EP1511595A1

EP1511595A1 - Coaxial lubrication system

Info

Publication number: EP1511595A1
Application number: EP03760290A
Authority: EP
Inventors: Wallace G. Boelkins
Original assignee: Unist Inc
Current assignee: Unist Inc
Priority date: 2002-06-12
Filing date: 2003-06-12
Publication date: 2005-03-09
Also published as: EP1511595A4; JP2005529757A; WO2003106104A1

Abstract

Lubricated and pressurized air is reliably provided to a machining point in machining a comparatively deep point in a workpiece via an inexpensive and simple coaxial manifold (17). Pressurized air enters an annular flow path (S1) and pressurized lubricant enters a central, coaxial flow path (S2) that terminates near the tool (2) and workpiece.

Description

COAXIAL LUBRICATION SYSTEM FIELD OF THE INVENTION

[0001] The present invention relates to a lubrication system for a spindle device for machine tools. More particularly, the present invention relates to an inexpensive coaxial lubrication system for the simultaneous delivery of air and lubricant to a workpiece.

BACKGROUND OF THE INVENTION

[0002] Machine tool lubrication systems of the past typically provided coolant/lubricant in large quantities to a machining point of a workpiece (sometimes called flood cooling) in order to cool down and lubricate the tool and workpiece and to eliminate cutting chips and other debris. There are, however, various problems with such systems, such as environmental pollution caused by the lubricant, adverse influence on human health, cost increase in line with treatment of waste lubricant, and lowering of the life of tools due to excessive cooling of workpieces. In addition, there are still other problems, for example, large costs associated with the mess and associated cleanup, as well as separation of the lubricant from the cutting chips when re-utilizing the cutting chips.

[0003] In order to solve these problems, devices have been developed that use very small amounts of lubricant by mixing air with the lubricant, usually a light water soluble oil, such as vegetable oil, to form a spray, where the lubricant spray is supplied to a machining point of a workpiece. In such units, using substantial amounts of air, the goal is not necessarily cooling, but rather elimination of the debris at the workpiece. That is, for example, when a drill bit is deeply penetrating into the workpiece, the orifices for the passage of lubricant flow become quite small and lubricant flow becomes attenuated. By replacing such liquid fluid with air combined with a small amount of lubricant, it is possible to quickly and faciley eliminate and blow away the debris from the drilling process and provide continuous lubrication to the workpiece as the drill continues to drill deeper into the workpiece. The air acts as a carrier for the lubricant, provides some cooling, evaporates the water, and keeps the lubricant in suspension.

[0004] An example of such a system may be found in U.S. Patent No. 5,676,506, which is hereby incorporated by reference. According to this patent, two supply path systems, which separately supply air and liquid into a spindle, are provided. A mist generating device, utilized to supply and jet air and liquid which are supplied by these supply paths, is provided in the front edge of the spindle or in the tool holder. Moreover, a bypass path is provided to cause an air supply path and the mist jetting side space of the mist generating device to communicate with each other. An opening and closing valve mechanism, which is maintained to be open only when the pressure of the mist generated by the mist generating device is less than a fixed pressure level, is provided halfway along said path. Also, a complicated stop valve, which is maintained to be closed when the liquid pressure is less than a fixed pressure level, is provided immediately before the mist generating device, which is the termination of the liquid supply path, in order to prevent liquid leakage from the mist generating device from occurring. While useful in delivering lubricant and air to a tool and workpiece, the above-described device is very complicated and quite expensive.

[0005] Thus, in comparison to the prior art, it is desired to sufficiently supply lubricant to a workpiece via an inexpensive and simple device.

[0006] According to the present invention, a lubricant and air spray are directly supplied to the tool, where the lubricant is simply entrained into the air stream via coaxial fluid paths without expensive and complicated devices. Further, in accordance with the present invention, it is also possible to restrict air bubbles in the lubricant path when the lubricant flow is terminated.

SUMMARY OF THE INVENTION AND ADVANTAGES

[0007] In order to achieve the above features, a spindle device includes a coaxial lubrication flow path, wherein the spindle has a spindle head having two inlet ports, one for the pressurized lubricant extending to a central lubricant manifold, and a second for pressurized air extending to an annular air manifold. The lubricant manifold is in fluid communication with a straight stationary lubricant inner tube extending deep into the spindle near the workpiece. Air flowing from the annular air manifold into the annular flow path about the lubricant inner tube likewise flows through the spindle to the workpiece. The lubricant flowing from the lubricant inner tube is entrained in the air flow and is delivered as a spray to the workpiece in the desired quantities as established by an external metering device. No complicated and/or expensive internal components are required or desired to provide the aforementioned device.

[0008] A capillary check valve may also be provided at the end of the lubricant inner tube. The capillary check valve includes an internal longitudinal port communicating with two external lateral ports orthogonally situated to the internal port, where the external ports are resiliently sealed with a quad seal, such that when the flow of lubricant is terminated, air bubbles in the lubricant flow circuit are retained in a pressurized state and are not allowed to evacuate to atmosphere pressure, preventing pneumatic buildup in the lubrication flow circuit. [0009] Thus, according to the present invention, a simple, facile and inexpensive method of delivering lubricant and air to the workpiece is provided. [0010] These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS [0011] Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: [0012] FIG. 1 is a longitudinal sectional view showing the spindle head portion according to the preferred embodiment of the invention; [0013] FIG. 2 is an enlarged longitudinal sectional view showing the upper part of the spindle head portion of the same preferred embodiment; [0014] FIG. 3 is an enlarged longitudinal sectional view showing a modified upper part of the spindle head of the same preferred embodiment; [0015] FIG. 4 is an enlarged longitudinal sectional view showing the lower part of the spindle head portion of the same preferred embodiment; [0016] FIG. 5 is a longitudinal sectional view showing the lower part of the spindle head portion according to a modified example of the same preferred embodiment; [0017] FIG. 6 is an enlarged longitudinal sectional view showing the lower part of the spindle head portion according to the same modified example of the same preferred embodiment; [0018] FIG. 7 is a longitudinal plan view showing the capillary check valve according to the same modified example of the same preferred embodiment; [0019] FIG. 8 is a longitudinal sectional view of the capillary check valve taken along line 8-8 of FIG 7; [0020] FIG. 9 is a longitudinal plan view showing the capillary check valve according to the invention; and

[0021] FIG. 10 is a cross-sectional view of the insert of the same preferred embodiment taken along line 10-10 of FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0022] In all the drawings attached to this specification, parts which are substantially identical to those in the respective drawings are given the same reference numbers in order to simplify the description of the invention.

[0023] Firstly, a description is given of the preferred embodiment of the invention. As shown in FIGS. 1 and 2, a tool 2 is fixed at the front edge of spindle 1. Spindle 1 has a head member 5, which rotatably surrounds the spindle 1. Pulley 6 transmits rotation to the spindle 1. Tool holder 8 is located at the end of spindle 1 near workpiece w.

[0024] A head 5 is fixed at the rear part of the spindle 1. The head 5 consisting of a staged axial cylindrical member 13 extendingly screwed in at the rear end face of the spindle 1. An outer cylindrical member 15 is fitted to the upper diameter-reduced part 13a thereof via bearings 14a, 14b, and at the same time a coaxial manifold 17 is fixed to the outer cylindrical member 15 by preferably three symmetrically disposed bolts 16. A cylindrical sliding member 19 is liquidtightly inserted into the inner opening 17a of the coaxial manifold 17 by an O ring 20. The cylindrical sliding member 19 has a flanged part 19a. A sliding ring body 21 is fixed at the front end thereof, is able to advance and retreat in the spindle 1 direction via a guide rod 22 fixed at the lower face of coaxial manifold 17 and is pressed to the spindle 1 side by a spring 23. A sliding ring body 24 in which said sliding ring body 21 is pressed to and brought into contact with the upper end face of said diameter-reduced part 13a of the axial cylindrical member 13 is fixed thereat. Supply port 31 (preferably a drilled and tapped 3/8 inch hole) supplies pressurized air into the air manifold 11a of the coaxial manifold 17, and supply port 32 (preferably a drilled and tapped 1/8 inch hole) supplies pressurized lubricant into the lubricant manifold 10 and the coaxial manifold 17 from a metering device 4.

[0025] Of course, other arrangements for the mounting of coaxial manifold 17 can be adapted. For example, existing rotating coolant unions, such as Deublin Model No. 1108 manufactured by Deublin Company of Waukegan, Illinois, can be installed via the standard reverse thread rotor thread into a standard spindle end and the aluminum end cap of the union can be simply replaced with an appropriately sized coaxial manifold 17 attached to intermediate member 18, as shown in FIG. 3. Thus, additional machining for the spring 23 and guide rod 22 can be avoided.

[0026] As shown in the drawings and noted above, head 5 includes the coaxial manifold

17 bolted to outer cylindrical member 15. An inner tube 12, preferably of nylon with an outer diameter of 1/8 inch, is sealingly and fixedly mounted in hole 10a of lubricant manifold 10 via seal 9. A triangular insert 12a, shown in FIG. 10, having three outwardly extending legs, is disposed about the inner tube 12 within the hole 13b of cylindrical member 13. Thus, the inner tube 12 is concentrically provided in an inner opening la of spindle 1, and the inside of the inner opening la is divided into two paths, one of which is an outside path SI and the other of which is an inside path S2 while making the wall face of the inner pipe 12 a boundary therebetween as shown, wherein the outside path SI is an air supply path and the inside path S2 is a lubricant supply path. The openings formed between the legs of the insert 12a provide air flow through outside path SI.

[0027] In the rotating joint between head 5 and spindle 1 , the outer cylindrical member

15, intermediate member 18 (if present), coaxial manifold 17, and inner tube 12 are supported in a non-rotating state, and the staged axial cylindrical member 13 is constructed so as to rotate integrally with the spindle 1. Sliding ring body 21 and sliding ring body 24 are caused to .relatively rotate in an under-pressure contacted state, liquidtight state. Therefore, even though the spindle 1 is rotating, air supplied from the supply port 31 reaches inside the supply path SI and the lubricant supplied by the supply port 32 reaches inside the other supply path S2, passing through the inner tube 12.

[0028] As shown in FIG. 4, the inner tube 12 terminates in an inner lower hole lb of the spindle 1. As lubricant is provided to the supply port 32, at significant pressures (usually less than 1000 psi), it flows from the lubricant manifold 10 into the inner tube 12 and down to the opening lb and flows outwardly therefrom by internal pressure. Air traveling down the fluid path SI, also under pressure (usually less than 100 psi), entrains the lubricant and causes the lubricant to flow toward the spindle holder 8 as a lubricant spray. In practice, the lubricant pressure must exceed the air pressure. Spindle holder 8 is fixed at the spindle 1 with a bolt, and a guide hole 8bl which is continuous from the center path 8b and which corresponds to the guide hole lb is secured at the center part on the upper end face of said holder 8. The front end of a path 2a (FIG. 1) of a tool 2 is branched to a plurality and the branched edges are made open at the points where each tool edge 2b exists.

[0029] When the device is started, rotations of a motor (not illustrated) are transmitted to the spindle 1 via a pulley 6, whereby pressurized air is supplied via a supply port 31 (FIG. 2) from a peripheral air supply line from metering device 4, and pressurized lubricant is supplied via another supply port 32 from a peripheral lubricant supply line, also from metering device 4.

[0030] The spindle head part moves downward as necessary in order to cause a tool 2 to machine a workpiece w. As machining continues, the tool edge 2b acts deep in the workpiece w. Since lubricant and air are supplied directly to the tool edge 2b, the supply thereof is not interrupted due to cutting chips, etc., whereby the machining part is able to be sufficiently lubricated and cooled.

[0031] FIG. 5 is a sectional view showing major parts of a preferred embodiment. In this embodiment, a capillary check valve 25 is attached to the end of the inner tube 12. With further reference to FIGS. 6-9, capillary check valve 25 includes a barbed end 26 that fits into tube 12. A sealing end 27 includes a longitudinal hole 28 that communicates with laterally disposed orthogonal holes 29, which extend outwardly at the sealing end 27. A quad seal or square O ring 30 is disposed over the holes 29 and between a pair of ribs 33, which hold the quad seal 30 in position. As the lubrication pressure in the inner tube 12 increases, the lubricant enters into the opening 28 and flows outwardly to openings 29, past the resilient quad seal 30 and into the opening lb. However, when the pressure in the inner tube 12 drops to a predetermined level (preferably about 40-50 psi), the resilient material, of which the quad seal 30 is comprised, causes the openings 29 to close.

[0032] This feature is desirable because it eliminates the capillary creation of air voids that would otherwise occur in the lower extremity of the inner tube 12 when pressure delivery to the lubricant flow path S2 is terminated. That is, when fluid flow through the inner tube 12 is terminated while allowed to vent to atmospheric pressure, air bubbles tend to form at the distal end. Cycling the lubricant pressure on and off, when the same is allowed to vent to ambient air pressure, tends to exaggerate the creation of air bubbles in the inner tube, which tends to interrupt the reliable flow of lubricant within the system. Thus, it is desirable to retain the pressure in the lubricant delivery system, including the inner tube 12, when lubricant flow is no longer necessary. This pressure tends to minimize the creation of air bubbles and provides reliable, predictable, and immediate flow when desired. Thus, lubricant and air are supplied via an inexpensive and simple device.

[0033] The capillary check valve 25 also provides acceleration of the air flow path SI due to the venturi effect created by the smaller flow area between the opening lb and the outer edges of the capillary check valve 25.

[0034] The above description is considered that of the preferred embodiments only.

Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention.

Claims

The invention claimed is:

1. A lubrication system for cutting tools, comprising: a metering device supplying pressurized liquid lubricant and pressurized gas; a manifold having first and second passages in fluid communication with said metering device, said first passage carrying gas, and said second passage carrying liquid lubricant; an elongated tube having a first end sealingly connected to said second passage; a spindle rotatably interconnected with said manifold and having a cavity having sidewalls and extending therethrough, said cavity sealingly and rotatably connected with said second passage, said elongated tube disposed in said cavity and defining a first axially extending pathway between said tube and said sidewalls, said tube having a substantially hollow construction and defining a first axially extending pathway therethrough; said tube having a second end positioned within a mixing portion of said cavity wherein said liquid lubricant and said gas are mixed, said spindle including a holder adapted to secure a cutting tool with said mixing portion in fluid communication with a passageway in a tool; and wherein: said first and second pathways are the sole fluid connections between said mixing portions and said manifold.

2. The lubrication system of claim 1, including: a check valve disposed at said second end of said tube.

3. The lubrication system of claim 2, wherein: said check valve includes an annular groove in fluid communication with said first pathway and a resilient ring-like member disposed in said annular groove.

4. The lubrication system of claim 1, wherein: said manifold is a one-piece member.

5. The lubrication system of claim 4, wherein: said tube is a one-piece member with said first end disposed in said second passage.

6. A lubrication system for cutting tools, comprising: a spindle assembly including a head and a spindle member rotatably and sealingly connected to said head; a supply of pressurized gas; a supply of pressurized liquid lubricant; a first pathway fluidly coupled to said supply of gas and extending through at least a portion of said head and said spindle member; a second pathway fluidly coupled to said supply of pressurized liquid and extending through at least a portion of said head and said spindle member; a cutting tool mounted to said spindle assembly; and said spindle member including a chamber fluidly coupled to said first and second pathways wherein gas and liquid lubricant are separately introduced and mixed.

7. The lubrication system of claim 6, including: a check valve disposed at said second end of said tube.

8. The lubrication system of claim 7, wherein: said check valve includes an annular groove in fluid communication with said first pathway and a resilient ring-like member disposed in said annular groove.

9. The lubrication system of claim 6, wherein: said spindle assembly includes a manifold with first and second passages fluidly coupled to said first and second pathways, respectively; and wherein: said spindle assembly includes a tube defining said second pathway, said tube having a first end disposed in said second pathway.

10. The lubrication system of claim 9, including: a check valve disposed at a second end of said tube.

11. The lubrication system of claim 10, wherein: said check valve includes an annular groove in fluid communication with said first pathway and a resilient ring-like member disposed in said annular groove.

12. The lubrication system of claim 11, wherein: said manifold is a one-piece member.

13. The lubrication system of claim 10, wherein: said tube is a one-piece member with said second end extending into said chamber.

14. The lubrication system of claim 13, wherein: said tube is made of a nylon material.

15. The lubrication system of claim 14, wherein: said check valve includes a barbed end received in said second end of said tube.

16. A lubrication system for cutting tools, comprising: a spindle assembly including a head and a spindle member rotatably and sealingly connected to said head; a supply of pressurized gas; a supply of pressurized liquid lubricant; a first pathway fluidly coupled to said supply of gas and extending through at least a portion of said head and said spindle member; a second pathway having a first end fluidly coupled to said supply of pressurized liquid and extending through at least a portion of said head and said spindle member; said spindle assembly including a chamber for mixing liquid and gas adjacent a second end of said second pathway; and a check valve at said second end of said second pathway disposed in said chamber.

17. The lubrication system of claim 16, including: a tube defining said second pathway.

18. The lubrication system of claim 17, wherein: said gas comprises air; and said supply of pressurized liquid lubricant cycles the pressure of the liquid lubricant on and off.

19. The lubrication system of claim 16, wherein: said check valve has an outer edge that reduces the flow area through said chamber and accelerates the flow of air due to the venturi effect.

20. The lubrication system of claim 19, wherein: said check valve includes an annular groove in fluid communication with said first pathway and a resilient ring-like member disposed in said annular groove.