US 3810408 A
An improved chain saw guide frame for power-driven saw chain which is fitted with a heat-sensitive colorant at a concave region in the nose part of the guide frame for detecting heat accumulation of the guide frame.
Description (OCR text may contain errors)
United States Patent 11 1 I Taira et al.
GUIDE FRAME FOR CHAIN SAW Inventors: Tetsuro Taira; Akira Somekawa, both of Tokyo, Japan Assignee: Kaoru Tsumura, Miki, Hyogo,
Japan Filed: Dec. 6, 1972 Appl. No.: 312,503
vs. C] 83/802, 83/522, 30/387, 116/114 v, 83/820, 83/821 Int. Cl. ..B27b 17/02, B23d 57/02, GOld 13/00, 601k 1/02 Field of Search '73/356; 184/1 B, 1 c;
l 16/] l4-V; 83/802, 820, 82l, 522; 30/38l-387 1451 May 14,- 1974  References Cited UNITED STATES PATENTS 3,569,695 3/l97l McLean 116/] 14 V 3,119,418 1/1964 Rayniak... 30/387 3,185,191 5/1905 Olsen 30/387 Primary Examiner-Donald R. Schran Attorney, Agent, or FirmWenderoth, Lind & Ponack 57] ABSTRACT An improved chain saw guide frame forpower-driven saw chain which is fitted with a heat-sensitive colorant at a concave region in the nose part of the guide frame for detecting heat accumulation of the guide frame.
2 Claims, 3 Drawing Figures GUIDE FRAME FOR CHAIN SAW The present invention relates to an improved guide frame for power-driven chain saws.
It has been observed that, when there is insufficient lubrication at the sliding surface of guide frame which guides the saw chain driven at a high speed or when the saw chain is not maintained under appropriate tension, the guide frame temperature rises due to the accumulation of heat therein.
This phenomenon makes it necessary for the opera- 'tor of a chain saw to be constantly concerned about the temperature of guide frame. On top of this disadvantage, usually finger-tips are used for feeling out the unusual rise of temperature of the guide frame, the method being extremely unsafe and also inaccurate.
A purpose of the present invention is to provide an improved guide frame, whose rise in temperature can easily be visually recognized and which is free from all the disadvantages described herein.
According to the present invention, the guide frame of a chain saw, around which an endless saw chain connected to a driving power source is guided, is fitted with a heat-sensitive colorant thereon. By watching the degree of color changes shown on the heat-sensitive colorant attached to the guide frame, harmful or dangerous temperature thereof can be easily detected.
Other and further objects and advantages of the invention will be fully understood hereinafter from the following description taken in connection with the accompanying drawings, in which FIG. 1 is a partial front view of the chain saw guide frame showing an embodiment of the present invention,
FIG. 2 is another partial view of the chain saw guide frame showing another embodiment of the present invention and FIG. 3 is an enlarged cross-sectional view of the em bodiment along the line A A shown in FIG. 2.
Referring now to the drawings, an endless saw chain 2 is guided around a guide frame 1 while being driven by a chain-driving power source (not illustrated).
The guide frame 1 is fitted with a heat-sensitive colorant applied thereto either in a form of paint or a sticker at an appropriate place on the surface of the guide frame 1 by a painting or pasting process.
Further, a guide frame 1 having a shallow concave region 4 formed, through the common manufacturing process thereof, at the nose part thereof may be caulked at 5 with proper caulking materials on which to fit the heat-sensitive colorant 3.
According to the present invention above described, any unusual rise in the temperature of the guide frame 1 while in use causes the heat-sensitive colorant 3 to change its color. Therefore, as soon as the danger is detected by the chain saw operator who reads the color of the heat-sensitive colorant 3, appropriate steps can be taken to avoid damage to the chain saw.
The chain saw guide frame in accordance with the present invention can indicate its degree of heat accumulation with the changes in the color of the heatsensitive colorant, whereby it does not require any direct touch thereto by human body such as fingers for feeling out the heat and it can detect the extent of unsafe temperature visually, thereby contributing greatly to the safety in chain saw work.
Furthermore, other advantages lie in the fact that the guide frame itself does not have to be manipulated for any changes in the shape thereof so that the embodied frame is not deterimental to any degree to the sawing work. A
While preferred embodiments of the present invention have been illustrated herein, it is understood that it may be apparent to those who are skilled in the art that modifications and alterations thereof can be made without deviating from the principles of the present invention set forth in the following claim:
What is claimed:
1. A safety means for warning chain saw operators of increases in temperature of a chain saw guide frame having a shallow concave region in the nose portion thereof, comprising a heat sensitive colorant layer securely located within said concave region for indicating temperature increases in said adjacent guide frame by changing colors in response to temperature change in said guide frame.
2. The means of claim 1 further comprising a layer of caulking material interposed within said concave region between said colorant layer and said guide frame for retaining said colorant.