Description

POSITIONING APPARATUS

Technical Field

[1] The present invention relates to a positioning apparatus; and, more particularly, to a positioning apparatus for fixedly positioning a cassette transferred along a conveyer and placed on a plate. Background Art

[2] Generally, a quantity of cathode ray tube panels used for manufacturing a color television set, a computer monitor or the like is ensured by mass-producing components used therefor on a manufacturing line at one time. The mass-produced cathode ray tube panels are loaded or transferred while being temporarily stocked in a cassette until a next process is performed. After the cassette transferred on the conveyer is fixed to an accurate position, a robot unloads the panels from the cassette to perform the next process.

[3] A trend toward an automated and unmanned assembly process has led to a demand for an apparatus for fixedly positioning a cassette so that a robot can directly unload products from the cassette at the accurate position. Hereinafter, the apparatus for fixedly positioning a cassette will be described with reference to Fig. 1.

[4] As shown in Fig. 1, cassettes 2 accommodating therein products, e.g., cathode ray tube panels, are transferred on a conveyer 1 one after another. Installed at an end portion of the conveyer 1 is a plate 3 fixed on a bottom surface of the conveyer 1 on the same plane. Another conveyer 1 is extended from one side of the plate 3 on the same plane. That is, the conveyer 1 is partitioned by the plate 3 therebetween.

[5] Therefore, the cassettes 2 transferred along the conveyer 1 are unloaded and/or restocked by a robot 5 on the plate 3. Then, the cassettes 2 that have been unloaded and/or restocked are transferred for a next process along the conveyer 1 shown at a right side of Fig. 1.

[6] The cassette positioning apparatus includes one or more positioning devices 10 being fixedly installed on the plate 3. It is preferable that one or more positioning devices 10 are installed at four corners of the plate 3.

[7] Fig. 2 illustrates a detailed cross sectional view of one of the positioning devices.

As depicted in Fig. 2, the positioning device 10 includes an upper plate 20; a lower plate 30; a cylinder 40 installed inside the lower plate 30; a circular plate shaped disk 50 disposed on the cylinder 40; and a circular table 70 connected to the circular disk 50, for mounting thereon the cassette 2.

[8] The upper plate 20 is formed in a circular shape having a central opening. A

plurality of slidable ball rollers 21 are installed on the upper plate 20. Further, a guide groove portion 22 of a specific depth is formed on a bottom surface of the upper plate 20 while extending outward, to thereby ensure a moving space of the circular disk 50.

[9] The lower plate 30 is also formed in a circular shape having a horizontal air hole 31 on one side surface thereof. Moreover, a flow path groove 32 for communicating with the air hole 31 is formed within the lower plate 30.

[10] The cylinder 40 is installed along with springs 41 in a hollow portion of the lower plate 30.

[11] The circular disk 50 having a circular plate shape is contacted with a top surface of the cylinder 40. An outer peripheral portion of the circular disk 50 is inserted into the guide groove portion 22 of the upper body 20, such that the circular disk 50 is constantly prevented from being separated upward therefrom.

[12] Meanwhile, a hollow cylindrical part 60 raised upward is formed on a central portion of the disk 50. A circular plate shaped table 70 has a shaft that is inserted into the hollow cylindrical part 60 so that the circular table 70 is installed at the cylindrical part 60. Further, a conical return spring 62 is installed on an outer peripheral surface of the cylindrical part 60. A lower outer peripheral surface of the return spring 62 is immovably fixed in an annular groove 23 formed on an inner peripheral surface of the upper plate 20.

[13] The following is a description of an operation of the positioning device configured as described above.

[14] When the cassette 2 transferred along the conveyer 1 reaches on the plate 3, the cassette 2 is placed on the positioning devices 10 provided on the plate 3.

[15] Then, a Y-shaped centering device 4 (see Fig. 1) pushes and pulls the cassette 2 placed on the positioning devices 10 in a diagonal direction, thereby positioning the cassette 2 on a center of the plate 3. As a result, the table 70 of the positioning device 10 is deviated along with the disk 50 away from the center while compressing the return spring 62 to one side. In this case, the disk 50 is moved within a restricted area along the guide groove 22.

[16] In the meantime, when external air is introduced through air hole 31 to maintain the centered position of the cassette 2, the air continuously flows through the flow path groove 32 and then pushes the cylinder 40 upwardly. Consequently, the cylinder 40 is elevated while compressing the springs 41, thereby adhering the disk 50 onto an inner top surface of the guide groove portion 33. As a result, the table 70 is fixed.

[17] In such a state, the robot 5 accurately unloads the products from the cassette 2.

[18] In order to transfer the cassette 2 that has been unloaded and/or restocked for the next process, the fixed position of the table 70 needs to be released. To do so, the air supply through the air hole 31 is stopped. Accordingly, the cylinder 40 returns to its

original position forced by a restoration force of the springs 41, and also, the table 70 released along with the disk 50 returns to the central position along with the disk 50 by the return spring 62.

[19] The aforementioned conventional positioning devices 10 have a configuration to fix a position of the cassette 2 by elevating the table 70 against a load of the cassette 2 mounted thereon. However, the load of the cassette 2 constantly keeps changing as the products stocked in the cassette 2 are unloaded and/or restocked. Particularly, in case where the cassette 2 becomes a lightweight gradually, the return spring 62 slightly gets restored upward accordingly while a pushing force of the cylinder 40 does not change, which causes the movement of the table 70 and thus moves the position of the cassette 2 slightly each time. Consequently, the product does not get accurately unloaded, which, in turn, increases a defective proportion and deteriorates productivity. Disclosure of Invention Technical Problem

[20] It is, therefore, a primary object of the present invention to provide a positioning apparatus capable of easily positioning a cassette and also maintaining a position of the cassette regardless of a load thereof.

[21] It is another object of the present invention to provide a lightweight and slim-sized positioning apparatus. Technical Solution

[22] In accordance with an aspect of the present invention, there is provided an apparatus for fixedly positioning a cassette having products thereon transferred along a conveyer and placed on a plate, which includes: centering means for adjusting the position of the cassette to place the cassette on a center of the plate; and a plurality of positioning devices installed on the plate for fixedly positioning the cassette.

[23] Further, each of the positioning devices includes a base plate; a cylindrical upper body; a cylindrical lower body mounted on the base plate and installed under the upper body, the lower body having an air hole; a cylinder having therein a hollow portion, installed inside the lower body, and configured to slide downward by a pressure of the air supplied through the air hole; a shaft installed to penetrate the hollow portion of the cylinder and that of the upper body; a table installed on the shaft to engage with the shaft, the table having the cassette mounted thereon and being deviated from its original position while positioning the cassette at the center of the plate; a return spring installed around the shaft, the return spring being deformed to one side depending on the deviation of the table; and a disk installed on a bottom portion of the shaft, the disk being pressed downward by the cylinder to adhere to the cylinder and the base plate, thereby fixing the movement of the table.

Advantageous Effects

[24] The positioning device of the present invention can easily position the cassette and maintain the position of the cassette regardless of a load thereof. Further, the positioning device can be highly competitive because of its light weight and slim size. Brief Description of the Drawings

[25] The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments, given in conjunction with the accompanying drawings, in which:

[26] Fig. 1 is a schematic view showing a transfer of cassettes transferred along a conveyer;

[27] Fig. 2 describes a cross sectional view of a conventional positioning apparatus;

[28] Fig. 3 provides a cross sectional view of a positioning apparatus in accordance with the present invention; and

[29] Figs. 4 and 5 illustrate operational states of the positioning apparatus in accordance with the present invention. Best Mode for Carrying Out the Invention

[30] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[31] Fig. 3 provides a cross sectional view of a positioning device in accordance with the present invention, and Figs. 4 and 5 illustrate operational states of the positioning device in accordance with the present invention. In this regard, like parts from the prior art will be assigned like reference numerals throughout the drawings.

[32] First of all, referring to Fig. 3 along with Fig. 1, an apparatus for fixedly positioning a cassette in accordance with the present invention includes a centering device 4 (see Fig. 1) and one or more positioning devices 100.

[33] The centering device 4 adjusts the position of the cassette transferred on a conveyer

1 and placed on a plate 3 by pushing and pulling the cassette 2, e.g., in a diagonal direction, thereby locating the cassette 2 at the center of the plate 3.

[34] The positioning devices 100 are installed on a top surface of the plate 3 provided at an end portion of the conveyer 1, the plate 3 being fixed on a bottom surface of the conveyer 1. Preferably, one or more positioning devices 100 are installed near four corners of the plate 3.

[35] Each of the positioning devices 100 includes a cylindrical upper and a cylindrical lower body 110 and 120 provided on a base plate 126, a cylinder 130 installed inside the lower body 120, a disk 140 whose movement is fixed by the cylinder 130, and a table 160 having the cassette mounted thereon.

[36] The upper and the lower body 110 and 120 contacted with a bottom surface of the

upper body 110 are formed in a cylindrical shape having a hollow inner portion therein. A plurality of ball rollers 112 is spaced from each other at regular intervals and is contained on the upper body 110 along a circumferential direction.

[37] Ball portions of the ball rollers 112 face upward and are configured to slid, so that the table 160 can be effectively moved and supported while being slide on the ball rollers 112.

[38] An air hole 122 for communicating with the outside is formed on a circumferential surface of the lower body 120 and also extended in a horizontal direction to the hollow inner portion of the lower body 120, the air hole 122 having stepped portions whose diameters are gradually reduced toward the inner portion.

[39] An annular space 124 of a specific depth is formed on a bottom surface of the lower body 120. The disk 140 is installed at the annular space 124 to thereby ensure a moving space of the disk 140. The bottom surface of the lower body 120 is disposed on the plate 3 while being blocked by a base plate 126.

[40] The circular cylinder 130 having a hollow portion 131 is installed at inside the hollow portion of the lower body 120 such that it can slide downward by a pressure of air supplied through the air hole 122. In addition, a plurality of sealing members 134 is installed between the lower body 120 and the cylinder 130 to prevent air leakage.

[41] A stepped surface 132 is formed on an end of a top surface of the cylinder 130 to communicate with the air hole 122. Formed on an inner surface of the hollow portion 131 is an annular groove 133 to which one end of a return spring 152 to be described later is immovably fixed.

[42] A circular plate shaped washer 135 having a diameter greater than that of the cylinder 130 is fixedly installed on a top portion of the cylinder 130 by fastening bolts 180. Thus, the circular plate shaped washer 135 can slide downward along with the cylinder 130 on a bottom surface of the hollow portion of the upper body 110.

[43] Springs 136 are installed between the lower body 120 and an outer bottom surface of the washer 135 separated in a horizontal direction from the cylinder 130 to thereby assist the washer 135 that has slid downward, thereby returning to its original position.

[44] Meanwhile, the disk 140 installed in the space 124 of the lower body 120 preferably has a diameter smaller than that of the space 124 and a thickness smaller than a depth of the space 124. A plurality of through holes 142 is formed in the disk 140 by penetrating the disk 140.

[45] A shaft 150 facing upward is installed between the centers of the table 160 and the disk 140 while penetrating the hollow portion 131 of the cylinder 130 and that of the upper body 110. The table 160 is installed on a top portion of the shaft 150 to engage with the shaft 150.

[46] The table 160 is formed of a flat circular plate having a diameter greater than that of

the upper and the lower body 110 and 120, and mounts thereon the cassette 2 accommodating therein products. When the cassette 2 is placed on the table 160, the shaft 150 is deviated along radial direction from its original position together with the table 160 and the disk 140 while positioning the cassette 2 at the center of the plate 3.

[47] Installed on an upper outer surface of the shaft 150 is the return spring 152 whose one end is fixedly inserted into the annular groove 133. The return spring 152 is preferably formed of a conical coil spring and is deformed to one side depending on the deviation of the shaft 150.

[48] Hereinafter, an operation of the positioning apparatus of the present invention configured as described above will be described with reference to Figs. 1, 4 and 5.

[49] As shown in Fig. 1, the cassettes 2 accommodating therein products are transferred along the conveyer 1 one after another.

[50] When a cassette 2 is positioned on the positioning devices 100, a centering device 4 forcibly locates the cassette 2 placed on the positioning devices 100 to the central position of the plate 3.

[51] In this case, as illustrated in Fig. 4, the table 160 of the positioning device 100 moves along the ball rollers 112 while being deviated from the center pursuant to the movement of the cassette 2 on the table 160 (e.g., toward left in Fig. 4). Moreover, the shaft 150 and the disk 140 are also moved within the space 124 while compressing to one side of the return spring 152 whose lower end is fixed to the annular groove 133.

[52] Since the cassette 2 has been positioned on the center of the plate 3 as shown in Fig.

4, there is needed to maintain the table 160 of the positioning device 100 as is.

[53] Referring to Fig. 5, air is supplied by a control air valve (not shown) connected to the air hole 122 of the lower body 120. The supplied air is introduced to the stepped surface 132 of the cylinder 130 sealed by the sealing members 134 and then is used to push the cylinder 130 downward.

[54] That is, the springs 136 are compressed by the washer 135 fastened with the cylinder 130 to thereby push the cylinder 130 downward. Then, the disk 140 that was freely movable in the space 124 is pressed by the cylinder 130 to get adhered to a bottom surface of the cylinder 130 and in turn an upper surface of the base plate 126. Thus, the movement of the disk 140 is fixed and, accordingly, a movement of the table 160 connected to the shaft 150 is restricted.

[55] When the table 160 lowered downward while pressing the ball rollers 112 does not move, the cassette 2 on the table 160 is fixed at that position without moving. Then, even if the products stocked in the cassette 2 are unloaded, as long as the table 160 does not move, the cassette 2 can be constantly and fixedly maintained at the position by a self weight.

[56] The air valve constantly supplies air through the air hole 122 until the table 160

needs to be fixed. After the products in the cassette 2 are unloaded and/or restocked with another in the next process, the air supply is stopped and, simultaneously, the cylinder 130 quickly returns to its original position by the restoration force of the springs 136.

[57] Moreover, the through holes 142 of the disk 140 introduce the air from the atmosphere to reduce an adhesion between the cylinder 130 and the disk 140 adhered to the bottom surface of the cylinder 130, thereby enhancing a responsiveness in returning the cylinder 130 to its original position.

[58] As the cassette 2 is removed or transferred from the plate 3 to the conveyer 1 (e.g., at right side in the figure) for a next process, the table 160 released along with the disk 140 returns to the central position by the restoration of the return spring 152.

[59] The aforementioned processes are repeated whenever the cassette 2 transferred along the conveyer 1 is mounted on the plate 3.

[60] In accordance with the present invention, when the table 160 is fixed while being lowered downward, the position of the cassette 2 on the table 160 can be constantly and fixedly maintained by the self weight as long as an external force is not applied. Therefore, it is possible to solve the conventional problem in which the position of the cassette continuously changes depending on the load thereof. Further, since the return spring 152 is installed into the hollow portion 131 of the cylinder 130, an entire height of the positioning device 100 can be lowered, thereby achieving a slim sized positioning device.

[61] While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.