Torque wrench having improved wear properties

Patent metadata

Field	Value
Publication number	US-9453288-B2
Application number	US-201414300864-A
Country	US
Kind code	B2
Filing date	Jun 10, 2014
Priority date	Jun 10, 2014
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

A method for improving wear properties of a torque wrench includes electroplating one or more components of the torque wrench with zinc. In an aspect, one or more of an interior surface of a tube component, a surface of a secondary arm, a surface of a cam, and a surface of a pawl components may be electroplated with zinc. These components may interact to provide a click mechanism. For example, the pawl component may be seated between the secondary arm and the cam components, and the cam is adapted to move against a bias force when the secondary arm shifts the pawl in response to a preset torque level being achieved. The electroplated zinc layer provides a corrosion-resistant, softer and smoother surface for these components, and serves as a frictional reducer when the zinc oxidizes to form zinc oxide, which improves the accuracy life of the tool.

First claim

What is claimed is:

1. A method for improving wear properties of a torque wrench, comprising:
obtaining a tube component of the torque wrench, the tube component adapted to house internal components of the torque wrench and couple to a head adapted to engage a workpiece; and
electroplating at least a portion of an interior surface of the tube component with zinc to form a first zinc layer.

2. The method of claim 1 , wherein the first zinc layer has a thickness of about 0.0005 inches to about 0.0015 inches.

3. The method of claim 1 , wherein the first zinc layer has a Rockwell C hardness of about 17 to about 22.

4. The method of claim 1 , further comprising:
obtaining a secondary arm component of the torque wrench, the secondary arm component adapted to be housed within the tube component and couple to the head, the secondary arm component further adapted to interact with a pawl component and a cam component of the torque wrench to provide a click mechanism; and
electroplating a surface of the secondary arm component with zinc to form a second zinc layer.

5. The method of claim 4 , wherein the second zinc layer has a Rockwell C hardness of about 10 to about 14.

6. The method of claim 4 , wherein the second zinc layer has a surface finish of about 22 Root Mean Square (RMS).

7. The method of claim 1 , further comprising:
obtaining a cam component of the torque wrench, the cam component adapted to be housed within the tube component and interact with a pawl component and a secondary arm component of the torque wrench to provide a click mechanism; and
electroplating a surface of the cam component with zinc to form a third zinc layer.

8. The method of claim 7 , wherein the third zinc layer has a Rockwell C hardness of about 10 to about 14.

9. The method of claim 7 , wherein the third zinc layer has a surface finish of about 22 RMS.

10. The method of claim 1 , further comprising:
obtaining a pawl component of the torque wrench, the pawl component adapted to be housed within the tube component and seated between a secondary arm component and a cam component of the torque wrench, the pawl component further adapted to interact with a secondary arm component and a cam component of the torque wrench to provide a click mechanism; and
electroplating a surface of the pawl component with zinc to form a fourth zinc layer.

11. The method of claim 10 , wherein the fourth zinc layer has a Rockwell C hardness of about 10 to about 14.

12. The method of claim 10 , wherein the fourth zinc layer has a surface finish of about 22 RMS.

13. A method for improving wear properties of a torque wrench, comprising:
obtaining a tube component, a secondary arm component, a cam component, and a pawl component of the torque wrench, wherein the tube component is adapted to house the secondary arm, cam, and pawl components and couple to a head adapted to engage a workpiece, the secondary arm component adapted to couple to the head, the pawl component adapted to be seated between the secondary arm and cam components, and the tube, secondary arm, cam, and pawl components further adapted to interact to provide a click mechanism;
removing burrs from each of the tube, secondary arm, cam, and pawl components; and
electroplating an interior surface of the tube component and respective surfaces of the secondary arm, cam, and pawl components with zinc, thereby forming respective zinc layers on the surfaces.

14. The method of claim 13 , wherein the zinc layers have a thickness of about 0.0005 inches to about 0.0015 inches.

15. The method of claim 13 , wherein the zinc layer of the interior surface of the tube component has a Rockwell C hardness of about 17 to about 22.

16. The method of claim 13 , wherein the respective zinc layers of the surfaces of the secondary arm, the cam, and the pawl components have a Rockwell C hardness of about 10 to about 14.

17. The method of claim 13 , wherein the respective zinc layers of the surfaces of the secondary arm, the cam, and the pawl components includes have a surface finish of about 22 Root Mean Square (RMS).

18. A torque wrench, comprising:
a head adapted to engage a workpiece and a pivot arm;
a tube portion having an interior surface electroplated with a first zinc layer and adapted to receive the pivot arm and couple the head to the tube portion;
a secondary arm having a surface electroplated with a second zinc layer and disposed in the tube portion and adapted to couple to the pivot arm;
a cam having a surface electroplated with a third zinc layer and disposed in the tube portion;
a bias member disposed in the tube portion and adapted to apply a bias force to the cam and bias the cam toward the secondary arm;
a pawl having a surface electroplated with a fourth zinc layer and disposed in the tube portion and seated between the secondary arm and the cam, wherein the cam is adapted to move against the bias force when the secondary arm shifts the pawl in response to a preset torque level being achieved.

19. The torque wrench of claim 18 , wherein the first zinc layer has a Rockwell C hardness of about 17 to about 22.

20. The torque wrench of claim 18 , wherein each of the second, third and fourth zinc layers has a Rockwell C hardness of about 10 to about 14.

Assignees

• Snap On Incorporated

Inventors

• Tomlinson Timothy D

Classifications

• C25D5/34

  Pretreatment of metallic surfaces to be electroplated · CPC title

• B25B23/1427

  by mechanical means · CPC title

• C25D7/04 Primary

  Tubes; Rings; Hollow bodies · CPC title

• C25D7/00 Primary

  Electroplating characterised by the article coated · CPC title

• C25D7/10 Primary

  Bearings · CPC title