Patent Grant
6889586
1. Field of the Invention
The present invention relates to a work cutting apparatus and a method for cutting a work, and specifically to a work cutting apparatus and a method for cutting a sintered compact such as a magnet.
2. Description of the Related Art
In the work cutting apparatus 1, the cutting blades 3 should ideally be mounted at exact right angle to the rotating shaft 2. In such a case, a cutting reaction will only develop within surfaces of the cutting blades, or no force causing the cutting blade 3 to deform vertically to a rotating plane of the cutting blade 3 is generated. Actually however, as shown in
Further, according to the convention, as shown in
It is therefore a primary object of the present invention to provide a work cutting apparatus and a method for cutting a work capable of improving the cutting accuracy and productivity.
According to an aspect of the present invention, there is provided a work cutting apparatus for cutting a work by rotation of a cutting blade, comprising: a first driving portion rotating the cutting blade, and a second driving portion moving at least either one of the cutting blade and the work relative to the other in the vertical direction when cutting.
According to another aspect of the present invention, there is provided a method for cutting a work, comprising: a first step of placing the work at a predetermined position; a second step of preparing a cutting blade; and a third step of rotating the cutting blade, moving at least either one of the cutting blade and the work relative to the other in the vertical direction, whereby cutting the work with the cutting blade.
According to the present invention, by a cutting through lowering the rotating cutting blade for example down to the work disposed at a predetermined position, it becomes possible to reduce the force that deforms the cutting blade than in the convention. Thus, load acting on the cutting blade becomes smaller, deformation of the cutting blade becomes smaller, resulting in improved accuracy of a cut surface. Further, since a stroke of the cutting blade necessary for the cutting can also be reduced, cutting time can be reduced, and productivity is improved.
According to still another aspect of the present invention, there is provided a work cutting apparatus for cutting a work by rotation of a cutting blade, comprising: a first driving portion rotating the cutting blade, and a second driving portion moving at least either one of the cutting blade and the work relative to the other along a normal line passing the point of contact between the cutting blade and the work when cutting.
According to another aspect of the present invention, there is provided a method for cutting a work, comprising: a first step of placing the work at a predetermined position; a second step of preparing a cutting blade; and a third step of rotating the cutting blade, moving at least either one of the cutting blade and the work relative to the other along a normal line passing the point of contact between the cutting blade, whereby cutting the work with the cutting blade.
In this case again, in which the cutting is made along a normal line passing the point of contact between the rotating cutting blade and the work disposed at a predetermined position, the load to the cutting blade becomes smaller. Therefore, deformation of the cutting blade becomes smaller, resulting in improved accuracy of the cut surface. Further, since the stroke of the cutting blade necessary for the cutting can also be reduced, the cutting time can be reduced, and productivity is improved.
According to the present invention, preferably, the cutting blade is mounted to a rotating shaft, and the rotating shaft has two end portions supported by a supporting portion mounted to a unit. By supporting at both end portions of the rotating shaft, it becomes possible to hold the cutting blade more stably, thereby reducing the deflection of the cutting blade during the cutting operation. Therefore, when cutting a brittle work such as a sintered compact, chipping can be reduced, and cutting accuracy can be improved. Further, since the deflection of the cutting blade can be reduced, the number of cutting blades to be mounted to the rotating shaft can be increased. As a result, the number of pieces obtained by a single cutting operation can be increased, and therefore productivity can be increased. Further, since the supporting portion supporting both end portions of the rotating shaft is mounted to one unit, holding accuracy of the cutting blade, particularly horizontal accuracy can be improved.
Further, preferably, the supporting portion includes a first supporting portion and a second supporting portion respectively supporting the two end portions of the rotating shaft. The first supporting portion is mounted movably to the second supporting portion.
Further, preferably, the rotating portion includes an arbor having two tapered end portions, and rotation supporting portions each having a receiving portion mated with one of the tapered end portions of the arbor. By forming the taper at each end portion of the arbor of the rotating shaft, and by mating each tapered end portion to the receiving portion, fixing accuracy of the cutting blade can be improved.
Further, preferably, the first driving portion includes a belt for rotating the cutting blade by belt transmission, and a tension adjusting portion for adjusting tension of the belt. By maintaining the tension of the belt always at a constant level by the tension adjusting portion, slippage of the belt can be prevented, and rotation of the belt can be stabilized. This is particularly effective in an arrangement in which the cutting is made by moving the cutting blade toward the work.
According to the present invention, preferably, a plurality of works are disposed on a recess of a work disposing portion. With such an arrangement, a large number of works can be cut at one time.
Further, preferably, the recess has a V-shaped section in at least either one of a plane including the cutting blade and a plane parallel thereto. By making the recess to have the V-shaped section, cost of machining the work disposing portion can be reduced, and applicability to a variety of kinds of works is achieved. Especially, a plate-like work can be positioned stably without rattling.
Further, preferably, the cutting blade include a disc-like substrate having a Young's modulus of 441,315 N/mm2˜686,490 N/mm2, and a cutting edge formed in an outer circumference of the substrate. By using a super hard metal for example, having the Young's modulus of 441,315 N/mm2˜686,490 N/mm2, as the substrate of the cutting blade, a cutting blade which is thin, hard and cuts well can be obtained. Therefore, margin allowed for the cutting blade can be narrowed, yield of products can be improved, and productivity can be improved.
Preferably, the apparatus further comprises a fixing member for fixing the work to the recess. The fixing member has a comb-like portion pressed to a surface of the work facing the cutting blade. According to this arrangement, since the work is fixed by the comb-like portion pressed from above to the surface of the work facing the cutting blade, differing from the convention, there is no need for bonding the work by adhesive and so on or un-bonding the adhesive after the work is cut, leading to reduced operation time and improved productivity.
Further, preferably, a plurality of the cutting blades are included into a cutting blade block. The cutting blade block have two end portions each mounted with a cutting blade having a thickness greater than a thickness of the other cutting blades. By increasing the thickness of the cutting blades at the ends, each end margin of the work potentially becoming a dimensionally inferior product can be ground into dust. Therefore, inclusion of the inferior products can be prevented, and yield and productivity can be improved.
Further, preferably, a plurality of cutting blade blocks are mounted axially thereof. According to this arrangement, a mounting error in each of the cutting blades will not adversely affect adjacent cutting blade blocks, or the error will not accumulate. Therefore, a plurality of cutting blade blocks can be axially disposed, and as a result, a greater number of works can be cut in a single cutting operation. Further, since the cutting blade block can be set for each of the works, mounting accuracy of the cutting blade can be improved, and inclusion of dimensionally inferior products can be reduced. Therefore, yield is increased, and productivity is improved.
According to the present invention, preferably, the apparatus further comprises a first coolant supplying portion including a first supplying port and a second supplying port each supplying a coolant to the works. By providing the first supplying port and the second supplying port each discharging the coolant from a position different from the other, thereby supplying the coolant to the works from the plurality of locations, the coolant can be supplied reliably even if the work disposing portion having the recess is used and the cutting blade has an increased area of contact with the works. Therefore, the cutting blade can be abraded efficiently, making possible to cut the works productively.
Further, preferably, the first supplying port is formed near the works, whereas the second supplying port is formed on an upstream side of rotation of the cutting blade than is the first supplying port. According to this arrangement, since the coolant is supplied to the cutting blade and the works from the same side thereof and from the plurality of locations, sludge can be discharged smoothly.
Further, preferably, the plurality of works are disposed on an upstream side and an downstream side of the rotation of the cutting blade, and the coolant from the second supplying port is directed toward the work on the downstream side of rotation of the cutting blade. According to this arrangement, the coolant can be supplied also to the work located on the downstream side of rotation of the cutting blade. Further, the coolant from the second supplying port interrupts an accompanying stream of air which follows the turning of the cutting blade. Therefore, the coolant from the first supply port becomes less affected by the accompanying stream of air, and therefore the coolant from the first supplying port can be supplied more reliably to the works.
Preferably, the apparatus further comprises a second coolant supplying portion including a supplying port formed in the recess for supplying the coolant. According to this arrangement, the coolant can be supplied to portions where the first coolant supplying portion can not efficiently supply the coolant such as a side surface of the work. Thus, cutting accuracy of the work is improved further. This arrangement is especially effective if the work has a large thickness.
Further, preferably, the apparatus further comprises an enclosing member enclosing the recess. According to this arrangement, it becomes possible to hold the coolant in the recess. Thus, the work can be cut while the work is being bathed in the coolant. Thus, the cutting accuracy of the work can be further improved.
Further, preferably, the cutting blade includes resin-bound diamond. If the cutting blade includes resin-bound diamond, insufficient amount of supply of the coolant will cause abnormal friction in the cutting blade, deteriorating the cutting accuracy. Thus, the present invention is especially effective.
Preferably, a discharge pressure of the coolant is 196,140 Pa˜471,050 Pa. According to this arrangement, the cutting blade including the resin-bound diamond can be abraded efficiently, making possible to cut the work smoothly.
The object described above, other objects, features, aspects and advantages of the present invention will become clearer from description of embodiments to be made hereinafter with reference to the attached drawings.
Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.
Referring to
The slider 18 has a front surface formed with supporting portions 26a, 26b each positioned at a same height, being spaced from the other by a predetermined distance. The supporting portions 26a, 26b support two end portions of a rotating shaft 30 mounted with the cutting blade block 28.
As shown in
Therefore, according to the rotating shaft 30, the receiving portions 42a, 42b are respectively fitted by the tapered portions 38a, 38b, integrating the rotation supporting portions 34a, 34b with the arbor 32. Further, the screw 36a is inserted into the threaded hole 44a and threaded into the threaded hole 40a, as well as the screw 36b is inserted into the threaded hole 44b and threaded into the threaded hole 40b. With the above arrangement, the arbor 32 is fixed accurately.
With the above constitution, the rotating shaft 30 is supported by the supporting portions 26a, 26b, with unillustrated bearings interposed respectively between the supporting portion 26a and the rotation supporting portion 34a, and between the supporting portion 26b and the rotation supporting portion 34b. Thus, the rotating shaft 30 is rotatably supported.
It should be noted here that as shown in
Referring also to
Returning to
Now, main actions of the work cutting apparatus 10 will be described.
First, the works 70 are fixed to the pasting board 68 by an adhesive for example. The pasting board 68 fixed with the works 70 is then set to the table 66. Then, a start button (not illustrated) is pressed, whereupon the cutting blades 48 begin rotating and lowering toward the works 70, commencing a cutting. When the works 70 have been cut, the cutting blades 48 are raised, and if the cutting operation is to be ceased, then the rotation of the cutting blades 48 is stopped.
According to the work cutting apparatus 10 as described above, even if the cutting blade mounting error θ is as large as in the convention, a tangential component force F1 becomes smaller as shown in
Further, as shown in
As an experiment, an arcuate neodymium magnet (U.S. Pat. No. 4,770,723) shown in
Further, by adopting so-called double-end support construction in which both end portions of the rotating shaft 30 are respectively supported by the supporting portions 26a, 26b, it becomes possible to hold the cutting blades 48 more stably, thereby reducing the deflection of the cutting blades 48 during the cutting operation. Therefore, when cutting a brittle work such as a sintered compact, chipping can be reduced, and cutting accuracy can be improved. Further, since the deflection of the cutting blades 48 can be reduced, the number of cutting blades 48 to be mounted to the rotating shaft 30 can be increased. As a result, the number of pieces obtained by a single cutting operation can be increased, and therefore productivity can be increased.
Supporting portions 26a, 26b supporting the end portions of the rotating shaft 30 are both mounted to a single unit, i.e. the slider 18. Therefore, holding accuracy of the cutting blades 48, particularly horizontal accuracy can be improved.
Further, the two end portions of the arbor 32 of the rotating shaft 30 are formed with the tapered portions 38a, 38b respectively, and these tapered portions 38a, 38b are respectively fitted into the receiving portions 42a, 42b of the rotation supporting portions 34a, 34b. This makes possible to improve fixing accuracy of the cutting blades 48.
Further, the tension adjusting portion 56 always maintains the tension of the belt 54 at a constant level. This prevents slippage of the belt 54, making possible to stabilize rotation of the belt 54. This is particularly effective in such an arrangement as in the present embodiment in which the cutting blades 48 are moved vertically.
Next, reference is made to
The work cutting apparatus 10a is a wider variation of the work cutting apparatus 10 shown in FIG. 1. Specifically, a bed 12a, a column 14a, a slider 18a and the slider supporting portion 20a, and so on are formed wider. Other components of the work cutting apparatus 10a essentially identical with those of the work cutting apparatus 10 are indicated by the same or similar alpha-numeral codes, and the descriptions will not be repeated for those components.
According to the work cutting apparatus 10a, supporting portions 26a, 26b rotatably supports a rotating shaft 30a mounted with a plurality of cutting blade blocks 28a.
As shown in
The cutting blades 74 and 76 respectively include disc-like substrates 74a and 76a. The substrates 74a and 76a respectively have outer circumferential edges mounted with cutting edges 74b and 76b. The substrates 74a and 76a should preferably be made of super hard metal such as tungsten carbide having a Young's modulus of 441,315 N/mm2˜686,490 N/mm2. The material meeting the above condition reduces blade deflection, making possible to narrow a margin allowed for the cutting blades 74 and 76, allowing to cut the work 70 more thinly. If the Young's modulus is smaller than 441,315 N/mm2, even the super hard metal is bent or made wavy by resistance during the cutting operation. As a result, the substrate 74a cannot be made thin enough, losing advantages of using the super hard metal. On the other hand, if the Young's modulus is greater than 686,490 N/mm2, although there is no problem in terms of bending or waving, the metal is harder and more brittle, being susceptible to failure during use, posing safety problems. For these reasons, the value of Young's modulus is limited to the range between 441,315 N/mm2˜686,490 N/mm2. The cutting edges 74b, 76b include diamond abrasive grains for example.
According to the present embodiment, for example, the substrate 74a has a thickness of 0.6 mm, the spacer 78 has a thickness of 2.5 mm, and the thicker substrate 76a has a thickness of 3 mm. By increasing the thickness of the cutting blade 76 at each end, each end margin of the work 70 can be ground into dust.
Further, preferably, the cutting blades 74 and 76 should have a radius greater than a radius of the spacers 78 by a length equal to (a thickness of the work 70+a thickness of a comb-like portion 98).
Returning to
Further, as shown in
By using the adjusting portion 96 having a different height or different slanting angle of its top surface, a mounting angle of the comb-like portion 98 can be varied, and pressing force to the work 70 can be varied. Further, by adjusting curvature of the comb-like portion 98 of the fixing member 92, the pressing force to the work 70, and thus the friction between the work 70 and respective coating members 90a, 90b can be adjusted. The comb-like portion 98 is set so as to allow each of the cutting edges 74b of the cutting blades 74 to pass through corresponding gap 92a at the time of cutting operation.
When the work 70 is fixed by the fixing member 92, a surface of the work 70 to be faced with the cutting blades 74, 76, i.e. the upper surface of the work 70, is pressed by the comb-like portion 98 to the table 84. By such a clamping, the work 70 can be held fixed during the cutting operation. The pressure from the fixing member 92 can be removed by outwardly tilting the upper portion 94c of the base portion 94. If the fixing member 92 is used, adjustment of the pressing force exerted to the work is not difficult. Thus, the work will not be chipped or otherwise damaged when being fixed even if the work is a member which is thin or fragile.
Further, as shown in
The table 84 has side surfaces each attached with a plate of enclosing member 112 so as to enclose the recess 82, making possible to hold the coolant 108 in the recess 82. If the enclosing members 112 are provided, the discharge pressure of the coolant 108 may not be greater than 294,210 Pa. It should be noted here that the bottom portion of the recess 82 is formed with positioning pins 114 for the disposing boards 88a, 88b.
Further, as shown in
As will be understood from
With the above arrangement, the discharge pressure of the coolant is 196,140 Pa˜1,471,050 Pa. Within this range, the cutting blades 74, 76 containing resin-bound diamond are abraded efficiently, cutting the works 70 smoothly. The discharge pressure of the coolant 108 should more preferably be 294,210 Pa˜686,490 Pa. Within this range, the discharge pressure will not deform the cutting blades 74, 76, making possible to accurately cut the works 70.
The lower port 122a supplies the coolant 108 to a cutting portion 126 where the works 70 make contact with the cutting blades 74, 76. The upper port 122b supplies the coolant 108 toward the work 70 on a downstream side of the rotating direction of the cutting blades 74, 76, i.e. toward the left work 70 shown in
Now, main actions of the work cutting apparatus 10a will be described with reference to FIG. 13A through FIG. 13D.
First, as shown in
According to the work cutting apparatus 10a as described above, a force which deforms the cutting blade 74 inevitably becomes smaller than in the convention shown in
The cutting blade 74 includes a substrate 74a made of a super hard metal such as tungsten carbide. As has been described above, this makes possible to reduce deformation and deflection of the cutting blade 74. Thus, a thickness of the substrate 74a can be further reduced, and the number of pieces obtained per work 70 can be increased.
Further, each of the works 70 can be set in alignment with corresponding one of the cutting blade blocks 28a, whereas the cutting blades 74, 76 are mounted at a high accuracy. Thus, it becomes possible to reduce inclusion of dimensionally inferior products particularly if there is dimensional inconsistency in the works 70.
Further, the thickness of the cutting blade 76 at each end of the cutting blade block 28a is made greater than the thickness of the cutting blades 74. This makes possible that each end margin of the work 70 potentially becoming a dimensionally inferior product can be ground into dust, preventing inclusion of the inferior products. Thus, yield can be improved, and productivity can be improved.
Further, as shown in
Further, if the radius of the cutting blades 74, 76 is set to a radius of the spacer added by (a thickness of the work 70+a thickness of the comb-like portion 98) for example, the radius of the cutting blades 74, 76 can be shortened. According to this arrangement, change in load acting on the cutting blades 74, 76 becomes smaller when cutting the work. Thus, the number of revolutions of the cutting blades 74, 76 can be stabilized, the deflection of the cutting blades 74, 76 can be reduced, leading to improved quality of the cut surface of work 70.
Further, as shown in
Since the work 70 is fixed by the fixing member 92 from above for the cutting, the cutting can be achieved without bonding the work 70 by adhesive. Thus, operations necessary for bonding and un-bonding become unnecessary, leading to improved productivity. An experiment showed that when a work of a size 20 mm×40 mm×60 mm was cut by the conventional work cutting apparatus 1, fifty-five minutes had to be used for bonding and un-bonding operations. On the other hand, according to the work cutting apparatus 10a, none of these operations were necessary, and therefore these operations could be eliminated. As for the cutting time, the work cutting apparatus 1 needed 18.5 minutes, whereas the work cutting apparatus 10a could decrease the time to 10 minutes. Therefore, the productivity can be improved.
It should be noted that by forming the recess 82 to have a V-shaped section, cost of machining the table 84 can be reduced, and applicability to a variety of kinds of works is achieved. Especially, a plate-like work can be positioned stably without rattling.
Further, the angle of the V which is the section of the recess 82 can be varied according to the shape and other conditions of the work. Further, if a work having a concave bottom surface such as the work 70 is to be placed, the coating members 90a, 90b may be formed with corresponding curvatures. Still further, the recess 82 may have an arcuate section. Especially in such a case, it is more preferable in further reducing the cutting time if the section should have the same curvature as of the cutting blade 74.
Further, according to the work cutting apparatus 10a, the supplying ports 122a, 122b provided in the coolant supplying portion 116 supply the coolant 108 from different locations. Moreover, by supplying the coolant 108 to the works 70 from the plurality of locations, the coolant 108 can be supplied reliably even if the cutting blades 74, 76 have an increased area of contact with the works 70 as shown in FIG. 15B. Therefore, the cutting blades 74, 76 can be abraded efficiently, making possible to cut the works 70 accurately and productively.
Further, since the coolant 108 is supplied to the cutting blades 74, 76 and the works 70 from the same side thereof and from the plurality of locations, sludge can be discharged smoothly.
Further, discharge of the coolant 108 from the supply port 122b makes possible to supply the coolant 108 to the work 70 located on the downstream side of the rotation of the cutting blades 74, 76. In this situation, the coolant 108 hitting the spacer 78 is spun off the spacer 78 and directed toward the downstream side work 70. Further, the coolant 108 from the supplying port 122b interrupts an accompanying stream of air which follows the rotating cutting blades 74, 76. Therefore, the coolant 108 from the supply port 122a becomes less affected by the accompanying stream, making possible to supply the coolant 108 more reliably from the supplying port 122a to the works 70.
Further, if the cutting blades 74, 76 include resin-bound diamond, insufficient amount of supply of the coolant 108 will cause abnormal friction in the cutting blades 74, 76, deteriorating the cutting accuracy. Thus, the present invention is especially effective.
Further, if the work 70 is a sintered compact such as a magnetic member, poor cutting accuracy easily cause cracking or chipping. Thus, the present invention is especially effective.
Further, by forming the supplying port 110 of the coolant 108 in the recess 82, it becomes possible to supply the coolant 108 to portions where the coolant supply portion 116 can not efficiently supply the coolant 108 such as a side surface of the work 70. Thus, cutting accuracy of the work 70 is improved further. This arrangement is especially effective if the work 70 has a large thickness.
Further, by enclosing the recess 82 by the enclosing members 112, it becomes possible to hold the coolant 108 in the recess 82. Thus, the work 70 can be cut while the work 70 is being bathed in the coolant 108. In addition, even if the discharge pressure from the supply port 110 is lower than the discharge pressure from the supply ports 122a, 122b, the coolant 108 can be supplied to the cutting blades 74, 76. Thus, the cutting accuracy of the work 70 can be further improved. Especially, it becomes possible to supply the coolant 108 sufficiently to the work 70 on the downstream side of rotation of the cutting blades 74, 76, which also prevents sludge buildup, facilitating accurate cutting of the work 70.
Now, description will cover an experiment conducted to the work cutting apparatus 10.
The experiment was made under the conditions shown in Table 1:
Cuttings were made in the setting shown in
The “dimensional inconsistency” was determined by the following method. Specifically, the thickness of a piece 132 obtained by cutting the work 70 was measured at five points as shown in FIG. 17A. Then, a difference between a maximum value and the minimum value of the thickness was obtained as the “dimensional inconsistency”. The “parallelism” was determined by the following method. Specifically, as shown in
The experiment revealed that the work cutting apparatus 10a could supply the coolant sufficiently. On the other hand, when only the coolant supply portion 130 was used as the coolant supplying portion, the coolant 108 could be supplied to the cutting portion 126 upon start of the cutting operation shown in FIG. 16A. However, during (in the latter phase of) the cutting operation shown in
Results of the experiment shown in FIG. 18A through
Results of the experiment shown in
As a reference, comparison was also made in the work cutting apparatus 10a, between two cases: In one case the coolant supplying portion only included the coolant supplying portion 116; in the other case, the coolant supplying portion included the coolant supplying portion 116 and the coolant supplying path 106. Results show that when the number of cutting operations increases, the increase in the abrasion rate becomes more significant in the case where only the coolant supplying portion 116 is used.
It should be noted here that the work cutting apparatus 10a may be provided with a table 84a as shown in FIG. 20. The table 84a is provided with a recess 82 having a bottom portion formed with slit-type supplying ports 110a. Other constitutions are the same as of the table 84. The slit-type supplying ports 110a can discharge the coolant 108 more uniformly to each of the cutting blades 74, 76.
Further, a coolant supplying portion 116a as shown in
According to the above embodiments, description was made for a case in which the cutting blades are moved toward the works 70. This is not limiting however; for example, the works 70 may be moved toward the cutting blades, further, both the works 70 and the cutting blades may be moved. Further, discretionary means maybe adopted for moving the works 70 or the cutting blades, so that the direction of relative movement between the cutting blades and the works 70 at the time of the cutting is in the vertical direction or along a normal line passing a contact point between the cutting blades and the works 70.
The present invention being thus far described and illustrated in detail, it is obvious that these description and drawings only represent an example of the present invention, and should not be interpreted as limiting the invention. The spirit and scope of the present invention is only limited by words used in the accompanied claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 11-21811 | Jan 1999 | JP | national |
| 11-21819 | Jan 1999 | JP | national |
This application is a Divisional Application of prior application having U.S. Ser. No. 09/494,124 filed Jan. 28, 2000 now U.S. Pat. No. 6,595,094.
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| Number | Date | Country | |
|---|---|---|---|
| 20030205119 A1 | Nov 2003 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09494124 | Jan 2000 | US |
| Child | 10448221 | US |
