it indicates damage to the crucible 22, especially the hole passage 30 in the curved element 24. The sticking is easily removed using a doctor blade, such as a knife, about 2.5 to 6 feet from the hole, particularly near the drum surface 14. In this arrangement, the cast strip is removed from the drum 12 by the doctor blade. Such doctorblades are particularly useful for the manufacture of thin amorphous strip materials that tend to adhere to the casting surface 14 rather than crystalline strip materials. The force that leaves the lower strip on the casting surface reflects the quality of thermal contact between the strip 10 and the casting surface 14. An air knife or the like may also be used to separate strip 10 from wheel 12.

Using the apparatus and process described above, a good quality strip material can be cast, including at least 25% amorphous material, for the purposes of the present invention. Compared with crystalline strip materials of similar dimensions, the quench rate for the non-crystalline material is greater and the quench rate can be accelerated by increasing the speed of the casting surface 14. This process can be carried out in two effective ways. As measured between the outer leaf protruding surface 38 and the casting surface 14, the hole passage 30 in close contact with the casting surface 14 was used. A 003 inch thick strip can be cast with either amorphous or crystalline material. When the outer leaf protruding surface 38 of the first side portion 32 of the curved element 24 is placed further away from the casting surface 14, and the casting surface speed is decelerated. A 050 inch thick strip can be cast. In the latter method, the quenching speed is lowered because the thickness of the product increases.

Claims (1)

A device for continuous casting of metal strips comprises a tundish 22 for receiving and retaining molten metal and a casting surface 14 movable relative to the nozzle and the discharge end of the nozzle capable of supplying molten metal to the casting surface 14. Wherein the nozzle is formed of a U-shaped insulator 24 having a recess disposed inwardly of the tundish 22 and having a length substantially equal to the width of the strip 10 to be cast on the insulator 24. The elongate orifice passage 30 is arranged in the longitudinal direction of the U-shaped prosecution 24 and the elongate orifice passage 30 is traditionally configured to have a uniform cross section at the end, and the cast piece 14 is at least cast. It is larger than the width of the strip and is disposed at a distance (h) of not more than 0. 12 inches from the nozzle end, and is also movable to the orifice discharge end in a direction perpendicular to the longitudinal axis of the orifice passage 30, casting surface 14 Orifice belonging to the rear with respect to the direction of movement of The side portion 32 of the passageway 30 has a protruding surface 38 opposite and completely parallel to the casting surface at the inner side 36 and the protrusion 42 of the orifice passage 30 and the width of the protruding surface 38. (c) is a continuous casting apparatus for an amorphous metal strip, characterized in that it is configured to at least 0.01 inches.