Hitachi Construction Machinery Co., Ltd.

Takayuki Shimodaira

Takeshi Takahashi

Makoto Sugaya

Ryuji Takada

Hiroyuki Ohta

Hiromi Shimazu

Hiroshi Aoyama

Yohei Tanno

Tomoatsu Iihama

A work arm of a work machine includes a box-shaped structure including multiple plate members, a pair of bosses attached to opposing plate members, and a cylindrical boss coupling member coupling the pair of bosses together. Each boss includes a boss body section having a pin insertion hole through which a coupling pin is inserted and extending in an arrangement direction of the plate members, and a flange section extending outward from an outer circumferential portion of the boss body section and joined to a corresponding one of the plate members via a first weld. The boss body section includes a cylindrical outer body portion on an outer surface side of the box-shaped structure and a cylindrical inner body portion on an inner surface side of the box-shaped structure. The boss coupling member is joined, at both axial ends thereof, to respective ends of the inner body portions via second welds. The inner body portion is configured such that an outer diameter at a flange section-side part thereof is smaller than an outer diameter at an axial end of the outer body portion. This allows improvement of fatigue life of the weld joining the boss and the plate member.

Work arm of work machine

An arm of a hydraulic excavator is formed as a box-shaped structural body surrounded by left and right side plates, an upper plate, a lower plate, and a thick rear plate. An upper end of the thick rear plate is protruded upward from an outer surface of the upper plate. Upper ends of a pair of arm cylinder brackets joined to an outer surface of the thick rear plate are arranged higher than the outer surface of the rear thick upper plate and lower than the upper end of the thick rear plate. As a result, in each of the arm cylinder brackets, a joint area with the thick rear plate can be ensured large, and joint strength can be improved.

Arm for construction machine with upper ends of rear plate protruding upward

An arm of a hydraulic excavator is formed as a box-shaped structural body surrounded by left and right side plates, an upper plate joined to each of the upper end sides of each side plate, a lower plate joined to each of the lower end sides of each side plate, and a thick rear plate joined to each of the rear end sides of each side plate and the upper plate. The side plates are formed by joining a rear thick side plate and a front thin side plate. The upper plate is formed by joining two members, that is, a rear thick upper plate and a front thin upper plate, and the lower plate is formed by joining two members, that is, a rear thick lower plate and a front thin lower plate.

Arm for construction machine

In an arm for a construction machine formed as a box-shaped structural body by left and right side plates, an upper plate, a lower plate, and a rear plate, a left rear thick side plate constituting the left side plate, a right rear thick side plate constituting the right side plate, a rear thick upper plate constituting the upper plate, and a rear thick lower plate constituting the lower plate are formed by using a soft steel material having a large plate thickness. A left front thin side plate constituting the left side plate, a right front thin side plate constituting the right side plate, a front thin upper plate constituting the upper plate, and a front thin lower plate constituting the lower plate are formed by using a high tensile steel material having a small plate thickness. As a result, the weight of the entire arm can be reduced.

The invention provides a load sensor which is driven by a low electric power consumption, can measure at a high precision, and has a high reliability without being broken. The load sensor is structured such that a detection rod for detecting a strain is provided in an inner portion of a hole formed near a center of a pin via a shock relaxation material and a semiconductor strain sensor is provided in the detection rod, in a load sensor detecting a load applied to the pin from a strain generated in an inner portion of the pin.

Growing community of inventors

Ryugasaki, Japan

Takayuki Shimodaira