Cutting by use of rotating axially moving tool – Processes – Bit detachable
Reexamination Certificate
2000-02-11
2001-04-03
Howell, Daniel W. (Department: 3722)
Cutting by use of rotating axially moving tool
Processes
Bit detachable
C408S059000, C408S226000, C408S238000, C279S020000
Reexamination Certificate
active
06210083
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Method of providing a cutting tool with lubricating coolant.
2. Background Information
One problem encountered in the cutting of work pieces, and of metal work pieces in particular, is that the boring tool, such as a drill, reamer or a rotating tool in general (the following description relates in particular to drills), heats up during the cutting process along with the material of which the work piece is made. In automatic mass production operations in particular, cooling and lubrication using a lubricating coolant (designated a “lubricant” below) is therefore necessary. In wet machining processes, a large excess of liquid lubricant is introduced into the hole as it is being drilled. This type of lubricating and cooling action entails relatively high costs for equipment, not to mention the costs of the lubricant supply, the necessary cleaning, etc. In drilling operations, moreover, it is not always possible to deliver the lubricant directly into the hole being drilled. Therefore, lubricating systems are used in which the lubricant is transported by means of transport devices via the spindle of a drilling machine and at least one lubricant channel in the drill to the site of the drilling. The site of the drilling is approximately in the vicinity of the major cutting edges or the chip faces of the drill. In these known lubrication systems a relatively large quantity of lubricant is required, because the supply lines which lead from the supply device to the drill or to the spindle of the drill must be filled with lubricant. In addition, a precise and controlled dispensing of small quantities of lubricant is very difficult to achieve using the conventional delivery devices.
OBJECT OF THE INVENTION
The object of the present invention is therefore a method, as well as a boring tool and tool holder to carry out the method, to accurately dispense a controlled and extremely small quantity of lubricant using technically simple means.
SUMMARY OF THE INVENTION
The present invention teaches that this object can be accomplished in accordance with one possible embodiment by a method for supplying rotating cutting tools, in particular a drill, with a lubricant which is used for cooling and/or lubrication. The lubricant is contained in a reservoir which is connected directly or indirectly to the boring tool and which reservoir functions as a dispenser from which the lubricant is transported through at least one lubricant channel and at least one discharge opening in the boring tool to a working part to be lubricated and/or cooled.
The present invention teaches that this object can also be accomplished in accordance with one possible embodiment by a boring tool, in particular a drill, to carry out the method. The boring tool has a shank, a cutter and at least one internal lubricant channel. At least one reservoir which functions as a dispenser for a lubricant is directly or indirectly connected mechanically to the boring tool and hydraulically to the at least one lubricant channel.
In addition, the present invention teaches that this object can be accomplished in accordance with one possible embodiment by a tool holder for holding a boring tool. The tool holder has an integrated dispenser for a lubricant, whereby the dispenser, when the boring tool is held in the tool holder, is hydraulically connected to at least one internal lubricant channel of the boring tool.
In the method of the present invention, a lubricant which is used for cooling and/or lubrication is contained in a reservoir. The reservoir acts as a dispenser and is directly or indirectly connected to the boring tool. The lubricant is transported from this dispenser to the respective working parts by at least one lubricant channel in the boring tool.
An advantage of the method taught by the present invention is that expensive supply devices, relatively expensive rotary transmission feed-throughs or adjustable pump units are no longer necessary. The dispenser can be connected directly to the boring tool, for example, and rotates along with the boring tool during the cutting of the work piece. A further advantage of the method taught by the present invention is that a precisely controlled quantity of lubricant can be made available for one, or preferably, for a plurality of drilling processes. For example, it is also conceivable that a dispenser, which dispenser is integrated into the shank of a boring tool, can contain a quantity of lubricant which is sufficient for the entire useful life of the boring tool. Such a boring tool can always be independently supplied with a sufficient quantity of lubricant, in particular, an extremely small quantity of lubricant, from a lubricant supply device which is installed on a drilling machine.
In one method taught by the present invention, there are a variety of possibilities for the propulsion of the lubricant flow during a drilling or cutting process. The propulsion force for the lubricant flow can advantageously be generated by locating the dispenser above the working parts of the boring tool. This situation occurs when the drilling operation is essentially from top to bottom. In an embodiment where discharge openings are located on the side of the boring tool, the centrifugal force which is generated by the rotation of the boring tool also acts on the lubricant. The lubricant transport caused by the hydrostatic pressure of the dispenser, which dispenser is located above the working parts, is therefore generally assisted by centrifugal forces. To prevent the lubricant from escaping when the boring tool is not in use, it is advantageous to use a lubricant which is solid or highly viscous at room temperature and which liquefies at the temperatures which are encountered during cutting operations. The lubricant, which is solid or highly viscous at room temperature, is retained in the lubricant channel by adhesion or cohesion forces. When the boring tool is in use, the boring tool heats up after a brief period of operation to a point where the lubricant is converted into a liquid or less viscous state. Gravity then acts on the lubricant, as well as the centrifugal forces in the vicinity of the discharge openings, so that the lubricant is transported to the working parts of the boring tool. The lubricant can also be liquid even at room temperature, in which case the lubricant can be prevented from escaping through the discharge openings by coordinating the cross sectional area of the discharge opening and the viscosity of the lubricant so that the adhesion and cohesion forces are greater than the forces generated by the hydrostatic pressure.
The transport of the lubricant to the working parts of the boring tool can also be advantageously promoted by a capillary fluid transport device. This term is used to include, among other things, sponge-like or fibrous storage media which are used to fill at least the lubricant channel or channels. It may also be advantageous if the dispenser is filled with such a storage medium. In this method, the lubricant is discharged from the discharge openings by centrifugal force, and the discharge of the lubricant may also be assisted by a temperature-dependent reduction in viscosity. The lubricant, which lubricant is consumed in the working parts of the boring tool, is replaced by capillary action with lubricant which is discharged from the storage medium in the lubricant channel and the dispenser. The advantage of such a method is that the cooling and lubrication action can be accomplished practically independently of the current position of the boring tool.
Lubrication which is independent of the position of the boring tool is also possible if there is pressure in the dispenser or if such a pressure is generated. In this manner, even higher-viscosity lubricants and those lubricants which do not sufficiently liquefy even at the operating temperatures and which could not be transported to the working parts without the application of pressure can be used. The quantity of lubricant or the lubricant flow can generall
Borschert Bernhard
Kammermeier Dirk
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