Abstract:
A cutting tool for a machine tool including a tool body, at least one cutting edge and a cutting medium supplier. The tool body has one and another end portions along an axis thereof and is configured to be attached to a machine tool at the another end portions to be rotatable. At least one cutting edge is provided on the one end portion of the tool body. The cutting medium supplier supplies an atomized cutting fluid or a chilled gas to a place where a work is cut by the cutting edge.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cutting tool having at least one cutting edge and a method for supplying a cutting medium to a place where a work is cut by the cutting edge. 
     2. Discussion of the Background 
     A face milling cutter, as an example of cutting tools of the type having cutting edges provided on a tool body, has been known as disclosed in Japanese Unexamined Patent Application Publication No. 3-281114. 
     As seen from FIG. 16, this face milling cutter  1  has a tool body  2  and a plurality of cutting tips  3  attached to an end of the tool body  2  around its circumference at a predetermined interval. Guide members  4  guide shavings or metal chips generated as a result of a cutting. The guide members  4  are attached to the tool body  2  and each guide member faces the rake surface of the end cutting edge and outer peripheral cutting edge on the respective cutting tip  3 . At the same time, a substantially cylindrical member  5  serves as a receiver for receiving the chips and is provided coaxially with the tool body  2 . Chip receiving spaces  6  are formed between the inner peripheral surface of the chip receiver  5  and the outer peripheral surface of the tool body  2 , and the tool body  2  is rotatable relatively with respect to the chip receiver  5 . 
     In operation of the face milling cutter  1 , chips generated by the end cutting edge and outer peripheral edge on each tip  3  are forcibly hurled into the chip receiver  5  via the gap formed between the chip guide member  4  and the rake surfaces of the tip  3 . The chips are then urged towards the inner peripheral surface of the chip receiver  5  and expelled through a discharge port  7  so as to be collected in, for example, a collecting box which is not shown. 
     This arrangement serves to prevent the uncontrolled scattering of the chips, thus, contributing to an improvement in the working environment. Also, it prevents breakage of the cutting tool and damage to a workpiece surface since these problems tend to occur due to jamming of chips between the cutting edges and a workpiece. 
     The purposes of supplying a cutting oil are lubrication of the rake surface and relief surface of the tip, cooling of the tool and a workpiece, removal of stagnant fine chips, and protection and rust-prevention of the finished surface of a workpiece. 
     Hitherto, due to the use of a cutting oil in a liquid phase, there have been problems such as impairment of the working environment caused by scattering of the cutting oil, necessity of costly disposal of waste oil and so on. 
     The cutting oil in a liquid state is supplied inside the chip receiver  5  externally through a hose or the like. This involves a risk that the tips of the cutting tool and the surface of a workpiece are not steadily supplied with the cutting oil since these parts are encased inside the chip receiver  5 . 
     SUMMARY OF THE INVENTION 
     A first object of the present invention is to provide a cutting tool for a machine tool by which the amount of wasted cutting fluid is reduced. A second object of the present invention is to provide a cutting medium supplier for a cutting tool by which the amount of wasted cutting fluid is reduced. A third object of the present invention is to provide a method for supplying a cutting medium in a machine tool by which the amount of wasted cutting fluid is reduced. 
     The first object is achieved according to the present invention by providing a new cutting tool including a tool body, at least one cutting edge and a cutting medium supplier. The tool body has one and another end portions along an axis thereof and is configured to be attached to a machine tool at the another end portion to be rotatable. At least one cutting edge is provided on the one end portion of the tool body. The cutting medium supplier supplies an atomized cutting fluid or a chilled gas to a place where a work is cut by the cutting edge. 
     The second object is achieved according to the present invention by providing a new cutting medium supplier including a cutting medium supply mechanism which supplies an atomized cutting fluid or a chilled gas to a place where a work is cut by the cutting edge. 
     The third object is achieved according to the present invention by providing a new method for supplying a cutting medium in a machine tool having at least one cutting edge. In the method, an atomized cutting medium or a chilled gas is supplied to a place where a work is cut by the cutting edge. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will become readily apparent with reference to the following detailed description, particularly when considered in conjunction with the accompanying drawings, in which; 
     FIG. 1 is a sectional view of a face milling cutter in accordance with a first embodiment of the present invention, showing particularly a critical portion thereof; 
     FIG. 2 is a longitudinal sectional view of the face milling cutter of FIG. 1, showing the entirety of the cutter; 
     FIG. 3 is an end view of the face milling cutter shown in FIG. 1; 
     FIG. 4 is an enlarged sectional view of a critical portion of a modification of the face milling cutter shown in FIG. 1; 
     FIG. 5 is an enlarged sectional view of a critical portion of a face milling cutter in accordance with a second embodiment of the present invention; 
     FIG. 6 is a sectional view of a face milling cutter in accordance with a third embodiment of the present invention; 
     FIG. 7 is a plan view of the face milling cutter shown in FIG. 6; 
     FIG. 8 is a sectional view of a face milling cutter in accordance with a fourth embodiment of the present invention; 
     FIG. 9 is a sectional view of a face milling cutter in accordance with a fifth embodiment of the present invention; 
     FIG. 10 is an end view of a face milling cutter shown in FIG. 9; 
     FIG. 11 is a sectional view of a critical portion of a face milling cutter in accordance with a sixth embodiment of the present invention; 
     FIG. 12 is an enlarged view of a portion of the face milling cutter shown in FIG. 11; 
     FIG. 13 is a block diagram illustrating a step of coloring a cutting oil by a visualizing mechanism employed in a seventh embodiment of the present invention; 
     FIG. 14 is a block diagram illustrating a step of coloring a mixture of oil mist and air by a visualizing mechanism employed in an eighth embodiment of the present invention; 
     FIG. 15 is a block diagram illustrating a step of mixing a colored smoke in chilled air by a visualizing mechanism employed in a ninth embodiment of the present invention; and 
     FIG. 16 is a sectional view of a conventional face milling cutter. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will now be given of a face milling cutter in accordance with a first embodiment of the present invention, with specific reference to FIGS. 1 to  3 . 
     Referring to FIGS. 2 and 3, a tool body  11  has a generally cylindrical form with a reduced-diameter end. Tip-mounting seats  12  are formed in the outer peripheral edge at an axial end of the tool body  11 . The plurality of tip-mounting seats  12  is arranged at a predetermined circumferential pitch and each of the tip mounting seats is opened in the radial as well as axial directions of the tool body. 
     A replaceable tip (referred to simply as a “tip”, hereinafter)  13  is detachably seated on and fixed to each tip-mounting seat  12  by means of a clamping mechanism  14 . A face cutting edge  13   a  is formed on a ridge of the tip  13  projecting from the end of the tool body  11 , while an outer peripheral cutting edge  13   b  is formed on a ridge of the tip  13  projecting beyond the outer peripheral end of the tool body  11 . In FIG. 3, tip pockets  15  are formed at an axial end of the tool body  11  around its outer peripheral edge and each tip pocket  15  is positioned just ahead of its respective tip  13  in the rotational direction of the tool body  11 . The tip pockets  15  have the shape of a recess opening in an arcuate form and are opened in the radial as well as axial directions of the tool body  11 . 
     A chip guide member  16  is embedded in the bottom of the tool body  11  and is fixed thereto by means of countersunk screws  17 . The chip guide member  16  guides chips generated by the cutting edges  13   a ,  13   b  into chip reservoir spaces which will be described later. The chip guide member  16  has a flat annular form and hook-shaped projections  16   a  are formed on the outer periphery of the chip guide member  16 . Each hook-shaped projection  16   a  is disposed just in front of its respective tip  13  so as to face the rake surface of the respective tip  13 , leaving a slight gap therebetween. Therefore, chips generated by the cutting edges  13   a ,  13   b  are guided into a chip reservoir space R by the chip guide member  16 . 
     A mounting hole  18  is coaxial with the tool body  11 . A stem portion  19   a  of an arbor  1   9  is inserted into the mounting hole  18  from the smaller-diameter end (upper end as viewed in FIG. 2) of the tool body  11 . A fastening bolt  20  is screwed into the stem  19   a , thereby fixing the tool body  11  to the arbor  19 . 
     A taper shank  19   c  is provided on the end of the arbor  19  opposite to the stem  19   a . The taper shank  19   c  is chucked on a spindle S of a machine tool, thus the tool body  11  is fixed to the machine tool. 
     The stem  19   a  of the arbor  19  has a large-diameter journal portion  19   b  which is fixed to a bearing  21 . A fixed part  22   a  of a chip receiver  22  (simply referred to as a “fixed part  22   a ”) has an upper end portion that fits on the outer race of the bearing  21 . The fixed part  22   a  is fixed by means of bolts  24  to a cover  23  that is secured to the outer race of the bearing  21 , whereby relative rotation is allowed between the tool body  1  and the fixed part  22   a  about the axis of the tool body  11 . 
     The chip receiver  22  also has a movable part  22   b  (simply referred to as a “movable part  22   b ”) which also has a cylindrical form and which is telescopically received in the fixed portion  22   a  so as to be slidably adjustable up and down along the inner peripheral surface of the fixed-part  22   a . The movable part  22   b  is secured by means of a bolt  25  to the fixed part  22   a  such that the end extremity of the movable part  22   b  is retracted axially inward (upward as viewed in FIG. 2) from a level of the cutting depth of the outer peripheral cutting edge  13   b  of the tip  13 . 
     As seen from FIG. 1, the diameter of the movable part  22   b  becomes progressively smaller at its lower end, so that the diameter of the inner peripheral surface of the movable part  22   b  is slightly greater than the circle formed by the locus of the outer peripheral cutting edge  13   b . A plurality of oil passage bores  26  is formed in the wall of the movable part  22   b  so as to extend axially linearly, at a regular interval in the circumferential direction. 
     More specifically, the lower end portion of the movable part  22   b  is bent radially inward such that the inner and outer diameters progressively decrease towards the lower end extremity. Thus, the outer peripheral surface of the movable part  22  is tapered at the lower end portion  22   b A in which discharge ports  26   a  of the oil passage bores  26  are provided. 
     Thus, the fixed part  22   a  and the movable part  22   b  in combination provide the chip receiver  22  which covers the tool body  11  and the outer peripheral cutting edges  13   b , from the upper side of the tool body  11 . The inner peripheral surface of the chip receiver  22  and the outer peripheral surface of the reduced-diameter portion of the tool body  11  define therebetween the chip reservoir space R to which chips are introduced via the tip pockets  15 . 
     The chip receiver  22  is provided with a chip discharge opening  27  which penetrates the wall of the chip receiver  22 . A connecting pipe  28  fits at its one end in the chip discharge opening  27 . 
     A duct hose  29  has one end fitting on the other end of the connecting pipe  28  and another end that is connected to a suction device (not shown) for inducing air flow from the chip reservoir space R. 
     An oil mist m is generated by a mist generating device  152  which is connected to a cutting oil source  151  and an air source  179 . Further, the mist generating device  152  is connected to the oil passage bores  26  via a hose  178 . The mist generating device  152  atomizes a trace amount of cutting oil (preferably a vegetable oil) into uniform microfine particles in a well known method and mixes these particles with a large volume of air supplied by the air source  179 , thereby forming the oil mist m that is eventually jetted from a mist outlet. Accordingly, the oil mist is generated by the mist generating device  152  in a well known method and then introduced into the oil passage bores  26  through the hose  178 . 
     The oil mist m can flow even into tiny gaps and wet much greater surface area of an object to be cut than a cutting oil in liquid, thereby enhancing the cooling and lubricating effects. Furthermore, since only a trace amount of oil mist m is used, the quantity of wasted oil to be collected is significantly reduced. 
     In order that a workpiece w is milled by the face milling cutter having the described construction, the tool body  11  is chucked to a machine tool and then the workpiece w is fixed on a working platform such that the surface to be milled is normal to the axis of the spindle S of the machine tool. 
     Then, either the spindle S or the platform is moved in the axial direction of the spindle S so that the cutting tool comes in contact with the workpiece fixed on the platform. The cutting tool cuts into the surface of the workpiece w as either the spindle S or the platform moves while they remain perpendicular to each other. 
     Consequently, the surface of the workpiece w is cut by the face cutting edge  13   a  and the outer peripheral cutting edge  13   b , as illustrated in FIG.  1 . 
     The chips generated as a result of the cutting are introduced into the tip pockets  15  via the gap between the rake surface of the tip  13  and the end surface of the hooked projection  16   a  of the chip guide member  16  and further into the chip reservoir space R via the tip pockets  15 . The chips are then sucked and collected into the suction device through the connecting pipe  28  and the duct hose  29 . 
     The air pressure in the chip reservoir space R is reduced due to the effect of the swirl generated as a result of rotation of the tool body  11  and the effect of the suction generated by the suction device. Accordingly, the oil mist m discharged from the end of the chip receiver  22  is introduced into the inside of the chip receiver  22 , so as to wet the surface of the work w, as well as the cutting edges  13   a ,  13   b . Therefore, the better lubricating and cooling effects can be obtained. 
     A description will now be given of a modification of the face milling cutter, with specific reference to FIG.  4 . In this Figure, the same or equivalent parts as those in the first embodiment are designated by the same reference numerals and the descriptions of such parts are omitted. 
     This modification features an annular anti-scattering member  31  attached to the outer peripheral surface  22   b A of the chip receiver  22  (specifically the lower end of the movable part  22   b ). The anti-scattering member  31  is attached on the peripheral surface  22   b A and located further away from the tool body  11  than the oil discharge ports  26   a ; as a result, the outer peripheral surface of the movable part  22   b  is extended in the axial direction of the tool body  11  (downward as viewed in FIG.  4 ). 
     Thus, the described modification of the face milling cutter employs the anti-scattering member  31  that extends along the outer peripheral surface of the movable part  22   b  so as to cover the discharge ports  26   a . The anti-scattering member  31  effectively prevents the oil mist m from scattering radially outward, even when the discharged oil mist m tends to spread conically from the oil discharging ports  26   a . Further, the anti-scattering member ensures a sufficiently large rate of supply of the mist to the workpiece surface and the cutting edges  13   a ,  13   b.    
     In the described modification of the first embodiment, the anti-scattering member  31  is formed as a separate member from the movable part  22  and then fixed to the latter by means of welding, bolts or the like. This, however, is only illustrative and the anti-scattering member  31  may be formed as an integral part of the movable member  22   b . The annular form of the anti-scattering member  31  also is illustrative, and the anti-scattering member  31  may be substituted by a plurality of arcuate baffle plates that are arranged at positions corresponding to the positions of the oil discharge ports  26   a.    
     Although a cutting oil is specifically used in the above and following embodiments, other cutting fluids commonly used in machining may be used in place of the cutting oil. Similarly, a face milling cutter is an exemplary application of a cutting tool of the present invention; hence, other applications of the present invention are possible. 
     A second embodiment of the present invention will now be described with reference to FIG.  5 . In this Figure, the same or equivalent parts as those in the first embodiment are designated by the same reference numerals and the descriptions of such parts are omitted. 
     The face milling cutter of the second embodiment features the oil discharge ports  41   a  directed toward the tool body  11 . 
     More specifically, in this embodiment, the oil passage bores  41  run through the movable parts  22   b  in the axial direction of the tool body  11 . However, the oil passage bores  41  bend along the lower end portion  42  of the movable part  22   b  which bends toward the tool body  11 . The oil discharge pores  41   a  is located at the end extremity of the lower end portion  42  of the movable part  22   b.    
     In the face milling cutter of the second embodiment, the oil mist m is jetted at positions closer to the cutting edges  13   a ,  13   b  and the cut surface of a workpiece than that in the first embodiment. Thus, the face milling cutter discharges the oil mist m more efficiently and also facilitates a more effective suction of the excessive cutting oil. 
     A third embodiment of the present invention will now be described with reference to FIGS. 6 and 7. In these Figures, the same or equivalent parts as those in the previous embodiments are designated by the same reference numerals and the descriptions of such parts are omitted. 
     The face milling cutter of this embodiment features a cover  51  provided around the tool body  11  such that the tool body  11  is rotatable relative to the cover  51 . A chip reservoir space R is formed between the inner peripheral surface of the cover  51  and the outer peripheral surface of the tool body  11  A discharge opening  52  communicating with the chip reservoir space R is formed in the cover  51 . In addition, an auxiliary chamber  53  is provided so as to communicate with the discharge opening  52 . The auxiliary chamber  53  is formed to expand progressively outward in the radial direction of the tool body  11  along the circumference of the cover  51 . The auxiliary chamber  53  has an open end which serves as a chip outlet  54 . 
     A plurality of oil passage bores  55 , each having a substantially L-shaped section, is formed at an end portion of the cover  51  around its circumference at a certain pitch and opens at the outer peripheral surface and axial end surface of the cover  51 . In the illustrated embodiment, there are eight such oil passage bores. A nozzle  56  is inserted into each oil passage bore  55 . The nozzles  56  are connected to hoses  58  via connecting members  57 . Accordingly, an oil mist m is supplied to the nozzles  56  via the hoses  58 . 
     In operation of the face milling cutter of the illustrated embodiment, chips generated by the cutting edges  13   a ,  13   b  and introduced into the chip reservoir space R, are urged towards the inner peripheral surface of the cover  51  and are moved via the discharge opening  52  into the auxiliary chamber  53 , and are finally discharged through the chip outlet  54 . 
     The rotation of the tool body  11  creates a swirl that causes air to flow from the chip reservoir space R into the auxiliary chamber  53  and subsequently to be discharged from the chip outlet  54 . Accordingly, a lower air pressure is maintained in the chip reservoir space R and the oil mist m discharged from the end of the cover  51  is drawn towards the inside of the cover  51 . Thus the oil mist m is supplied to the surface of the workpiece w and the cutting edges  13   a ,  13   b  without being scattered, and affords the superior lubricating and cooling effects. 
     A description will now be given of a fourth embodiment of the present invention, with specific reference to FIG.  8 . In FIG. 8, the same or equivalent parts as those in the previous embodiments are designated by the same reference numerals and the descriptions of such parts are omitted. 
     The chip receiver  61  used in this embodiment has a base end portion  62  which is connected to the outer peripheral surface of the bearing  21 . The base end portion  62  has a cylindrical surface whose axis coincides with the axis O of the tool body  11 . The outer peripheral surface  63  has an upper peripheral surface portion  63   a  and a lower peripheral surface portion  63   b . The upper peripheral surface portion  63   a  has an outside diameter slightly smaller than that of the lower peripheral surface portion  63   b , whereby a step  64  is formed in the outer peripheral surface  63 . 
     An annular block ring  65  is detachably fixed on the upper peripheral surface portion  63   a . A part of the block ring  65  is expanded radially outward so as to provide an expanded portion  66  in which a locating pin (locating member)  68  is mounted. The locating pin  68  is engageable with a mating recess  67  formed in a spindle head S 1 . 
     More specifically, an insert hole  71  is formed in the expanded portion  66  and extends parallel to the axis O, so that the above-mentioned locating pin  68  can be inserted in and out of the hole  71 . A through-hole  72  having a small diameter upper portion  72   a  and a large-diameter lower portion  72   b  is formed in the locating pin  68 . A spring  73  is loaded between the bottom of the insertion hole  71  and the upper end of the large-diameter lower portion  72   b  in the locating pin  68 . 
     A communication hole  81  is formed in the mating recess  67  of the spindle head S 1  and communicates with the aforesaid mist generating device  152  via the hose  178 , so that the oil mist m can be supplied from the mist generating device  152  which is connected to the cutting oil source  151  and the air source  179 . Thus, the oil mist m flows into the through-hole  72  in the locating pin  68  when the locating pin  68  is connected to the mating recess  67 . Another through-hole  82  is formed in the bottoms of the insertion hole  71  and expanded portion  66 . 
     In this embodiment, the chip receiver  61  has an expanded portion  61   a  which is located diametrically across the connecting pipe  28 . A hose  85  disposed between the expanded portion  61   a  and the expanded portion  66  of the block ring  65  provides a communication between the aforementioned through-hole  82  and an oil passage bore  83  formed in the expanded portion  61   a.    
     The oil passage bore  83  has a base end portion that extends coaxially with the through-hole  72  and the hose  85 , but turns toward the axis of the chip receiver  61  at a substantially mid portion, then turns again just before the outer peripheral surface of the chip receiver  61  and continues to extend along the outer peripheral surface of the chip receiver  61 . 
     In the operation of the face milling cutter of this embodiment, the tool body  11  mounted on an arbor  19  is chucked on the spindle S of a machine tool by means of an automatic tool exchanging device, typically a machining center. To this end, the locating pin  68  is positioned so as to be aligned with the mating recess  67  in the spindle head S 1 . Subsequently, with the key  92  of the spindle S fitting in a keyway  91  formed in the arbor  19 , the arbor  19  is fitted in the spindle S. At the same time, the end portion  68   a  of the locating pin  68  is received in the mating recess  67  of the spindle head S 1 . 
     Consequently, a complete oil passage includes the communication hole  81 , through-hole  72 , hose  85  and oil passage bore  83 , whereby the oil mist m supplied by the mist generating device  152  is sprayed from the end of the chip receiver  61 . Thus, the face milling cutter of this embodiment can be used without hampering the automatic operation of the automatic tool exchanging device, typically a machining center. 
     During the milling operation, air is discharged from the chip reservoir space R via the connecting pipe  28 , by the effect of the swirl which is generated as a result of rotation of the tool body  11 . Consequently, a reduced air pressure is maintained inside the chip reservoir space R, so that the oil mist m discharged from the end of the chip receiver  61  is effectively drawn towards the inner peripheral surface of the chip receiver  61 . The oil mist m is therefore supplied to the surface of the workpiece w and the cutting edges  13   a ,  13   b  without being scattered. Thus, the excellent lubricating and cooling effects can be obtained. 
     A description will now be given of a fifth embodiment of the present invention with reference to FIGS. 9 and 10. In these Figures, the same or equivalent parts as those in the previous embodiments are designated by the same reference numerals and the descriptions of such parts are omitted. 
     In this embodiment, a plurality of hook-shaped chip guide members  91  is disposed on the end of the tool body  11  around its circumference at a certain pitch and fixed thereto by means of countersunk screws  17 . The tool body  11  is further provided with discharge bores  101  for discharging the oil mist m from the lower end thereof The discharge bores  101  are disposed at a suitable circumferential pitch. The number of the discharge bores  101  is equal to that of the tips  13 . The discharge bores  101  extend from the base end face  11 A towards the lower end  11 B in a diverging manner so as to deviate progressively from the axis O. The passage bores  101  lead to the discharge openings  101   a  which open on the lower end surface  11 B near the tips  13 . 
     The arbor  19  has a spindle-receiving bore  102  formed therein so as to extend from the base end surface  19 A toward the large-diameter journal portion  19   b . The arbor  19  further has communication bores  103  that extend from an end of the spindle-receiving bore  102  so as to open on the end surface  19 B of the large-diameter journal portion  19   b.    
     The spindle receiving bore  102  extends to a position near the end of a threaded bore  104  into which the fastening bolt  20  is screwed. A spline  106 , which is formed near a middle section of the spindle-receiving bore  102 , engages with the spindle  105  of the machine tool so as to prevent relative rotation of the spindle  105 . 
     As in the case of the discharge bores  101 , the communication bores  103  of the same number as that of the tips  13  are formed inside the large-diameter journal portion  19   b  at a certain spacing and extend in a diverging manner to radiate progressively outward from the axis O to the end surface of  19 B of the large diameter journal portion  19   b . Each communicating bore  103  communicates with the respective discharge bore  103  via a stepped bore  107 . 
     A bearing  111  is fixed to the large-diameter journal portion  19   b  of the arbor  19 . A substantially cylindrical chip receiver  112  has an upper end portion  112   a  that fits on the outer race of the bearing  111 . The upper end portion  112   a  is fixed by a bolt (not shown) to a cover  113  which in turn is fixed to the outer race of the bearing  111 . Accordingly, the tool body  11  is allowed to rotate relatively with respect to the chip receiver  112  about the axis O. 
     The upper end portion  112   a  of the chip receiver  112  has a radially outwardly expanded portion  114  which has a mating bore  115  opening in the upper end surface of the expanded portion  114 . A locating pin  117  is slidably received in the mating bore  115  with a compression spring loaded therebetween. 
     The locating pin  117  is provided with a locking portion  118  at its upper end portion. The locking portion  118  projects towards the axis O and engages with a recess  119  formed in the outer peripheral surface of the arbor  19 . The arrangement is such that, when the arbor  19  is not mounted on a machine tool, the locating pin  117  is lifted by the force of the spring  116  as shown in FIG. 9, so as to cause the locking portion  118  to engage with the recess  119 , thereby preventing relative rotation between the arbor  19  and the chip receiver  112 . 
     A lower end part  112   b  of the chip receiver  112  extends along the axis O and surrounds the tool body  11  and outer peripheral cutting edges  13   b ; therefore, the inner peripheral surface of the lower end portion  112   b  and the outer peripheral surface of the tool body  11  define the chip reservoir space R. The end portion of the lower end part  112   b  is bent toward the tool body  11  close to the outer peripheral cutting edges  13   b . The chip reservoir space R receives chips generated by the cutting edges  13   a ,  13   b  through the tip pockets  14 . 
     A connecting pipe  28  is formed integrally to the lower end part  112   b  of the chip receiver  112  and communicates between the chip reservoir space R and the exterior of the chip receiver  112 . The connecting pipe  28  has an open end which serves as a chip discharge opening  29 ; hence, the chips are expelled from the chip reservoir space R. A suction machine may be connected to the open end of the connection pipe  28  through, for example, a duct hose, in order to create air flow from the chip reservoir space R. 
     The spindle  105  has an axial central communication bore  131  extending along the axis O and opening at the lower end of the spindle  105 . The communication bore  131  is designed to channel the oil mist m which is generated by the mist generating device  152 . The oil mist m jetted from the discharge openings  101  is drawn into the chip reservoir space R due to the vacuum created by the suction machine and the rotation of the tool body  11 , and is eventually expelled from the chip outlet  29  together with the chips. 
     In the state in which the arbor  19  has been mounted on the machine tool, the spindle  105  is in the spindle receiving bore  102  of the taper shank portion  19   c  and the locating pin  117  is in a mating recess formed in the machine tool. The locating pin  117  is pressed into the mating recess against the spring  116 . In this state, the locking portion  118  is disengaged from the recess  119 ; therefore, the tool body  11  fixed to the arbor  19  is allowed to rotate while the chip receiver  112  is held stationary by the machine tool. 
     At the same time, the communication bore  131 , spindle receiving bore  102 , communication bores  103  and discharge bores  101  complete a passage for the oil mist m. Therefore, the oil mist m is generated by the mist generating device  152  which is connected to the cutting oil source  151  and the air source  179  and then discharged from the end of the tool body  11  through the hose  178  and the aforementioned passage. 
     The chips generated in the course of the cutting operation are collected in tip pockets  14  via the gaps formed between the rake surfaces of the tips  13  and the chip guide members  91 , and are further introduced into the chip reservoir space R. The chips are then sucked and collected by the suction machine via the connection pipe  28 , together with the oil mist m discharged from the discharge openings  101   a.    
     In the face milling cutter of this embodiment, the oil mist m is supplied through the discharge passages  101  formed in the tool body  11  and is discharged from the discharge openings  101   a  which open at positions near the cutting edges  13   a ,  13   b . Accordingly, the oil mist m is steadily supplied to the cutting edges  13   a ,  13   b  and the surface of the workpiece which is being machined, while any surplus oil mist is sucked and collected by the suction machine without being scattered to the environment. Therefore, excellent working performance is developed under a clean working environment. 
     Obviously, the third, fourth and fifth embodiments can have a suction machine connected to the connection pipe  28  via a duct hose  29  as in the case of the first embodiment, so that the suction of the oil mist m and the discharge of the chips are further promoted. 
     Chilled air of −30° C. to −40° C. may be directly jetted to a cooling object as the cutting medium in place of the oil mist m. It is also possible to form the oil mist by mixing a trace amount of cutting oil with such chilled air. Likewise, other gases commonly used in machining may be used in place of air. When these cutting media are used, the cost incurred for the disposal of the waste oil can be substantially reduced because the consumption of the oil is drastically reduced. In addition, working performance equivalent or superior to that realized with the use of liquid cutting oil can be achieved under a clean working environment. 
     A sixth embodiment of the present invention will now be described with specific reference to FIGS. 11 and 12. In these Figures, the same or equivalent parts as those in the previous embodiments are designated by the same reference numerals and the descriptions of such parts are omitted. 
     This embodiment is devoid of any passage bore  26  formed in the movable part  22   b . Instead, a hose  141  is extended from the machine tool so as to be able to spray an oil mist m to a region near the end of the chip receiver  22 . The aforesaid mist generating device  152  which is connected to the cutting oil source  151  and the air source  179  is also connected to the base end of the hose  141  via the hose  178 . Thus, the oil mist m is supplied during the machining. 
     The machining employing an oil mist has the following problem. Since the oil mist is formed by mixing a trace amount of cutting oil in a large volume of air, it is impossible to recognize the oil mist visually. Thus, it is often extremely difficult to check whether the oil mist is adequately supplied during the machining or whether the oil mist is aimed at the target position. Consequently, it is difficult to confirm and direct the sprayed oil mist correctly to the target position. 
     The same problem is encountered also in the system that employs the chilled air as the cutting medium, because in such a system the chilled air of −30° C. to −40° C. is supplied directly or together with a small amount of cutting oil to form an oil mist. 
     In view of this problem, the face milling cutter of this embodiment employs, as shown in FIGS. 11 and 12, a light projecting device  142  serving as a visualizing mechanism that projects infrared rays or other light rays L to a predetermined area. Thus, the oil mist m jetted from nozzles  141   a  becomes visible. The light projecting device  142  turns on and off between light-emitting and non-emitting modes. 
     To mill a workpiece w by using the face milling cutter of this embodiment, a user sets the tool body  11  on the machine tool and fixes the workpiece w such that the surface of the workpiece lies normal to the axis of the spindle. Then, the nozzle  141   a  is aimed at the target area where the oil mist m will be jetted or an area near the end of the chip receiver  22 . The nozzle  141   a  sprays the oil mist m while the light projecting device  142  projects the light rays L. 
     The light rays L impinging upon the oil mist is reflected randomly, so that the user can visually recognize the shot of the oil mist m. If the aim is deviated from the target region, the user can adjust the direction of the nozzle  141   a  so as to correct the locus of the oil mist m. The light projecting device is then turned off to stop the emission of the light rays L and thus the preparation for a cutting operation is completed. 
     Then, either the spindle or the working platform is moved along the axial direction of the spindle, thereby allowing the cutting tool to come in contact with the surface of the workpiece w. The cutting tool cuts into the surface of the workpiece w as the spindle or the working platform is moved while they remain perpendicular to each other. Consequently, the surface of the workpiece w is cut by the face cutting edge  13   a  and the outer peripheral cutting edge  13   b.    
     The chips generated as a result of the cutting are temporarily collected into the tip pockets  15  after being guided through the gap between the rake surfaces of the tips  13  and the end surfaces of the hook-shaped projections  16   a . Then, the chips are further hurled into the chip reservoir space R and finally, through the connection pipe  28  and duct hose  29 , collected to the suction machine. 
     In this embodiment of the face milling cutter, the light projecting device is provided to project the light rays L to the sprayed oil mist m, so that the oil mist m is reflected in the light rays and becomes visible. As a result, the density as well as range of the sprayed oil mist m can be ascertained and that will facilitate the adjustment of the nozzle  141   a  prior to a cutting operation. 
     The light projection device is turned off during a cutting operation so that the operator can observe the cutting and will not be disturbed by the light rays which may be reflected otherwise. 
     A description will now be given of a seventh embodiment of the present invention, with specific reference to FIG.  13 . In this Figure, the same or equivalent parts as those in the previous embodiments are designated by the same reference numerals and the descriptions of such parts are omitted. 
     This embodiment also employs a visualizing mechanism. In place of the light projecting device  142  used in the sixth embodiment, the seventh embodiment employs a coloring device which colors the cutting oil to enhance the visibility of the sprayed oil mist m. 
     More specifically, the visualizing mechanism employs, as shown in FIG. 13, a buffer portion  153  interposed between a source  151  of the cutting oil and the mist generating device  152 , and a colorant injection device  154  which injects a colorant into the buffer portion  153 . The buffer portion  153  is capable of reserving a predetermined amount of the cutting oil. The cutting oil stored in the buffer portion  153  is colored when the colorant is injected by the colorant injection device  154 , and the cutting oil thus colored is sent to the mist generating device  152 . 
     The colored cutting oil is atomized by the mist generating device  152  and is mixed with air to form a colored oil mist m that is discharged from the nozzle  141   a . The density as well as range of the sprayed oil mist can be easily recognized because the oil mist m is colored. 
     The visualizing mechanism of this embodiment also serves to facilitate the position adjustment of the nozzle  141   a  prior to a cutting operation. When the cutting operation is started, the oil mist m can be discolored as the injection of the colorant into the buffer portion  153  is stopped. This eliminates the necessity of an additional step of washing the colorant away from the workpiece w after the cutting. 
     A description will now be given of an eighth embodiment, with specific reference to FIG.  14 . In this Figure, the same or equivalent parts as those in the previous embodiments are designated by the same reference numerals and the descriptions of such parts are omitted. 
     This embodiment employs a visualizing mechanism that sprays an oil mist m together with an atomized colorant, thereby enhancing visibility of the oil mist m. 
     The visualizing mechanism includes a chamber  161  disposed downstream of the mist generating device  152 , and a spraying device  162  that atomizes a mist of a colorant into the chamber  161 . An oil mist m generated by the oil mist generator  152  is introduced into the chamber  161 . At the same time, the mist of colorant is sprayed by the spraying device  162  into this chamber  161 . Thus, the oil mist m and the mist of the colorant are mixed together. The mist mixture thus formed is sprayed from the nozzle  141   a . Consequently, the mist of the colorant is sprayed together with the oil mist m, thus facilitating the visual recognition of the sprayed oil mist m. 
     The visualizing mechanism of this embodiment also facilitates the position adjustment of the nozzle  141   a  conducted prior to a cutting operation. During a cutting operation, uncolored oil mist m alone can be sprayed as the supply of the mist of the colorant into the chamber  161  is stopped. Hence, the necessity of the washing step is eliminated as in the case of the preceding embodiment. 
     A ninth embodiment of the present invention will now be described with reference to FIG.  15 . 
     Chilled air is used as the cutting medium in this embodiment. This embodiment employs a visualizing mechanism that makes the chilled air visible by mixing a colored smoke. 
     Air is supplied to a heat exchanger  171  and chilled through a heat exchange with a refrigerant such as liquid nitrogen. Thus, chilled air of −30° C. to −40° C. is obtained. The visualizing mechanism includes a chamber  172  disposed downstream of the heat exchanger  171  and a smoke mixing device  173  which generates a colored smoke and introduces the same into the chamber  172 . The smoke mixing device  173  generates and sends a color smoke into the chamber  172 . The chilled air and colored smoke flow into the chamber  172  and thus are mixed together. The mixture is discharged from the nozzle  141   a , thus the density and range of the chilled air can be visually recognized without difficulty. 
     The visualizing mechanism of this embodiment also facilitates the adjustment of the nozzle  141   a  prior to a cutting operation. During a cutting operation, the smoke making device  173  stops sending a colored smoke into the chamber  161  so that chilled air alone can be sprayed. Therefore, the necessity of the washing step is eliminated as in the case of the preceding embodiment. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.