JP5660327B2 - Drilling method for brittle materials - Google Patents

Description

  The present invention relates to an improvement in a technique for sequentially drilling a plurality of brittle materials using a drill in which abrasive grains are fixed with a binder.

  When drilling small-diameter holes in brittle materials such as glass and ceramic, abrasive grains such as diamond grains are fixed to the surface with a binder such as metal bond, resin bond, and electroplated layer for electrodeposition. Drills are widely used.

  Such drills, for example, perform exhaust and gas encapsulation in a panel on a glass substrate used in a flat panel display such as a plasma display (PDP), a field emission display (FED), and an electroluminescence display (ELD). It is used when forming a through hole (vent hole) for the purpose.

  When drilling a brittle material such as glass or ceramic using a drill in which the abrasive grains are fixed with a binder as described above, the occurrence of rough skin on the hole processed surface can be an important problem.

  Specifically, for example, if a necessary heat treatment step is performed after the hole processing is performed on the glass substrate such as the flat panel display, the glass substrate is damaged due to rough skin. In order to cope with such a problem, the following Patent Document 1 describes an electrodeposition grindstone every time the finish surface roughness of a work reaches a preset upper limit value when machining the work with an electrodeposition grindstone. A method of applying truing to the ground surface of the steel is disclosed.

JP 2001-246560 A

  However, like the technique disclosed in Patent Document 1 above, the finished surface roughness of the workpiece is frequently measured, and truing is performed each time the measured value reaches a predetermined upper limit value. If the heights are aligned, the work efficiency is extremely deteriorated, which causes a fatal problem of greatly reducing the production efficiency.

  An object of the present invention is to improve the production efficiency and the production cost of a plurality of brittle materials subjected to drilling, while efficiently suppressing the occurrence of rough surface of the drilled surface when drilling a plurality of brittle materials. Is to reduce the cost.

  The inventors of the present invention, as a result of diligent efforts regarding the technology for drilling a brittle material using a drill in which abrasive grains are fixed with a binder, are as follows. It came to know that it originates in the mechanism shown.

  That is, the abrasive grains fixed to the rotating drill cut the workpiece (brittle material) to generate workpiece debris. This cutting debris is a bond located behind the abrasive grains in the drill rotation direction. Remove the surface of the agent. And the generation | occurrence | production of the cutting waste of this workpiece | work and the scraping of the binder surface by a cutting waste are repeated, and the thickness of the binder radial direction of a binder becomes thin gradually. For this reason, the abrasive grains held by the binder and fixed to the drill gradually protrude relative to the binder. When such a state proceeds, when the abrasive cannot fully hold the abrasive grains against the cutting resistance, the abrasive grains (worn abrasive grains) fall off from the binder. Furthermore, as the cutting of the surface of the binder with cutting waste proceeds, the heads of the abrasive grains embedded in the binder (the sharp abrasive grains that are not worn) are exposed from the binder, and the workpiece is cut. To start. The sharpness of the drill is improved by the function of the self-repetitive function in which the worn abrasive grains fall off from the binder and the non-weared sharp abrasive grains are repeatedly exposed from the binder. It is possible to keep things.

  Among the above-described processes, the binder part that is in close contact with the rear part of the abrasive grains among the binder existing behind the abrasive grains in the rotation direction becomes a shading of the abrasive grains, thereby scraping off with the cutting scraps. It is hard to receive. For this reason, the binder part becomes a bond tail whose thickness in the drill radial direction is thicker than other binder parts. This bond tail has a property that it easily grows as the cutting resistance applied to the abrasive grains in close contact with it increases. The grown bond tail functions to hold the abrasive grains against the cutting resistance applied to the abrasive grains and prevent the abrasive grains from falling off early.

  However, if there are abrasive grains in the abrasive grains that cut the workpiece that are subjected to excessive cutting resistance compared to other abrasive grains, the bond tail that is in close contact with the abrasive grains is As a result of the diligent efforts of the present inventors, it has been found that excessive growth is achieved as compared with other bond tails. And the present inventors came to know that such a bond tail causes the following problems.

  In other words, the excessively grown bond tail keeps the abrasive grains that should be dropped off without being dropped from the binder, thereby hindering the above-described self-generating action of the drill. In addition, the abrasive grains (hereinafter referred to as projecting abrasive grains) held by such an excessively grown bond tail are relatively in comparison with other abrasive grains in which the autogenous function is functioning normally. It will be in the state which protruded in the drill radial direction. For this reason, due to the presence of the protruding abrasive grains, the heights of the abrasive grains held in the binder in the radial direction of the drill may be uneven.

  As described above, if the abrasive grains are uneven in height due to the presence of the protruding abrasive grains, the machining accuracy when drilling the workpiece is lowered, which causes a rough surface on the drilled surface.

  For the above problems, it is conceivable to employ a solution as shown below.

  One is a method of using a dummy workpiece, and is a method of wearing the protruding abrasive grains by drilling the dummy workpiece using a drill having protruding abrasive grains. Other methods include a method of dressing a drill with a grindstone typified by white alundum, a method of replacing with a new drill, and the like.

  However, according to the method using a dummy workpiece, it takes a lot of time and labor to wear the protruding abrasive grains, so that there is a problem that the production efficiency tends to deteriorate particularly during continuous production of products. Moreover, depending on the method using dressing, there is a problem that the rough surface of the hole-processed surface is further promoted depending on the case. Furthermore, the method of exchanging with a new drill has a problem that the procurement cost of the drill increases and the production cost increases.

The method according to the present invention, which was created based on the above-mentioned knowledge by the present inventors, is a hole drilling method that sequentially drills a plurality of brittle materials using a drill in which abrasive grains are fixed with a binder. A forward rotation process for drilling a predetermined number of brittle materials with the drill rotated forward, and a reverse rotation process for drilling a predetermined number of brittle materials with the drill rotated reversely. Thus, it is characterized in that the hole is drilled in the brittle material using the reverse rotation process as the subordinate process while the hole is drilled in the brittle material as the main process . Here, the above “forward rotation” may be either the case where the drill is rotating in the clockwise direction or the case where the drill is rotating in the counterclockwise direction. Means that the drill is rotating in the direction opposite to the “forward rotation” described above. That is, when “forward rotation” is the clockwise direction, “reverse rotation” is the counterclockwise direction, and when “forward rotation” is the counterclockwise direction, “reverse rotation” is the clockwise direction.

According to such a method, during the positive rotation process of the drill, the protruding abrasive grains held by the excessively grown bond tail do not fall off from the binder, so that the self-acting function of the drill is difficult to function. For example, even if the height of each abrasive grain in the radial direction of the drill is not uniform, this protruding abrasive grain receives the following action by shifting from the forward rotation process to the reverse rotation process, and the binder Easily fall off from. That is, once the hole drilling moves to the reverse rotation process, there is no bond tail at the rear of the protruding abrasive grains in the rotation direction (the forward direction of rotation at the time of forward rotation), so the binder cuts the protruding abrasive grains. It cannot be held against resistance. Thereby, after shifting to a reverse rotation process, the protruding abrasive grains loaded with cutting resistance easily fall off from the binder. As a result, it is possible to recover the self-generating action of the drill, and it is possible to obtain a good hole machining surface with high machining accuracy and no rough skin. In addition, since complicated operations and exchanging drills are not necessary, it is possible to improve production efficiency and reduce production costs. In addition, in this method, when it is estimated that there has been a concern about the occurrence of rough skin on the drilled surface by drilling a large number of brittle materials in the main rotation step, which is the main rotation process, The process is switched to the reverse rotation process. In this reverse rotation process, the protruding abrasive grains fall out of the binder by subjecting a very small number (extremely one) of brittle materials to drilling. As a result, the self-generating action of the drill is restored, and thereafter, the process is switched again to the forward rotation process, and a large number of holes are drilled. Therefore, the reverse rotation process of drilling holes in a very small number of brittle materials can be a maintenance process for continuously maintaining the self-generating action of the drill.

  In the above method, the brittle material may be a glass plate.

  In this way, it is possible to obtain the various advantages described above for a glass plate that requires a high-quality hole processed surface that is not particularly rough. In addition, as a brittle material, a ceramic plate etc. can be mentioned besides a glass plate.

  In the above method, the abrasive grains are preferably diamond grains.

  In this way, the effects described above can be made more prominent.

  In the above method, the binder is preferably a metal bond.

  In this way, the metal bond surface is scraped off by the brittle cutting material and the formation of the bond tail due to this becomes remarkable, so that the effect of the self-generating action of the drill can be obtained accurately.

  The brittle material that has been drilled by the above method can be a high-grade brittle material that does not have rough skin on the drilled surface.

  As described above, according to the present invention, when drilling a plurality of brittle materials, it is possible to form a high-quality drilled surface that does not cause rough skin, and Production efficiency and production cost can be improved.

It is a partially broken schematic front view which shows the hole processing apparatus which concerns on embodiment of this invention. It is a principal part expanded horizontal sectional view of the periphery of a hole processing surface which shows the outline of the hole processing method which concerns on embodiment of this invention. It is a principal part expanded horizontal sectional view of the periphery of a hole processing surface which shows the outline of the hole processing method which concerns on embodiment of this invention. It is a principal part expanded horizontal sectional view of the periphery of a hole processing surface which shows the outline of the hole processing method which concerns on embodiment of this invention. It is a principal part expanded horizontal sectional view of the periphery of a hole processing surface which shows the outline of the hole processing method which concerns on embodiment of this invention.

  Hereinafter, a hole drilling apparatus according to an embodiment of the present invention will be described. In this embodiment, diamond abrasive grains are used as polishing abrasive grains, and metal bonds are used as binders, and the brittle material that is a workpiece is a glass plate. Further, a variable speed motor capable of forward and reverse rotation is used as a drive source for executing the forward rotation process and the reverse rotation process.

  FIG. 1 is a partially broken schematic front view showing a hole drilling apparatus 1 according to the present embodiment. As shown in the figure, the hole drilling device 1 includes a drill 2 for cutting a glass plate G, and a cutting portion 2a of the drill 2 includes a convex curved surface portion (substantially hemispherical portion) 2aa located on the tip side thereof. And a cylindrical surface portion 2ab located on the base end side. Diamond abrasive grains K are fixed to the surface of the cutting portion 2a by metal bonds B.

  Further, the hole drilling device 1 rotates the drill 2 in the forward rotation direction (A direction in the figure) to drill a predetermined number of glass plates G, and the drill 2 in the reverse rotation direction (same as the same). Drive means 3 is provided for performing a reverse rotation process in which a predetermined number of glass sheets G are drilled by rotating in the R direction in the figure. The drive unit 3 includes a motor M that is a drive source that executes the above two steps, and a control unit 3a that controls the rotation direction and the rotation speed of the motor M.

  Hereinafter, the implementation status of the hole drilling method using the hole drilling apparatus 1 will be described. 2-5 shows the outline of the hole processing method which performs a hole processing to the some glass plate G sequentially using said drill 2 in time series order.

  As shown in FIG. 2, when the hole H is formed in the glass plate G while rotating the drill 2 in the A direction (forward rotation direction), the diamond abrasive grains K fixed to the surface of the drill 2 by the metal bond B However, the inner peripheral surface Z of the hole H of the glass plate G is cut. In this case, cutting waste S is generated from the inner peripheral surface Z of the hole H of the glass plate G cut by the diamond abrasive grains K.

  Then, as shown in FIG. 3, the cutting scraps S scrape the surface of the metal bond B located behind the diamond abrasive grain K in the drill rotation direction (rear of the rotation direction A of the drill 2), and also the diamond abrasive grains K. Due to the cutting force F applied to the diamond, the diamond tail K immediately after the drill rotation direction (immediately after the rotation direction A of the drill 2) starts to form a bond tail T in close contact with the diamond abrasive grain K.

  Furthermore, if the cutting with respect to the inner peripheral surface Z of the hole H of the glass plate G by the diamond abrasive grain K advances, generation | occurrence | production of the cutting waste S of the glass plate G and the scraping of the metal bond B surface by the cutting waste S will be repeated. . As a result, as shown in FIG. 4, the surface of the metal bond B is positioned relatively low with respect to the diamond abrasive grains K, and accordingly, the diamond abrasive grains K (abrasion worn out in the metal bond B). The head of diamond abrasive grain K) that is not sharp begins to be exposed. In such a state, the diamond abrasive grains K worn by cutting the inner peripheral surface Z of the hole H of the glass plate G are successively subjected to the metal bond B as shown by the dotted line in FIG. Will fall out of.

  In this case, if there is a diamond abrasive grain K to which an excessive cutting resistance F is applied to other diamond abrasive grains K, the bond tail T in close contact with the diamond abrasive grain K is excessive. It will stop growing. As a result, the diamond abrasive grains K (protruding abrasive grains) that should originally fall off against the cutting resistance F may be held without dropping from the metal bond B. Under such a state, as can be understood from the drawing, the heights of the diamond abrasive grains K in the radial direction of the drill 2 become uneven, and the self-generating action of the drill 2 may be hindered. Therefore, if the cutting of the glass plate G is continued in this state, the inner peripheral surface Z of the hole H becomes rough, and it is inevitable that the processing accuracy is lowered and the quality is lowered.

  Therefore, when the above state is reached, a signal is transmitted from the controller 3a to the motor M, and the rotation direction of the motor M is reversed as shown in FIG. Switch to R direction. As a result, the bond tail T does not exist immediately after the rotational direction of the diamond abrasive grains K (protruded abrasive grains) that protrude relatively relative to the other diamond abrasive grains K. Thereby, since the metal bond B cannot hold the diamond abrasive grains K (protruding abrasive grains) against the cutting resistance F, when the cutting resistance F is loaded, the diamond abrasive grains K are As shown by the dotted line in FIG.

  Therefore, the height of each diamond abrasive grain K in the radial direction of the drill 2 can be appropriately adjusted, and the self-generating action of the drill 2 can be continuously maintained, whereby there is no rough skin. It is possible to obtain a high-quality hole processed surface (inner peripheral surface Z of the hole H). In addition, since complicated operations and exchanging drills are not necessary, it is possible to improve production efficiency and reduce production costs.

  Next, a switching procedure between the forward rotation process and the reverse rotation process in the hole drilling method having the above-described configuration will be described.

  As a first switching procedure, there is a technique in which a hole is formed in the glass plate G using a reverse rotation step as a subordinate step while the hole processing is performed on the glass plate G as a main step.

  According to this first switching procedure, rough processing occurs on the hole processed surface (inner peripheral surface Z of the hole H) by sequentially drilling a large number of glass plates G in the forward rotation process which is the main process. When it can be estimated that a fear has occurred, the process is switched to the reverse rotation process, which is a secondary process. In this reverse rotation process, the abrasive grains K (protruding abrasive grains) are dropped from the metal bond B by subjecting a very small number (for example, one or several) of glass plates G to hole processing. As a result, the self-generating action of the drill 2 is maintained, and thereafter, the process is switched again to the forward rotation process, so that a number of glass plates G are sequentially drilled. Therefore, the reverse rotation process of drilling holes in a very small number of glass plates G can be a maintenance process for continuously maintaining the self-generating action of the drill 2.

  Further, as the second switching procedure, there is a method in which the reverse rotation process is continuously executed after the normal rotation process is continuously executed.

  In the case of this second switching procedure, first, it is assumed that the drill 2 is rotated in either the forward or reverse direction to perform the hole processing on the plurality of glass plates G, and the hole processing surface (inside the hole H The limit of the number of machinings that does not cause defects such as rough skin on the peripheral surface Z) is clarified in advance. For example, if the limit number of times of processing is 50 times, it is possible to sequentially perforate 50 sheets of glass sheets G without switching in both the forward rotation process and the reverse rotation process. it can. As a result, the number of forward / reverse switching of the rotation direction of the drill 2 by the control unit 3a (motor M) can be reduced as much as possible. As a result, even when a large number of glass plates G are subjected to hole processing, it is possible to improve work efficiency while maintaining the formation of a high-quality hole processed surface.

  In the present embodiment, the present invention is applied when diamond abrasive grains K are used as abrasive grains and metal bond B is used as a binder. In addition, CBN abrasive grains and the like are used as abrasive grains. Alternatively, a vitrify bond, a resin bond, an electroplating layer for electrodeposition, or the like may be used as a binder. Further, the brittle material that is a workpiece is not limited to a glass plate, and may be a ceramic plate or the like. Furthermore, although the motor M is used as a drive source for executing the forward rotation process and the reverse rotation process, other drive sources may be used. Further, the switching procedure between the forward rotation process and the reverse rotation process is not limited to the above-described mode.

  As an example of the present invention, the following heat strength test was performed.

  The work of rotating the drill forward and sequentially drilling a plurality of glass plates of length: 500 mm, width: 600 mm, and thickness: 1.8 mm causes rough skin on the hole processing surface of the glass plate. Continued until. Then, a glass plate having a rough surface on the hole processed surface is collected as Sample A (Comparative Example), and then the drill used for the hole processing of Sample A is used, and the rotation direction of the drill is reversed and then the hole processing is performed. Was taken as Sample B (Example). By repeating these, 20 samples A and B were prepared. Next, after attaching a rubber heater to each of 20 samples A and 20 samples B, thermal bending was applied until each sample broke, and the thermal strength was measured from the fracture surface of each sample. Then, the average value of the heat intensity of sample A and sample B was calculated from the heat intensity measurement results of 20 samples A and 20 samples B. In addition, the drill which performs a hole process uses the diamond abrasive grain as an abrasive grain, and uses the bronze type metal bond as a binder, A drill diameter is 1.5 mm and a drill rotational speed is 15000 rpm. Moreover, the rubber heater is affixed on the surface of each sample in the position 25 mm from the hole processed into the sample A and the sample B. FIG.

The measured heat intensity values of Sample A and Sample B are as shown below.
Average value of heat intensity of sample A (comparative example): 939.9 kg / cm ²
Average value of heat intensity of sample B (Example): 1253.5 kg / cm ²

  Considering the measured values of the heat intensity, the heat intensity of the example of the present invention is higher than that of the comparative example. In the embodiment of the present invention, it is assumed that the self-generating action of the drill is maintained due to the change of the rotation direction of the drill in the forward and reverse directions, and the hole machining surface has become high-grade accordingly. The As a result of the above, according to the present invention, the glass substrate used in a flat panel display or the like is subjected to hole processing, and even when heat treatment is performed, the glass substrate is damaged due to rough surface of the hole processed surface. It can be inferred that it is effectively deterred.

DESCRIPTION OF SYMBOLS 1 Hole processing apparatus 2 Drill 2a Cutting part 2aa Convex-curved surface part 2ab Cylindrical surface part 3 Drive means 3a Control part M Motor G Glass plate A Drill rotation direction (forward rotation)
R Drill rotation direction (reverse rotation)
H Hole Z Inner peripheral surface F Cutting resistance K Diamond abrasive grain B Metal bond S Cutting waste T Bond tail

Claims (4)

A drilling method for sequentially drilling a plurality of brittle materials using a drill in which abrasive grains are fixed with a binder,
A forward rotation step of drilling a predetermined number of the brittle materials with the drill rotated forward, and a reverse rotation step of drilling a predetermined number of the brittle materials with the drill rotated reversely seen including,
A hole drilling method for a brittle material , wherein the brittle material is drilled using the reverse rotation step as a subordinate process while the brittle material is drilled as the main rotation step . The method for drilling a brittle material according to claim 1 , wherein the brittle material is a glass plate. The brittle material drilling method according to claim 1 , wherein the abrasive grains are diamond abrasive grains. The brittle material drilling method according to claim 1 , wherein the binder is a metal bond.

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