Tool lubricant supply monitoring system and procedure

Abstract

Tool lubricant supply system comprising: a fluid supply unit (20) arranged on a spindle (22), the fluid supply unit (20) including a valve assembly (40) containing a valve (52), the valve (52) moving along an axis (60) between a closed position in which flow of a lubricant is blocked and an open position in which flow of the lubricant is permitted; and an accelerometer (44) arranged on the valve assembly (40) along the axis (60) and detecting the acceleration of the valve (52).

Description

A tool lubricant supply system and a control method are disclosed.U.S. Pat. No. 6,167,318 A discloses an oil mist generation system and method. Systems for supplying lubricant are known, for example DE102009011336 A1, which relates to a spindle having a lance unit of a processing machine for a single lubricant. WO 2010 / 077 282 A1 describes a lubricant system for bearings which supplies lubricant in accordance with the bearing state. US7089895B2 describes a multi-valve control system that controls the interaction of the valves, and US 6588385B2 relates to the drive control of valves of an internal combustion engine.DE 102009011336 A1 again describes a spindle which is usable in use with two-channel minimum quantity lubrication. The supply of the lubricating oil takes place via a central oil tube which is connected in a rotationally fixed manner to a spatially fixed base part and is radially supported in the radial direction on the revolving spindle via at least one rotary bearing.SUMMARYAt least one embodiment of a tool lubricant delivery system is disclosed. The tool lubricant supply system includes a fluid supply unit disposed on a spindle. The fluid supply unit has a valve arrangement containing a valve. The valve moves along an axis between a closed position blocking flow of lubricant and an open position allowing flow of lubricant. An accelerometer is disposed on the valve assembly along the axis for sensing the acceleration of the valve.In at least one embodiment, a method for monitoring lubricant flow to a cutting tool is provided. The method includes providing a baseline acceleration profile representing a position of a lubricant flow control valve of a valve assembly. Data from an accelerometer disposed on the valve assembly indicative of a position of the valve is compared to a threshold range based on the baseline acceleration profile. A warning signal is provided if the data is not within the threshold range.In at least one embodiment, a method of controlling a tool lubricant delivery system is provided. The method includes providing a basic acceleration profile indicative of operation of a fluid supply unit disposed on a spindle that controls delivery of an aerosol with a lubricant to a fluid channel of a cutting tool. The basic acceleration profile has a first, a second and a third region. Based on the first, second and third ranges, first, second and third thresholds are determined, respectively. Data from an accelerometer disposed on the fluid supply unit is provided and one of the first, second and third thresholds is selected. The data from the accelerometer is compared to the selected one of the first, second and third thresholds. If the data exceeds the selected threshold value, a warning signal is generated.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a fragmentary sectional view of an exemplary tool lubricant delivery system. FIG. 2 is an example base profile diagram based on data from an accelerometer provided with the system. FIG. 3 is a flow diagram of an example method of controlling the system.DETAILED DESCRIPTIONAs required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. Referring to FIG. 1, an exemplary embodiment of a tool lubricant delivery system 10 is shown. The system 10 may be associated with a machine tool employing a minimum amount lubrication (MMS) system in which a first fluid, such as a lubricant, is mixed with a second fluid, such as air, and is supplied to a cutting tool. The system 10 may include a fluid supply unit 20, a spindle 22, a tool holder 24, a cutting tool 26, and a control subsystem 28. The fluid supply unit 20 may be configured to supply a first fluid 30 and a second fluid 32. In at least one embodiment, first fluid 30 may be a lubricant, such as oil or cutting fluid, and second fluid 32 may be a gas, such as air. The fluid supply unit 20 may include a valve assembly 40, a metering block 42, an accelerometer 44, and a rotary gear 46.The valve assembly 40 may be configured to control or regulate the delivery of the first fluid 30. The valve assembly 40, which may also be referred to as a quick-action valve, may include a housing 50, a valve 52, a first actuator 54, and a second actuator 56.The housing 50 may receive and guide movement of a valve 52. For example, the housing 50 may include a cavity that receives the valve 52 and allows the valve to move along an axis 60. The valve 52 may be configured to move between an open position in which the valve 52 permits flow of the first fluid 30 and a second position in which the valve 52 blocks flow of the first fluid 30. In at least one embodiment, valve 52 may be disposed coaxial with axis 60 and move therealong.The valve 52 may include a first end 62 and a second end 64 opposite the first end. The first end 62 may be configured to extend from the housing cavity, through an opening in the housing 50, and to the metering block 42. In at least one embodiment, first end 62 of valve 52 may engage metering block 42 when valve 52 is in closed position and may be spaced from first end 62 in open position.The first actuator 54 can be provided to actuate the valve 52 in a targeted manner. The actuator 54 may be of any suitable type, such as a solenoid. The first actuator 54 may be electrically connected to the control subsystem 28, which may control the operation of the first actuator 54, as described in more detail below.The second actuator 56, if provided, may also be configured to actuate the valve 52. The second actuator 56 may be of any suitable type. In the embodiment shown, the second actuator 56 is configured as a spring having a first end that engages the housing 50 and a second end that is disposed opposite the first end and engages the second end 64 of the valve 52. The second actuator 56 may bias the valve 52 to the closed position.The metering block 42 may be fixedly disposed on the valve assembly 40. The dosing block 42 may be provided as a separate component or may be integrated with the valve assembly 40 in one or more embodiments. The metering block 42 may include a first inlet 70 that receives the first fluid 30. The first fluid 30 may be supplied under pressure from a container that may be positioned away from the fluid supply unit 20. The first inlet 70 may be fluidly connected to a first chamber 72 of the dosing block 42. The first chamber 72 may include a valve seat surface 74 engageable by the valve 52 when the valve 52 is in the closed position. A first channel 76 may be disposed adjacent the valve seat surface 74. The first fluid 30 may flow through the first passage 76 when the valve 52 is not in the closed position.The accelerometer 44 may be disposed on the valve assembly 40 and may be configured to sense acceleration forces associated with the valve 52 and the first fluid 30. The accelerometer 44 may be disposed on the housing 50 opposite the dosing block 42. Furthermore, the accelerometer 44 may be disposed coaxial with the axis 60 so that it can properly sense acceleration forces along the axis 60, such as axial movement of the valve 52 or the first fluid 30. The accelerometer 44 may detect movement of the valve 52, such as deceleration of the valve 52 when it reaches the open or closed position. Moreover, the accelerometer 44 may sense acceleration or deceleration associated with the movement of the first fluid 30, such as movement relative to the first axis 60. The accelerometer 44 may be of any suitable type. For example, the accelerometer 44 may have a piezoelectric, capacitive, electromechanical, or acoustic emissions-based configuration. Accelerometer 44 may be electrically coupled to control subsystem 28, as will be discussed in more detail below.The rotation gear 46 can facilitate coupling of the fluid supply unit 20 to the spindle 22. The rotation gear 46 can be arranged fixedly on the metering block 42 opposite the valve arrangement 40. An opposing surface of the rotation gear 46 may engage the spindle 22 and allow rotation of the spindle 22 relative to the fluid supply unit 20. The rotary transmission 46 may include a second inlet 80 that receives the second fluid 32. The second fluid 32 may be supplied under pressure from a container, such as a pneumatic cylinder, which may be positioned remote from the fluid supply unit 20. The second inlet 80 may be fluidly connected to a second passage 82, which may extend partially through the rotary gear 46 and at least partially through the spindle 22 in one or more embodiments. The second channel 82 may be disposed coaxially about the axis 60.A lance 90 may be disposed in the second channel 82. The lance 90 may be configured as a hollow tube and may have a first end 92 and a second end 94 opposite the first end 92. The first end 92 may be fluidly connected to the first channel 76 of the dosing block 42 for receiving the first fluid 30. The second end 94 may be disposed proximate the tool holder 24, as will be discussed in more detail below. The lance 90 may be at least partially spaced from a surface of the second passage 82 such that the second fluid 32 may flow around the lance 90 and through the rotary gear 46 and the spindle 22 to the second end 94. Moreover, the lance 90 may be disposed coaxial with the axis 60.The spindle 22 may be configured about the axis 60 with respect to the fluid supply unit 20. The spindle 22 may be actuated or rotated in any suitable manner, such as with a motor in a manner known to those skilled in the art. The spindle 22 may be configured to rotate the tool holder 24 and cutting tool 26 about the axis 60. The second channel 82 may extend through the spindle 22, as discussed above. The tool holder 24 may be fixedly attached to the spindle 22. The tool holder 24 may include a coupling 100, a feed tube 102, and a bore 104.The coupling 100 may be fixedly disposed on the tool holder 24 proximate the spindle 22. The coupling 100 may be mounted to the tool holder 24 in any suitable manner, such as with an external thread that engages a corresponding thread on the tool holder 24. The coupling 100 may include a mixing chamber 110 in which the first and second fluids 30, 32 are received. For example, the second end 94 of the lance 90 and an end of the second channel 82 may be disposed proximate the mixing chamber 110. Thus, the lance 90 and the second channel 82 may supply the first and second fluids 30, 32, respectively, to the mixing chamber 110 where they may be mixed or combined. In at least one embodiment, first and second fluids 30, 32 may be mixed in mixing chamber 110 to form an aerosol in which particles or droplets of first fluid 30 are suspended in second fluid 32.The feed tube 102 may be disposed in the tool holder 24 and may fluidly connect the mixing chamber 110 and the cutting tool 26. In at least one embodiment, a first end of feed tube 102 may be disposed in or engage coupling 100 and receive mixture of first and second fluids 30, 32 from mixing chamber 110. A second end of the delivery tube 102 opposite the first end may be disposed proximate the bore 104. The feed tube 102 may be omitted in one or more embodiments.The cutting tool 26 may be received in the bore 104. The cutting tool 26 may be configured to do so. Material to be removed from a workpiece may be of any suitable type including, but not limited to, a chamfering tool, a drill, a drilling machine, a milling cutter, a reamer, or a tap. One end of the cutting tool 26 may be disposed near or engage the second end of the feed tube 102. Thus, the cutting tool 26 may receive the mixture of the first and second fluids 30, 32 in one or more fluid channels 120. The fluid channels 120 may supply or direct the mixture to the cutting surface 122 of the cutting tool 26. The cutting tool 26 may be attached to the tool holder 24 in a variety of ways known to those skilled in the art.The control subsystem 28 may be configured to monitor and / or control the operation of the system 10. The control subsystem 28 may include one or more controllers and may be microprocessor based in one or more embodiments. In at least one embodiment, control subsystem 28 may be associated with or configured as a programmable logic controller (PLC). The control subsystem 28 may control the operation of the first actuator 52 and may receive signals from the accelerometer 44. In addition, control subsystem 28 may include an output device 130 that may provide acoustic and / or optical information to a user. For example, the output device 130 may include a buzzer or speaker for acoustic communication or feedback and a display lamp or screen for optical communication or feedback. The control subsystem 28 may further monitor and / or control the operation of the spindle 22, the supply of the first and second fluids 30, 32, and / or the execution of machining operations of a machine tool or other device accompanying the system 10. The control subsystem 28 may communicate with or be part of a machine tool monitoring system or a machine tool data management system, as disclosed, for example, in U.S. Pat. Nos. 7,383,097 and 7,571,022, assigned to the assignee of the present application and incorporated herein by reference in its entirety. In addition, control subsystem 28 may acquire or receive information about the operation of system 10, such as initiation or termination of a preprogrammed machine tool operating cycle and filtering and identifying or associating accelerometer signals with the operation of the machine tool or the position of valve 52.Referring to FIG. 2, an example baseline data diagram is shown. The base data diagram may be based on (a) signal or data sensed by the accelerometer 44. In FIG. 2, acceleration data are plotted with speed on the vertical axis and time on the horizontal axis. The diagram may represent the basic operating profile in which the system 10 operates within the desired operating parameters (e.g., with a cutting tool installed, with proper operation of the valve and other system components, and without undesirable fluid flow blockages). For example, the base profile may be obtained by establishing the system 10 with a desired cutting tool and operating the system 10 in a predetermined manner according to which the valve 52 is actuated to provide a predetermined or desired amount of the first and / or second fluids 30, 32 that may facilitate tool lubrication for a workpiece material removal operation. The system 10 may be operated for a predetermined period of time in which the valve 52 is regularly actuated to allow a desired amount of lubricant to flow through the lance 90. Thus, the valve 52 may be cyclically operated or repeatedly operated at different times to control the flow of the first fluid 30. The target lubricant amount may be determined based on experimentation, or may be stored in memory or a look-up table.The base profile diagram shows three distinct regions that may be detected and may repeat in response to cyclical operation of the valve 52. The first portion 200 may indicate movement of the valve 52 to the closed position. The second region 202 may be indicative of a change in flow of the first fluid 30 in the valve assembly 40. For example, upon movement of the valve 52 to the closed position, data for the second region 202 may be acquired and may indicate the associated deceleration of the first fluid 30 after blocking flow of the valve assembly 40 through the valve 52. The third portion 204 may show movement of the valve 52 to the open position. The positioning of the regions 200, 202, 204 may change depending on the plotted time range. For example, if the plot window begins with the second region 202 and the third region 204 is contiguous, then the first region 200 may be shown after the third region 204 when the valve is cycled again. One or more of the regions 200, 202, 204 may be used as a basis for a comparison to determine whether the system 10 is operating within desired operating parameters. Thus, baseline acceleration profile attributes, such as the size and / or duration of one or more regions, may be stored in memory and used as a basis for comparison during regular system operation, for example when removing a material from a workpiece.Referring to FIG. 3, a flowchart of an example control method that may be used with the system is shown. The method can be used after obtaining a base profile. For example, the method may be performed after completion of the set-up of the tool or selection of the tool from a tool magazine and before machining or performing a chip forming operation on a workpiece to check that appropriate lubrication is provided to the cutting tool. Moreover, the method may be performed during or after completion of a machining or machining operation. In various embodiments, one or more method steps may be omitted. Moreover, in one or more embodiments, one or more of the method steps, such as the decision steps, may be performed in a different sequence. Furthermore, the method may be performed as a continuous loop while the system 10 is operating. Data used by the control method can be obtained in the same sequence as data for the basic profile was obtained. Thus, data may be assigned to a particular portion or region of the base profile based on its order in a sequence.At 300, the method may determine if flow of the first fluid is satisfactory. The determination of whether flow of the first fluid is satisfactory may be based on a comparison of the accelerometer sensor data to the base profile. For example, a data range associated with the fluid stream, such as the second range 202, may be converted to a threshold or threshold range. A threshold may be a maximum or minimum acceleration or velocity value associated with the region. Such data may be based on an average of a plurality of baseline measurements, or may be maximum or minimum absolute values from a sample of a plurality of baseline measurements. Likewise, a threshold range may be a range that includes absolute or averaged maximum or minimum baseline measurements. If the accelerometer data is not within the threshold range, exceeds a maximum value based on one or more base measurements, or is less than a minimum value based on one or more base measurements, then the flow of the first fluid is unsatisfactory and the method continues to block 302. Fluid flow may be unsatisfactory due to blockage downstream of the valve, such as blockage in a fluid channel in the cutting tool or lance, blockage upstream of the valve, insufficient supply pressure of the first fluid, or an empty receptacle of the first fluid. Otherwise, the flow of the first fluid is satisfactory and the method continues to block 304.At block 302, a current warning may be performed. The power alert may be performed with the control subsystem 28 and may include acoustic and / or optical communication to a user or system operator, as discussed above. In one or more embodiments, the current warning may be executed upon receipt of a predetermined number of repeating or consecutive unsatisfactory readings to further emphasize that an unsatisfactory condition prevails. In addition, the method may include executing a shutdown strategy automatically, or when a user does not respond to the power alert. Shutdown may include retracting the cutting tool 122 from the workpiece to help avoid tool damage or terminating a machining operation without retracting the tool. At block 304, the method may determine whether the valve is properly opening. The determination of whether the valve is properly opening may be based on a comparison of the accelerometer sensor data to the base profile. For example, a range of data associated with valve retraction, such as third range 204, may be converted to a threshold or threshold range. A threshold may be a maximum or minimum acceleration or velocity value associated with the region. Such data may be based on an average of a plurality of baseline measurements, or may be maximum or minimum absolute values from a sample of a plurality of baseline measurements. Likewise, a threshold range may be a range that includes absolute or averaged maximum or minimum baseline measurements. If the accelerometer data is not within the threshold range, exceeds a maximum value based on one or more base measurements, or is less than a minimum value based on one or more base measurements, then the valve may not open properly, and the method continues to block 306. Improper opening of the valve may indicate failure or impairment of the first actuator 54, obstruction to movement of the valve 52, and ultimately insufficient amount of a first fluid or lubricant that may be supplied to the cutting tool. Otherwise, opening the valve is satisfactory and the method continues to block 308.At block 306, a valve opening warning may be executed. The valve opening alert may be performed with the control subsystem 28 and may include acoustic and / or optical communication to a user or system operator, as discussed above. In one or more embodiments, the valve opening warning may be executed upon receipt of a predetermined number of repeating or consecutive unsatisfactory readings to further emphasize that an unsatisfactory condition prevails. Moreover, the method may include executing a shutdown strategy automatically, or when a user does not respond to the valve opening warning. Shutdown may include retracting the cutting tool from the workpiece to help avoid tool damage or terminating a machining operation without retracting the tool.At block 308, the method may determine whether the valve is properly closing. The determination of whether the valve is properly closing may be based on a comparison of the accelerometer sensor data to the base profile. For example, a range of data associated with valve retraction, such as the first range 200, may be converted to a threshold or threshold range. A threshold may be a maximum or minimum acceleration or velocity value associated with the region. Such data may be based on an average of a plurality of baseline measurements, or may be maximum or minimum absolute values from a sample of a plurality of baseline measurements. Likewise, a threshold range may be a range that includes absolute or averaged maximum or minimum baseline measurements. If the accelerometer data is not within the threshold range, exceeds a maximum value based on one or more base measurements, or is less than a minimum value based on one or more base measurements, then the valve may not close properly, and the method continues to block 310. Improper closing of the valve may indicate failure or degradation of the second actuator 56, obstruction to movement of the valve 52, and ultimately, insufficient or excessive amount of a first fluid or lubricant that may be supplied to the cutting tool. Otherwise, closing the valve is satisfactory and the method continues to block 312 where operation continues and the method may be repeated.At block 310, a valve closing warning may be executed. The valve closing alert may be performed with the control subsystem 28 and may include acoustic and / or visual communication to a user or system operator, as discussed above. In one or more embodiments, the valve closing warning may be executed upon receipt of a predetermined number of repeating or consecutive unsatisfactory readings to further emphasize that an unsatisfactory condition prevails. Additionally, the method may include executing a deactivation strategy automatically, or when a user does not respond to the valve closing warning. Shutdown may include retracting the cutting tool from the workpiece to help avoid tool damage, terminating a machining operation without retracting the tool, or completing machining of the workpiece before shutdown occurs.A method of monitoring lubricant flow to a cutting tool according to the invention comprises: providing a base acceleration profile representing a position of a lubricant flow control valve of a valve assembly; comparing data from an accelerometer disposed on the valve assembly indicative of a position of the valve to a threshold range based on the base acceleration profile; and providing a warning signal if the data is not within the threshold range.The warning signal preferably indicates improper closing or opening of the valve or blockage between the valve and a coolant channel in the cutting tool.More preferably, the base acceleration profile includes first, second and third ranges, wherein first, second and third threshold ranges are based on the first, second and third ranges, and wherein the data is continuously provided by the accelerometer such that the data is compared to the first, second and third threshold ranges. In this case, the accelerometer is preferably arranged on the axis along which the valve is moved linearly.More preferably, the step of providing a baseline acceleration profile comprises acquiring acceleration data with the accelerometer for multiple cycles of the valve between a closed position and an open position.While exemplary embodiments have been described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the terms used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Moreover, the features of various implementation embodiments may be combined to form further embodiments of the invention.

Claims

A tool lubricant delivery system comprising: a fluid supply unit (20) disposed on a spindle (22), the fluid supply unit (20) including a valve assembly (40) including a valve (52), the valve (52) moving along an axis (60) between a closed position blocking flow of lubricant and an open position allowing flow of lubricant; and an accelerometer (44) disposed on the valve assembly (40) along the axis (60) and sensing acceleration of the valve (52).The tool lubricant delivery system of claim 1, wherein the valve assembly (40) moves linearly along the axis (60).The tool lubricant supply system according to claim 1, wherein the acceleration meter (44) detects acceleration of the lubricant (30) by the fluid supply unit (20).The tool lubricant delivery system of claim 1, further comprising a control subsystem (28) that controls actuation of the valve (40) and receives data from the accelerometer (44), wherein the control subsystem (28) compares data received from the accelerometer (44) with a base acceleration data profile indicative of desired valve actuation data to determine when the valve (44) is in the closed position.The tool lubricant delivery system of claim 4, wherein the control subsystem (28) compares data received from the accelerometer (44) to a portion of the baseline acceleration data profile to determine whether the valve (40) is in the open position.The tool lubricant delivery system of claim 1, further comprising a control subsystem (28) based on an PLC and controlling actuation of the valve (40) and receiving data from the accelerometer (44), wherein the control subsystem (28) compares data received from the accelerometer (44) indicative of the flow of the lubricant (30) with a portion of a baseline acceleration data profile to determine when the flow of the lubricant (30) through the valve assembly (40) is blocked.A method of controlling a tool lubricant delivery system, comprising: providing a base acceleration profile indicative of operation of a fluid supply unit (20) disposed on a spindle (22) and controlling delivery of an aerosol including a lubricant (32) to a fluid channel (82) of a cutting tool (26), the base acceleration profile having a first (200), a second (202), and a third region (204); determining a first, a second, and a third threshold based on the first, the second, and the third region, respectively; providing data from an accelerometer (44) disposed on the fluid supply unit; selecting the first, the second, or the third threshold; comparing the data from the accelerometer (44) to the selected first, second, or third threshold; generating a warning signal when the data exceeds the selected threshold value.

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