JP2010214545A - End mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill in which cooling efficiency of a cutting blade is improved without lowering a chip discharge property to further extend the service life thereof. <P>SOLUTION: The cutting blade 4 having an end cutting edge 4b is provided to a head 3 of the end mill 1, and a coolant supply passage 10 is formed so as to penetrate through the end mill 1. An end of the coolant supply passage 10 is opened in a second clearance surface 7 arranged in a rear side in a rotating direction of the cutting blade 4. A recessed part 12 working as a coolant reservoir is formed at least in a region in the rear side in the rotating direction out of a region surrounding an opening 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an end mill that is mounted on a machine tool such as a machining center and performs a workpiece surface cutting process and the like.

  For example, the seating of the workpiece is performed by plunge feeding an end mill mounted on a machine tool such as a machining center and cutting the workpiece with a cutting blade provided at the tip of the end mill. During this type of processing, at the tip of the end mill, the cutting blade is cooled to prevent damage to the cutting blade, etc., and for the purpose of extending the life of the end mill. Coolant such as lubricating oil is supplied for the purpose of increasing the cutting accuracy (machining accuracy) of the workpiece. The coolant supply method is roughly divided into an external supply method that supplies from the outside using a separate supply tool such as a nozzle and an internal supply method that supplies the coolant through a coolant supply passage formed in the end mill. Since the supply system has difficulty in supplying coolant at a high speed of the end mill, the internal supply system is often adopted in recent years when the high speed rotation of the end mill is progressing.

  As an end mill provided with a coolant supply path, for example, one disclosed in Patent Document 1 below is known. As shown in FIG. 4, the end mill 100 disclosed in this document has a coolant supply path opened in a groove bottom (“gash” in the document) 103 on the rake face 102 side of the cutting edge 101 provided at the tip. It is. According to such a configuration, the coolant discharged from the opening 104 can be directly applied to the rake face 102, so that the effect of preventing damage to the cutting blade 101 can be enhanced.

JP-A-8-318419

  However, when the workpiece is cut using the end mill of Patent Document 1, the chips are scraped off to the groove bottom 103 on the rake face 102 side as shown in FIG. For this reason, most of the discharged coolant comes into contact with the shaved chips and is discharged together with the chips, and there is a possibility that a necessary and sufficient amount of coolant cannot be supplied to the cutting blade 101 (the rake face). Moreover, since the opening part 104 is arrange | positioned in the position adjacent to the scoop surface 102 of the cutting blade 101, there exists a possibility that a coolant cannot be supplied to the cutting blade 101 whole. Therefore, the conventional configuration cannot cool the entire cutting edge 101 uniformly and sufficiently, and is insufficient for effectively preventing damage to the cutting edge 101 and the like.

  An object of the present invention is to provide an end mill that improves the cooling efficiency of the cutting blade without lowering the discharge of chips and thereby further extends the life.

  In order to achieve the above object, according to the present invention, in an end mill having a cutting edge at a tip portion and having a coolant supply passage for supplying coolant to the tip portion, it is provided on the rear side in the rotation direction of the cutting blade. There is provided an end mill characterized in that a coolant supply passage is opened in the flank and a recess is formed at least in a region on the rear side in the rotational direction in a peripheral region of the opening.

  As described above, in the end mill according to the present invention, the coolant supply path is opened on the flank. If it does in this way, compared with the structure of the said patent document 1, a coolant will be discharged from the position spaced apart from the cutting blade (the rake face). As a result, the amount of the coolant that is discharged can be reduced in direct contact with the shaved chips, so that the amount of coolant that can be supplied to the cutting blade can be relatively increased. Further, the coolant discharged from the opening flows to the rear side in the rotational direction as the end mill rotates. If such a coolant flow is possible, the coolant diffuses along with this flow, so that the coolant can be uniformly supplied to the entire cutting blade. Accordingly, the cooling efficiency of the cutting blade can be improved. On the other hand, the chips that have been scraped off come into contact with the coolant that flows as the end mill rotates, so that the chips may stick to the rake face of the cutting blade and reduce its discharge performance, and in turn the cutting accuracy. As a result, it is possible to prevent as much as possible.

  The end mill according to the present invention has a recess in the peripheral region of the opening in addition to the above configuration. Since the recess functions as a coolant reservoir for holding the coolant, even if chips are scraped off in the vicinity of the opening, it is possible to prevent a situation in which the opening is completely blocked by the chip. Further, since the recess is provided at least in the region on the rear side in the rotational direction, the coolant held in the recess can be efficiently flowed in the direction of the rake face of the cutting blade as the end mill rotates.

  It is desirable that the width of the recess is gradually increased toward the rear side in the rotation direction. By doing so, the diffusibility of the coolant held in the recess can be increased during the rotation of the end mill, so that the above-described operational effects can be obtained more remarkably.

  The configuration of the present invention described above can be applied to various known end mills regardless of what is called a ball end mill whose tip has an arc shape or what is called a square end mill whose tip is flat.

  As described above, according to the present invention, it is possible to improve the cooling efficiency of the cutting blade without lowering the chip discharging performance and consequently the cutting accuracy. Thereby, the life of the end mill can be further extended, the labor required for replacement can be reduced, and the production efficiency can be improved.

It is a side view of the end mill concerning one embodiment of the present invention. It is the figure which looked at the end mill shown in FIG. 1 from the arrow X direction. Both (a) figure and (b) figure are the principal part enlarged views of the end mill which concerns on other embodiment. It is the figure which looked at the end mill of the conventional structure from the front end side.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing an end mill 1 according to an embodiment of the present invention. An end mill 1 shown in FIG. 1 is a so-called solid type, and is provided with a shaft-shaped shank portion 2 held by a machine tool such as a machining center (not shown), and a pair of cutting blades 4, 4. The head part 3 having the main part is made a main part, and the center part O can be rotated about the center of rotation O. Note that the end mill 1 of the present embodiment rotates in the counterclockwise direction, that is, in the direction of arrow A in FIG. The cutting blades 4 and 4 are respectively provided at the spiral outer peripheral blade 4 a provided at the outer peripheral portion of the head portion 3 and the tip portion of the head portion 3 (the tip portion of the end mill 1). It is comprised with the front-end | tip blade 4b extended in the orthogonal direction. The end mill 1 having such a configuration is also referred to as a square end mill. The surface on the front side in the rotational direction of the tip blade 4b constituting the cutting blade 4 is a rake surface 5 for scooping up chips generated by cutting the workpiece with the tip blade 4b.

  On the front side in the rotational direction of each cutting edge 4, as shown in FIG. 2, a concave groove 8 formed by cutting out the meat of the head portion 3 in a substantially V-shaped cross section from the outer diameter side to the inner diameter side. Provided. As shown in FIG. 1, the concave groove 8 is defined by a rake face 5 and an inclined surface 9 that is inclined with respect to the central axis O, and spirally formed from the distal end side to the proximal end side of the head portion 3. It extends and functions as a discharge groove for chips generated as the workpiece is cut.

  A relief surface is provided on the rear side in the rotational direction of each cutting edge 4. That is, with the rake face 5 of the cutting edge 4 as a reference, a flank face and an inclined face 9 (concave groove 8) are provided in this order toward the rear side in the rotational direction. In the present embodiment, the first flank 6 is provided along the outer peripheral blade 4 a, and the second flank 7 is provided at the rear side in the rotation direction of the first flank 6 and on the tip side of the head portion 3. Provided. Of course, the form of the flank is not limited to this, and can be changed as appropriate.

  The end mill 1 is provided with a pair of coolant supply passages 10 so as to penetrate the shank portion 2 and the head portion 3. Each coolant supply passage 10 has a base end connected to a coolant tank (not shown), and a front end opened to each of the second flank surfaces 7 and 7. The coolant supply path 10 shown in FIG. 1 extends spirally along the central axis O, but this form is merely an example, and any other form is adopted as long as the tip opens to the flank. can do. For example, a single center hole may be formed from the shank portion 2 to the vicinity of the tip of the head portion 3, and branch holes branched from the center hole may be opened in the second flank surfaces 7 and 7, respectively. The usable coolant is not particularly limited, and oil, water, etc. may be appropriately selected according to the material of the workpiece.

  A recess 12 is formed in the peripheral area of the opening 11 of the coolant supply path 10 in the second flank 7. Here, a recess 12 is formed in a region on the rear side in the rotational direction in the peripheral region of the opening 11, and the concave portion 12 has a substantially fan shape whose width is gradually enlarged toward the rear side in the rotational direction. . One end of the concave portion 12 on the rear side in the rotation direction opens into the concave groove 8. The recess 12 functions as a coolant reservoir that holds the coolant during cutting using the end mill 1.

  The end mill 1 according to the present embodiment is mainly configured as described above, and workpiece seating using this is performed, for example, in the following manner.

  First, the end mill 1 is plunge-fed while rotating in the direction of arrow A in FIG. 2, and the workpiece surface is cut by the tip edge 4 b of the cutting edge 4. At the same time as the cutting of the workpiece is started, the coolant is discharged from the opening 11 of the coolant supply path 10. When the workpiece is cut by the tip edge 4b of the cutting edge 4, the generated chips are scraped off by the rake face 5 and scraped off to the concave groove 8 (inclined face 9) side. Chips that have been scraped off are moved and discharged to the rear side in the feed direction along the groove 8 while colliding with the inclined surface 9. The cutting edge 4, particularly the rake face 5 on the front side in the rotational direction of the tip edge 4b, is hot due to cutting heat or frictional heat generated by friction between the rake face 5 and the chips as the workpiece is cut. It becomes. If this high temperature state continues, problems such as damage to the cutting edge 4 and adhesion of chips to the rake face 5 and reduction in cutting accuracy occur. However, the coolant discharged from the opening portion 11 is sequentially removed from the cutting edge 4 and Such problems are prevented as much as possible by contacting the chips.

  At this time, if the coolant supply path 10 is opened on the flank (second flank 7) as described above, the cutting edge 4 can be compared with the conventional configuration in which the coolant supply path is opened in the gasche. Since the coolant is discharged from the separated position, the amount of the coolant discharged from the opening 11 directly contacting the scraped chips can be reduced. Therefore, the amount of coolant that can be supplied to the cutting blade 4 is increased compared to the conventional configuration in which most of the discharged coolant comes into contact with the scraped chips and is discharged together with the chips. The cooling effect of 5 can be enhanced. Further, the coolant discharged from the opening 11 flows backward in the rotational direction as the end mill rotates. If such a coolant flow is possible, the coolant diffuses along with this flow, so that the coolant can be evenly supplied to the entire cutting edge 4 (rake face 5). On the other hand, since the coolant flowing along with the rotation of the end mill 1 comes into contact with the shaved chips, good chip discharge is ensured.

  In addition, since the recess 12 is provided in the peripheral region of the opening 11 of the coolant supply path 10, a part of the discharged coolant is held in the recess 12. That is, since the coolant pool is provided around the opening 11, even if chips are scraped off near the opening 11, the situation in which the opening 11 is completely blocked by the chips is prevented. Can do. Further, since the recess 12 is provided in at least the region on the rear side in the rotation direction of the end mill 1 in the peripheral region of the opening 11 and one end on the rear side in the rotation direction is opened in the recess 8, the rotation of the end mill 1 is performed. Accordingly, the coolant held in the recess 12 can be efficiently flowed in the direction of the rake face 5 of the cutting edge 4. Furthermore, since the concave portion 12 is formed in a fan shape whose width gradually increases toward the rear side in the rotation direction of the end mill 1, the diffusibility of the coolant is enhanced, and the supply efficiency of the coolant to the cutting edge 4 (rake face 5) is increased. Can be increased.

  However, since the centrifugal force acts on the coolant discharged from the opening 11 when the end mill 1 rotates, the cutting blade 4 (tip blade 4b) and the rake face 5 are disposed if the opening 11 is arranged too far in the radial direction. It may be difficult to supply a sufficient amount of coolant to the radially inner region. Therefore, it is desirable to determine the formation position of the opening 11 in consideration of the centrifugal force (rotational speed of the end mill 1) acting on the discharged coolant. For example, when the radius of the tip of the head 3 is r The opening 11 is preferably arranged radially inward of 3/4 · r with respect to the central axis O.

  Similarly, when the end mill 1 rotates, centrifugal force also acts on the coolant flowing out from the recess 12, and thus, among the two side walls that define the recess 12 described above, the side surface 12 a that is formed on the radially outer side is particularly formed. Depending on the case, there is a possibility that the coolant flowing out from the recess 12 cannot be used effectively. As one measure for solving such a problem, among the two side walls forming the recess 12, the side wall 12a on the outer side in the radial direction, in particular, urges the flowing force toward the inner side in the radial direction as much as possible. For example, it may be formed in an arc shape curved inward in the radial direction as shown in FIG.

  From the above, according to the present invention, it is possible to improve the cooling efficiency of the tip edge 4b of the cutting edge 4 and the rake face 5 without reducing the chip dischargeability. Thereby, the lifetime of the end mill 1 can be further extended, the labor required for replacement can be reduced, the production efficiency can be increased, and the machining accuracy of the workpiece can be increased. Incidentally, as a result of verification by the inventor of the present application, it has been found that the end mill 1 adopting the above-described configuration of the present invention can perform good cutting on the number of workpieces about 5 to 6 times that of the conventional configuration.

  In the above, the case where the concave portion 12 is provided only in the region on the rear side in the rotational direction of the end mill 1 in the peripheral region of the opening 11 formed in the second flank 7 has been described. For example, FIG. ), The recess 12 may be provided so as to surround the opening 11. In the embodiment described above, the opening 11 is arranged at a substantially intermediate position in the circumferential direction of the second flank 7, but the opening 11 is formed at the flank (the second flank in this embodiment). It can be arbitrarily set as long as it is within the circumferential range of 7).

  Moreover, although the case where the structure of this invention was applied to the end mill 1 which has a pair (two pieces) cutting blade 4 was demonstrated above, this invention is the end mill 1 which has one or three or more cutting blades 4. It is applicable to. In the above description, the case where the present invention is applied to a so-called square end mill whose tip is flat (the tip blade 4b extends in a direction perpendicular to the central axis O) has been described. Of course, the present invention can be applied to a so-called ball end mill in which the outer peripheral edge 4a and the front edge 4b constituting the cutting edge 4 are smoothly connected.

DESCRIPTION OF SYMBOLS 1 End mill 2 Shank part 3 Head part 4 Cutting blade 4a Outer peripheral blade 4b Tip blade 5 Rake face 6 First flank 7 Second flank 8 Groove 10 Coolant supply path 11 Opening 12 Recess (Coolant pool)
O Center axis

Claims (2)

In an end mill having a cutting edge at the tip, and having a coolant supply passage for supplying coolant to the tip,
The coolant supply path opens on a clearance surface provided on the rear side in the rotation direction of the cutting blade, and a recess is formed at least in a region on the rear side in the rotation direction in a peripheral region of the opening. End mill.   The end mill according to claim 1, wherein the width of the concave portion is gradually enlarged toward the rear side in the rotation direction.

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