An apparatus of chamfering planar plate

Abstract: The invention concerns an apparatus of chamfering edges of planar plates, particularly of printed wiring boards. According to the invention the plates are stacked in a first step and then chamfered in such a manner that the lower edge of an upper plate and the upper edge of a lower plate are chamfered simultaneously.

Description: The present invention relates to an apparatus according to the preamble of claim 1. Description of the Prior Art An apparatus for chamfering printed circuit boards is already known (Patents Abstracts of Japan, Vol. 10, No. 37 (M-453) (2094) 14 February 1986 & J-A-60191710, Nihon Shii Emu Kei K. K., 30 September 1985). In this apparatus a number of printed circuit boards are loaded onto the loading surface of a surface plate so that each terminal part is set upwardly. The circuit boards are attached so as to be leaned against each other successively and arranged aslantly in rectilinear form and fixed. A twist drill is transferred in parallel to the loading surface, and the chamfering for one edge of the terminal part is completed. Still, an apparatus for chamfering the edges of stacked plates is known which chamfers the outer edges of adjacent stacked plates simultaneously (SU-A-1 271 678 representing the closest prior art). Disadvantage of the Prior Art The disadvantage of the prior art lies either in the fact that the plates cannot be stacked one above the other or that it is not easily possible to detect the boarders of adjacent stacked plates. Technical Problem The object of the present invention is to eliminate or at least mitigate the above mentioned disadvantages and to provide an improved apparatus of chamfering planar plate, so that the chamfering process is performed to a plurality of stacked plates and positioning errors and warp problems are not caused. Solution of the Technical Problem According to the present invention the above problem is solved by the combination of the features of claim 1. Advantageous Effects of the Invention As the plates are stacked, positioning of the plates is one for stacked plates and no reverse process is necessary. As the border between two stacked plates is detected precisely, the tool guide is accurately performed and the edges to be chamfered are accurately determined. As the tool forms V-shaped grooves, no reverse problem occurs. The apparatus performs accurate chamfering in a very short time period, even if the plates to be chamfered include thickness variety. Whereas conventional chamfering processes need about 3 - 5 seconds per sheet and the chamfer result is not sufficient, the present process performs sufficiently accurate chamfering in about 1/3 of the time. Brief Description of the Drawings Figure 1 is a schematic side view of the chamfering apparatus according to the present invention, a portion of which is broken away. Figures 2A, 2B and 2C are plan views showing an arrangement of stacked plates and working tools, and Figure 3 is similar to Fig. 2 whereby four tools are provided. Detailed Description of the Preferred Embodiment As to chamfering apparatus, the present invention is not merely an improvement of the prior art, since resembled prior art cannot be found. Now, a preferred embodiment of the present invention as a printed wiring boards chamfering apparatus will be described referring to the drawings. The printed wiring boards chamfering apparatus includes a stacking device, an aligning device, a border detecting device, a chamfering device, a turning device and a discharge device. The stacking device stacks a plurality, e. g. 10 to 250 sheets, of base plates which are cut by a cutting machine in a suitable container of easily disassembled. At the aligning device, the plates are pushed from both sides to be in parallel with each other, and they are pushed from above to maintain stacked state. Then they are supplied to the chamfering device. The border detecting device detects the border between adjacent plates by means of CCD camera or a proximate sensor detecting copper film which covers the printed wiring board at the chamfering station. The chamfering device utilizes a numerical control device to move the V-shaped tool to align the tool precisely to the detected border and corrects the copper film thickness of 17 - 35 µm so that the center of the tool precisely aligns with center of the border. Then the cutter moves along the border cutting the lower edge of the upper plate and the upper edge of the lower plate by one movement of the cutter. The cutting process is shown in Fig. 1. A copper film 2 on a stacked base plate 1 is detected by a detecting device, not shown, and center line 4 of a tool 5 is aligned with the border line 3 on the copper film 2. The included angle of the tool may be between 45 - 90° and the tool cut along the border desired depth such as shown in Fig. 1. Cutting is performed sequentially from below. Of course, when both surfaces of the base plate are clad with copper film, the above mentioned correction of copper thickness is not necessary. When chamfer cutting reaches to uppermost plate, the turning device turns the stack of plates at 90° to face the tool 5 next surface of the stack of plates 1. As shown in Fig. 2, when two sets of tools are used, one turning is sufficient to chamfer four edges of the plates, and when four sets of tools are utilized as shown in Fig. 3, no turning is necessary to complete chamfer work. In this case, 250 sheets can be chamfered in about 5 minutes. A tool hold and moving device 6 is shown in Fig. 2. After complete chamfering of eight edges of the plates, the base plates are conveyed to a discharge device where the plates are prepared for a next process not related to the present invention. In the drawings shown, a rotary cutter is used to perform 45° chamfer. Other desired tool e. g. end mill can be used to perform 90° chamfer. Angle and depth of the chamfer can be selected as desired. The present invention concerns the chamfering of stacked printed wiring boards as a preferred embodiment. Nonmetallic plates having metal film can be chamfered by utterly the same process. Other plates can be chamfered by utilizing necessary border detect devices having the desired accuracy. As described, by chamfering the plates in stacked condition, production efficiency is remarkably improved. Flatness of plates is maintained sufficiently, so that warp or incorrect chamfer is not produced. Instead of mechanical cutting means also beam cutting means may be used, such as laser beams or beams of ions or electrons, respectively.

Claims: An apparatus for chamfering the edges of stacked plates comprising chamfering means (5) positionable adjacent to opposed outer edges of respective ones of two adjacent stacked plates (1) and relatively movable along the opposed outer edges for simultaneously chamfering both opposed edges, characterized by contactless detecting means for detecting the boundary between two adjacent stacked plates in a stack of plates and for controlling said chamfering means (5). An apparatus according to claim 1, characterized in that the contactless detecting means comprises a CCD camera. An apparatus according to claim 1, characterized in that the contactless detecting means comprises a sensor for detecting the presence of a metal film on the major surface of one of the two adjacent stacked plates. An apparatus according to claim 1, characterized in that the chamfering means comprises a rotary working tool having a tapered cutting edge. An apparatus according to claim 1, characterized in that the chamfering means comprises a working tool, and a positioning device for positioning the working tool adjacent opposed edges of respective ones of the two adjacent stacked plates in response to detection of the boundary. An apparatus according to claim 1, characterized in that the center line (4) of a tool (5) is aligned with a border line (3) on a copper film (2). An apparatus according to claim 6, characterized in that the cutting portion of the tool (5) includes an angle between 45° and 90°. An apparatus according to claim 1, characterized in that the depth of the cut portion of the plate (1) is about 1/20 of the total width of the plate (1). An apparatus according to claim 1, characterized in that two sets of tools (5) are used together with turning means which turns the stacked plates about 90°. An apparatus according to claim 1, characterized in that the tool (5) comprises a rotary disk the end of which consists of cutting means having an angle between 45° and 90°, said disk being movable along a vertical axis, thus cutting two edges of the lowermost plates simultaneously up to the edges of the uppermost plates.

Inventors: KUBO ISAMU, SEKI KAMEHARU, KUBO, ISAMU, SEKI, KAMEHARU
Applicants: NIPPON CMK KK, NIPPON CMK CORP.
Application year: 1989
Main classification: B23C3
IPC codes: H05K3, B23C3, B23D79, H05K1, B24B9