Guide bar for a motor chainsaw and method for producing a guide bar

Patent metadata

Field	Value
Publication number	US-11485040-B2
Application number	US-202016937618-A
Country	US
Kind code	B2
Filing date	Jul 24, 2020
Priority date	Jul 26, 2019
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A guide bar for motor chainsaws has side plates and a middle section between the side plates connected fixedly and non-movably to the side plates. The side plates form a clamping section and a deflection section opposite the clamping section. A guide groove extends circumferentially about the guide bar. The middle section forms the guide groove bottom in the deflection section. A guide bar tip is located where the longitudinal center axis of the guide bar intersects the deflection section. The side plates each have a guide surface extending continuously across a first longitudinal side of the guide bar, the deflection section, and a second longitudinal side of the guide bar. The guide surfaces of the side plates have hardened regions at the first and second longitudinal sides and at the guide bar tip with a hardness greater than a hardness of a middle region of the side plates.

First claim

What is claimed is:

1. A guide bar for a motor chainsaw, the guide bar comprising:
a first one-piece side plate and a second one-piece side plate;
a middle section arranged between the first and second side plates, wherein the middle section is connected fixedly and non-movably to the first and second side plates;
wherein the first and second side plates form a clamping section of the guide bar and a deflection section at a free end of the guide bar, wherein the free end is arranged opposite the clamping section along a longitudinal center axis of the guide bar;
a guide groove extending circumferentially about the guide bar, wherein the middle section forms a bottom of the guide groove in the deflection section;
a guide bar tip located at the deflection section where the longitudinal center axis of the guide bar intersects the deflection section;
wherein the first and second side plates each comprise a guide surface extending continuously across a first longitudinal side of the guide bar, across the deflection section, and across a second longitudinal side of the guide bar;
wherein the guide surfaces of the first and second side plates comprise at least one hardened region at the first and second longitudinal sides and at the guide bar tip, respectively, wherein the at least one hardened region comprises a hardness which is greater than a hardness of a middle region of the first and second side plates, respectively;
wherein the guide surfaces comprise a first intermediate region between the first longitudinal side and the deflection section and a second intermediate region between the second longitudinal side and the deflection section, respectively, wherein the first and second intermediate regions have a reduced hardness compared to the hardness of the at least one hardened region.

2. The guide bar according to claim 1 , wherein the first and second intermediate regions are arranged at a distance from the guide bar tip, wherein the distance is measured parallel to the longitudinal center axis of the guide bar, wherein the distance amounts to 40% to 70% of a height of the guide bar.

3. The guide bar according to claim 1 , wherein the deflection section extends from the guide bar tip to a plane which extends perpendicularly to the longitudinal center axis through a point where a radius of at least one of the guide surfaces amounts to 100 mm, wherein the first and second intermediate regions are arranged at least partially outside of the deflection section.

4. The guide bar according to claim 1 , wherein the first and second intermediate regions comprise a length measured parallel to the longitudinal center axis of less than 20 mm.

5. The guide bar according to claim 1 , wherein the first and second intermediate regions comprise a depth measured perpendicularly to the guide surfaces, wherein the depth is smaller than a depth of the guide groove.

6. The guide bar according to claim 1 , wherein a depth of the first and second intermediate regions amounts to less than 20% of a height of the guide bar.

7. The guide bar according to claim 1 , wherein the middle section and at least one of the first and second side plates together form a one-piece element.

8. The guide bar according to claim 7 , wherein the middle section and the at least one of the first and second side plates are embodied separate from each other and are connected to each other by weld spots.

9. The guide bar according to claim 8 , wherein the at least one hardened region is arranged at a distance relative to the weld spots.

10. A method for producing a guide bar for a motor chainsaw, wherein the guide bar comprises a first one-piece side plate and a second one-piece side plate; wherein the first and second side plates form a clamping section of the guide bar and a deflection section at a free end of the guide bar, wherein the free end is arranged opposite the clamping section along a longitudinal center axis of the guide bar; wherein a guide groove extends circumferentially about the guide bar; wherein a guide bar tip is located at the deflection section where the longitudinal center axis of the guide bar intersects the deflection section; wherein the first and second side plates each comprise a guide surface extending continuously across a first longitudinal side of the guide bar, across the deflection section, and across a second longitudinal side of the guide bar; the method comprising:
inductively hardening the guide bar at the first and second longitudinal sides and at the guide bar tip to provide the guide surfaces of the first and second side plates with at least one hardened region at the first and second longitudinal sides and at the guide bar tip, respectively, wherein the at least one hardened region comprises a hardness which is greater than a hardness of a middle region of the first and second side plates, respectively;
wherein the inductively hardening comprises a step of hardening the guide bar tip with an inductor whose shape is matched to a shape of the guide bar tip and further comprises a step of hardening the first and second longitudinal sides in a continuous process by moving the guide bar in a direction of the longitudinal center axis past two inductors that are stationary in the direction of the longitudinal center axis.

11. The method according to claim 10 , wherein the step of hardening the guide bar tip and the step of hardening the first and second longitudinal sides are carried out separately at different times.

12. The method according to claim 10 , wherein the inductively hardening comprises hardening of the deflection section in a first hardening zone and further comprises hardening of the first and second longitudinal sides in at least one second hardening zone, wherein the first hardening zone and the at least one second hardening zone overlap in at least one overlap region so that a material in the overlap region, after hardening in one of the hardening zones of the first hardening zone and the at least one second hardening zone, is heated again during hardening of the other one of the hardening zones of the first hardening zone and the at least one second hardening zone and thereby annealed so that an intermediate region is formed.

13. The method according to claim 10 , wherein the guide bar comprises a middle section arranged between the first and second side plates and forming a bottom of the guide groove in the deflection section, the method further comprising, prior to the inductively hardening, connecting the middle section fixedly and non-movably to the first and second side plates.

14. The method according to claim 10 , wherein the inductively hardening includes providing the guide surfaces of the first and second side plates with the hardened regions simultaneously.

Assignees

• Stihl Ag & Co Kg Andreas

Inventors

• Lux Thomas
• Leiendecker Martin
• Mitrega David

Classifications

• C21D2221/00

  Treating localised areas of an article · CPC title

• B23D57/023

  hand-held or hand-operated · CPC title

• B27B17/02 Primary

  Chain saws equipped with guide bar (B27B17/06 takes precedence) · CPC title

• B23D57/02 Primary

  with chain saws · CPC title

• Y02P10/25

  Process efficiency · CPC title