WO1984003649A1

WO1984003649A1 - Liquid cooled cutting tool holder

Info

Publication number: WO1984003649A1
Application number: PCT/US1983/000393
Authority: WO
Inventors: Marvin L Robey; Richard M Baker
Original assignee: Marvin L Robey; Richard M Baker
Priority date: 1983-03-18
Filing date: 1983-03-18
Publication date: 1984-09-27
Also published as: EP0140883A1

Abstract

An improved cutting tool holder for liquid cooled cutting tools (10) that allows a cutting tool (50) during operation, to be completely flooded with coolant fluid from one end of the tool to the other. The tool holder (10) is designed to be used with lathes, drilling machines or milling machines and is adaptable to both tool holders that remain stationary while the workpiece rotates and those that rotate while the workpiece is stationary. The tool holder (10) is basically comprised of a collet holder (12) to which is attached a nose piece (14) having a collant nozzle (18) from where the stream of coolant fluid flows longitudinally throughout the length of the cutting tool (50).

Description

LI^QUID COOLED CUTTING TOOL HOLDER

TECHNICAL FIELD

The invention pertains to the general field of chuck mounted internal cutting tools and more particu¬ larly to cutting tools that are cooled by a coolant fluid while in operation.

BACKGROUND ART

Most chuck mounted internal cutting tools, such as twist drills, boring bars and reamers, that are used with a lathe, drilling machine or a milling machine must be continuously cooled during operation to prevent the tool from heating and eventually burning. This cooling is normally accomplished by allowing a stream of coolant fluid to be applied directly to the cutting surface of the tool. The coolant is normally applied under pressure through a coolant delivery line, i.e., copper tubing, that is separated from the cutting tool. The copper tubing nozzle is located near the surface of the tool and is manually adjusted to assure that the coolant is directed at the surface of the cutting tool. The four most prevalent problems associated with this generally used cooling method are:

1. The copper tubing and nozzle must be period- ically adjusted to allow the coolant to be directed at the cutting tool. This may require several adjustments before an adequate directed flow is achieved.

2. A heavy chip from the cutting action may strike the copper line with sufficient force to move the line. This movement can redirect the coolant flow away from the cutting tool often causing the tool to burn.

3. With a single directed spray the total working surface of a cutting tool may not be adequately flooded with sufficient coolant fluid to prevent tool damage.

4. With internal cutting tools it is best to. mount the tool as close to the tool holder as possible to maintain maximum tool rigidity. Tool rigidity is important to maintain concentricity and prevent tool chatter which, in turn, prolongs tool life. Because of the bending arc required in the tubing it is neces¬ sary that the cutting tool be extended by as much as 1.5 in. (38.1 mm) which reduces the potential cutting depth of the tool by the same distance. A search of the prior art did not uncover any patents that directly read on the claim of the inven¬ tion. However, the following U.S. patents are related and are representative of the current state of the prior art. PATENT INVENTOR ISSUED DATE

4,231,354 Dahinden 22 July 1980

4,037,982 Clement 26 July 1977

3,577,808 Visser 4 May 1971

The Dahinden patent discloses a method and means for cooling a stationary twist drill by a coolant. The coolant is supplied through a main delivery line and a conduit based in the tool holder by coolant pumps. The coolant then enters into a ring having two opposite ball jets from where the coolant is conveyed having two opposite ball jets from where the coolant is conveyed in two concentrated streams onto the grooves of the drill. The Clement patent discloses an axially-moveable rotatable tool having a suction chamber that abutts against a work surface during machining to remove chippings and dust particles. The suction is combined with the blowing of a compressed fluid that is gen¬ erally directed towards the operative point of the tooL

The Visser patent discloses a sub-zero cutting fluid generator that applies coolant to drills through an external mist delivery generator. The generator comprises an air intake with an air filter and dryer means. The air is thus cleaned, dehydrated and is compressed through an air compressor connected to a nozzle that is aimed at the drill cutting area.

DISCLOSURE OF THE INVENTION The improved cutting tool holder for liquid cooled cutting tools allows a cutting tool i.e., drills, boring bars, and reamers to be constantly and completely flooded with coolant fluid during operation. The tool holder is designed to be used with lathes, drilling machines, or milling machines and is adaptable to tool holders that remain stationary while the work¬ piece rotates or those that rotate while the workpiece is stationary.

The problem with using cutting tools, and especially high speed tools, is that the cutting tool must be continuously cooled during operation to prevent the tool from heating and eventually burning. Tool cooling is currently accomplished by directing a stream of coolant fluid onto the cutting surface of the tool. The coolant is normally applied under pressure through a copper coolant line that is separated from the cutting tool holder. This coolant line is adjusted so that nozzle is located near the surface of the cutting tool. Because the line is flexible and there have been inci- dents where the line has been displaced by an

O PI inadvertent bump or a heavy flying chip it is necessary that the line be periodically adjusted to assure that the line nozzle is properly directed at the cutting tool. This problem as well as the other problems described in the BACKGROUND ART section are solved by the inventive tool holder.

The tool holder is basically comprised of a collet holder that incorporates a collet for holding the cutting tool, and a nose piece that holds the collet and has a removable coolant nozzle that is selected in accordance with the size of the cutting tool. The coolant fluid is inserted, under pressure, at the rear of the collet holder and flows out of the coolant nozzle with sufficient pressure to allow the fluid to flow longitudinally throughout the length of the cutting tool. With this arrangement, the cooling line with its inherent problems is eliminated. Also, since the fluid flow covers the entire cutting tool, it is now possible to mount the tool closer to the tool holder. Thus, providing better tool rigidity, concentricity and a prolonged tool life, as well as increased machine capacity.

In addition to the above advantages it is also an objective of the invention to provide a cutting tool holder that: o is completely free from adjustments after operation begins, o is cost-effective in terms of material and manhours saved in adjustment time, and o is easy to use and maintain.

OMPI WIP BRIEF DESCRIPTION OF THE DRAWINGS

The details of the invention are described in connection with the accompanying drawings in which:

FIGURE 1 is a side sectional view of the first embodiment of the invention showing the tool holder connected to a pressurized coolant source.

FIGURE 2 is a front view of the collet holder nose piece.

FIGURE 3 is a side view of the collet holder nose piece.

FIGURE 4 is a front view of the coolant nozzle.

FIGURE 5 is a partial cutaway side view of the coolant nozzle showing one design configuration of the orifice. FIGURE 6 is a front view of the stop screw.

FIGURE 7 is a side view of the stop screw.

FIGURE 8 is a front view of the collet.

FIGURE 9 is a side sectional view of the second embodiment of the invention showing the tool holder connected to a pressurized coolant source through a rotary fluid coupling.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the invention of an improved cutting tool holder for liquid cooled cutting tools is described in terms of two embodiments. The first embodiment is generally used with lathes while the second is used with milling and drilling machines. The basic difference in the two embodiments is that in the first embodiment the collet holder remains stationary while the workpiece rotates while in the second embodiment the collet holder rotates while the workpiece remains stationary. Thus, each embodiment requires a different method for applying the coolant fluid into the tool holder.

The first embodiment of the improved cutting tool holder for liquid cooled cutting tools 10 is shown in FIGURES 1 through 8 and is comprised of six major elements: a collet holder 12, a collet holder nose piece 14, a standard collet 16, a coolant nozzle 18, a stop screw 20, and a pipe nipple 22.

The collet holder 12 as shown in FIGURE 1 is comprised in the first embodiment of a cylindrical housing constructed of 4140 tool steel or the like, and having a partial tapered bore 12a extending there¬ through. At the front inside end of the collet holder, is a threaded front bore 12b while at the back is a threaded back bore 12c. The body of the collet holder has a set of longitudinal flats 12d to allow the holder to be mounted on a lathe tool holder mounting block with set screws.

The collet holder nose piece 14, as shown in FIGURES 2 and 3, is also made of 4140 tool steel, or the like, and is threaded at its front side with threads sized to allow the nose piece to be inserted into the threaded front bore 12b of the collet holder 12. The nose piece is essentially a standard item that is modified for the purpose of the invention.

The modification consists of extending the thickness of the nose piece flange and threading a conventional tool entry hole to form a threaded nozzle bore 14a into which is inserted the coolant nozzle 18 described infra.

In one of its configurations the nose piece, as best shown in FIGURE 4, is internally comprised, in sequential order, of a roller or ball bearing 14b, a push ring 14c, a strip ring 14d and a retaining spring washer 14e. The internal elements primarily function, in combination, as a collet 16 holding

O PI and adjusting means.

The collet 16 is a standard element located with¬ in the tapered bore 12a of the collet holder and used to clamp or loosen the cutting rool 50 when the collet holder nose pice 14 is respectively rotated. Around the collet circumference is a plurality of alternating straight-through slots 16b and partial slots 16c. The slots terminate at the collet front in a radial pattern as shown in FIGURE 8. The collet front edge is design- ed to rest against the edge of the roller or ball bear¬ ing 14b while the push ring 14c pushes the collet 16 back against the tapered bore 12a causing the collet to close and tighten on the cutting tool 50. The strip ring 14d, which fits into the circumferential collet groove 16a, causes the collet to more forwardly when the nose piece 14 is loosened. This action loosens the grip on and releases the cutting tool 50. The retain¬ ing spring washer 14e sequentially retains the strip ring 14d, the push ring 14c and the bearings 14b. The coolant nozzle 18, as shown in FIGURES 4 and

5, is a cylindrical piece having threads 18a that fit into the threaded nozzle bore 14a on the nose piece 14. In the preferred embodiment the nozzle has a centered orifice 18b as shown in FIGURE 5 that has a flat sec- tion 18c at the front of the orifice and a downward slops18d commencing at the end of the flat and extend¬ ing to the rear of the nozzle. By having this shape, the fluid develops a laminar flow at the orifice exit causing the coolant to flow around and throughout the longitudinal surface of the cutting tool. The design of the orifice however, is not critical thus, other orifice designs with different ratios of flat and slope surfaces or a plurality of orifice bores directed at the cutting tool will also adequately function. The bore diameter 18b is dependent upon the diameter of the cutting tool. For example, an orifice diameter of 0.3125 in. (7.938 mm) will work on any cut- ing tool up to a diameter of 0.250 in. (6.350 mm) while an orifice diameter of 0.375 in. (9.525 mm) will work on cutting tools from 0.203 in. (5.159 mm) up to 0.3125 in. (7.938 mm). The only critical design re¬ quirement of the nozzle is that the orifice diameter must be larger than the diameter of the cutting tool 50, but small enough to maintain a sufficient flow pressure. The front of the coolant nozzle 18 has a split groove 18e to allow the nozzle to be tightened into or loosened from the threaded nozzle bore 14a.

The final element described is the stop screw 20. This element is threaded 20b, as shown in FIGURES 6 and 7, to allow it to be inserted into the threaded back bore 12c in the collet holder 12. The stop screw has a coolant bore 20a that is sized and threaded to accept a standard pipe nipple 22. The pipe nipple, in turn, is attached by means of a standard coolant line 52 to a pressurized coolant fluid source 54. Note that the coolant bore 20a must be offset from center to pre¬ vent the back end of the cutting tool from obstructing the flow of the coolant fluid.

The second embodiment of the invention 10 is shown entirely in FIGURE 9. As previously mentioned, the basic functional difference in this embodiment is in the manner in which the coolant fluid enters the cutting tool holder. The second embodiment is com¬ prised of seven major elements: a second collet holder 24, a second collet holder nose piece 26, a second collet 28, a second coolant nozzle 30, a hollow draw bar 32, a second stop screw 34 and a rotary fluid coupling 56. The structural differences include the addition of the hollow draw bar 32 and the rotary fluid coupling 56 that is attached to the rear end of the draw bar. Additionally, the second embodiment will function with or without the stop screw 34. The collet holder 24 is comprised of a cylin¬ drical housing constructed of 4140 steel or the like and having a partial tapere_^d bore 24a extending there¬ through where the taper narrows as it approaches the rear of the collet holder. The front end of the holder is threaded to form the front threads 24b while at the back of the holder is a threaded second stop screw bore 24c followed to the rear by a draw bar bore 24d. The holder 24 is designed to be inserted into a spindle shaft 58 where the shaft 58 rotates about a stationary spindle 60 as shown in FIGURE 9. If the second collet holder employs a second stop screw it is equipped with threads that allow the stop screw to be threaded into the stop screw bore 24c. The second collet holder nose piece 26 is also made of 4140 steel or the like, and has a threaded nose piece bore 26a having threads that are sized to allow the nose piece to be threaded onto the front threads 24b of the second collet holder 24. The inside surface of the nose piece is equipped with a collet holding means that is similar to that described in the first embodiment. The front of the nose piece has a threaded nozzle bore 26b into which is inserted the second coolant nozzle 30. The second collet 28 is a standard element that is located within the tapered bore 24a of the second collet holder 24. The second collet is constructed in a similar manner as in the first embodiment and is also used to clamp down on the cutting tool when the second collet holder nose piece 26 is tightened. The collet is held within the second collet holder nose piece 26 by a collet holding means that is standard and well known in the tool holding industry.

The second coolant nozzle 30 consists of a cylindrical piece that is sized and threaded to allow the nozzle 30 to be attached to the threaded nozzle bore 26b located on the front end of the second collet holder nose piece 26. The design of the second coolant nozzle 30 is similar to the coolant nozzle 18 described in the first embodiment. The coolant fluid is supplied to the second col¬ let holder 24 by means of the hollow draw bar 32 and the rotary fluid coupling 56. The draw bar 32 is hollowed by having a bore 32a extending therethrough and threads 32b on one end to allow the hollow draw bar 32 to be inserted into the threaded draw bar bore 24d on the second collet holder 24. A flange 32d is pro¬ vided to limit the forward travel of the draw bar. The other end of the hollow draw bar 32 has a conventional rotary fluid coupling attaching means 32c that allows the draw bar to be attached to the rotary fluid coupl¬ ing 56. The other end of the rotary fluid coupling 56 is equipped with an input end having a standard pipe nipple 56a or the like that attaches through a standard coolant line 52 to a pressurized coolant fluid source 54.

OPERATION - Both embodiments of the invention as shown in FIGURES 1 and 9 operate in a similar manner. There¬ fore, the operation is primarily described in terms of the first embodiment with differences between the two covered at the end of the discussion.

Initially the pressurized coolant fluid from the pressurized coolant source 54 enters the tool holder 10 through the coolant bore 20a on the stop screw 20. From the stop screw the pressurized coolant flow is directed primarily through the straight-through slots 16b and secondarily through the partial slots 16c in the collet 16. The fluid then flows through the space between the front of the collet 16 and the back of the coolant nozzle 18 through the nozzle orifice 18b and onto the circumferential and longitudinal surface of the cutting tool 50.

JUSE

O PI fa_y, WIPO In the second embodiment the fluid enters the tool holder through the hollow draw bar 32 that is coupled to the rotary fluid coupling 56. Note that in the second^" embodiment the use of a stop screw is not mandatory for the proper functioning of the invention.

Although the invention has been described in complete detail and pictorially shown in the accompany¬ ing drawings, it is not to be limited to such details, since many changes and modifications may be made to the Improved Cutting Tool Holder for Liquid Cooled Cutting Tools without departing from the spirit and scope thereof. Hence, it is described to cover any and all modifications and forms which may come within the language and scope of the claims.

Claims

1. An improved cutting tool holder for liquid cooled cutting tools comprising a collet holder having an internal collet that secures a cutting tool, with said collet holder having a coolant nozzle located at its front end with said nozzle having an orifice with a diameter that is larger than the diameter of the cutting tool, and where said collet holder has an attaching means for connecting to a source of pres- surized coolant fluid, where said fluid is directed through said collet holder and collet out of said nozzle and onto the path of an attached cutting tool.

2. The tool holder as specified in claim 1 wherein said pressurized coolant fluid attaching means is comprised of a stop screw attached to the back sec¬ tion of said collet holder, with said stop screw having a threaded bore into which is attached a standard pipe nipple to where a coolant fluid pressure line is attached.

3. An improved cutting tool holder for liquid cooled cutting tools comprising: a) a collet holder, b) a collet holder nose piece attached to the front of said collet holder with front of said nose piece having a nozzle bore and where a collet holding means is included within said nose piece, c) a coolant nozzle having an orifice and means for attaching said nozzle to the nozzle bore located on the front of said collet holder nose piece, d) a standard collet held in place within said collet holder nose piece by the collet holding means, e) a stop screw attached to the back of said collet holder with said stop screw having a bore

OMPI into which is attached a standard pipe nipple, and f) means for supplying coolant fluid into the pipe nipple on said stop screw.

4. An improved cutting tool holder for liquid cooled cutting tools comprising: a) a collet holder comprised of a cylin¬ drical housing having a partial tapered bore there¬ through with the front inside end of said holder having a threaded front bore and the back inside end having a threaded back bore, b) a collet holder nose piece having an external threaded section at its front end that is sized to allow said nose piece to be threaded into the threaded front bore on said collet holder and with the front of said nose piece having a threaded nozzle bore and where the nose piece includes a collet holding and adjusting means, c) a coolant nozzle consisting of a cylin¬ drical piece that is sized and threaded to fit into the threaded nozzle bore on said collet holder, with said coolant nozzle having a centered orifice with a diameter that is larger than the diameter of the cutting tool, d) a standard collet centrally located and held in place within said collet holder nose piece by said collet holding means where said collet has a circumferential groove located near its front and hav¬ ing around its circumference a plurality of alternating straight-through slots and partial slots, e) a stop screw having external threads sized to all w said stop screw to be threaded into the threaded back bore on said collet holder and with said stop screw having a coolant bore sized to accept and retain a standard pipe nipple, and

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OMPI f) means for supplying pressurized coolant into the pipe nipple on said stop screw.

5. The tool holder as specified in claim 4 wherein said collet holding means within said collet holder nose piece is comprised of a combination of a ball bearing, a push ring, a strip ring and a retaining spring washer, where said standard collet front edge rests against the edge of the ball bearing while the push ring pushes said collet back against the tapered bore of said collet holder causing said collet to close and tighten on the cutting tool, and where the strip ring fits into the circumferential groove in said collet causing said collet to move in a forward direc¬ tion when said nose piece is loosened causing a release of the cutting tool, and where the retaining spring washer sequentially retains the push ring, the strip ring and the ball bearing.

6. The tool holder as specified in claim 4 wherein said coolant nozzle having a plurality of orifice bores directed at said cutting too.

7. The tool holder as specified in claim 4 wherein the coolant bore on said stop screw is offset from center.

8. The tool holder as specified in claim 5 wherein said colletholding means is comprised of a combination of a roller bearing, a push ring, a strip ring and a retaining spring washer.

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OMPI

9. An improved cutting tool holder for liquid cooled cutting tools comprising: a) a second collet holder consisting of a cylindrical housing having a partial tapered bore there- through with the front end of said holder being threaded and with the back of said holder having a threaded draw bar bore, b) a second collet holder nose piece hav¬ ing a threaded nose piece bore with the threads sized to allow said second collet nose piece to be threaded into the front threads of second collet holder and where the front surface of said nose piece has a second coolant nozzle fastening means and where the inside surface of said nose piece is equipped with a collet holding means, c) a second coolant nozzle consisting of a cylindrical piece that is attached to the front end of said nose piece by the second coolant nozzle fasten¬ ing means with said coolant nozzle having an orifice with a diameter that is larger than the diameter of the cutting tool, d) a standard collet centrally located and held in place within said collet holder nose piece by said collet holding means, e) a draw bar having a collant bore there¬ through and threads on one end to allow said draw bar to be threaded into the threaded draw bar bore on said second collet holder and where other end of said draw bar has a rotary fluid coupling attaching means, f) a rotary fluid coupling having an input end with a standard pipe nipple and an output end attached to the fluid coupling attachment means on the other end of said draw bar, and g) means for supplying pressurized coolant into the pipe nipple located on said rotary fluid coupling.

10. The tool holder as specified in claim 9 wherein said second collet holder further comprises a structure having a threaded second stop screw bore located forward of the draw bar bore and into which is inserted a threaded second stop screw.