Cutting by use of rotating axially moving tool – Processes – Bit detachable
Reexamination Certificate
1999-09-08
2001-03-06
Howell, Daniel W. (Department: 3722)
Cutting by use of rotating axially moving tool
Processes
Bit detachable
C082S001110, C082S001500, C408S013000, C408S016000, C408S057000, C408S147000
Reexamination Certificate
active
06196773
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to tools utilizing pressurized fluid to actuate tool components and more particularly, to a tool for controlling pressure and/or fluid flow in such tools with a fluid axis.
BACKGROUND OF THE INVENTION
Machine tools generally manipulate a workpiece by actuating and/or biasing tool components in many different directions. For example, one machine tool is a machining center with a removable generating head. As discussed below and in light of this machining center example, each component of motion effected by the machine tool is herein called an “axis.”
The generating head can rotate in a rotational direction about its center line so that its blade removes material from a workpiece by physical interference. The rotational position is considered to be one axis of the tool, herein called the rotational axis. Of course, the rotational position of the head is related to the rotational velocity and acceleration, and these quantities are also considered to be part of the rotational axis. Generally speaking, the rotational component of motion effected by the machining center tool is the rotational axis.
The machining center can also actuate the generating head along the longitudinal direction of its centerline, in order to move further in or out of the body of the workpiece. This longitudinal motion is considered to be a second axis of the tool, herein called the longitudinal axis.
In some machining centers, the workpiece can be moved in one or more directions relative to the generating head. The motion (e.g., position acceleration, etc.) of the workpiece in these directions would be additional axes of the machining center tool. Now that the concept of an “axis” has been explained, the use of a “fluid axis” will be discussed below.
In some conventional tools, pressurized fluid can be utilized to help cool, position or provide a biasing force on the operative parts of the tool. For example, U.S. Pat. No. 5,775,853 discloses a squirt reamer wherein hydraulics control the longitudinal position of the squirt reamer head.
As another example, U.S. Pat. No. 4,913,602 to Peter et al. discloses a boring head for treating or cutting of hollow cylinder surfaces with a cutting edge that is radially adjustable by means of hydraulic pressure. The hydraulic pressure, and the radial adjustment effected thereby, can be considered to be the fluid axis of this boring head tool.
As used herein, the term reference information means any information used in controlling a tool axis. Feedback, which is derived from the controlled axis itself, is one kind of reference information. Conventionally, some tools control a fluid axis based upon feedback reference information to effect closed loop servo control of the fluid axis (e.g., fluid pressure). However, the feedback reference information employed in this closed loop servo control is generally limited to the fluid pressure itself. Of course, feedback reference information based on the actual fluid pressure can be usefully employed to control the fluid pressure to maintain some constant, predetermined pressure value.
However, fine adjustments and continuous adjustments to the fluid axis can not be made based on the other axis of the tool, because the values (e.g., positions, velocities, etc.) related to the other axes of the tool are not employed as reference information in control of the fluid axis.
It is advantageous to use only fluid axis feedback information to effect closed loop servo control of a fluid axis. This kind of control requires relatively infrequent binary signals to be sent between the computerized numeric control (CNC), which controls the electromechanical components of the tool, and the fluid regulation hardware (e.g., a valve). For example, a low speed serial interface can be used between a CNC and fluid regulation hardware.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a tool that addresses and overcomes the above-mentioned procedures and short comings in this industry.
It is also an object of the present invention to provide a tool effecting control of a fluid axis based at least in part on reference information (e.g., positional information) from at least one other axis of the tool.
It is a further object of the present invention to provide a tool where fine adjustments to fluid flow and or pressure can be made continuously, even during the period that the tool is operating on a workpiece.
Additional objects, advantages and other features of the present invention will be set forth and may become apparent to those skilled in the art upon examination of the following, or may be learned with practice of the invention.
In some embodiments of the present invention, the reference information from the other axis will be supplied by a control program executed in a computer. In some embodiments of the present invention, the reference information from the other axis will be supplied by measurement on the other axis.
In some embodiments of the present invention, a fluid axis transducer, which measures the operation of the fluid axis, provides feedback information which can be used to help determine the reference signal in conjunction with reference information relating to at least one other tool axis. By using feedback information from the fluid axis itself in determining the reference signal, closed loop control of the fluid axis can be effected.
According to some embodiments of the present invention, a tool having a fluid axis and actuation along an additional axis includes a reference signal generator, a fluid conduit, a fluid regulation device, and a fluid regulation controller.
The reference signal generator is structured to determine a reference signal based at least in part on operation of the tool with respect to the additional axis. For example, the additional axis may be the longitudinal position of a generating head, while the reference signal to control the fluid axis may be determined at least in part on this longitudinal position. One way to implement this example is to utilize a computerized numeric controller, which also controls the longitudinal position of the generating head, as the reference signal generator and to obtain information from the head control program to help determine the reference signal for the fluid axis.
The fluid conduit is structured to contain pressurized fluid which pressurized is utilized as the fluid axis. For example, the fluid conduit may be a through spindle coolant conduit which runs from a fluid supply, through a tool spindle and rotating generating head, and out through a fluid exit. In this example, the fluid can be used both to bias or actuate portions of the tool (e.g., a generating blade cartridge) and to cool the interface between the tool and a workpiece.
The fluid regulation device is structured to regulate the fluid in the fluid conduit and thereby control the fluid axis. For example, the fluid regulation device may be a valve which can be opened and closed by degrees to control the fluid pressure in the fluid conduit and thereby, control the fluid axis. As a further example, the fluid axis may be a variable speed pump which can pump fluid through the fluid conduit at a controlled volumetric flow rate to thereby control the fluid axis.
The fluid regulation controller is structured to control the fluid regulation device based on the reference signal. For example, the fluid regulation controller may be a servo motor, which opens or closes a valve. As a further example, the fluid regulation controller may be the speed control of a variable speed pump. In either case, the reference signal look is based at least in part on the operation of at least one other axis of the tool. In this way, the fluid axis can be continuously and simultaneously controlled with respect to one or more of the other axes of the tool.
Some preferred embodiments of the present invention further include a fluid axis transducer structured and located to measure operation of the tool with respect to the fluid axis, wherein the
Hyatt Gregory Aaron
Pruyn John
Wilcox Andrew
Dinsmore & Shohl LLP.
Howell Daniel W.
Makino Inc.
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