JPH072165Y2 - Saw chain center link structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an improvement in the center link structure of a saw chain.

(Prior Art and Problems) In order to automate the cutting work by converting the PVC pipe for water supply and a manual saw used for interior wall construction into a chain saw, the present applicant has a plurality of upper parts shown in FIG. 3 and FIG. While having a cutting edge 11 of the above, a plurality of center links 1 having an engaging concave portion 13 that meshes with the convex portion 41 of the drive sprocket 4 in the center of the bottom portion are sandwiched by a pair of side links 2 and 2, and endless with a pin P. We have come to provide a chainsaw CS that is compact and has a small cutting width.

When the structure of such a chain saw is compared with a chain saw for general woodworking, for example, it is as shown in Table 1.

Despite the thin center link,
Since the hardness is high, the center link receives lateral torsional stress when cutting with multiple cutting edges, so if the center link and side link pin connection points are set above half of the total height to suppress pivot action, In particular, there is a problem that cracks are easily formed from the blade bottom of the cutting edge to the pin insertion hole, the saw chain is broken, and the durability is poor.

(Problem of the invention) The present invention aims to provide a saw chain having excellent durability. Since the object to be cut is a harder material than wood, the hardness of the center link forming the cutting edge is reduced. It is an object to solve the conflicting problems that the toughness against torsional rupture cannot be provided.

(Means for Solving the Problem) The present invention is focused on the use of a bimetal material as the material for the center link, and has a plurality of cutting edges on the upper portion and an engaging recess for engaging with the drive sprocket at the center of the bottom portion. In a saw chain in which a plurality of center links are sandwiched by a pair of side links and endlessly connected by pins, a bimetal material obtained by welding and joining a hard steel plate and a soft steel plate in the longitudinal direction is used as a center link material. While forming the cutting edge on the hard steel plate portion, front and rear pin insertion holes and engagement recesses are formed on the soft steel plate portion, and a hard portion above the hole from the distance from the pin insertion hole to the front and rear ends of the center link. The distance to the joint between the steel plate portion and the soft steel plate portion or the distance to the blade bottom, whichever is shorter, or from the hole There that the distance to reach the engagement concave portion formed by setting to be longer a center link structure of the saw chain to be subject matter.

In the present invention, it is preferable to set the joint position between the hard steel plate portion and the soft steel plate portion to be above the cutting edge separating position of the cutting edge because a large cutting width can be reasonably formed.

(Effect) According to the present invention, as a material for the center link, the cutting edge has a desired hardness, while the toughness is provided around the connecting portion between the center link and the side link, so that the center link front side is provided through the pin insertion hole. And from the shortest distance L ₁ to the rear end, whichever of the distance from the pin insertion hole that easily breaks to the joint between the hard steel plate portion and the soft steel plate portion above or to the blade bottom, whichever is shorter, L ₂ and The distance L ₃ from the hole to the engaging recess becomes long, that is, L ₁ <L ₂ ,
Since it was set to be L _3, at a site from the site and the hole leading to the junction of the pin insertion above the rigid steel plate portion from the hole and a soft steel plate portion extending to the engaging recess preferentially during cutting crack It won't happen.

Hereinafter, the present invention will be described in detail based on specific examples shown in the accompanying drawings.

(Embodiment) In the drawings, CS is a small portable chain saw, which is attached to a pin P so as to sandwich an even number of center links 1 having an appropriate number of cutting edges 11 at the upper end via a pair of side links 2 and 2. Saw chain C which is pivotally connected
Is extended around the guide bar 3 endlessly, and the bottom portion 12 of the center link 1 is guided by fitting the bottom portion 12 of the center link 1 into the guide recessed groove 31 formed on the periphery thereof.
The tooth portion 41 of the chain sprocket 4 is meshed with the recess 13 of 12 to be driven to rotate, so that the saw chain C travels along the circumference of the guide bar 3.

The chainsaw CS is
Stopper 7 with a guide rod 71 protruding downward for guiding during cutting
And the clasp 7 that does not have a guide bar, the long hole 3 of the guide bar 3
The tension of the saw chain C is adjusted by bolts B and B so as to sandwich 2 and 32, and is also attached to the bearing 61 located at the center of the protrusion of the handle 6 and driven by a motor (not shown). The shaft 8 is assembled so that the components of the chain chain rocket 4 are connected to the keyway.

In the present invention, in the present invention, a bimetal material obtained by welding and joining cobalt high speed steel as a hard steel plate and spring steel as a soft steel plate in the longitudinal direction is used as a center link material, and a hard steel plate portion is formed as shown in FIG. Formed so that the joint of the soft steel plate is located below the height center of the cutting edge (blade height a is a / 2>
b) The cutting edge is divided at the position of the soft steel plate, and the cutting width is generally 2.7 times larger than the center link thickness and larger than that for woodworking (1.5 times larger than the center link thickness) While making it possible to carry out assortment without any hindrance,
The front and rear pin insertion holes H and the engaging recesses 13 are formed in the soft steel plate portion.
Forming a distance reaches the junction between the pin insertion shortest distance above the rigid steel plate portion from the hole than L ₁ from the hole H extending from the hole leading to the center link front and rear ends to the center link peripheral edge and the soft steel plate portion or The distance to the blade bottom, whichever is shorter
L ₂ and set to the distance L ₃ extending in the engaging recess becomes longer from the hole, a crack does not enter reached by the lateral torsional stress from the pin insertion hole reached the cutting edge blade bottom, or the engaging recess during cutting I am trying.

(Effect of the Invention) As is apparent from the above description, according to the present invention, a plurality of center links having a plurality of cutting edges on the upper portion and an engaging concave portion for engaging with the drive sprocket at the center of the bottom portion are provided. In a saw chain that is sandwiched by side links and connected endlessly with pins, a bimetal material obtained by welding a hard steel plate and a soft steel plate by welding in the longitudinal direction is used as the material for the center link, and the cutting is performed on the hard steel plate portion. While forming the edge, front and rear pin insertion holes and engagement recesses are formed in the soft steel plate portion, and the hard steel plate portion and the soft steel plate portion above the hole from the distance from the pin insertion hole to the center link front and rear ends. The saw chain is characterized in that the distance from the hole to the joint and the distance from the hole to the engaging recess are set to be long. Since it has a terlink structure, it can have a desired hardness for the cutting edge as a material for the center link, and also has toughness around the connecting portion between the center link and the side link, which is particularly fragile. It is said that the portion from the pin insertion hole to the joint between the upper hard steel plate portion and the soft steel plate portion and the portion from the hole to the engaging recess are distanced from the pin insertion hole to the front and rear ends of the center link. As a result of the longer length, cracking does not occur preferentially during cutting, the problems peculiar to small chainsaws for cutting relatively hard materials can be solved, and durability can be improved.

In the embodiment, only the tip of the cutting edge is made of a hard steel plate, but the hole from the pin insertion hole to the center link front and rear ends to the center link peripheral edge from the shortest distance L ₁ from the hole. If the distance L ₂ from the upper part to the joint between the hard steel plate part and the soft steel plate part becomes longer, even if a bimetal material in which the above joint part comes below the cutting edge blade bottom is used, This has the effect of suppressing crack rupture due to torsional stress and improving the durability of the saw chain.

[Brief description of drawings]

1 is a front view showing a center link structure according to the present invention, FIG. 2 is an enlarged view of a main part of a cutting edge in FIG. 1, FIG. 3 is a perspective view of a chainsaw to which the present invention is applied, and FIG. FIG. 3 is an enlarged cross-sectional view of the relevant part. 1 …… Center link, 11 …… Cutting edge, 12
...... Base, 13 ...... Engagement concave part, ...... Soft steel plate part, ...
… Bonded part ………… Hard steel plate part

Claims (2)

[Scope of utility model registration request] 1. A pair of side links sandwiches a plurality of center links having a plurality of cutting edges at the top and an engaging recess at the center of the bottom that engages with a drive sprocket, and is endlessly connected by pins. In a saw chain consisting of, using a bimetal material formed by welding and welding a hard steel plate and a soft steel plate in the longitudinal direction as a material for a center link, while forming the cutting edge on the hard steel plate portion, front and rear pin insertion holes and The engaging recess is formed, and the distance L ₁ from the pin insertion hole to the front and rear ends of the center link
The distance from the hole to the joining portion between the upper hard steel plate portion and the soft steel plate portion or the distance to the cutting edge blade bottom, whichever is shorter L ₂ and the distance L ₃ from the hole to the engaging recess is Saw chain center link structure characterized by setting so that L ₁ <L ₂ , L ₃ . 2. A distance L ₂ extending to the junction between the pin insertion above the rigid steel plate portion from the hole than the distance L ₁ extending to the center link front and rear ends of the hole and the soft steel plate portion and L ₁ <L ₂ The center link structure of the saw chain according to claim 1, wherein the position of the joint between the hard steel plate portion and the soft steel plate portion is set to be above the cutting edge cutting position under the following conditions.