MACHINE CONTROL FOR GRINDING MACHINE

Description

BACKGROUND

[0001] The present disclosure is directed to grinding machines and particularly to safety features for grinding machines.

[0002] 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. US 2017 / 320191 A1 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. US 2022 / 023995 A1 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. US 2020 / 122292 A1 describes an angle grinder comprising: a transmission extension housing for connecting to the dust hood as recited in claim 11; 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. DE 199 08 353 A1 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.SUMMARY

[0003] 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. Preferred embodiments are defined in the dependent claims.

[0004] 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 480 volt alternating current 3 phase electrical power supply electrically coupled to the drive motor.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] In accordance with the present invention, there is provided a grinding machine as defined in claim 1.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] In accordance with the present invention, there is provided a process as defined in claim 9.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Fig. 1 is a schematic representation of an exemplary grinding machine. Fig. 2 is an electrical schematic representation of the exemplary grinding machine and accessories. DETAILED DESCRIPTION

[0026] Referring now to Fig. 1 and Fig. 2, there is illustrated at Fig. 1 an exemplary grinding machine 10. The grinding machine 10, shown as a pedestal bench grinder includes a support pedestal 12. The support pedestal 12 supports a drive motor 14 that supports an abrasive wheel 16. The abrasive wheel 16 can be driven by the drive motor 14 along a common drive shaft 18.

[0027] The drive motor 14 is operatively coupled to a motor drive 20. The motor drive 20 is programmable and configured to maintain operation of the drive motor 14 at an optimum speed for the particular process of material removal. The motor drive 20 is equipped with a safe torque off (STO) feature 22. The safe torque off feature 22 allows for the drive motor 14 to spin feely, upon predetermined input.

[0028] An E-stop 24 is operatively coupled to a safety controller 26. The E-stop 24 can be actuated by an operator (not shown) in order to shut down the grinding machine 10. The E-stop 24 can be a dual channel device. The E-stop 24 can actuate the safe torque off feature 22.

[0029] The safety controller 26 is electronically coupled to the E-stop 24, a vacuum pressure / air flow sensor 28 and the like. The safety controller 26 prevents operation of the motor 14 responsive to predetermined conditions. For example, if the safety controller 26 receives a signal from the vacuum / air flow sensor 28 that the exhaust ventilation unit 30 is not in operation, then the safety controller 26 will not allow actuation of the drive motor 14. The safety controller 26 can be configured to test any safety devices 32 of the grinding machine, such as the E-stop 24, the vacuum pressure / air flow sensor 28, foot pedal switch 34 and the like.

[0030] The foot pedal switch 34 is operatively coupled to the safety controller 26. An operator provides foot pressure on the foot pedal switch 34 to provide a signal to the safety controller 26 for drive motor 18 operation.

[0031] The safety controller 26 can detect electrical faults, such as short circuits, welded contacts and the like. The safety controller 26 can provide a signal to a fault light 36 on a panel 38. An E-stop reset 40 is electrically coupled to the safety controller 26. The E-stop reset 40 is needed to bring the grinding machine 10 back into operation.

[0032] A 480 volt AC 3 phase electrical power supply 42 is electrically coupled to the drive motor 14. The 3 phase configuration allows for the drive motor 14 brake to be a dynamic brake 44. As the phasing is reversed, responsive to a safety controller 26 condition precedent, the drive motor 14 turns in an opposite direction. In an exemplary embodiment, the foot pedal switch 34, upon depression, activates the drive motor 14. Release of the foot pedal switch 34 initiates the dynamic brake 44, in 2 seconds. The foot pedal switch 34 also prevents operation of the grinding machine 10 when unattended.

[0033] Redundant safety relays 46, 48 can be electrically coupled with the safety controller 26 and power supply 42.

[0034] A technical advantage of the grinding machine disclosed includes redundant safety features that prevent operator injury.

[0035] Another technical advantage of the grinding machine disclosed includes programmable motor controller for speed optimization.

[0036] Another technical advantage of the grinding machine disclosed includes advanced safety features that prevent the drive motor from spinning after shut down.

[0037] Another technical advantage of the grinding machine disclosed includes multiple sensors that ensure safety devices are active before operation of the grinding machine.

[0038] There has been provided a grinding machine. While the grinding machine has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.

Claims

1. A grinding machine (10) comprising: a support pedestal (12) supporting a drive motor (14) that supports an abrasive wheel (16) rotatably coupled to the drive motor (14); an exhaust vacuum (30) coupled to the support pedestal (12) proximate the abrasive wheel (16), the exhaust vacuum including a vacuum / air flow sensor (28); a motor drive (20) operatively coupled to the drive motor (14); a safety controller (26) operatively coupled with the drive motor (14) and motor drive (20); an E-stop (24) operatively coupled to the safety controller (26); a foot pedal switch (34) operatively coupled to the safety controller (26); and a 480 volt alternating current 3 phase electrical power supply (42) electrically coupled to the drive motor (14).

2. The grinding machine (10) according to claim 1, wherein said motor drive (20) is equipped with a safe torque off feature (22).

3. The grinding machine (10) according to claim 1 or 2, wherein said motor drive (20) is programmable and configured to maintain operation of the drive motor (14) at a predetermined speed for a material removal.

4. The grinding machine (10) according to any one of claims 1 to 3, wherein the safety controller (26) is electronically coupled to the E-stop (24) and / or a vacuum pressure / air flow sensor (28).

5. The grinding machine (10) according to any one of claims 1 to 4, wherein the safety controller (26) is configured to prevent operation of the drive motor (14) responsive to predetermined conditions.

6. The grinding machine (10) according to any one of claims 1 to 5, further comprising: a drive motor brake operatively coupled to the drive motor (14).

7. The grinding machine (10) according to claim 6, wherein said drive motor brake is configured as a dynamic brake (44).

8. The grinding machine according (10) to any one of claims 1 to 7, wherein the safety controller (26) is configured to detect electrical faults and / or short circuits and / or welded contacts; and / or further comprising: a fault light on a panel, wherein the safety controller (26) is configured to provide a signal to the fault light on the panel.

9. A process for configuring a grinding machine (10) for safety, the grinding machine (10) comprising: a support pedestal (12) supporting a drive motor (14) that supports an abrasive wheel (16) rotatably coupled to the drive motor (14) the process comprising the steps of; coupling an exhaust vacuum (30) to the support pedestal (12) proximate the abrasive wheel (16), the exhaust vacuum including a vacuum / air flow sensor (28); coupling a motor drive (20) to the drive motor (14); coupling a safety controller (26) with the drive motor (14) and motor drive (20); coupling an E-stop (24) to the safety controller (26); coupling a foot pedal switch (34) to the safety controller (26); and supplying a 480 volt alternating current 3 phase electrical power supply (42) to the drive motor (14).

10. The process of claim 9, wherein said motor drive (20) is equipped with a safe torque off feature (22).

11. The process of any one of claims 9 or 10, wherein said motor drive (20) is programmable and configured to maintain operation of the drive motor (14) at a predetermined speed for a material removal.

12. The process of any one of claims 9 to 11, further comprising the step of: electronically coupling the safety controller (26) to the E-stop (24) and / or a vacuum pressure / air flow sensor (28).

13. The process of any one of claims 9 to 12, further comprising: configuring the safety controller (26) to prevent operation of the drive motor (14) responsive to predetermined conditions.

14. The process of any one of claims 9 to 13, further comprising the steps of coupling a drive motor brake operatively coupled to the drive motor (14); and / or equipping the motor drive (20) with a safe torque off feature (22), wherein the safe torque off feature (22) is configured for the drive motor (14) to spin feely upon predetermined input.