JP2012056018A - Light guide blanking device and machining method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blanking device which forms a cut end face having a superior optical performance as a light guide plate.SOLUTION: The blanking device blanks a light guide plate out of a base material W made of thermoplastic organic glass by holding the base material W between a cutting blade 3 at one side and a receiving blade 4 at the other side and narrowing a gap between the blade edge 3a of the cutting blade 3 and the blade edge 4a of the receiving blade 4 to press-cut the base material W. With respect to the surface of the base material W, the cutting blade 3 is vertical on a product side and has an acute angle on a removal side. With respect to the surface of the base material W, the receiving blade 4 is formed into a trapezoidal shape having a flat blade edge 4a parallel with the surface of the base material W. A blade fixing portion of the cutting blade 3 and a blade fixing portion of the receiving blade 4 have heaters 5b and 6b for heating the cutting blade 3 and receiving blade 4 at temperatures in a range from a softening temperature of the base material W to a liquefying temperature of the same under control by a temperature control unit 7. The cutting blade and the receiving blade are each provided with a blade edge advance control unit that controls the advance, stop, retreat, and advance speed of the cutting.

Description

  The present invention relates to a punching apparatus using a press for a light guide plate used in a light-emitting display unit of an electronic apparatus and the like, and a processing method thereof.

In light emitting display parts of electronic devices such as mobile phones and personal computers that display visual information on a liquid crystal, a light source such as an LED is arranged on the end face of the light guide plate, and light is introduced into the base material to form a reflection on the plate surface. Characters and figures are optically displayed at irregular reflection processing parts such as dots.
In the light guide plate, a thin organic glass plate having a high light transmittance such as polymethyl methacrylate resin (hereinafter referred to as acrylic resin) or polycarbonate resin is cut into a desired shape that can be incorporated into an electronic device. It is used as.
In the processing of such a light guide plate, the end face of the light guide plate obtained by processing is required to have a light incident performance that provides high luminance in the display portion.
Conventionally, in the cutting process, the router process that can process the cut end face uniformly without causing breakage or cracks is performed, but in the router process, the blade is moved along the periphery of the workpiece and cut. So there was the difficulty of taking time.

  On the other hand, punching with a press machine cuts the work instantly with a die blade, so it is suitable for mass production and cost reduction because it can be processed in a much shorter time than router processing, but acrylic resin etc. Because the light guide plate is hard, cracks are generated on the plate surface from the cut portion, so that a good quality product cannot be obtained, and even if it can be cut without cracks, unevenness due to breakage occurs on the cut end surface There is a problem that sufficient light performance as a light guide plate cannot be obtained. For this reason, the processing by a press is not implemented until now in the cutting process of a light-guide plate.

On the other hand, in the field of punching by resin card press, by providing base material pressing guides on the top and bottom of the resin card base material, an attempt is made to obtain a stable quality product free from burrs and undulations in the punching process. The proposal of the invention of the following patent document 1 has been made.
However, even if this is used for the manufacture of a light guide plate, the base material of the light guide plate is thin and hard, so that cracks occur when the plate thickness is about 0.6 mm or more, and cracks when the plate thickness is less than 0.6 mm. However, even if it can be cut without cracks or breakage, it cannot prevent the occurrence of a streak break line at the center of the plate thickness. Since the optical performance as the light guide plate cannot be obtained on the cut end face, the invention described in Patent Document 1 cannot be used for manufacturing the light guide plate.

  Further, in the field of plastic lens manufacturing, regarding the cutting process of the gate part of the resin product performed after injection molding, the following Patent Document 2 discloses that the cutting blade is heated during the cutting of the runner part to remove fine chips. There is a proposal of a device that suppresses generation and prevents chips from adhering to the lens product.

JP 2001-205597 A JP 2005-470099 A

  However, even if the technique of heating and cutting the cutting blade described in Patent Document 2 is used for manufacturing the light guide plate, cracks and breakage of the cut end face can be eliminated, but the cutting blade is 120. It is difficult to obtain a light guide plate that requires high flatness and stability of the light emitting display surface of the acrylic resin plate by inducing bending deformation of the thin acrylic resin plate due to the high heat in order to heat up to ~ 160 ° C. It becomes. For this reason, the technique of patent document 2 cannot be used for manufacture of a light-guide plate.

  Therefore, the present invention provides a punching apparatus that can obtain excellent light performance as a light guide plate on the cut end face while maintaining high flatness from the base material in punching processing of an organic glass light guide plate made of acrylic resin or the like. An object of the present invention is to provide a high-quality light guide plate in an extremely short time compared with a conventional router processing method.

  In order to solve the above-mentioned problem, in the invention according to claim 1 in the light guide plate punching apparatus according to the present invention, a light guide plate obtained from a thermoplastic organic glass substrate is used as a processing target. A punching device for press-cutting by sandwiching the base material between a cutting blade on the side and a receiving blade on the other side and narrowing a space between the cutting edge and the cutting edge of the receiving blade, the cutting blade being a base plate The processed product side is perpendicular to the surface and the removal side is formed into an acute-angled letter shape, and the receiving blade is formed in a trapezoidal shape having a blade edge parallel to and flat with the plate surface of the substrate, A heater capable of heating the cutting blade and the receiving blade to a temperature range not lower than the softening temperature of the base material and not higher than the temperature at which the base material changes from solid to liquid is provided in the blade fixing portion of the cutting blade and the receiving blade. Features.

  According to a second aspect of the present invention, in the above invention, each of the cutting blade and the receiving blade is provided with a blade edge advancement control unit that controls the progress, stop, retreat, and advancement speed of the cutting, and the blade edge advancement. When both cutting edges come into contact with the surface of the base material during processing under the control of the control unit, the cutting is allowed to proceed after temporarily stopping until the cutting edge proximity portion of the surface layer portion of the base material is softened.

  The invention described in claim 3 is characterized in that, in the above invention, a temperature control unit is provided which enables heating control of the temperature of each cutting edge of the heater and the receiving blade.

  The invention according to claim 4 is characterized in that, in the above invention, the tip of the processed product side portion of the cutting edge of the cutting blade is formed in a round surface of 5 to 9 μm.

  The invention according to claim 5 is characterized in that, in the above invention, the width of the flat portion of the cutting edge of the receiving blade is 0.03 to 0.1 mm.

In invention of Claim 6, it is the punching method using the punching apparatus of the light-guide plate of the said Claims 1-5,
A blade edge heating adjustment step in which the blade edge of the cutting blade is heated and adjusted with a heater to a temperature range not lower than the softening temperature of the organic glass substrate of the light guide plate and the temperature at which the substrate changes from solid to liquid, and
A base material charging step for setting the base material at a set position above the receiving blade;
A blade edge progression starting step for advancing the cutting blade until it contacts the substrate plate surface;
After the cutting blade comes into contact with the plate surface of the base material, the progress of the cutting blade is temporarily stopped, and during the stoppage, the base material softening standby step of softening the blade tip adjacent portion of the surface layer portion to the optimum temperature; ,
A base material shearing process for controlling the cutting speed to an appropriate speed at which a good cutting surface can be obtained with the cutting blade, and stopping the progress of the cutting blade at the cutting completion setting position when the cutting blade and the receiving blade are close to each other;
A blade tip retraction process for retracting the cutting blade at high speed;
A product take-out process for taking out the cut light guide plate from the top of the blade,
Returning to the input process from the product take-out process, repeated process to repeat the subsequent processes many times,
And is characterized in that a high-performance light guide plate can be obtained efficiently.

  The invention according to claim 7 is characterized in that, in the above-mentioned method invention, an acrylic resin is used for the base material of the organic glass.

  In the invention according to claim 8, in the invention of the method described above, in the base material softening standby step, 0.2 to 3 seconds when the cutting edge and the cutting edge of the receiving blade come into contact with the plate surface of the base material. The stop time is set.

  The invention according to claim 9 is characterized in that, in the invention of the method described above, in the blade edge heating adjustment step, the blade edge temperatures of the cutting blade and the receiving blade are in the range of 60 to 110 ° C.

In the present invention, an apparatus for punching an organic glass substrate having thermoplasticity as a raw material of a light guide plate with a press includes a cutting blade formed into an acute-angled letter shape on one side and a flat receiving blade on the other side. The cutting blade and the receiving blade can be heated to a softening temperature of the base material with a heater, and when the cutting process is performed using this apparatus, the surface of the cutting portion of the base material is cut between the cutting blade and the receiving blade. By softening the base material by heating with the blade edge, it prevents the base material from being broken during cutting, and the difference in sharpness due to the tip shape of the cutting blade and the receiving blade and the difference in softness due to the difference in heating temperature The cutting blade and the receiving blade are caused to have different shear resistances, and the cutting blade is preferentially advanced due to the difference in the shearing resistance, so that the separation trace of the base material is close to the edge of the base surface layer portion on the receiving blade side. Generated as a result, the processed base It is possible to form an end surface having a high optical performance capable of expressing high luminance as the light guide plate to cut edge of the.
At that time, even if the base surface is covered with a soft protective film made of polyethylene or vinyl chloride, they are easily cut by the heat applied to the flat blade edge. In addition, the optical performance of the light guide plate is not deteriorated.

In the case of using an acrylic resin for the base material, the surface of the base material was heated in the range of 60 to 110 ° C. for a set stop time of 0.2 to 3 seconds before the cutting edge digged into the base material. It is possible to prevent breakage of the base material during cutting by bringing the cutting edge into contact with the softening locally.
Furthermore, since the cutting speed of the cutting blade can be adjusted to match the time required for softening the base material by controlling the blade edge advancement control unit, it is suppressed so that the hard base material is not broken by the cutting blade. However, it is possible to perform normal cutting continuously.

  In the present invention as described above, the substrate is heated locally through the cutting blade and the receiving blade, but when the acrylic resin is used for the organic glass substrate, the cutting blade and the receiving device are used. By setting the blade tip temperature within the range of 60 to 110 ° C., the temperature of the entire base material does not rise significantly, and even if the base material is softened, it does not occur until melting, and the base plate surface of the base material is It is possible to obtain a stable product that is not deformed by heat and does not undergo dimensional changes due to thermal expansion.

  The punching process can be performed in a much shorter time than the router process, so that the production efficiency can be remarkably improved.

  Then, by the punching device, the blade heating adjustment process, the substrate charging process, the blade edge advancement start process, the substrate softening standby process, the substrate shearing process, the blade edge retracting process, the product takeout process, and the repetition process are performed according to the procedure. As a result, a high-performance light guide plate can be obtained by punching.

  At that time, by providing a blade edge advancement control unit, the progress, stop, retreat and advancement speed of the cutting blade and the receiving blade are controlled, and by providing a temperature control unit, the temperature of the cutting edge and the blade edge of the receiving blade is set to 60. It becomes possible to control within a range of ˜110 ° C., and further, when the width of the flat part of the blade edge of the receiving blade is formed to 0.03 to 0.1 mm, the tip shape of the cutting blade with respect to the acrylic resin plate Different softening degrees and different shear resistances are generated, and the cutting blade is preferentially advanced from the difference, and the separation trace of the base material is generated in the edge portion adjacent to the base surface layer part on the receiving blade side, resulting in high brightness. It becomes possible to process the base material on the cut end face having excellent optical performance capable of exhibiting.

  In addition, when the cutting edge is formed on a round surface of 5 to 9 μm, it is possible to form almost uniform fine irregularities on the entire cutting end face, and the optical performance incident from this end face is simply a mirror of the end face. Even when compared with the case of smooth formation as described above or with the processing by router processing, it is possible to obtain better high luminance.

It is a vertical side view which shows the principal part of the die part of the punching apparatus of the light-guide plate of this invention. It is a vertical side view which shows a base material injection | throwing-in process. It is a vertical side view which shows a base-material softening standby process. It is a vertical side view which shows the base-material cutting process in the middle of shearing. It is a vertical side view which shows the base-material cutting process of the completion | finish of shearing. It is a vertical side view which shows a blade edge | tip retraction process. It is a vertical side view which shows the state with which the base material after extraction was connected. It is a vertical side view which shows the state which the light-guide plate after taking out isolate | separated. It is the expanded vertical side view of the principal part periphery of a blade edge | tip which shows a base-material softening standby process. It is an expanded vertical side view of the principal part around the blade edge | tip in the base-material cutting process of completion | finish of a shear. It is the vertical side view which expanded the principal part around a blade edge | tip which shows a blade edge | side retraction process. It is the expanded vertical side view which shows the state with which the base material after extraction was connected. It is the expanded vertical side view which shows the state which the light-guide plate after taking out isolate | separated. It is a vertical side view of the sharp blade edge of a cutting blade. It is a vertical side view of the round blade edge of a cutting blade. It is a photograph figure of the shear end face of the light-guide plate processed with the sharp blade edge | tip of the cutting blade obtained by this invention. It is a photograph figure of the shearing end surface of the light-guide plate processed with the round blade edge of the cutting blade obtained by this invention. It is an enlarged photograph figure of FIG. It is a photograph figure of the processed surface of the light-guide plate obtained by the conventional router process. It is a flowchart which shows the punching process process of the light-guide plate of this invention.

  The form for implementing the punching apparatus of the light-guide plate of this invention and its processing method is demonstrated from a punching apparatus previously.

  The punching apparatus of the present invention is a press machine that can control the forward, backward, stop, and speed of the cutting portion using a servo motor or the like as a drive source, and has a shape corresponding to the shape of the light guide plate as shown in FIG. The molds 1 and 2 having the upper cutting blade 3 and the lower receiving blade 4 formed in the above are mounted, and a thin plate made of organic glass, which is a base material W of the product raw material, is put into the molds 1 and 2. This is a device for performing a punching process by shearing to obtain a light guide plate used for a light emitting display portion of an electronic device such as a mobile phone or a personal computer.

The substrate W to be processed is a thin plate of organic glass which is a thermoplastic resin such as a polymethyl methacrylate resin plate (hereinafter referred to as an acrylic plate) or a polycarbonate resin. For example, the acrylic plate is hard and highly transparent. Therefore, it is generally used as a light guide plate, begins to soften and deform at about 80 to 100 ° C., and glass point transfer has a property of becoming liquid at about 110 ° C. or higher.
In the present invention, not only the substrate W alone, but also a substrate in which a protective sheet or a protective film that can be melted at a lower temperature than the organic glass is stretched is processed.

  As shown in FIG. 1, the punching apparatus of the present invention includes various peripheral auxiliary mechanisms that allow the base material W to be set between the upper and lower molds 1 and 2 including the cutting blade 3 and the receiving blade 4. The press machine is provided with a drive mechanism and a blade edge advancement control unit 7 that can control the movement, stop, and speed of the upper cutting blade 3 and the lower receiving blade 4, but other than the press machine body and the blade edge. Since the blade mold fixing part A of the molds 1 and 2 is a known structure that is usually used, each drawing showing the following apparatus shows the main part of the cutting process part of the substrate W, and the other parts are omitted. To explain.

FIG. 1 shows a main part of a punching section in the punching apparatus of the present invention. As shown in FIG. 1, the product side is a vertical surface and the removal side is above the substrate W of the organic glass thin plate. The molds 1 and 2 to which the cutting blade 3 formed with the cutting edge 3a having a letter shape that is an inclined surface is attached are mounted on the upper blade mold fixing portion A.
Further, the die 2 provided with a trapezoidal receiving blade 4 provided with a flat cutting edge 4a that is parallel to the plate surface of the substrate W is provided below the base W. Attach to mold fixing part A.
The molds 1 and 2 are embedded with thermocouples 5a and 6a for sensing the temperature of the cutting edges 4a and 4b and heaters 5b and 6b for generating heat by electricity, and the thermocouples 5a and 6a and the heater 5b. Temperature control units 5c and 6c are connected to the respective electric circuits 6b, and the temperature can be controlled by adjusting and heating the cutting blade 3 and the receiving blade 4 to different temperatures.
In the present invention, one or both of the upper and lower blade mold fixing parts A are moved up and down to cut the substrate W by narrowing the space between the cutting blade 3 and the receiving blade 4, Hereinafter, the case where only the upper blade mold fixing part A is moved up and down will be described.

First, the cutting blade 3 and the receiving blade 4 will be described in more detail.
As shown in FIG. 1, the cutting blade 3 is formed in a wedge-shaped letter shape at the tip of a straight base. As shown in FIG. 4, the processed product side is a vertical surface, but the removal side is the vertical surface. The one having an inclination of 25 to 40 degrees to the angle is used.
And, the shape of the cutting edge 3a at the tip formed at the acute angle is as shown in FIG. 14, with a sharp cutting edge 3a and a shape formed on a round surface having a radius of 5 to 9 μm as shown in FIG. The blade edge 3a can be used, and is selected and used according to the application required as a product.
In particular, in the cutting blade 3 having the tip shown in FIG. 15 formed on a round surface with a radius of 8 μm, the surface roughness is rougher than that formed in a sharp shape, but the light incident performance is improved.

The receiving blade 4 facing the cutting blade 3 has a trapezoidal shape as a whole, and the cutting edge 4a at the tip thereof is formed in a flat shape parallel to the plate surface of the substrate W. The flat portion is used with a width of several 0.03 mm to 0.2 mm.
In consideration of the strength and the propagation of the heating temperature, the base of the receiving blade 4 is straight, and the base is formed into a trapezoidal shape or various mountain shapes as a whole as shown in FIG. can do.

Next, heating by the heaters 5b and 6b of the molds 1 and 2 will be described.
As shown in FIG. 1, a thermocouple 5a and a heater 5b that generates heat are connected to the temperature control section 5c of the upper mold 1, and a thermocouple 6a and heat generation are connected to the temperature control section 6c of the lower mold 2. The upper die 1 and the lower die 2 can be individually controlled to be heated, and the temperature of the cutting blade 3 and the receiving blade 4 can be controlled at different temperatures. .
In the case of processing the acrylic resin plate, the upper cutting edge is set to a generally higher 80 to 120 ° C., and the lower receiving blade 4 is set to a substantially 60 to 70 ° C. The reason why the set temperature of the upper cutting blade is wide is that it is necessary to adjust the temperature according to the shape and quality of the cutting edge and the surface hardness of the acrylic plate.
The temperature is adjusted by checking the temperature of each blade with the thermocouples 5a and 5b. When the temperature exceeds the set temperature, the heating is turned off to stop the heating. It is possible to increase and decrease the temperature in the temperature range.

Next, the press machine to be used will be described in detail.
As shown in FIG. 1, the die 1 of the cutting blade 3 is fixed to the upper blade die fixing portion A, and the blade die fixing portion A is supported by a press slide surface of a press machine. As the slide surface moves up and down, the mold 1 of the upper cutting blade 3 moves up and down.
A servo motor is used as the power source to drive the press slide surface up and down. By controlling the servo motor with a blade edge advancement control unit (not shown), it is possible to stop the cutting blade 3 at an arbitrary accurate position and finely adjust the vertical movement speed.
Further, when the press machine receives a cutting load, the frame is stretched and the stop position is changed. However, in the processing of the present invention, the cutting edge 3a of the cutting blade 3 and the cutting edge 4a of the receiving blade 4 come close to contact. Therefore, the stop position is very important, and the servo motor control is accurate using the scale feedback mechanism used in high-precision NC machine tools etc. so that the stop position does not change even if the frame is extended. It is necessary to correct the position stop.

As shown in FIG. 9, when the cutting edge 3 and the cutting edges 3 a and 4 a of the receiving blade 4 come into contact with the upper and lower surfaces 8 and 9 of the base material W, the upper and lower surface layers of the base material W are shown. Until the blade edge adjacent portions 8a and 9a are softened by the contact between the two blades 3 and 4, the cutting blade 3 is temporarily stopped, and when the blade contact portion of the substrate W locally exceeds the set temperature, the cutting is performed. The cutting of the blade 3 proceeds and the base material W is punched.
The setting of the moving speed, stop position, and stop time of the cutting blade 3 at this time varies depending on the acrylic thickness, surface hardness, and the presence or absence of coating with a protective film, so it must be arbitrarily set.
It should be noted that the setting of the substrate W and the removal of the product and the end material after the punching of the substrate W can be performed either by a person or by a robot arm.

The punching apparatus according to the present invention has been described above. A punching method performed using the punching apparatus will be described below.
As shown in FIG. 20, the punching method of the present invention is performed in the following order of steps (a) to (h).
(A) Cutting edge heating adjustment step The cutting edge of the cutting edge is preliminarily set to a temperature range not lower than the softening temperature of the organic glass substrate and not higher than the temperature at which the substrate changes from solid to liquid. Adjust the heating with a heater.
(B) Substrate loading step The substrate is set at a set position above the receiving blade.
(C) Cutting edge progression starting step The cutting edge is advanced until it contacts the substrate plate surface.
(D) Substrate softening standby step After the cutting blade comes into contact with the plate surface of the base material, the progress of the cutting blade is temporarily stopped, and during the stop, the blade edge proximate portion of the surface layer portion of the base material is brought to an optimum temperature. Soften.
(E) Substrate shearing process The cutting edge is controlled to an appropriate speed at which a good cutting surface can be obtained with the cutting edge, and the cutting is advanced. When the cutting edge and the receiving edge come close to each other, the progress of the cutting edge is stopped at the cutting completion set position.
(F) Cutting edge retraction process The cutting edge is retreated at high speed.
(G) Product removal process The cut light guide plate is taken out from above the blade.
(H) Repeating process The process returns from the product take-out process to the charging process, and the subsequent processes are repeated many times.
And it becomes possible to produce a high performance light-guide plate in large quantities and to obtain it efficiently by the process of the above (a)-(h).

Each of the above steps will be described in more detail based on the drawing of the apparatus.
First, in the (a) cutting edge heating adjustment step, prior to setting the base material W, the cutting edges 3a and 4a of the cutting blade 3 and the receiving blade 4 are previously connected to the base of the light guide plate prior to the following punching process. The heaters 5b and 6b are individually heated and adjusted to a temperature at which a good cut surface not lower than the softening temperature of the material and not higher than the temperature at which the base material changes from solid to liquid can be obtained.
When the base material is an acrylic resin, the material of the plate has a softening temperature of 60 to 120 ° C. However, in the present invention, the upper cutting blade 3 is formed with a narrow tip portion, so the heat transfer speed is low, so The lower trapezoidal receiving blade 4 is set to a high temperature of 80 to 120 ° C., and is set with a difference of about 60 to 70 ° C., and the temperature is controlled by the temperature control units 5c and 6c to be heated.
The temperature of the cutting blade 3 can be set by selecting a wide range of set temperatures in order to adjust the shear condition according to the shape and quality of the blade edge 3a and the surface hardness of the acrylic plate.
In addition, when the substrate W is the above-mentioned acrylic plate, it is not preferable that the temperature is 60 ° C. or lower because the substrate does not soften. In the beginning, it is not preferable because corrugated deformation of the base plate tends to occur.

  Next, in the (b) base material charging step, as shown in FIG. 2, the base material W is set on the receiving blade 4 as shown in FIG. Set to. This set position is designed in advance so that the effective brightness can be obtained in the dot pattern even if the substrate is pre-processed, such as a dot pattern. Set correctly. Since the set positioning method of the base material is a known method in press working, description thereof is omitted.

Next, in the (c) cutting edge advancement starting step, the cutting edges 3a and 4a of the cutting blade 3 and the receiving blade 4 are placed on the substrate W under the cutting edge advance conditions set in the control device of the press machine by the cutting edge advancement control unit. The upper cutting blade 3 is advanced until it contacts the upper and lower surfaces 8 and 9.
At this time, the base material W is set in the base material charging step, as shown in FIG. 2, because the base material W rides on the cutting edge 4a of the receiving blade 4 and comes into contact. In the case of 70 ° C. or higher, if the mold 2 is provided with a lift pin (not shown) for floating the base material, the base material W is separated from the mold 2, so that the heat of the mold 2 hardly reaches the base material W. Can be prevented from being deformed by heat.
In this step, as shown in FIG. 3, until the cutting blade 3 comes into contact with the surface of the substrate W, in order to increase production efficiency and to prevent deformation such as warpage of the substrate plate surface due to heat, It is better to descend at the maximum speed that the press has.

Next, in the substrate softening standby step (d), as shown in FIG. 3, after the cutting blade 3 contacts the surface of the substrate, the substrate W is brought into contact with the opposing receiving blade 4. The advancement of the cutting blade 3 is temporarily stopped while being sandwiched.
And the cutting edge proximity portions 8a and 9a of the surface layer portion of the base material are kept in contact with the cutting edges 3a and 4a of the receiving blade 4 on the surfaces 8 and 9 of the base material on which the cutting blade 3 is stopped. The cutting edges 3a and 4a are softened to an optimum temperature by heat. In FIG. 9, the softened portions of the blade edge adjacent portions 8a and 9a are displayed in black.
The waiting time of the cutting blade 3 necessary for softening the blade edge adjacent portions 8a and 9a varies depending on the plate thickness and hardness of the substrate W, but is about 0.4 for a general acrylic plate having a thickness of 0.2 mm. For a second, 0.4 mm acrylic plate, about 1 second is a suitable stop time. Thus, the time for stopping the advancement of the cutting blade 3 is set to the best time in consideration of the type, thickness, and hardness of the substrate W.
However, if the stop time is too long, the softening progresses too much, and sagging may occur in the base material 8a, 9a after the cutting process, which is not preferable. Moreover, since the softening whose stop time is too short is insufficient and there is a possibility that the cut end face may be abnormally broken, it is not preferable.
In addition, until the cutting blade 3 contacts the surface of the substrate W, it is preferable to lower it at the maximum speed of the press machine in order to increase production efficiency.

Next, in the (e) base material shearing step, as shown in FIG. 4, the inside of the base material W is started from the portion where the base material W is locally softened in the blade edge proximate portions 8 a and 9 a of the surface layer portion of the base material W. When the cutting edge 3a of the cutting blade 3 is caused to enter and the cutting of the base material is started, the cutting edge 3a of the cutting blade 3 is lowered and moved continuously as shown in FIG.
At this time, the cutting speed of the cutting edge 3a is controlled by the cutting edge progress control unit at an appropriate speed (a speed at which softening is promoted but not melted) at which a good cut surface is obtained. The descent proceeds while shearing.
At this time, since the lower receiving blade 4 has a slightly flat portion on the opposite surface, the shear resistance is high, and the base material W is softened when the blade edge adjacent portion 9a of the surface layer receives the temperature of the blade edge 4a. Therefore, as shown in FIG. 10, the flat cutting edge 4 a bites into the substrate W in a slightly depressed state.
The cutting edge 3a of the cutting blade 3 is lowered and stopped at a position where the distance from the cutting edge 4a of the lower receiving blade 4 is kept at 10 to 20 μm. The reason why the opposing blade edges 3a and 4a are not in direct contact is to prevent contact damage between the blade edges.

  Regarding the influence that the cutting edge 4a of the receiving blade 4 slightly bites into the base material W, suppression of burrs that occur during cutting and the occurrence of burrs are not on the surface of the base material but on the cutting surface. Therefore, it has the effect of reducing the adverse effects of burrs. Further, since the bite into the base material is only a part of the edge of the cut end face, there is almost no effect on the optical performance of the light guide plate obtained after processing as shown in the photograph of FIG.

  As described above, since the cutting step is completed with the cutting edge 3a of the cutting blade and the cutting edge 4a of the receiving blade leaving a distance of 10 to 20 μm, the lower receiving blade 4 is immediately after cutting as shown in FIG. The part directly above is not completely separated but is slightly connected, but the remaining part of the base material is broken by the wedge shape of the cutting edge 3a of the cutting edge 3 if the degree of softening is slight. Is generated and separated spontaneously, and as shown in FIG. 13, if the degree of softening has progressed, it can be separated by a slight external force.

  In the next (f) cutting edge retreating step, as shown in FIG. 6, after the base material W is sheared, the cutting blade 3 is retreated at a high speed from the receiving blade 4 (from the base material W to the cutting edge 3). Is shown in FIG. 11). In order to increase the production efficiency, this speed may be controlled by the blade edge advancement control unit, and the cutting blade 3 may be moved backward at the maximum speed possessed by the press.

Next, in the (g) product take-out step, as shown in FIG. 6, after the base material W is sheared, the cutting blade 3 is raised and stopped at the uppermost position, and is cut as shown in FIG. The light guide plate W1 is quickly taken out from between the cutting blade 3 and the receiving blade 4 to obtain the light guide plate W1.
At this time, the outer end member W2, which is a cut end of a portion other than the light guide plate W1, is also taken out and removed together.
The light guide plate W1 and the outer end member W2 may be taken out in a state where the substrate W is slightly connected at the cutting groove portion K as shown in FIG. In that case, since the light guide plate W1 and the outer end member W2 can be taken out at the same time, the outer end member W2 can be easily removed because a slight external force is applied thereafter.

  When cutting is performed in a state where the substrate is covered with a protective film, the shearing process is completed with the distance between the cutting edge 3a of the cutting blade 3 and the cutting edge 4a of the receiving blade 4 remaining 10 to 20 μm. Thus, the substrate is completely sheared, leaving only the protective film in contact with the receiving blade 4a. In this state, the light guide plate W1 and the outer end member W2 are connected via a protective film when a plurality of light guide plates are punched from one base sheet, so that the light guide plate W1 and the outer side are connected from the mold. Since the operation of taking out the end material W2 can be performed at once after a plurality of punching processes required for one base sheet, the production efficiency can be increased.

(Comparative test example)
Next, for comparison with the present invention, the results of experiments on punching using male and female dies will be described.
The male and female molds were pressed at room temperature because the male blade and the female blade crossed with a clearance of about 10 μm and cannot be heated to cause expansion.
When a base material with an acrylic base material thickness of 0.6 or more was punched, a crack that would cause the base material to sever occurred and did not become a product. When a base material with an acrylic base material thickness of less than 0.6 was punched, no cracks that would break the base material occurred, but secondary shear occurred near the center of the plate thickness, and the top and bottom of the secondary shear part Large fractures occurred on both sides. Therefore, even in this case, the end face of the required quality as the light guide plate cannot be obtained.

  In addition, when the acrylic substrate was punched without heating using the apparatus of the present invention, secondary shear occurred in the vicinity of the thickness center. Further, when the temperature of the cutting blade 3 and the receiving blade 4 is heated to a temperature of 120 ° C. or more at the glass transition point of the base material, the plate surface of the base material undergoes undulation deformation, and the cross-sectioned end surface is the base material W. The liquefied resin was thermally deformed and mirror-finished, and a normal light guide plate could not be obtained.

  The light guide plate having the cut end surface having a preferable optical performance as the light guide plate is obtained by punching the light guide plate in the processing step by the light guide plate punching apparatus of the present invention. An example in which the light guide plate is obtained by the punching apparatus using an acrylic plate having a thickness of 0.4 mm as the material W will be described below.

As described above, the base material of the acrylic plate is thermoplastic, has high transparency, has a high hardness as a resin, and starts to soften and deform when it is an amorphous plastic at about 60 to 100 ° C. It has a property of being liquefied at a temperature of 110 to 120 ° C. or higher.
Therefore, the processing conditions of the apparatus are set according to the physical properties of such an acrylic plate.
Specifically, in the blade edge heating step, the set temperatures of the cutting blade 3 and the receiving blade 4 are controlled separately by the temperature control units 5c and 6c, and the upper mold 1 having the cutting blade 3 is 100 ° C. The lower mold 2 having the receiving blade 4 was set to 70 ° C.

In the base material softening standby step, the press machine controls the cutting blade 3 and the receiving edge 4 when the cutting edges 3 and 4a of the receiving blade 4 come into contact with the upper and lower surfaces 8 and 9 of the base material W. After the progress of the blade 4 is stopped for 1 second, in the base material shearing step, the upper cutting blade 3 is advanced toward the lower receiving blade 4, and after cutting the base material W, the cutting blade 3 and the receiving blade 4 was retracted from the substrate W.
The shear rate of the cutting blade 3 and the receiving blade 4 at this time was about 0.4 mm / sec.
And in the said product taking-out process, the base material W sheared from between the cutting blade 3 and the receiving blade 4 was taken out, and the light-guide plate W1 from which high brightness | luminance was obtained from the light which injected from the shearing surface was obtained.

  The cut end surface of the light guide plate W1 punched by the punching apparatus and the processing method is perpendicular to the plate surface and is a flat surface, and the case where the cutting edge formed with the round surface is used. What was different from the case of using a sharp cutting edge was obtained as follows. This is shown in the following photo FIGS.

The photograph of FIG. 16 is an observation of the cross section of the light guide plate cut with a sharp blade edge 3a as shown in FIG.
The photograph of FIG. 17 is an observation of a cross section of a light guide plate cut using a cutting edge having a round surface as shown in FIG.
The photograph of FIG. 18 is a cross-sectional view of FIG. 17 further observed at 500 times the electron microscope.
In FIG. 16, when a cutting blade with a sharp edge is used as the cutting blade, fine irregularities arranged in the cutting direction as if dragged in part are seen, but the whole is a uniform flat surface and is generally sheared. It can be confirmed that there is no occurrence of the breaking phenomenon seen in FIG.
FIG. 17 shows a case where the cutting edge is processed by using a round-shaped cutting edge, and almost no groove is seen on the surface portion, but a fine deep groove is connected to almost the entire center of the end face to be flattened as a whole. Make up surface.
For comparison, FIG. 19 shows a cut end face in the case of conventional router processing. On this processed end face, many blade rotation streaks parallel to the plate surface and streaks perpendicular to the streaks are recognized.

An experiment was conducted to evaluate the performance of the shear plane of the light guide plate obtained in the above example.
Table 1 below shows the case of “router processing”, the case of using the sharp cutting edge 3a “sharp blade processing” for the cutting blade 3 shown in FIG. 14 of the present invention, and the cutting blade shown in FIG. 15 of the present invention. Reflective dots for light display were provided at five locations on the four corners and the central portion of the plate surface of the square plate in each of the cases of using the round blade edge 3a “round blade processing”. It is comparison data of the test result which measured each brightness | luminance of the light-guide plate.

In Table 1 above, when the average luminance value is 16.8 Cd / m ² when the average value of brightness is obtained by router processing (this cut end face is shown in FIG. 19), the case where the sharp edge of the present invention is used (this cut end face) 16) is 16.9 Cd / m ² , and the case of using a cutting edge formed on a round surface (this cut end surface is shown in FIG. 17) is a high value of 20.8 Cd / m ² .
The cutting conditions at this time are the following (1) to (5).
(1) “Sharp blade machining” uses a sharp blade with a gradient of about 30 degrees for the blade edge 3a. (2) “Round blade machining” uses a round blade edge formed at a radius of 8 μm for the blade edge 3a.
(3) The receiving blade 4 uses a blade with a flat part width of 0.04 mm.
(4) The temperature of the cutting edge 3a of the cutting blade 3 is set to 100 ° C, and the temperature of the cutting edge 4a of the receiving blade 4 is set to 70 ° C.
(5) The stop time when contacting the plate surfaces 8 and 9 of the substrate W in the substrate softening standby step is set to 1 second.

It can be confirmed that the light guide plate obtained by the present invention is superior to both “round blade processing” and “sharp blade processing” as compared with the case of router processing as shown in the above experimental data.
Of the above (1) to (5), if the round surface of the cutting edge is formed with a radius of 12 μm, or if the cutting edge is cut at a temperature different from these, the cut surface will break. It was not possible to obtain a flat cut surface as it melted or melted. Further, when sharpening was performed by further sharpening the blade edge in sharp blade processing, there was almost no dragged fine irregularities as shown in FIG.

Next, a performance evaluation was performed on a cut end face of another light guide plate.
This test is a measurement test for luminance that requires performance as a light guide plate.
The results are shown in Tables 2 and 3 below.

Tables 2 and 3 are data comparing the difference in luminance between the light guide plate obtained by the conventional “router processing” and the light guide plate obtained by the “sharp blade processing” of the present invention.
In Table 3 above, the test results using each acrylic plate having a thickness t = 0.4 mm and in Table 4 using a thickness t = 0.5 mm are shown.
As the test body, a light guide plate on which pattern printing of five reflective dots was performed was used.
Unit of luminance is Cd / ^{m 2.}
Moreover, the input voltage of LED of the light source was 13V (0.68 mA), and all entered from the cut end face.
In addition, the numerical value of each said table | surface has shown the intensity | strength (luminance) of the light discharge | released from a board surface.
Also, 1, 2, 3, 4, and 5 of the measurement points are 1 at the upper left corner, 2 at the lower left corner, 4 at the upper right corner, 5 at the lower right corner, and 3 at the middle portion of the square light guide plate surface. The reflective dots for light display provided at the five locations are shown.

As shown in the above tables, with an acrylic plate having an average value of 0.4 mm, the router processing is 23.473 Cd / m ² whereas the present invention is 24.635 d / m ² , and the acrylic plate has a thickness of 0.5 mm. The router processing is 24.809 Cd / m ^2, while the present invention is 24.829 Cd / m ² , and from this figure, the processed product of the present invention gives better results in any case than the router processed product. It was confirmed that

Since the cut surface shown in FIG. 16 cut by the cutting edge 3a of the sharp cutting edge of the present invention is uniform and flat and has transparency, the light incident property is not inferior to that of router processing. Seem.
Further, in comparison with this, on the cutting end face shown in FIG. 17 cut by the cutting edge 3a of the cutting edge formed on the round surface of the present invention, fine grooves are continuous throughout, and the incident light is less than in the case of FIG. In fact, this is not the case, and when looking at the test results in Table 1 in the above examples, the rounded surface is shown in comparison with the numerical value 16.9 Cd / m ² when the sharp cutting edge 3a of the present invention is used. The numerical value 20.8 Cd / m ² depending on the cutting edge was a remarkably high numerical value.

Considering the factors that increase the brightness when machining with a round blade like this, the cut surface is formed as a flat surface with a series of finely irregular grooves as shown in FIG. When the photograph further enlarged is viewed, the bottom of the groove can be observed, and it can be confirmed that a large number of glossy transparent curved surfaces are formed almost toward the cut end surface at the bottom of the groove.
By forming the glossy curved surface at the bottom of the groove, a cut end face rich in light entering property is obtained, and the side surfaces around the bottom of the groove act to increase the light diffusibility. It is inferred that the brightness has increased as in the data.

  The cutting end surface obtained by the present invention is a flat state as shown in FIG. 16 or a state constituted by fine grooves as shown in FIG. 17 is a balance between the shear resistance of the cutting blade, the softened state of the base material, and the processing speed. The performance of the cut end face can be controlled by adjusting and controlling these three elements.

  As described above, the light guide plate manufactured in the present invention can obtain better luminance than the light guide plate provided by the conventional router processing, such as display of mobile phones and information terminals used in IT equipment. If the light guide plate obtained by the present invention is used for the part, it is possible to display the power consumption and brightly on the display surface of these devices. I think that it will be highly appreciated than ever in the point that the equipment can be used for a long time.

  The present invention enables an organic glass light guide plate to be punched by a press. However, a beautiful shear surface can be obtained without burrs even in the processing of various other resins. There is a possibility that it can be widely used for punching many resin substrates other than the optical plate.

DESCRIPTION OF SYMBOLS 1 Blade die 2 Blade die 3 Cutting blade 3a Cutting blade edge 4 Receiving blade 4a Cutting blade edge 5a Thermocouple 5b Heater 5c Temperature control part 6a Thermocouple 6b Heater 6c Temperature control part 7 Deletion 8 Upper surface of base material 8a Blade edge proximity part of upper surface layer of base material 9 Lower surface of base material 9a Blade edge proximity part of lower surface layer of base material W Base material W1 Light guide plate W2 End material K Cutting groove A Blade mold fixing part of press machine

Claims (9)

  With a light guide plate obtained from a thermoplastic organic glass substrate as a processing target, the substrate is sandwiched between a cutting blade on one side and a receiving blade on the other side, and a gap between the cutting edge and the cutting edge of the receiving blade A punching device for narrowing and press-cutting, wherein the cutting blade is formed in a letter-shaped shape perpendicular to the processed product side and an acute angle on the removal side with respect to the base plate surface, and the receiving blade is a base plate It is formed in a trapezoidal shape with a flat blade edge parallel to the surface, and the cutting blade and the receiving blade are heated to a temperature range not lower than the softening temperature of the base material and not higher than the temperature at which the base material changes from solid to liquid. An apparatus for punching a light guide plate, characterized in that a heater capable of being provided in a blade fixing portion of the cutting blade and the receiving blade.   Each of the cutting blade and the receiving blade is provided with a blade edge advancement control unit that controls the progress, stop, retreat, and advancement speed of the cutting, and the two blade edges come into contact with the surface of the base material during processing by the control of the blade edge advancement control unit. Then, the punching device for the light guide plate according to claim 1, wherein the cutting is allowed to proceed after temporarily stopping until the cutting edge proximity portion of the surface layer portion of the base material is softened.   3. The light guide plate punching apparatus according to claim 1, further comprising a temperature control unit that enables heating control of the temperature of each blade edge of the heater cutting blade and the receiving blade.   4. The light guide plate punching apparatus according to claim 1, wherein a tip end portion of a processed product side portion of the cutting edge of the cutting blade is formed in a round surface of 5 to 9 μm. 5.   5. The light guide plate punching apparatus according to claim 1, wherein the width of the flat portion of the blade edge of the receiving blade is 0.03 to 0.1 mm. 6. A punching method using the light guide plate punching apparatus according to any one of claims 1 to 5,
A blade edge heating adjustment step in which the blade edge of the cutting blade is heated and adjusted with a heater to a temperature range not lower than the softening temperature of the organic glass substrate of the light guide plate and the temperature at which the substrate changes from solid to liquid, and
A base material charging step for setting the base material at a set position above the receiving blade;
A blade edge progression starting step for advancing the cutting blade until it contacts the substrate plate surface;
After the cutting blade comes into contact with the plate surface of the base material, the progress of the cutting blade is temporarily stopped, and during the stoppage, the base material softening standby step of softening the blade tip adjacent portion of the surface layer portion to the optimum temperature; ,
A base material shearing process for controlling the cutting speed to an appropriate speed at which a good cutting surface can be obtained with the cutting blade, and stopping the progress of the cutting blade at the cutting completion setting position when the cutting blade and the receiving blade are close to each other;
A blade tip retraction process for retracting the cutting blade at high speed;
A product take-out process for taking out the cut light guide plate from the top of the blade,
Returning to the input process from the product take-out process, repeated process to repeat the subsequent processes many times,
A method of punching a light guide plate, characterized in that a high performance light guide plate can be obtained efficiently.   7. The light guide plate punching method according to claim 6, wherein an acrylic resin is used for the base material of the organic glass.   8. The stop time of 0.2 to 3 seconds is set when the cutting edge and the cutting edge of the receiving blade are in contact with the plate surface of the base material in the base material softening standby step. A method of punching a light guide plate.   9. The light guide plate punching method according to claim 7, wherein in the blade edge heating adjustment step, the blade edge temperatures of the cutting blade and the receiving blade are within a range of 60 to 110 ° C. 9.

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