JPH0220533Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a scraper used, for example, in a hydraulic cylinder, and particularly to a scraper that is effective even when the rod of the cylinder is eccentric.

(Prior Art) Welding robots have been widely used as a type of industrial robot in recent years. Hydraulic cylinders and pneumatic cylinders are used in the arms of this welding robot, but since welding spatter easily adheres to the rods of these cylinders, a scraper 12 is installed outside the rod seal 10 as shown in FIG. is provided to prevent welding spatter adhering to the outer circumferential surface of the rod 14 from entering the inside of the cylinder.

Furthermore, when a hydraulic cylinder is used in a construction machine such as a bulldozer or a power shovel, so-called heavy dust such as frozen earth and sand, adhesive, etc. adheres to the rod 14 of the hydraulic cylinder.

In order to prevent these heavy dust from entering the inside of the cylinder, the scraper 12 has an inner circumferential lip 16 that is in close contact with the outer circumference of the rod 14 and an outer circumferential lip 20 that is in close contact with the housing 18. The sides are sealed.

However, in such a conventional scraper, if the rod 14 becomes eccentric, the outer lip 20 is in close contact with the housing 18, so the inner lip 16 cannot follow the eccentricity of the rod 14, and the inner lip 16 becomes eccentric. There is a problem that it becomes distant from 14.

(Object of the invention) An object of the invention is to provide a scraper that can prevent dust from entering the cylinder from both the rod side and the housing side even when the rod is eccentric.

(Structure of the invention) The present invention is a resin scraper that has an inner lip that is in close contact with the outer periphery of the shaft and an outer lip that is in close contact with the housing. This scraper is characterized in that its tip is formed in close contact with the housing.

(Example) In FIG. 1 showing a scraper to which the present invention is applied, parts given the same reference numerals as in FIG. 6 indicate the same or equivalent parts.

The scraper 30 in FIG.
A peripheral lip 36 is provided which closely contacts 4a. The scraper 30 is made of a synthetic resin that is relatively hard and has appropriate elasticity, such as polyamide, polyacetal, polyamideimide, polyimide, polytetrafluoroethylene, ethylene/tetrafluoroethylene copolymer, or tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer. It is integrally formed into a ring shape using a material such as polybutylene terephthalate or polyethylene terephthalate.

The wall thickness of the inner peripheral lip 32 is T1 at the tip.
The inner peripheral lip 32 has a substantially uniform thickness over its entire length, or becomes thinner toward the tip of the lip. The outer circumferential lip 36 is set to a thickness T2 which is approximately 60% of the thickness T1, and the outer circumferential lip 36 also has a substantially uniform thickness over its entire length. In the natural state, the inner circumferential lip 32 and the outer circumferential lip 36 are formed so as to protrude outward from the outer circumferential surface of the rod 14 and the groove 34a by minute amounts δ1 and δ2.

Next, the action will be explained. If the rod 14 is eccentric for some reason, the outer lip 36, which is thinner than the inner lip 32, is easily deformed with its tip in pressure contact with the groove 34a. There is no risk that a gap will occur between the outer circumferential surface of the rod 14 and the tip of the inner circumferential lip 32, as in the conventional case, by following the eccentric rod 14 while the tip of the outer circumferential lip 36 remains in pressure contact with the surface. do not have.

Furthermore, when installing the scraper 30, simply fit the scraper 30 onto the outer periphery of the rod 14 and push the entire scraper 30 into the housing 18.
4b and comes into close contact with the groove 34a.

The inventors conducted the following experiment. That is, as shown in FIG. 2, a scraper fixing jig 44 is placed on a base 40 via a rubber sheet 42, and a scraper 30, for example, is interposed as a test piece between the scraper fixing jig 44 and the rod 14. , the rod 1 is pressed with a press 48 via a presser jig 46.
Press 4 to make the rod eccentric by the amount of eccentricity z, and then press the rod 14.
In this experiment, dust 50 was applied to the rod 14 and the rod 14 was slid in the R direction. In this experiment,
The diameter of Rod 14 is 36mm, and the diameter of Dust 50 is
Dust specified in JIS Z 8901 Class 7 is used, and the eccentricity z is set to 0.3 mm.

The above experimental results show that the outer lip 36 of the scraper 30 remains in close contact with the groove 34a, and the inner lip 32 remains close to the rod 1.
The scraper 30 is maintained in close contact with the outer peripheral surface of the rod 14 or the housing 1.
The dust 50 is sealed on both sides of the cylinder 8 to prevent the dust 50 from entering the inside of the cylinder.

However, the results of a similar experiment conducted on the conventional scraper 12 shown in FIG. 4 show that the thickness T3 of the outer circumferential lip 20 is set equal to the thickness T4 of the inner circumferential lip 16; A gap L is created between the rod 14 and the inner lip 16.

(Effects of the invention) As explained above, the scraper of the invention has an inner lip 32 that is in close contact with the outer periphery of the shaft and a housing 1.
8, the thickness T2 of the outer circumferential lip 36 is set thinner than the inner circumferential lip 32, and the outer circumferential lip 36
Since the tip of the rod 14 is formed to be in close contact with the housing, even if the rod 14 is eccentric, the outer lip 36, which is thinner than the inner lip 32, will remain in close contact with the groove 34a, and the inner lip 32 will remain in close contact with the rod. 1
4, the scraper 30 can form a sealing surface on both the rod side and the housing 18 side, and can prevent dust from entering the cylinder.

Moreover, when installing the scraper 30, simply fit the scraper 30 onto the rod 14 and push the entire scraper 30 into the housing 18.
The outer circumferential lip 36 is deformed so as to go over the convex circumferential wall 34b, and the outer circumferential lip 36 comes into close contact with the groove 34a, so that the scraper 30 can be easily mounted.

(Another embodiment) (1) The present invention has a housing 18 as shown in FIG.
The present invention is applicable not only to a scraper having a structure in which the outer circumferential lip 36 is in close contact with the groove 34a of the scraper, but also to a scraper having a structure in which a metal ring 60 is interposed between the housing 18 and the outer circumferential lip 36 as shown in FIG. 5, for example. In the case shown in FIG. 5, the metal ring 60 is fitted into the housing 18 by being pushed into the housing 18 while keeping the metal ring 60 fitted to the outer periphery of the outer circumferential lip 36.

(2) The outer circumferential lip 36 and the inner circumferential lip 32 are not limited to the case where the thickness is substantially uniform over the entire length as in the embodiment, but also when the thickness changes in the middle of the entire length. Can apply ideas.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional partial view showing the scraper according to the present invention, Fig. 2 is a structural schematic diagram showing the experimental equipment used by the inventors of the present invention, and Fig. 3 is a longitudinal cross-sectional view showing the scraper in a state where the rod is eccentric. FIG. 5 is a partial vertical cross-sectional view showing another embodiment, and FIGS. 4 and 6 are vertical cross-sectional views showing conventional scrapers, respectively. 14...
... Rod, 18 ... Housing, 30 ... Scraper, 32 ... Inner circumference lip, 34a ... Groove, 34
b... Convex peripheral wall, 36... Outer peripheral lip.

Claims (1)

[Scope of utility model registration request] In a resin scraper that has an inner lip that comes in close contact with the outer circumference of the shaft and an outer lip that comes in close contact with the housing, the thickness of the outer lip is set thinner than the inner lip so that the tip of the outer lip comes in close contact with the housing. A scraper characterized by forming.