Patent Description:
Limitations and disadvantages of conventional approaches to providing a circular cutting device will become apparent to one of skill in the art, through comparison of such approaches with some aspects of the present method and system set forth in the remainder of this disclosure with reference to the drawings.

<CIT> discloses electrically powered devices that are generally capable of automatically adjusting an operating speed of a tool removably connected to the device. <CIT> discloses a control system and apparatus for ultrasonic detection of wear of a grinding wheel and control of the peripheral speed. <CIT> discloses an arrangement including a grinding wheel and a hand-held power tool.

Methods and apparatus are provided for controlling a surface speed of a circular cutting device, substantially as illustrated by and described in connection with at least one of the figures, and as defined by the appended claims.

These and/or other aspects will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings.

While example methods and apparatus are disclosed, modifications to the example methods and apparatus may not be described in detail as they may be well known to a person of ordinary skill in the art.

Abrasive cutting devices are used to perform sectioning, which can be used for testing of components. Abrasive cutting devices generally have circular cutting wheels that are rotated at high speed to section a part. As the abrasive device is used, the abrasive cutting wheel is consumed and the diameter of the abrasive cutting wheel decreases as the cutting wheel is worn down. The speed of the cutting wheel edge may impact the quality of the cut. Disclosed example methods and apparatus automatically adjust the rotational velocity (e.g., in rotations per minute (RPM)) of the cutting wheel to compensate for the reduction in the cutting wheel diameter, thereby providing a more consistent edge speed and improved consistency in cutting results.

When a new abrasive cutting wheel is added, the rotational velocity is set to a predetermined starting value. In some examples, the cutting device may determine the starting value for a new cutting wheel and/or the increase in rotational velocity based on one or more of: the sample material being cut, a part number of the material being cut, an abrasive material type on the abrasive cutting wheel, an abrasive cutting wheel size, a concentration of the abrasive material on the abrasive cutting wheel, a thickness of the abrasive cutting wheel, a bonding agent material type, and/or a bonding agent material hardness. The predetermined starting value and/or the increase in rotational velocity may be empirically determined and stored in the cutting device (e.g., in a lookup table). In some examples, the abrasive cutting wheel and/or one or more qualities of the abrasive cutting wheel are determined by reading electronic indicia (e.g., a barcode, a quick response (QR) code, an RFID tag, a near field communications (NFC) tag, etc.) attached to the cutting wheel or the packaging of the cutting wheel. For example, the cutting device may include a barcode reader, a QR code reader, an RFID reader, and/or an NFC reader configured to determine the type of abrasive cutting wheel by reading the electronic indicia.

As an abrasive cutting wheel is used, disclosed example cutting devices increase the rotational velocity of the cutting wheel to maintain a substantially consistent surface speed (e.g., in surface feed per minute) of the outer edge of the abrasive cutting wheel and/or to reduce a rate at which the surface speed decreases (e.g., relative to maintaining a constant angular velocity as with conventional cutting devices).

Disclosed example methods and apparatus provide improved cut quality and consistency, particularly closer to the end of life of the abrasive cutting wheel. Disclosed example methods and apparatus may also improve the life of abrasive cutting wheel by operating the cutting wheel within the highest performance envelope for longer than conventional abrasive cutting devices. While the disclosed examples are described with reference to abrasive cutting devices and abrasive cutting wheels, the disclosed methods and apparatus may be modified and/or used for any other type of cutting device, such as rotary tools and/or any other type of rotational cutting device that uses consumable cutting wheels.

<FIG> illustrates a block diagram of an example cutting device in accordance with aspects of this disclosure. Referring to <FIG>, there is shown a cutting device <NUM> including a power source <NUM>, a actuator <NUM>, control circuitry <NUM>, and a cutting wheel <NUM>.

The power source <NUM> may be any power source that can be used by the actuator <NUM> to rotate the cutting wheel <NUM>. For example, the power source <NUM> may be an electric power source that provides appropriate current and voltage to the actuator <NUM>, where the actuator <NUM> may be a variable speed electric motor that rotates the cutting wheel <NUM> via, for example, the spindle <NUM>. Another power source may be, for example, an air compressor that may provide compressed air for the actuator <NUM> that runs on compressed air. Still another power source may be, for example, a hydraulic power source that provides hydraulic fluid for the actuator that runs on hydraulic fluid. Accordingly, the power source <NUM> may be any power source that can be used by an appropriate actuator <NUM> such that the cutting wheel <NUM> can be rotated at various desired speeds, including those power sources that are not mentioned in this disclosure.

The example control circuitry <NUM> of <FIG> may include analog and/or digital circuitry configured to determine a target rotational velocity (revolutions per minute - RPM) an/or a target surface speed of the cutting wheel <NUM>, and provide control signals to the power source <NUM> and/or the actuator <NUM> to rotate the cutting wheel at the target rotational velocity. For example, when the actuator <NUM> is an electric motor such as, for example, a servo motor, a stepper motor, etc., the power source <NUM> may provide power to the actuator <NUM>, and the control circuitry <NUM> may provide control signals (analog and/or digital) to control the voltage provided by the power source <NUM> to the actuator <NUM>. Additionally or alternatively, the control circuitry <NUM> may provide control signals to the actuator <NUM> to control the power from the power source <NUM> to rotate the cutting wheel <NUM> at the target rotational velocity.

Accordingly, the control circuitry <NUM> may include processing circuitry <NUM>, memory <NUM>, input/output (I/O) interface(s) <NUM>, and/or circuitry <NUM>. The processing circuitry <NUM> may be any type of processor or logic circuitry that is capable of executing instructions stored in a memory, including the memory <NUM>, and/or otherwise performing logic functions based on inputs. Example processors include central processing units (CPUs), systems-on-a-chip (SOCs), field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), discrete logic, and/or any other type of controller, processor and/or, more generally, logic circuitry. The memory <NUM> may comprise volatile and non-volatile memory, including mass storage devices. The I/O interface <NUM> is described in more detail below with reference to <FIG>. The circuitry <NUM> may comprise various hardware circuitry that may be needed for operation of the control circuitry <NUM>.

One or more of the power source <NUM>, actuator <NUM>, and/or the control circuitry <NUM> may be combined in different configurations without deviating from the scope of this disclosure.

As disclosed above, the rotational velocity of the cutting wheel <NUM> may be controlled to provide a substantially constant surface speed at an edge <NUM> of the cutting wheel <NUM>. Generally, the cutting wheel <NUM> may get smaller as the abrasive material of the cutting wheel <NUM> is consumed during the cutting process. Therefore, if the rotational velocity of the cutting wheel <NUM> remains constant as the cutting wheel <NUM> gets smaller, the surface speed at the edge <NUM> of the cutting wheel <NUM> decreases. Accordingly, the cutting effect may also decrease as the surface speed of the cutting wheel decreases due to reduced efficiency and/or changing cutting characteristic of the cutting wheel <NUM>.

For example, abrasive cutting wheels may operate at a peak efficiency within an envelope of surface speed, relative to speeds outside of the envelope. While users of conventional abrasive cutters may set the rotational velocity of the abrasive saw based on a particular surface speed (e.g., when changing the cutting wheel), the surface speed is only valid within a window of diameters of the abrasive cutting wheel. In contrast, the example cutting device <NUM> maintains the surface speed substantially constant throughout the life of the abrasive cutting wheel.

In some examples, the control circuitry <NUM> estimates a diameter of the cutting wheel <NUM> based on the parameters and duration of use of the cutting wheel <NUM>. For example, a user may register a new cutting wheel with the control circuitry <NUM> via the I/O interface <NUM>. Following the identification of the new cutting wheel and determining the parameters of the cutting wheel and/or the material under test, the control circuitry <NUM> tracks the use of the cutting wheel <NUM> and determines, based on a lookup table and/or an equation, the estimated consumption of the cutting wheel and/or remaining diameter. Based on the remaining diameter, the example control circuitry <NUM> sets the target<MAT>speed for the cutting wheel <NUM> based on Equation <NUM> below.

In Equation <NUM>, SFPM is the linear speed of the outer edge of the cutting wheel <NUM> in feet, respectively meter per minute, D is the estimated diameter of the cutting wheel in inches, respectively meter, and RPM is the angular velocity in rotations per minute.

<FIG> is block diagram of an example user interface of a cutting device in accordance with aspects of this disclosure. Referring to <FIG>, there is shown the example user interface <NUM> that includes an input interface <NUM>, an output interface <NUM>, and a transceiver <NUM>. The user interface <NUM> may also include a tag reader <NUM>. The user interface <NUM> may be used to implement the I/O device <NUM> of <FIG>. The user interface <NUM> may be a part of the cutting device <NUM>, where it is a part of one of the power source <NUM>, the actuator <NUM>, or the control circuitry <NUM>, or may be a separate module. The example input interface <NUM> may include any type of input device, such as a keyboard, a pointing device (e.g., a mouse, a trackpad), a microphone, a camera (e.g., gesture-based input), a touchscreen, buttons that can be rotated and/or pushed, sliding knobs, and/or any other type of user input and/or output device. The example output interface <NUM> includes any type of visual output device such as, for example, an LCD display, an LED display, etc., tactile feedback devices that may vibrate, audio output device such as speakers, and/or any other output devices that may be used to provide information or notice. The output interface <NUM> may display, for example, status/commands that may be entered for the cutting device <NUM>.

The example transceiver <NUM> communicates via wired and/or wireless communication with other electronic devices. The wired communication may, for example, use any of the different protocols such as, for example, USB, Firewire, TCP/IP, SCSI, IDE, or other protocols that may be appropriate for the cutting device <NUM>. The wireless communication may use any of the different protocols such as, for example, Wi-Fi, Bluetooth, NFC (near field communication), or other protocols that may be appropriate for the cutting device <NUM>.

The transceiver <NUM> may be used to control and/or view the status of the cutting device <NUM>. For example, an electronic device <NUM> may be used to enter parameters for the cutting tool, such as, for example, the initial diameter of the cutting wheel, the desired surface speed, etc. The transceiver <NUM> may also allow tables to be downloaded, for example, to the cutting device <NUM>. Accordingly, by entering parameters such as the sample material being cut, the overall part number of the material being cut, abrasive material type on the abrasive cutting wheel, size of the cutting wheel, concentration of the abrasive material on the abrasive cutting wheel, thickness of the abrasive cutting wheel, bonding agent material type, bonding agent material hardness, type of coolant used (if any), etc., the cutting device <NUM> may select a recommended surface speed so that the actuator <NUM> may rotate the cutting wheel <NUM> at the correct rotational velocity as the cutting wheel <NUM> changes in size.

Additionally or alternatively, the parameters may be determined by reading electronic indicia on the cutting wheel <NUM> and/or on the material under test using the tag reader <NUM>. The tag reader <NUM> may read electronic indicia, such as RFID tags, NFC tags, barcodes, QR codes, etc., which may be present on the cutting wheel, packaging of the cutting wheel, the material under test, and/or an identifier tag attached to the material under test.

The electronic device <NUM> may also display, for example, status of the cutting device <NUM> on the electronic device <NUM>. For example, the status may be the status that may be displayed on the output interface <NUM> and/or other information that may not be displayed on the output interface <NUM>.

<FIG> illustrate an example method to detect a size of a cutting wheel. Referring to <FIG>, there are shown examples of the actuator <NUM> and the cutting wheel <NUM>. The actuator <NUM> includes a sensing device <NUM> that comprises a light source <NUM> and a sensor <NUM>, and the cutting wheel <NUM> includes multiple reflectors <NUM> including reflectors 306a-306d that are configured to reflect light from the light source <NUM> to the sensor <NUM>. The light source <NUM> may emits a light that can be easily detected from the ambient light that may be present in an environment where the cutting device <NUM> is used. The light source <NUM> may emit, for example, in the infrared spectrum, the ultraviolet spectrum, or the visible light spectrum. The emitted light may also be, for example, modulated as structured light. The emitted light may also be, for example, modulated as structured light. The light source <NUM> may be one or more LEDs (e.g., an array of LEDs) or any other type(s) of light sources suitable for the purposes. The wavelength of the LEDs or other light source <NUM> may be selected to enable penetration through coolant and/or coolant vapor.

In operation, the light source <NUM> may emit light continuously or periodically. The light emission and modulation may be controlled, for example, by the processing circuitry <NUM> of <FIG>. The light received by the sensor <NUM> may be processed, for example, by the processing circuitry <NUM> to determine which of the multiple reflectors 306a-306d may have reflected the received light.

As the cutting wheel <NUM> is consumed, some of the reflectors 306a-306d are eliminated from the cutting wheel <NUM> from the outer edge toward the center, and the number of reflectors <NUM> is reduced. For example, in <FIG>, the outermost of the reflectors <NUM> is the reflector 306a. However, as the cutting wheel <NUM> gets smaller, the reflector 306a falls off and the outermost reflector is now the reflector 306b. The processing circuitry <NUM> may estimate the cutting wheel diameter based on the outermost (e.g., closest to the cutting edge <NUM>) reflector 306b that is identified via the light source <NUM> and the sensor <NUM>, or the number of reflectors <NUM> that is detected on, for example, along a radius or a diameter. The light source <NUM> may adjust its emission such that the emitted light hits only one of the reflectors <NUM> in turn, or the emitted light may hit all of the available reflectors <NUM> and the intensity of the received light may determine how many reflectors reflected the light, etc..

Additionally or alternatively, the processing circuitry <NUM> may compare the wavelength of the light source <NUM> to the received wavelength to determine Doppler shift. The processing circuitry <NUM> may then estimate the linear speed of the outermost reflector 306a based on the highest detected Doppler shift. Various embodiments may not use a reflector(s) <NUM>, but may reflect off the surface of the cutting wheel <NUM>. The light may be transmitted to a largest radius of the cutting wheel <NUM>, and then moved toward the center either continuously or by steps until a reflection is detected. The next transmission can then start at the point where the last reflection was detected.

The cutting wheel <NUM> may not have reflectors <NUM> as discrete elements, but the surface of the cutting wheel <NUM> facing the sensor <NUM> may be embedded with reflectors <NUM> that comprise reflective material such that an intensity of light reflected to the sensor <NUM> may be predictable for different diameters of the cutting wheel <NUM>. Accordingly, the light source <NUM> may shine light onto a portion or more of the cutting wheel <NUM>, and an intensity of the received light may be processed to determine the size of the reflecting area, and, hence, the diameter of the cutting wheel <NUM>. The reflectors <NUM> may be embedded uniformly over the surface of the cutting wheel <NUM>, or in specific areas.

While the light source <NUM> and the sensor <NUM> are shown as being on the actuator <NUM>, in other examples the light source <NUM> and/or the sensor <NUM> may be positioned at other locations such that the reflectors <NUM> can reflect the light from the light source <NUM> to the sensor <NUM>.

By determining the diameter of the cutting wheel <NUM>, the rotational velocity of the cutting wheel <NUM> can be adjusted to provide a substantially constant surface speed. The surface speed over time will depend on how accurate the determination of the diameter of the cutting wheel <NUM> is. However, the cutting device <NUM> may also predict the change in rotational velocity based on a history of the change in size of the cutting wheel <NUM> over time. For example, if the change in size is determined due to measurement at time T1 and time T2, this change rate during this period may be used to adjust the rotational velocity during a period when size determination is not being made.

While some examples for measuring a size of the cutting wheel <NUM> have been described, any of various other methods that may be applicable can also be used. For example, the reflectors <NUM> may be lighter colored material or a radial stripe that may be painted white. In some embodiments, additional reflective material may not be embedded in the surface of the cutting wheel <NUM>, but the intensity of light reflected by the surface of the cutting wheel <NUM> may be used as a baseline when the cutting wheel <NUM> is first used, and the diminishing intensity of the reflected light may be used to determine the size of the cutting wheel <NUM>.

Another method may be to determine the power needed to rotate the cutting wheel <NUM> at the present speed and then determine the weight of the cutting wheel <NUM> based on the power, thereby determining the diameter of the cutting wheel <NUM>. The power may then be increased as needed to increase the rotating speed of the cutting wheel <NUM>. The power needed for a constant rotational velocity may differ when the cutting wheel <NUM> is not touching the item to be cut as when the cutting wheel <NUM> is pressed against the item being cut. Accordingly, one way to determine power used for a certain rotational velocity may be when there is a decrease in power used to drive the cutting wheel <NUM> as this may indicate a reduced load when the cutting wheel <NUM> has been taken away from the item being cut. The power to drive the cutting wheel <NUM> may then be a more accurate indication of the power needed to sustain the cutting wheel <NUM> at that rotational velocity for the purpose of determining the size of the cutting wheel <NUM>.

Other methods may also be used. For example, an estimate may be made of the time that the cutting wheel <NUM> is driven by the actuator <NUM> and use a rule that the diameter of the cutting wheel <NUM> decreases by a certain amount per a given amount of time. This estimate may be made more accurate by keeping track of the time where the actuator <NUM> is under abnormal load, indicating the time that the cutting wheel <NUM> is pressed against the item being cut. For example, the time measurement can be for the periods from when power to the actuator <NUM> increases indicating a heavier load to the time when power to the actuator <NUM> decreases indicating that the load decreased.

In other examples, the cutting device <NUM> may use a camera as the sensor <NUM> to determine the size of the cutting wheel <NUM>. The sensor <NUM> may be a still camera or a video camera. The image(s) captured by the sensor <NUM> may be processed to determine the size of the cutting wheel <NUM>. For example, edge detection may be performed to get an outline of the cutting wheel <NUM> and the outline of the cutting wheel <NUM> may be compared to a baseline image or a given baseline size of the cutting wheel <NUM>. The image of the cutting wheel <NUM> may be processed to determine the size of the cutting wheel <NUM> since the distance from the sensor <NUM> to the cutting wheel <NUM> may be constant or otherwise known.

In some other examples, markers are spaced along at least one diameter of the cutting wheel <NUM>. Identification of the markers may allow determination of the size of the cutting wheel <NUM> (e.g., via the sensor <NUM>, a camera, etc.). The markers may be any items that may be differentiated from the rest of the cutting wheel <NUM>. For example, the markers may be reflective material, different colored material, etc., that may be embedded as a part of the cutting wheel <NUM> or painted on the cutting wheel <NUM>. The markers may also be, for example, openings in the cutting wheel <NUM>.

Other parts of the electromagnetic spectrum or sound waves may also be used, as appropriate, to perform the tasks similar to those described using light.

<FIG> illustrate example methods to detect a size of a cutting wheel in accordance with aspects of this disclosure. Referring to <FIG>, there are shown the actuator <NUM>, the cutting wheel <NUM>, and an item <NUM> that is to be cut by the cutting wheel <NUM> positioned (e.g., clamped) to a member <NUM>. The actuator <NUM> includes the sensing device <NUM> to determine a distance to the surface of the member <NUM>. The position and orientation of the surface of the member <NUM> are assumed to be constant for ease of explanation. However, even if the position and/or the orientation are not constant, the change may be compensated for to determine the distance to the surface from the sensing device <NUM>. The sensing device <NUM> may comprise a light source <NUM> that transmits light to reflect off an object, and a sensor <NUM> that receives the reflection, and processes the reflection to determine distance from the sensor <NUM> to the object. Accordingly, a distance from the sensing device <NUM> to the surface of the member <NUM> can be determined by the time it takes from when the light is transmitted by the transmit portion to when the light is received by the receive portion. This time may be referred to as time-of-flight.

In other examples, the measurement may be made to the surface of the item being cut. For example, if the member <NUM> is being cut, then the distance to the member <NUM> is measured if it is more convenient to measure that distance than the distance to another member that may be supporting the member <NUM>. Still other examples may measure the distance to the member <NUM> and the item <NUM> supported by the member <NUM>.

As shown in <FIG>, the sensing device <NUM> determines the distance to the surface of the member <NUM> when the cutting wheel <NUM> is at its full size as it first starts the cutting process. The initial measurement provides the baseline for determining the diameter of the cutting wheel <NUM> at later times. At any later point(s) in time, the sensing device <NUM> may determine the distance to the surface of the member <NUM> as the cutting wheel <NUM> decreases in size. Accordingly, the cutting device <NUM> may be able to determine the diameter of the cutting wheel <NUM>, and, hence, adjust the rotational velocity of the cutting wheel <NUM>.

<FIG> illustrates an example method to detect a size of a cutting wheel. Referring to <FIG>, there are shown the actuator <NUM> and the cutting wheel <NUM> coupled to the actuator <NUM> by the spindle <NUM>. The actuator <NUM> may comprise a light source <NUM> and a sensor <NUM>. The cutting wheel <NUM> may comprise openings 316a-316d. The placement, shape, and/or number of the openings 316a-316d may be design dependent for the cutting wheel <NUM>.

The light from the light source <NUM> may be transmitted through the openings 316a-316d and the beams of light 302a-302d through the holes 316a-316d may be detected by the individual sensors <NUM>-<NUM> - <NUM>-<NUM>. The light from the light source <NUM> may be transmitted to each of the openings 316a-316d in turn to determine which of the opening are present to direct the light to the sensor <NUM>, or the light may shine through all the openings 316a-316d and light detected by the sensor <NUM> may determine which openings are still present too determine the size of the cutting wheel <NUM>. Other embodiments may use different number of light sources as shown in <FIG> and/or different number of individual sensors. The sensors <NUM>-<NUM> to <NUM>-<NUM> may compare, for example, the light detected to a threshold to determine whether light from the light source <NUM> has been detected. The threshold may be different for the different ones of the sensors <NUM>-<NUM> to <NUM>-<NUM>. This may be, for example, because if there is only one light source, the beam of light 302a may be dimmer than the beam of light 302d.

Various embodiments may not have the openings 316a-316d, and may use the sensor <NUM> to detect light 302z that is not blocked by the cutting wheel <NUM>. That is, the sensor <NUM> may detect light 302z that leaks around the edge of the cutting wheel <NUM>.

Other embodiments may use the openings 316a-316d as well as detecting the light 302z that leaks around the edge of the cutting wheel <NUM>.

While light was described as being transmitted, sound or other wavelengths of the electromagnetic spectrum may also be used with an appropriate transmitter and sensor.

Controlling light transmission and processing the received light may be controlled by, for example, the processing circuitry <NUM> or some other processing circuitry in the cutting device.

<FIG> illustrates an example method to detect a size of a cutting wheel. Referring to <FIG>, there are shown the actuator <NUM> and the cutting wheel <NUM> coupled to the actuator <NUM> by the spindle <NUM>. The actuator <NUM> may comprise a light source <NUM> and a sensor <NUM>. The cutting wheel <NUM> of <FIG> may not have openings for light to shine through.

The light source <NUM> may comprise individual lights <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>, which may project narrow beams that can be individually detected by the corresponding individual sensors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. For example, the beam of light 302a from the individual light <NUM>-<NUM> may be blocked by the outer portion 108a of the cutting wheel <NUM> when the cutting wheel <NUM> is new. However, as the cutting wheel <NUM> is used, the outer portion 108a may be worn away to allow the beam of light 302a to be detected by the sensor <NUM>-<NUM>. As the cutting wheel <NUM> is used even more, the outer portion 108a may get larger (worn away). Accordingly, for example, the processing circuitry <NUM> may be able to determine the size of the cutting wheel <NUM> by knowing which of the sensors <NUM>-<NUM> to <NUM>-<NUM> detect light. As the cutting wheel <NUM> wears away more, the sensors <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> may also be able to detect the beams of light 302b, 302c, and 302d, respectively. Similarly as for <FIG>, there may be thresholds for light detected by the sensors <NUM>-<NUM> to <NUM>-<NUM>.

Therefore, as can be seen, various embodiments may be used to detect light and/or sound to determine the size of the cutting wheel.

<FIG> illustrate example methods to detect a size of a cutting wheel in accordance with aspects of this disclosure. Referring to <FIG>, there are shown the actuator <NUM> and the cutting wheel <NUM> coupled to the actuator <NUM> by the spindle <NUM>. While <FIG> shows the spindle <NUM> to be at a right angle, other angles may also be used. When the spindle <NUM> has an angle as shown in <FIG>, the spindle <NUM> includes appropriate gears (not shown) to allow the spindle to be angled.

The light source <NUM> may transmit light to the cutting edge <NUM> of the cutting wheel, and the sensor <NUM> may detect the reflected light from the cutting edge <NUM>. Accordingly, the size of the cutting wheel <NUM> may be determined. As the cutting wheel <NUM> wears down with use, the distance to the cutting edge <NUM> increases. Therefore, as the initial distance to the cutting wheel <NUM> and the initial size of the cutting wheel <NUM> are known, subsequent sizes of the cutting wheel <NUM> can be determined as the distance to the cutting edge <NUM> changes.

Also, as shown in <FIG>, the spindle may be straight, and the light source <NUM> and the sensor <NUM> may be placed appropriately to determine the size of the cutting wheel <NUM>.

Therefore, it can be seen that any of a number of different methods may be used to determine a size of the cutting wheel <NUM> so as to adjust its rotational velocity to keep the surface speed constant. These various calculations/estimations may be made by, for example, the control circuitry <NUM> with appropriate information from the sensor <NUM>, the actuator <NUM>, power source <NUM>, etc. The methods of determining the diameter of the cutting wheel <NUM> may be grouped into, for example, two groups. The first group may be referred to as the direct method and the second group may be referred to as the indirect method.

The direct method may use information directly regarding the cutting wheel <NUM> such as, for example, by using light reflection from the cutting wheel <NUM>. The indirect method may use information not directly regarding the cutting wheel <NUM>. For example, the information may be a distance from the sensor <NUM> to the surface of the item being cut or to the surface of a supporting member that supports the item being cut, the power used to drive the cutting wheel <NUM>, etc..

The size of the cutting wheel <NUM> may be determined continuously or periodically. The size determination may also be performed at any time using, for example, the user interface <NUM>, where the determination may be requested using the input interface <NUM> or a remote electronic device <NUM>.

<FIG> is a flow diagram illustrating an example method to control a surface speed of a cutting wheel in accordance with aspects of this disclosure. Referring to <FIG>, there is shown a flow diagram <NUM> with blocks <NUM> to <NUM>. The example method shown in the flow diagram <NUM> may be used to implement the control circuitry <NUM> of <FIG> to control the actuator <NUM> and/or the power source <NUM>. For example, the example method may be implemented using machine readable instructions, which may be stored in the memory <NUM> and/or executed by the processing circuitry <NUM>. The example method is described below with reference to the cutting device <NUM> of <FIG>.

In block <NUM>, the control circuitry <NUM> determines the initial parameters associated with the cutting wheel <NUM>. For example, the parameters may include the item being cut, the overall part number of the item being cut, an abrasive material type on the cutting wheel, a size of the cutting wheel, a concentration of the abrasive material on the cutting wheel, a thickness of the cutting wheel, a bonding agent material type, and/or a bonding agent material hardness. Determination of the parameters may be done by a user entering the size directly or entering an identifier for the cutting wheel <NUM> and/or by recognition of electronic indicia associated with the cutting wheel <NUM> and/or the item to be cut based on the identifier(s), in which the cutting device <NUM> may look up the parameter(s) of the cutting wheel <NUM> and/or the item to be cut based on the identifier(s). The information may be entered or read using, for example, the user interface <NUM> either locally via the input interface <NUM> and/or the tag reader <NUM>, or remotely via the electronic device <NUM> and/or the tag reader <NUM>.

The present size of the cutting wheel <NUM> may also be determined using any of the methods described in this disclosure, or any other methods that may be applicable for determining a size of the cutting wheel <NUM>. The desired surface speed may also be similarly entered, or the identifier for the cutting wheel <NUM> and/or the entered characteristics of the item to be cut may be used to determine a desired surface speed.

The determination may be performed, for example, by the processing circuitry <NUM> in the control circuitry <NUM>, or any other capable processor that may be a part of the cutting device <NUM>.

At block <NUM>, the control circuitry <NUM> determines the present size of the cutting wheel <NUM>. This may be done upon a prompt by a user or another person or device, periodically, or continuously. At block <NUM>, the control circuitry <NUM> determines the surface speed of the cutting wheel <NUM> based on the present size of the cutting wheel <NUM>. The surface speed SFPM may be determined using Equation <NUM> above: SFPM = (D)(π)(RPM)/<NUM>.

A value of <NUM> is used for π, D is the diameter of the cutting wheel <NUM>, and RPM is the rotational velocity of the cutting wheel <NUM> per unit time. Accordingly, a cutting wheel <NUM> with an initial diameter of <NUM> meters (<NUM> inches) rotating at <NUM> RPM has a an SFPM of π(<NUM>)(<NUM>)/<NUM> = <NUM>,<NUM> feet/minute (which corresponds to <NUM> meters/minute). It should be noted that a larger number of decimal places can be used for π for greater accuracy.

After some time, the diameter of the cutting wheel <NUM> may be, for example, <NUM> meters (<NUM> inches). Without adjusting the rotational velocity to compensate for the smaller diameter, the surface speed is now <NUM> meters/minute (<NUM> feet/minute), or about <NUM>% less than the desired surface speed.

At block <NUM>, this surface speed may be compared to the desired surface speed, and the rotational velocity of the cutting wheel <NUM> may be adjusted as needed. If the surface speed is within a desired tolerance and does not need to be adjusted, the next step may be to block <NUM>. If the surface speed needs to be adjusted to be within a desired tolerance, such as, for example, <NUM>%, then the next step may be at block <NUM>.

At block <NUM> the rotational velocity may be increased to, for example, <NUM> RPM, resulting in a surface speed of <NUM> meters/minute (<NUM> feet/minute). The next step may be to block <NUM> to again determine the size of the cutting wheel <NUM>.

The cutting device <NUM> described above provides a general description for the sake of brevity, and other types of cutting devices that have other configurations may also be used without deviating from the scope of the disclosure. Accordingly, the cutting device <NUM> may comprise other blocks/functions without deviating from the scope of the disclosure. While various embodiments are described, other embodiments may also be used in accordance of this disclosure.

Additionally, while a specific example flow diagram is described, other flow diagrams may also be implemented for the use of the cutting device <NUM>. For example, since Equation <NUM> is a linear equation, the present diameter (or radius) may be compared to the baseline diameter (radius) to determine whether the rotational velocity should be adjusted. Or, when an intensity of light is used to determine the diameter of the cutting wheel <NUM>, the intensity may be used directly to be compared to a baseline intensity for the cutting wheel <NUM>, if applicable.

<FIG> is a flow diagram illustrating another example method to control a surface speed of a cutting wheel in accordance with aspects of this disclosure. <FIG> is a flow diagram illustrating an example method to control a surface speed of a cutting wheel in accordance with aspects of this disclosure. Referring to <FIG>, there is shown a flow diagram <NUM> with blocks <NUM> to <NUM>. The example method shown in the flow diagram <NUM> may be used to implement the control circuitry <NUM> of <FIG> to control the actuator <NUM> and/or the power source <NUM>. For example, the example method may be implemented using machine readable instructions, which may be stored in the memory <NUM> and/or executed by the processing circuitry <NUM>. The example method is described below with reference to the cutting device <NUM> of <FIG>.

In block <NUM>, the control circuitry <NUM> determines the initial parameters associated with the cutting wheel <NUM> in a manner similar to that described in block <NUM> of <FIG>. For example, the parameters may include the item being cut, the overall part number of the item being cut, an abrasive material type on the cutting wheel, a size of the cutting wheel, a concentration of the abrasive material on the cutting wheel, a thickness of the cutting wheel, a bonding agent material type, and/or a bonding agent material hardness. Determination of the parameters may be done by a user entering the size directly or entering an identifier for the cutting wheel <NUM> and/or by recognition of electronic indicia associated with the cutting wheel <NUM> and/or the item to be cut based on the identifier(s), in which the cutting device <NUM> may look up the parameter(s) of the cutting wheel <NUM> and/or the item to be cut based on the identifier(s). The information may be entered or read using, for example, the user interface <NUM> either locally via the input interface <NUM> and/or the tag reader <NUM>, or remotely via the electronic device <NUM> and/or the tag reader <NUM>.

At block <NUM>, the control circuitry <NUM> determines the present size of the cutting wheel <NUM>. This may be done upon a prompt by a user or another person or device, periodically, or continuously.

At block <NUM> the rotational velocity is controlled to correspond to the target surface speed. The next step may be to block <NUM> to again determine the size of the cutting wheel <NUM>.

<FIG> is a flow diagram illustrating an example method of controlling operation of a cutting wheel in accordance with aspects of this disclosure. Referring to <FIG>, there is shown the flow diagram <NUM> with blocks <NUM> to <NUM>. At block <NUM>, the present cutting wheel size is determined. The determination may be performed using any of the various methods described above, or any other method suitable method.

At block <NUM>, a rate of change in size of the cutting wheel <NUM> may be determined by comparing the present size with a previous size. If the change in size over time (change rate) is larger than a threshold rate, then the cutting wheel <NUM> may be stopped at block <NUM>. This may be due to, for example, a concern that the cutting wheel <NUM> may have broken, shattered, etc. If the change rate is not greater than the threshold rate, then the cutting wheel size may be determined again at block <NUM>. The size determination may be continuous, at some periodic rate, on demand, etc..

Depending on the change rate, a warning may be provided to the user of the cutting device <NUM> that comprises the cutting wheel <NUM>. For example, if the change rate is less than a first threshold rate, but above a second threshold rate, then a warning may be provided that the cutting wheel <NUM> is getting smaller than expected during its use.

Additionally, while light was given as an example, other wavelengths of the electromagnetic spectrum, sound waves, etc. may also be used as appropriate for determining speed and/or distance, as well as presence of a marker. Accordingly, various embodiments of the disclosure may use any appropriate method to determine a diameter of the cutting wheel <NUM> and/or the surface speed of the cutting wheel <NUM> to control the rotational velocity of the cutting wheel <NUM>.

Various embodiments of the disclosure may disclose a method for controlling a rotational velocity of a cutting device by determining a present diameter of a cutting wheel of the cutting device, and adjusting a rotational velocity of the cutting wheel based on the present diameter to have a surface speed of the cutting wheel at substantially a pre-determined constant surface speed. The present diameter may be determined upon demand by a user of the cutting device or periodically without user input. The present diameter may be determined by, for example, detecting one or both of: light or sound reflected from at least one reflector of the cutting wheel, light or sound reflected from an area of the cutting wheel, light reflected from the edge of the cutting wheel, and/or light reflected from and/or received on an opposite side of the cutting wheel from the light. The light or sound may be transmitted, for example, by a source on a first side of the cutting wheel toward the cutting wheel and received by a sensor on a second side of the cutting wheel.

The present diameter is determined by determining an amount of power used to maintain a present rotational velocity. The power used is electric power. The determining the present diameter comprises determining a distance from a sensor to a surface of an item being cut by the cutting wheel and/or a distance to a surface of a member supporting the item being cut, and the distance is used to determine the present diameter of the cutting wheel.

The present diameter may also be estimated based on an amount of time the cutting device is in operation. For example, the cutting wheel may be assumed to decrease in size by a certain amount for each minute the cutting device is in operation, and the known initial diameter may be reduced appropriately. The initial diameter may be known because the diameter may be entered prior to operation or the diameter may be looked up based on identifier of the cutting wheel being entered prior to operation.

Similarly, the present diameter may be estimated based on an amount of time the cutting wheel is in contact with an item being cut, and a diameter of the cutting wheel may be known prior to a first contact with the item being cut as explained above.

The present diameter may be compared with a previous diameter, and a change rate of the diameter may be determined. When the change rate is greater than a first threshold, the rotational velocity of the cutting wheel may be adjusted to zero. A warning may be provided when the change rate is less than or equal to the first threshold and greater than or equal to a second threshold.

The constant surface speed may be one of a plurality of constant surface speeds, where each of a plurality of constant surface speeds may be correlated to, for example, a type of material being cut. Various other parameters may also be used to determine a desired surface speed.

Various embodiments of the disclosure may disclose a cutting device that comprises a cutting wheel, an actuator to rotate the cutting wheel, a power source configured to provide power to the actuator for rotating the cutting wheel at an adjustable rotational velocity, and control circuitry configured to adjust the rotational velocity of the cutting wheel to maintain a substantially constant surface speed.

The constant surface speed may be one of a plurality of constant surface speeds. The control circuitry may be configured to determine a present diameter of the cutting wheel based on power needed to rotate the cutting wheel at a present rotational velocity. The control circuitry may also be configured to adjust the rotational velocity of the cutting wheel based on the present diameter to maintain a substantially constant surface speed of the cutting wheel.

A sensor may be configured to determine a distance from the sensor to a surface of an item being cut by the cutting wheel and/or a distance to a surface of a member supporting the item being cut, wherein the distance may be used to determine the present diameter of the cutting wheel. The sensor may be configured to detect one or both of light or sound reflected from at least one reflector of the cutting wheel, and light or sound reflected from an area of the cutting wheel.

Various embodiments of the disclosure may also disclose a method for controlling a rotational velocity of a cutting device by determining a present surface speed of a cutting wheel of the cutting device, and adjusting a rotational velocity of the cutting wheel based on the present surface speed to have a surface speed of the cutting wheel at substantially a pre-determined constant surface speed.

Claim 1:
A method for controlling a rotational velocity of a cutting device (<NUM>), comprising:
determining a present diameter of a cutting wheel (<NUM>) of the cutting device (<NUM>); and
adjusting a rotational velocity of the cutting wheel (<NUM>) based on the present diameter to have a surface speed of the cutting wheel (<NUM>) at substantially a pre-determined constant surface speed,
characterised in that determining the present diameter comprises determining an amount of power used to maintain a present rotational velocity, wherein the power is electric power and wherein the determining the present diameter comprises determining a distance from a sensor (<NUM>) to at least one of a surface of an item being cut by the cutting wheel (<NUM>) and a member supporting the item, and the distance is used to determine the present diameter of the cutting wheel.