Patent Description:
Physical vapor deposition (PVD) refers to a process technology of heating the metal to be coated under vacuum to deposit the metal in a gaseous manner on a base material to form a coating. PVD can be classified into electric heating PVD (resistance type or induction type), electron beam heating PVD (EBPVD) and other ways by heating methods. As a surface modification and coating process, vacuum coating has been widely used in electronics, glass, plastics, and other industries. The main advantages of the vacuum coating technology include environmental protection, good coating performance, and diversity of coating materials. The key to apply the vacuum coating technology to continuous strip steel includes several aspects such as continuous, large area, high speed, and large scale of coating production. Since the <NUM>, the world's major iron and steel companies have conducted lots of research on this technology. With the maturity of hot-dip galvanizing and electro-galvanizing technologies, this technology has attracted unprecedented attention and is considered as an innovative surface coating process.

The key issue in the vacuum coating process is how to obtain a uniform coating with a consistent thickness through the arrangement of nozzles. At present, foreign published information mainly includes the following aspects.

Applications <CIT> and <CIT> respectively disclose the crucible nozzle structures as shown in <FIG>. In the structure of <FIG>, an upper cover <NUM> is arranged on an upper part of a crucible <NUM>, so that a nozzle structure is formed between the upper cover <NUM> and a furnace wall for the direct spray of evaporated metal. In the structure of <FIG>, a filter plate <NUM> is additionally arranged in an evaporation crucible, and then metal steam is sprayed from a slit nozzle at the top. In the nozzle design processes of the two devices, one adopts a de Laval nozzle, and the other adopts a convergent nozzle. Regarding the orientation of the nozzles, one adopts the lateral spray, and the other adopts the vertical spray.

Applications JPS59177370A and <CIT> also disclose related evaporation crucible and nozzle structure. <FIG> illustrates a crucible nozzle structure with automatic replenishment of molten metal. A nozzle <NUM> uses a wide outlet, and a heater <NUM> is also arranged at an upper part of the crucible for heating the crucible. In the crucible nozzle structure shown in <FIG>, the structure is spread by an arc <NUM> on one side, realizing lateral spraying; and a heating tube <NUM> is also arranged on the periphery of a crucible wall for heating the periphery surface.

Application<CIT> discloses a split crucible nozzle structure. As shown in <FIG>, in the device, the bottom of the crucible is connected to a molten metal supply tank <NUM>, and the upper part of the supply tank <NUM> conveys metal steam to a tubular distributor and a steam nozzle at the front end through a split pipe <NUM>; and then, the nozzle sprays the metal steam to a metal plate at a high speed.

Application <CIT> discloses a split structure of a flow distributor and a nozzle. As shown in <FIG>, steam is delivered into an upper horizontal pipe <NUM> through a vertical pipe. The horizontal pipe <NUM> is provided with a multi-hole nozzle at the top to uniformly spray metal steam onto a surface of a metal plate.

Application <CIT> discloses a metal steam flow distributor and a nozzle form. For a sectional form of a nozzle as shown in <FIG>, a wire is wound outside a flow distributor pipe <NUM> to heat the pipe; and the nozzle has a square shell. As shown in <FIG>, a ringlike pipe made from another material is nested inside a square shell <NUM> and is used for spraying the metal steam. The steam outlet of the nozzle is multi-hole.

<CIT> relates to an evaporation deposition apparatus and an operating method thereof. The evaporation deposition apparatus comprises: a first cavity for receiving an evaporation material; a second cavity for receiving steam through the first cavity and a connection channel; an evaporator formed in the second cavity, including an outlet for radially discharging the steam having a point source, and formed of a conductive material; a reflective nozzle formed of a conductive material, connected to the outlet, and including a through-hole having a gradually-increased diameter; an inductive coil for covering the reflective nozzle and the evaporator; and an alternating current power source for applying alternating current electric power to the inductive coil. The inductive coil inductively heats the evaporator and the reflective nozzle to evaporate the evaporation material, and the steam is discharged through the reflective nozzle.

The above-mentioned applications all relate to the specific forms of nozzles. However, not all of these nozzles can achieve sufficient uniform coatings with consistent thickness. Moreover, those researches do not focus on the yield of the coating.

In order to solve the above-mentioned defects in the prior art, the present invention aims to provide a vacuum coating device, which can form uniform coatings with consistent thickness and improve the yield of the coating. The yield of coating refers to the ratio of the width of the effective coating to the width of the strip steel, the effective coating can be understood as a coating with a thickness of <NUM>~<NUM>. The thickness deviation (dmax-dmin) is less than or equal to <NUM>%.

In order to achieve the foregoing objective, the present invention provides the following technical solutions.

A vacuum coating device for coating a steel plate, comprising: a crucible (<NUM>), an induction heater (<NUM>) provided on the periphery of the crucible (<NUM>), a flow distribution box (<NUM>) connected to the top of said crucible (<NUM>) via a steam pipe (<NUM>), wherein said steam pipe (<NUM>) is provided with a pressure regulating valve (<NUM>), said flow distribution box (<NUM>) is provided inside with a horizontal pressure stabilizing plate (<NUM>), said flow distribution box (<NUM>) is connected on the top with a nozzle (<NUM>), a deflector (<NUM>) being arranged above said nozzle (<NUM>) along the emitting direction of the steam and wherein
a distance Da from nozzle outlet to steel plate (<NUM>) is <NUM>~<NUM>, a height Db of said deflector (<NUM>) is <NUM>~<NUM>; a distance Dc from top of said deflector (<NUM>) to steel plate (<NUM>) is <NUM>~<NUM>; an angle Dd between said deflector (<NUM>) and said nozzle outlet is <NUM>°~<NUM>°; wherein Da, Db, Dc, and Dd satisfy the following relationships: Da=Db+Dc;.

In the prior art, steam is emitted from the nozzle and spreads out, thus the amount of steam at the edge of the steel plate is relatively low, leading to a non-uniform coating formed by metal vapor on the middle area and edge area of the steel plate. Then additional processes are required to cut off the unevenly coated part of the steel plate. The cutting ratio usually reaches <NUM>~<NUM>%, which not only leads to poor yield of coating, but also increases the production cost. The technical solution adopted in the present invention restricts the path of steam from the nozzle to the steel plate by the arrangement of the deflector, which prevents the metal steam from spreading out and concentrates the steam in the area where the steel plate passes, thus a uniform coating can be obtained.

The distance Da from said nozzle outlet to said steel plate is <NUM>~<NUM>. Based on actual installation distance from the nozzle outlet to the steel plate, Da is usually greater than or equal to <NUM>. When Da≥<NUM>, the injection angle of the steam increases, the injection range is large, and the coating thickness decreases, resulting in that the coating cannot have an effect of anti-erosion. Moreover, when Da≥<NUM>, the speed of steam ejecting to the steel plate decreases, leading to the poor adhesion and low density of the coating.

The height Db of said deflector is <NUM>~<NUM>. That height is determined by the distance between the nozzle outlet and the steel plate. When the nozzle outlet is very close to the steel plate, the height of the deflector reaches lower limit, which is <NUM>; when the nozzle outlet is far from the steel plate, the height of the deflector reaches upper limit, which is <NUM>. In the technical solution of the present invention, Da is usually greater than or equal to Db. That is, when the width of steel plate is less than the effective width of nozzle outlet, the deflector is flush with the edge of the steel plate in height.

The distance Dc from the top of said deflector to steel plate is <NUM>~<NUM>. For example, when Db=<NUM>, Dc=<NUM>; when Db=<NUM>, Dc can be10mm.

When the pressure inside the nozzle is <NUM>~<NUM>,000Pa, and the pressure of the external ambient where the nozzle is located is <NUM>-<NUM>~<NUM> Pa, the angle Dd between said deflector and said nozzle outlet is <NUM>°~ <NUM>°. When the width of steel plate is less than the width of nozzle outlet or the effective width of the steel plate needs to be coated is less than the width of nozzle outlet, Dd can be less than <NUM>° according to production needs. For example, Dd can be <NUM>°, and then a uniform coating can be obtained. When the width of steel plate is greater than the width of nozzle outlet, a large Dd can be adopted according to production needs. For example, a Dd of <NUM>° can be adopted to improve the uniformity of the coating thickness at the edge of the steel plate. However, when Dd is greater than <NUM>°, the speed and range of the jet at the edge of the steel plate cannot be satisfied.

Said pressure stabilizing plate is a pressure stabilizing plate made of multi-hole media. That type of pressure stabilizing plate filters gas through irregular holes that resemble honeycombs. And according to the production needs, different porosity can be used to change the steam distribution, so as to have uniform steam.

Or, said pressure stabilizing plate is of a multi-hole structure. The holes in said pressure stabilizing plate are rectangular, circle or triangular in shape. Or, the shape of holes can be arbitrary polygonal or circle. And those holes run in linear, curvilinear or have a multilayer structure in the direction of steam rise. Since the pressure stabilizing plate has a certain thickness, the distribution direction of holes refers to the path of steam through the thickness direction of the pressure stabilizing plate. That is, when steam passes through the pressure stabilizing plate, not only the distribution of steam can be changed by the distribution of holes in the pressure stabilizing plate, but also the path of its rise can be changed by the direction of holes. The multilayer structure refers to a structure in which the distribution direction of holes directs the steam to rise in steps. For example, the multilayer structure can be steps formed by multiple sets of folds, which can increase the resistance of steam rise, but allow for more evenly distributed steam.

Said nozzle outlet is of a slit shape or a multi-hole. Preferably, the nozzle outlet is of a slit shape.

The nozzle outlet is of a linear slit or a curvilinear slit. The slit shape refers to that the nozzle outlet is a whole slit rather than made up of multiple tiny slits set at intervals. That is because if the steam is emitted from each tiny slit, it will spread out to a certain extent, and the overlap area makes the coating thickness larger and does not form a uniform coating.

The multi-hole nozzle outlet is rectangular, round or trapezoidal in shape.

Said nozzle is made of graphite, ceramic or metal.

Da, Db, Dc, and Dd satisfy the following relationships: <MAT>.

If the above relationships are satisfied, the yield can reach more than <NUM>%; and if the above relationships are not satisfied, the yield cannot reach <NUM>%.

The vacuum coating device further comprises a vacuum chamber, wherein both said flow distribution box and said steel plate are placed in said vacuum chamber. By adopting this technical solution, on the one hand, it can prevent the oxidation of the nozzle material and steel plate coating. On the other hand, it can cause an internal and external pressure difference in the nozzle, so that the steam emitted from the nozzle outlet can reach supersonic speed.

The present invention discloses a vacuum coating device for improving the yield of vacuum coating, where the metal steam is obtained by melting and evaporating the metal material in the crucible. The steam enters the flow distribution box through the pipe, the flow distribution box is arranged with a pressure stabilizing plate and other relative devices, and then the uniform steams can flow from the nozzle. Since a deflector is arranged at the top of said nozzle, even steam distribution can be given between the deflector and the steel strip to be coated. The deflection of the steam field at the edge of the steel strip can be adjusted by changing the distance between the deflector and the steel strip, thus improving the yield of the coating on the steel strip. The present invention is low cost, simple to operate, and can be exported in sets with vacuum coating technology in the future.

The technical solutions of the present invention are further described below with reference to the accompanying drawings and embodiments.

Referring to <FIG>, the present invention provides a vacuum coating device. Said vacuum coating device is located underneath the steel plate <NUM> when in use. The vacuum coating device comprises a crucible <NUM>, and the crucible <NUM> contains the molten metal <NUM>. An induction heater <NUM> is arranged on the periphery of the crucible <NUM>, the molten metal <NUM> and metal steam <NUM> can be obtained after the metal materials in crucible <NUM> are heated by the induction heater <NUM>. The power of the induction heater <NUM> is adjustable, thus the pressure of the metal steam <NUM> in crucible <NUM> can be controlled. A flow distribution box <NUM> is connected to the top of said crucible <NUM> via a steam pipe <NUM>, wherein said flow distribution box <NUM> and said steel plate <NUM> are placed in the vacuum chamber <NUM>. A pressure regulating valve <NUM> is arranged in said steam pipe <NUM>, the exchange between the steam in crucible <NUM> and the steam in the flow distribution box <NUM> and the vacuum chamber <NUM> can be blocked by the pressure regulating valve <NUM>. A horizontal pressure stabilizing plate <NUM> is arranged in said flow distribution box <NUM>, and a nozzle <NUM> is connected to the top of said flow distribution box <NUM>. In addition, a deflector <NUM> is arranged at the top of said nozzle <NUM> along the direction of steam emission to increase the yield. When said pressure regulating valve <NUM> on said steam pipe <NUM> is open, said metal steam <NUM> reaches said steel plate <NUM> through said pressure stabilizing plate <NUM> and said nozzle <NUM>, and then a coating is formed.

Preferably, said deflector <NUM> serves to make the steam through said nozzle outlet as vertical as possible towards said steel plate <NUM>, avoiding flow deflection and thus increasing the yield of coating on the steel plate <NUM>.

Wherein, the distance Da from the outlet of said nozzle <NUM> to said steel plate <NUM> is <NUM>~<NUM>; the height Db of said deflector <NUM> is <NUM>~<NUM>; the distance Dc from the top of said deflector <NUM> to said steel plate <NUM> is <NUM>~<NUM>; the angle Dd between said deflector <NUM> and the outlet of said nozzle <NUM> is <NUM>°~<NUM>°.

Further, Da, Db, Dc, and Dd satisfy the following relationships: <MAT>.

Preferably, said nozzle <NUM> operates with an internal pressure of <NUM>~<NUM>,<NUM> Pa.

Preferably, the nozzle <NUM> is made of graphite, ceramic or inert metals, as well as other materials that are resistant to high temperature, wear and can be processed.

Preferably, said nozzle outlet is of a slit shape or multi-hole. Wherein, the slit shape nozzle outlet is linear of curvilinear, and the multi-hole outlet is rectangular, round or trapezoidal in shape.

Preferably, said pressure stabilizing plate <NUM> has a multi-hole structure, the holes in said pressure stabilizing plate are rectangular, circle or triangular in shape. Or, the hole shape can be arbitrary polygonal or circle, the present application does not specifically limit the shape of the holes. And those holes run in linear or curvilinear direction or have a multilayer structure.

Preferably, said molten metal <NUM> contains metals such as zinc, magnesium, aluminum, tin, nickel, copper, iron, etc., in addition to low melting point (below <NUM>) oxides of these metals.

Preferably, the steel plate <NUM> is cleaned by plasma or other devices before vacuum coating, and the preheating temperature reaches <NUM>~<NUM>.

The specific steps for using the vacuum coating device of the present invention are as follows.

The steel plate <NUM> is galvanized, and the width of the steel plate <NUM> is <NUM>,<NUM>. After cleaning and drying, the steel plate <NUM> is heated to <NUM>. Zinc on steel plate surface is vaporized by the induction heater <NUM>, and then adjust the power of the induction heater to raise the pressure in the crucible <NUM> to <NUM>,<NUM> Pa, at which point the pressure regulating valve <NUM> is closed. When the pressure in the crucible <NUM> reaches <NUM>,<NUM> Pa, the pressure regulating valve <NUM> is opened, and then the metal steam <NUM> enters into the flow distribution box <NUM> through the steam pipe <NUM>. The pressure stabilizing plate in the flow distribution box <NUM> has a multi-hole structure or adopts a pressure stabilizing plate made of multi-hole media. The working pressure in the flow distribution box <NUM> is <NUM>,<NUM> Pa. The nozzle <NUM> is made of graphite, and the nozzle outlet is of a linear slit.

The deflector <NUM> is rectangular, and the relevant parameters are as follows:.

Claim 1:
A vacuum coating device for coating a steel plate (<NUM>), comprising:
a crucible (<NUM>),
an induction heater (<NUM>) provided on the periphery of the crucible (<NUM>),
a flow distribution box (<NUM>) connected to the top of said crucible (<NUM>) via a steam pipe (<NUM>), wherein
said steam pipe (<NUM>) is provided with a pressure regulating valve (<NUM>), said flow distribution box (<NUM>) is provided inside with a horizontal pressure stabilizing plate (<NUM>), said flow distribution box (<NUM>) is connected on the top with a nozzle (<NUM>),
a deflector (<NUM>) being arranged above said nozzle (<NUM>) along the emitting direction of the steam, and wherein
a distance Da from nozzle outlet to steel plate (<NUM>) is <NUM>-<NUM>,
a height Db of said deflector (<NUM>) is <NUM>-<NUM>;
a distance Dc from top of said deflector (<NUM>) to steel plate (<NUM>) is <NUM>~<NUM>;
an angle Dd between said deflector (<NUM>) and said nozzle outlet is <NUM>°~<NUM>°;
wherein Da, Db, Dc, and Dd satisfy the following relationships: <MAT>
when Da=<NUM>~<NUM> and Db=(<NUM>/<NUM>~<NUM>/<NUM>)Da, Dd=<NUM>°~<NUM>°;
when Da=<NUM>-<NUM> and Db=(<NUM>/<NUM>~<NUM>/<NUM>)Da, Dd=<NUM>°~<NUM>°;
when Da=<NUM>-<NUM> and Db=(<NUM>/<NUM>~<NUM>/<NUM>)Da, Dd=<NUM>°~<NUM>°;
when Da=<NUM>~<NUM> and Db=(<NUM>/<NUM>~<NUM>/<NUM>)Da, Dd=<NUM>°~<NUM>°;
when Da=<NUM>~<NUM> and Db=(<NUM>/<NUM>~<NUM>/<NUM>)Da, Dd=<NUM>°~<NUM>°;
when Da=<NUM>~<NUM> and Db=(<NUM>/<NUM>~<NUM>/<NUM>)Da, Dd=<NUM>°~<NUM>°.