Patent Description:
A grinding machine employs a grind wheel that is formed from an abrasive material or that has an abrasive material thereon. To perform a grinding operation, the grind wheel is generally caused to rotate via a motor. Once the grind wheel is rotating at a desired rate, the grind wheel contacts a workpiece to perform a grinding operation. Typical grinding machines include a latch style on/off switch that allows for the machine to remain in operation even while being unattended by an operator. Moreover, subsequent a power outage, a grinding machine can have the switch remain in the on position, and upon reenergizing, the machine can spontaneously operate, creating a hazard. Grinding machines create substantial quantities of fine airborne particulate during operation. However, grinding machines are optionally equipped with exhaust vacuum particulate removal devices. These exhaust vacuum devices are optionally operated during the grinding operation. <CIT> describes a bench grinder safety and monitoring system for maintaining worker safety while using a bench grinder having a motor operatively coupled to a contactor wheel, a tool rest in lower proximity to the contactor wheel that defines a tool rest gap between the tool rest and contactor wheel and having a tongue guard in upper proximity to the contactor wheel that defines a tongue guard gap between the tongue guard and the contactor wheel, said grinder safety and monitoring system, comprising: a first optical sensor situated within in the tool rest gap having an emitter portion coupled to the tool rest adjacent a first side of the contactor wheel and a receiver portion coupled to the tool rest adjacent a second side of the contactor wheel, said emitter portion configured to project a beam of light across the tool rest gap toward said receiver portion; a controller electrically connected to the motor of the bench grinder and in data communication with said receiver portion of said first optical sensor, said controller configured to determine if said light beam is received by said receiver portion and, if so, to deenergize the motor. <CIT> describes a system for polishing an outer surface of a specimen, the system comprising: a motor and a rotatable shaft extending from a first end of the motor, wherein the specimen is removably attachable to the rotatable shaft; a safety cover configured to at least partially surround at least a portion of the rotatable shaft, the safety cover comprising: a top panel; a first side panel and a second side panel spaced from each other across a width of the safety cover and extending downwardly from the top panel;
and at least one aperture extending through at least one of the first and second side panels; and an abrasive material insertable through the at least one aperture so that the abrasive material is positionable to contact the outer surface of the specimen. <CIT> describes an angle grinder comprising: a transmission extension housing for connecting to the dust hood as recited in claim <NUM>; and rotational speed control electronics, the rotational speed control electronics being, upon connection of the dust hood, connected by signals to the sensor unit via an interface in such a way that the rotational direction of the cutting wheel of the angle grinder is predefinable as a function of a sensor signal coming from the sensor unit. <CIT> describes a disc sander comprising: a base having a shroud, said shroud including a scroll type baffle forming a fan housing, the fan housing having at least one inlet port and an exit nozzle; an electric motor attached to said base, said electric motor having an output shaft extending normal to said shroud; a sanding disc attached to said shaft adjacent to said shroud, said sanding disc having a plurality of spaced apart fins extending into said fan housing and forming therewith a vane type pump; and an inlet manifold having an inlet disposed adjacent to a surface of said sanding disc on the side opposite said shroud and an outlet connected to said at least one inlet port to said fan housing the inlet manifold conducting an air flow from the region in front of the sanding disc on the side opposite the shroud into the fan housing.

The present invention relates to a grinding machine and a process for configuring a grinding machine for safety as specified in the independent claims respectively.

In accordance with the present invention, there is provided a grinding machine comprising a support pedestal supporting a drive motor that supports an abrasive wheel rotatably coupled to the drive motor; an exhaust vacuum coupled to the support pedestal proximate the abrasive wheel,the exhaust vacuum including a vacuum/air flow sensor; a motor drive operatively coupled to the drive motor; a safety controller operatively coupled with the drive motor and motor drive; an E-stop operatively coupled to the safety controller; a foot pedal switch operatively coupled to the safety controller; and a <NUM> volt alternating current <NUM> phase electrical power supply electrically coupled to the drive motor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the motor drive is equipped with a safe torque off feature.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the motor drive is programmable and configured to maintain operation of the drive motor at a predetermined speed for a material removal.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the safety controller is electronically coupled to the E-stop, a vacuum pressure/air flow sensor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the safety controller is configured to prevent operation of the drive motor responsive to predetermined conditions.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the grinding machine further comprising a drive motor brake operatively coupled to the drive motor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the drive motor brake is configured as a dynamic brake.

In accordance with the present invention, there is provided a grinding machine as defined in claim <NUM>.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the safety controller is electronically coupled to the E-stop, the vacuum pressure/air flow sensor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the safety controller is configured to detect electrical faults, short circuits, welded contacts.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the grinding machine further comprising a fault light on a panel, wherein the safety controller is configured to provide a signal to the fault light on the panel.

In accordance with the present invention, there is provided a process as defined in claim <NUM>.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising electronically coupling the safety controller to the E-stop, a vacuum pressure/air flow sensor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising the step of configuring the safety controller to prevent operation of the drive motor responsive to predetermined conditions.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising a drive motor brake operatively coupled to the drive motor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising equipping the motor drive with a safe torque off feature, wherein the safe torque off feature is configured for the drive motor to spin feely upon predetermined input.

Other details of the grinding machine are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.

Referring now to <FIG> and <FIG>, there is illustrated at <FIG> an exemplary grinding machine <NUM>. The grinding machine <NUM>, shown as a pedestal bench grinder includes a support pedestal <NUM>. The support pedestal <NUM> supports a drive motor <NUM> that supports an abrasive wheel <NUM>. The abrasive wheel <NUM> can be driven by the drive motor <NUM> along a common drive shaft <NUM>.

The drive motor <NUM> is operatively coupled to a motor drive <NUM>. The motor drive <NUM> is programmable and configured to maintain operation of the drive motor <NUM> at an optimum speed for the particular process of material removal. The motor drive <NUM> is equipped with a safe torque off (STO) feature <NUM>. The safe torque off feature <NUM> allows for the drive motor <NUM> to spin feely, upon predetermined input.

An E-stop <NUM> is operatively coupled to a safety controller <NUM>. The E-stop <NUM> can be actuated by an operator (not shown) in order to shut down the grinding machine <NUM>. The E-stop <NUM> can be a dual channel device. The E-stop <NUM> can actuate the safe torque off feature <NUM>.

The safety controller <NUM> is electronically coupled to the E-stop <NUM>, a vacuum pressure/air flow sensor <NUM> and the like. The safety controller <NUM> prevents operation of the motor <NUM> responsive to predetermined conditions. For example, if the safety controller <NUM> receives a signal from the vacuum/air flow sensor <NUM> that the exhaust ventilation unit <NUM> is not in operation, then the safety controller <NUM> will not allow actuation of the drive motor <NUM>. The safety controller <NUM> can be configured to test any safety devices <NUM> of the grinding machine, such as the E-stop <NUM>, the vacuum pressure/air flow sensor <NUM>, foot pedal switch <NUM> and the like.

The foot pedal switch <NUM> is operatively coupled to the safety controller <NUM>. An operator provides foot pressure on the foot pedal switch <NUM> to provide a signal to the safety controller <NUM> for drive motor <NUM> operation.

The safety controller <NUM> can detect electrical faults, such as short circuits, welded contacts and the like. The safety controller <NUM> can provide a signal to a fault light <NUM> on a panel <NUM>. An E-stop reset <NUM> is electrically coupled to the safety controller <NUM>. The E-stop reset <NUM> is needed to bring the grinding machine <NUM> back into operation.

A <NUM> volt AC <NUM> phase electrical power supply <NUM> is electrically coupled to the drive motor <NUM>. The <NUM> phase configuration allows for the drive motor <NUM> brake to be a dynamic brake <NUM>. As the phasing is reversed, responsive to a safety controller <NUM> condition precedent, the drive motor <NUM> turns in an opposite direction. In an exemplary embodiment, the foot pedal switch <NUM>, upon depression, activates the drive motor <NUM>. Release of the foot pedal switch <NUM> initiates the dynamic brake <NUM>, in <NUM> seconds. The foot pedal switch <NUM> also prevents operation of the grinding machine <NUM> when unattended.

Redundant safety relays <NUM>, <NUM> can be electrically coupled with the safety controller <NUM> and power supply <NUM>.

A technical advantage of the grinding machine disclosed includes redundant safety features that prevent operator injury.

Another technical advantage of the grinding machine disclosed includes programmable motor controller for speed optimization.

Another technical advantage of the grinding machine disclosed includes advanced safety features that prevent the drive motor from spinning after shut down.

Another technical advantage of the grinding machine disclosed includes multiple sensors that ensure safety devices are active before operation of the grinding machine.

Claim 1:
A grinding machine (<NUM>) comprising:
a support pedestal (<NUM>) supporting a drive motor (<NUM>) that supports an abrasive wheel (<NUM>) rotatably coupled to the drive motor (<NUM>);
an exhaust vacuum (<NUM>) coupled to the support pedestal (<NUM>) proximate the abrasive wheel (<NUM>), the exhaust vacuum including a vacuum/air flow sensor (<NUM>);
a motor drive (<NUM>) operatively coupled to the drive motor (<NUM>);
a safety controller (<NUM>) operatively coupled with the drive motor (<NUM>) and motor drive (<NUM>);
an E-stop (<NUM>) operatively coupled to the safety controller (<NUM>);
a foot pedal switch (<NUM>) operatively coupled to the safety controller (<NUM>); and
a <NUM> volt alternating current <NUM> phase electrical power supply (<NUM>) electrically coupled to the drive motor (<NUM>).