Pipe cutter

• US 8,763,257 B2
• Filed: 08/27/2008
• Issued: 07/01/2014
• Est. Priority Date: 03/15/2007
• Status: Active Grant

• Current Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Original Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Inventors: Thorson, Troy C., Alberti, Daniel J., Bednar, Thomas R., Scott, John S., Anderson, Scott
• Primary Examiner(s): Alie, Ghassem
• Application Number:
  US12/745,340
• Publication Number:
  US 20110005084A1
• Time in Patent Office: 2,134 Days
• Field of Search: 30/95, 30/92, 301/01, 301/233, 30/97, 30/96, 30/93, 301/02, 305/00, 301/88, 301/80, 173/11, 173/217, 173/1, 82/59, 82/62, 82/64, 82/76, 82/77, 821/00, 82/991, 82/992
• US Class Current: 30/95
• CPC Class Codes: B23D 21/04 Tube-severing machines with rotating tool-carrier
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially

Abstract

A power tool, such as a pipe cutter, includes a rotatable cutting head assembly, an electric motor connectable to a rechargeable battery, and a controller. The controller is configured to monitor the state of charge on the battery, compare the state of charge to one or more thresholds, and prevent or limit operation of the power tool when the state of charge is less than or equal to one or more of the thresholds. In some embodiments, the threshold includes the state of charge required to cut a pipe, the state of charge required to return the cutting head assembly to a home position, and a state of charge indicative of an overdischarged condition of the battery. In some embodiments, the controller is configured to detect when the pipe cutter has completed cutting the pipe and returns the cutting head assembly to the home position.

Claims

1. A power tool configured to cut an object, comprising:

a motor configured to drive an operation;

a cutting assembly for cutting the object, the cutting assembly including a blade and a body portion positioned opposite the blade, the blade and the body portion defining a cutting area for receiving the object;

a controller configured to

monitor a state of charge of a battery connected to the motor,

compare the state of charge to a predetermined first threshold, the first threshold being greater than the state of charge needed by the motor to complete the operation, and the first threshold being greater than a second threshold, the second threshold related to the state of charge at which an over-discharged condition occurs in the battery,

wherein the operation includes performing at least a portion of a cutting action and returning the cutting assembly to a starting position, and

prevent the motor from driving the operation when the state of charge is less than or equal to the first threshold.

2. The power tool of claim 1, wherein the first threshold is approximately equal to the state of charge required to drive the operation ten times.

3. The power tool of claim 1, wherein the first threshold is approximately equal to 5% of a maximum state of charge of the battery.

4. The power tool of claim 1, wherein the controller is further configured to

store a second threshold that is greater than a state of charge indicative of an overdischarged state that causes damage to the battery, and

stop the motor when the state of charge is less than or equal to the second threshold.

5. The power tool of claim 1, further comprising a removable battery pack, and wherein the removable battery pack includes the battery.

6. The power tool of claim 1, wherein the cutting assembly is operated by the motor.

7. The power tool of claim 6, wherein the operation driven by the motor includes rotating the cutting assembly around a circumference of the object in a first direction.

8. The power tool of claim 7, wherein the controller is further configured to

store a third threshold that is greater than the state of charge required to return the cutting assembly in a second direction to a home position,

stop rotation of the cutting assembly in the first direction when the state of charge is less than or equal to the third threshold, and

allow the motor to rotate the cutting assembly in the second direction when the state of charge is less than or equal to the third threshold.

9. The power tool of claim 7, wherein the controller is further configured to

control the operation of the motor and, thereby, control the operation of the cutting assembly, and

detect when the cutting assembly is in a home position.

10. The power tool of claim 9, wherein the controller is further configured to

store a third threshold that is greater than the state of charge required to return the cutting assembly to the home position,

interrupt and prevent regular operation of the motor when the state of charge is less than the third threshold, and

rotate the cutting assembly to the home position when the state of charge is less than the third threshold.

11. The power tool of claim 7, wherein the controller is further configured to detect when the cutting assembly has finished cutting the object.

12. The power tool of claim 11, wherein the controller is configured to detect when the cutting assembly has finished cutting the object by

detecting a current draw of the motor, and

comparing the current draw of the motor to a fourth threshold, wherein the fourth threshold is lower than the current draw when the motor is running and the cutting assembly is cutting the object, and the fourth threshold is greater than the current draw when the motor is running and the cutting assembly is not cutting the object.

13. The power tool of claim 11, wherein the controller is configured to automatically rotate the cutting assembly to a home position when the controller detects that the cutting assembly has finished cutting the object.

14. The power tool of claim 1, wherein

the operation includes the cutting action followed by a second action, and

the controller is further configured to

store a third threshold that is greater than the state of charge required to drive the second action,

prevent performance of the cutting action when the state of charge is less than the third threshold, and

allow the motor to drive the second action when the state of charge is greater than the third threshold.