Background Art Generally, structural interior or exterior panels have been made of various materials with desired durability and heat insulation. In addition, high fire resistance has been increasingly emphasized due to frequent fire accidents, as a necessary condition which the structural panels must satisfy.

Therefore, there have been developed a variety of structural panels having desired fire-resistance as well as desired durability and desired heat insulation.

Furthermore, the structural interior or exterior panels are required to have a good appearance, in addition to the above characteristics.

However, a conventional structural panel is problematic in that the surface of the panel is not smooth, because laborers manually spray a mixture onto the top surface of a base panel with a mortar dispensing gun in producing the structural panel. This structural panel has another problem in that the process of drying the panel in an additional drying chamber and the process of cutting the panel to a predetermined size are not carried out automatically, so it wastes labor, reduces work efficiency, takes additional time and increases costs.

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an apparatus for manufacturing structural panels, which automatically accomplishes the process of producing the structural panels having an appearance and touch similar to that of natural stone panels, thus manufacturing the structural panels in large quantities for a short period of time as well as reducing labor costs, and improving productivity, in addition to supplying consumers with inexpensive, high quality structural panels.

Another object of the present invention is to provide an apparatus for manufacturing structural panels, which is capable of producing structural panels having a smooth surface.

In order to accomplish the above object, the present invention provides an apparatus for manufacturing structural panels, which comprises a base panel, a base panel feed conveyor conveying the base panel in a horizontal direction, a mixture feed hopper provided on a lower portion thereof with an output control valve and feeding a silica sand mixture at a constant rate, a coating unit positioned under the mixture feed hopper and forming a predetermined thickness of silica sand mixture layer on the base panel, and a spraying unit for spraying a coating liquid onto the top surface of the silica sand mixture layer formed on the base panel.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a side sectional view of an apparatus for manufacturing structural panels according to the present invention; Fig. 2 is a front view of the structural panel manufacturing apparatus according to the present invention; Fig. 3 is a perspective view showing a coating unit, included in the

structural panel manufacturing apparatus, according to the first embodiment of this invention; and Fig. 4 is a perspective view showing a coating unit, included in the structural panel manufacturing apparatus, according to the second embodiment of this invention Best Mode for Carrying Out the Invention Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

As shown in the drawings, the apparatus for manufacturing structural panels according to the present invention includes a base panel 14, a base panel feed conveyor 12, a mixture feed hopper 20, a coating unit 30, and a spraying unit 40. The base panel feed conveyor 12 conveys the base panel 14 in a horizontal direction. The mixture feed hopper 20 is positioned above the base panel feed conveyor 12 and temporarily contains a silica sand mixture 10 therein. The coating unit 30 is positioned between the mixture feed hopper 20 and the base panel feed conveyor 12 and coats a predetermined thickness of silica sand mixture 10 onto the base panel 14. The spraying unit 40 sprays a coating liquid onto the top surface of the silica sand mixture 10 layered on the base panel 14.

Also, it is preferred to additionally install a vibrating unit 50, a drying unit 60 and a cutting unit 70 in sequence in the apparatus.

The mixture feed hopper 20 is designed to receive the silica sand mixture 10 from a screw conveyor 23 positioned above the mixture feed hopper 20. The mixture feed hopper 20 is also provided on its lower portion with an output control valve 22 for feeding the silica sand mixture 10 at a constant rate. Since the silica sand mixture 10 contained in the mixture feed hopper 20 is water-soluble, this mixture 10 is liable to be dried and solidified in the atmosphere. It is thus necessary to prevent this mixture 10 from being solidified by supplying a proper quantity of moisture to the mixture 10. Thus, in order to isolate both the hopper

20 and the coating unit 30 from the atmosphere, a humidification tower 11 encloses them.

The coating unit 30 consists of a rectangular frame 31 communicating with the mixture feed hopper 20. The lower edge of the rear wall of the frame 31 is terminated at a position higher that that of the front wall by the thickness of the silica sand mixture layer coated onto the base panel 14.

The frame 31 is also installed such that its bottom is spaced apart from the base panel feed conveyor 12 by the thickness of the base panel 14.

The coating unit 30 communicates with the outlet 21 of the mixture feed hopper 20 at the top of its front portion. A plurality of blades 34a, 34b, 34c and 34d are transversely set within the rear portion of the rectangular frame 31 of the coating unit 30 so as to uniformly level the silica sand mixture 10 layered on the base panel 14. The number of the blades 34a, 34b, 34c and 34d is one or more.

The first blade 34a has a V-shaped profile where its center portion is bent forward, so the silica sand mixture 10 concentrated on the center portion is uniformly distributed throughout the base panel 14. In addition, this blade 34a is inclined backward at a predetermined angle for easily distributing the silica sand mixture 10.

The blades 34a, 34b, 34c and 34d sequentially decrease in the height of their lower edges from the base panel feed conveyor 12 in a moving direction of the feed conveyor 12.

The rear wall of the frame 31 serves as a final blade for determining the thickness of the silica sand mixture 10 coated on the top surface of the base panel 14. Since it is necessary to change the thickness of the silica sand mixture 10 layer on the base panel 14 according to the purpose of the structural panels and the demand of consumers, the frame 31 is installed in such a way to be adjustable in height.

The last blade 34d of the blades 34a, 34b, 34c and 34d is inclined downwards at its lower portion, and rotatably hinged to the frame 31 by a hinge pin 35 at the opposite ends of its upper portion. The lower portion of the blade 34d receives a longitudinal adjusting bolt 36 passing through the opposite side

walls of the frame 31 for allowing a user to adjust the height of the blade 34d as desired. An arc-shaped guide slit 37 is formed on each side wall of the frame 31.

The adjusting bolt 36 is freely movable up and down along the guide slits 37 for positioning the blade 34d at a desired height. A nut 38 is tightened to the end of the adjusting bolt 36 after the position of the bolt 36 is adjusted, thus maintaining the adjusted height of the blade 34d.

Since the base panel feed conveyor 12 should be maintained horizontally even when pressurized downward by the base panel 14 passing through the coating unit 30, a plurality of rod-shaped feed rollers 13 are horizontally installed at short intervals. Preferably, a ball-roller may be used in place of the rod-shaped feed rollers 13.

It is preferred to use a servo-motor as a drive motor, because the motor operating the feed conveyor 12 has to change its speed according to the kinds of the base panels and to keep the rpm (revolution per minute) constant.

The base panel feeding speed of the feed conveyor 12 becomes slower due to resistance when the silica sand mixture 10 is coated on the base panel 14 fed in an axial direction. Thus, in order to prevent the base panel feeding speed from being irregularly changed, a feed roller 13 is also installed at each side end of the feed conveyor 12.

The spraying unit 40, having a nozzle, is positioned following the coating unit 30, and sprays the coating liquid onto the top surface of the silica sand mixture layer formed on the base panel 14.

The vibrating unit 50 is positioned following the spraying unit 40 for vibrating the base panel 14, so it uniformly levels the silica sand mixture 10 on the base panel 14, removes foam from the silica sand mixture 10 and reduces pores formed therein. The drying unit 60 is positioned following the vibrating unit 50, and uses a hot air for drying the base panel 14. Following the drying unit 60, the cutting unit 70 is positioned for cutting the dried panel in a desired size.

The operating process of the apparatus for manufacturing structural panels of this invention is as follows.

First, the base panel 14 is put on the base panel feed conveyor 12 and then

is fed to the coating unit 30. At this time, the coating unit 30 is spaced apart from the feed conveyor 12 by the thickness of the base panel 14, so the base panel 14 easily passes through the coating unit 30 at a constant rate.

When the base panel 14 passes through the coating unit 30, the silica sand mixture 10 stored in the feed hopper 20 communicating with the coating unit 30 is supplied to the base panel 14 in a constant amount regulated by means of the output control valve 22.

The base panel 14 supplied with the silica sand mixture 10 is continuously fed, while the silica sand mixture 10 is thinly coated onto the base panel 14 by being evenly leveled by a plurality of blades 34a, 34b, 34c and 34d transversely set within the rear portion of the rectangular frame 31. Further, the blades 34a, 34b, 34c and 34d sequentially decrease in height of their lower edges from the base panel feed conveyor 12 in a moving direction of the feed conveyor 12, so the silica sand mixture layer gradually decreases in thickness by the sequentially arranged blades 34a, 34b, 34c and 34d. The resistance of the silica sand mixture 10 against the blades 34a, 34b, 34c and 34d during the leveling process is thus reduced.

In particular, the first blade 34a has a V-shaped profile where its center portion is bent forward, so the silica sand mixture 10 concentrated on the center portion in front of the blade 34a is divided into two parts toward both side portions of the frame 31, thus being more uniformly distributed.

When it is required to adjust the thickness of the silica sand mixture 10 coated on the base panel 14, the nut 38 is loosened from the longitudinal adjusting bolt 36 set in the last blade 34d, and the bolt 36 is moved upward or downward along the guide slit 37 and then tightened by the nut 38 at a proper position determined by the movement of the bolt 36.

In this way, the last blade 34d levels the silica sand mixture 10 coated on the base panel 14 at a desired thickness.

After that, the spraying unit 40 sprays a coating liquid through its nozzle to the top surface of the silica sand mixture 10 layered on the base panel 14.

Next, the vibrating unit 50 vibrates the base panel 14, so the silica sand mixture 10 coated on the base panel 14 is evenly leveled, and the foam formed in

the silica sand mixture 10 is removed, thus allowing the silica sand mixture 10 to become dense.

Thereafter, the base panel 14 treated by the vibrating unit 50 is fed to the drying unit 60, and quickly dried by the hot air of the drying unit 60.

Finally, the base panel 14 is fed to the cutting unit 70 such that the part of the base panel 14 which is not coated with the silica sand mixture 10 is cut off and then cut to a desired size. In this way, the process of manufacturing a desired structural panel is completed.

In the second embodiment of this invention, the construction of the coating unit 30 is altered as follows.

As shown in Fig. 4, the coating unit 30 of the second embodiment additionally includes an inlet opening 32, an outlet opening 33, and a panel guide 39, different from that of the first embodiment. The inlet opening 32 is transversally formed by the lower edge of the front wall of the rectangular frame 31, which is spaced apart from the feed conveyor 12 by the thickness of the base panel 14, with the base panel 14 entering the frame 31 through the inlet opening 32. The outlet opening 33 is formed by the lower edge of the rear wall of the frame 31 such that the base panel 14 coated with the silica sand mixture 10 leaves the frame 31 through the outlet opening 33. The panel guide 39 is installed at each end of the front wall of the frame 31 such that the base panel 14 correctly enters the frame 31 through the inlet opening 32, with the panel guide 39 being at an obtuse with the front wall of the frame 31.

In this case, the panel guide 39 correctly guides the base panel 14 to the inlet opening 32. After that, this panel 14 is coated with the silica sand mixture 10, and then leaves the frame 31 through the outlet opening 33. According to the second embodiment, the lower portions of the opposite side walls of the frame 31 guide the opposite side edges of the base panel 14, so the base panel 14 is desirably fed in the correct direction.

Industrial Applicability

As described above, the present invention provides an apparatus for manufacturing structural panels, which automatically accomplishes a coating process, a spraying process, a drying process, and a cutting process, thus manufacturing the structural panels in large quantities for a short period of time as well as reducing labor cost, and improving productivity, in addition to reducing its manufacturing cost.

The present invention provides an apparatus for manufacturing structural panels, which is capable of evenly leveling a silica sand mixture layer coated on a base panel by using a plurality of blades, and smoothes the surface of the structural panel by means of a vibrating unit.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.