JP2013014301A - Propeller for outboard engines - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a propeller which is light in weight, strong and excellent in corrosion resistance and has such a structure that it can cope with multikind and small quantity production as compared with an object which has a cast integral structure.SOLUTION: In a propeller 1 for an outboard engine which includes a boss 2 where an inner cylinder 3 and an outer cylinder 4 are connected with each other with a plurality of ribs 5, and a plurality of banes 7 on the peripheral side 12 of the boss, the inner cylinder, the ribs, and the vanes are molded of extensible materials formed of pure titanium or titanium alloys, and the inner cylinder, the ribs, the outer cylinder and the vanes are joined severally with one another by welding.

Description

  The present invention relates to an outboard motor propeller. In general, outboard motor propellers (hereinafter sometimes referred to simply as “propellers”) are used not only to generate hydraulic power to the hull, but also as an exhaust device for exhaust gas generated by the outboard engine when sailing. ing.

  For this reason, the outer peripheral part of the boss | hub which comprises a propeller is provided with the blade | wing, the boss | hub is divided by the inner cylinder, the outer cylinder, and the rib, and the several exhaust passage is provided in the rotating shaft direction.

  The exhaust gas generated in the engine at the time of sailing is discharged into the water through the exhaust passage provided in the boss.

Such propellers for outboard motors are complicated in shape, and therefore, an integral structure by casting is mainly used. The die casting method of aluminum alloy (Patent Document 1), and high-grade stainless steel lost wax method is used for high-end models. It was manufactured by the precision casting method.
JP 2001-58598 A, page 2, right column, lines 16 to 17

  However, the aluminum alloy propeller manufactured by the die casting method has the advantages of low price due to mass production and low specific gravity of about 2.7. However, due to its low strength, it is thickened, measures against casting defects and the final polishing process of the surface. However, there were drawbacks such as being necessary for wear and being vulnerable to abrasion caused by sand and mud.

  On the other hand, the high-strength stainless steel propeller by the lost wax method, which is a precision casting method, has the advantage that it can be thinned because its strength is 4.5 times that of an aluminum alloy, and it has few casting defects and is highly reliable. The lost wax method has a long process, requires not only distortion correction and final polishing process, but also has a high specific gravity of about 8.0 and a large inertial force when propeller is accelerated or reversely rotated. However, there are disadvantages such as a slow reaction and an increased load on the rotating shaft.

In addition, since it is manufactured by casting, a mold is required for each size and pitch of the propeller (the distance that the propeller makes one revolution and travels theoretically in the direction of the rotation axis), resulting in an increase in cost.

  An object of the present invention is to solve the above-described problems. Specifically, the propeller is light, strong, and excellent in corrosion resistance. An object of the present invention is to provide a propeller having a structure that can be used for production.

  The outboard motor propeller according to the first aspect of the present invention that achieves the above object includes a boss in which the inner cylinder and the outer cylinder are connected by a plurality of ribs, and a plurality of blades on the outer peripheral side of the boss. In an outboard motor propeller, the inner cylinder, ribs, outer cylinder and blades were molded from a wrought material made of pure titanium or titanium alloy, and the inner cylinder, ribs, outer cylinder and blades were joined by welding. It is characterized by.

  According to the propeller for an outboard motor of the first invention of the present invention, the boss and the blades are formed of a stretched material made of pure titanium or a titanium alloy, so that it is about 40% lighter than a stainless steel propeller. Rotating performance as a propeller, for example, acceleration, reactivity by reverse rotation and reduction of load on the shaft, corrosion resistance to seawater is much better, and it has the same strength as a stainless steel propeller, and casting A highly reliable propeller can be obtained as compared with a casting integral structure having a risk of inherent defects.

  In addition, since the inner cylinder and the outer cylinder are joined by welding with a plurality of ribs, the material yield is not only better than that formed by cutting out the boss from a round bar, but on the outer periphery of the boss. Since the plurality of blades are joined by welding, the same shape boss can be shared with the propellers of blades having different pitches or sizes.

  An outboard motor propeller according to a second aspect of the present invention is the outboard motor propeller according to the first aspect of the present invention, wherein the outer cylinder is divided by welding along the axis of the outer cylinder by welding. It is what was joined.

  According to the outboard motor propeller of the second aspect of the present invention, since the divided pieces that are equally divided along the axis of the outer cylinder are welded, the outer cylinder is welded to the rib or the inner cylinder. The process can be facilitated and a high-quality propeller can be obtained.

  Moreover, since it is the structure by which the division | segmentation piece was equally divided | segmented, it can assemble with the division | segmentation piece of the same shape, and can improve production efficiency.

  An outboard motor propeller according to a third aspect of the present invention is characterized in that, in the propeller for an outboard motor according to the second aspect, the number of divided pieces is the same as the number of ribs.

  According to the propeller for an outboard motor of the third invention of the present invention, since the divided pieces have the same number as the number of ribs, each divided piece can be welded to the respective ribs. Can be obtained.

  An outboard motor propeller according to a fourth aspect of the present invention is characterized in that in the propeller for an outboard motor according to the second or third aspect of the invention, the joining portion of the divided pieces is in the vicinity of the rib.

  According to the propeller for an outboard motor of the fourth invention of the present invention, since the joint portion of the split piece is in the vicinity of the rib, the positioning and welding process at the time of mutual welding can be easily performed. A high-quality propeller can be obtained.

  The propeller for an outboard motor of the fifth invention of the present invention is the propeller for an outboard motor of any one of the first to fourth inventions, wherein the blades are formed by press-molding a smooth rolled plate. Features.

  According to the propeller for an outboard motor of the fifth invention of the present invention, since it is a configuration in which a smooth rolled plate is press-molded, not only can an arbitrary curved surface be created, but surface polishing for finishing may be omitted. It can be done.

  According to the present invention, it is possible to obtain a propeller for an outboard motor that can be rotated at a high speed by being reduced in weight, is strong and excellent in corrosion resistance, and can be used for various kinds of small-volume production.

It is the front view seen from the reverse side of the propeller for outboard motors of the present invention. It is a front view of what joined the rib to the perimeter part of the inner cylinder, and has arranged the outer cylinder on the rib. It is a principal part enlarged view of the state which welded the outer cylinder to the rib outer peripheral part.

Hereinafter, an example will be described as an embodiment of the present invention.
In the outboard motor propeller 1 of the present invention, as shown in FIG. 1, the boss 2 is divided into an inner cylinder 3 and an outer cylinder 4 by three ribs 5 at equal intervals to form three exhaust passages 6. The outer cylinder 4 is provided with three blades 7 on the outer peripheral side where the respective ribs 5 are arranged. The inner cylinder 3, the rib 5, the outer cylinder 4 and the blades 7 are made of pure titanium. The inner cylinder 3, the rib 5, the outer cylinder 4, and the blades 7 are each joined by welding.

  The inner cylinder 3, the rib 5, the outer cylinder 4 and the blades 7 are made of pure titanium (JIS H4600, type 2 TP-35H) having a chemical composition (wt%) of H: 0.001, O: 0. .11, Fe: 0.07, N: 0.006, C: 0.005 The balance is titanium.

  In addition, although the material of a present Example is a wrought material made from pure titanium, when using the wrought material made from a titanium alloy, for example, 6Al-4V-Ti alloy, the chemical component (wt%) is Al. : 6.34, V: 4.20, O: 0.18, N: 0.008, C: 0.012, Fe: 0.18, H: 0.0081 The balance is titanium.

  It is also possible to reduce costs by using a titanium alloy material for the blades 7 that require strength and forming a composite structure by molding the boss 2 with a pure titanium material, for example, where the strength is relatively weak. It is.

  In addition, a bush 8 is fitted inside the inner cylinder 3, and a rotating shaft (not shown) is fitted in the bush 8 to transmit the rotational force transmitted from the engine to the boss 2 and the blade 7. .

Next, an example of the manufacturing method of the propeller of this invention is demonstrated based on figures.
The inner cylinder 3 is formed by cutting a plate of a wrought material made of pure titanium into a rectangular shape, and forming groove surfaces 91 by groove processing at both ends orthogonal to the rotation direction of the plate material. Pressing was performed at room temperature so that the 91 sides were in contact with each other to form a cylindrical shape, and then welding was performed in a vacuum chamber to join the groove surfaces 91 together. Hereinafter, in this embodiment, welding in each step is all performed in a vacuum chamber.

  Next, a method for joining the rib 5 to the outer peripheral side of the inner cylinder 3 will be described. The rib 5 is for supporting the outer cylinder 4 disposed outside the inner cylinder 3 and for forming an exhaust passage 6 for exhaust gas generated from the engine between the inner cylinder 3 and the outer cylinder 4. .

  Three ribs 5 cut from a pure titanium wrought material plate with a width that can secure the space between the inner cylinder 3 and the outer cylinder 4 and slightly shorter than the lengths of the two cylinders are the outer peripheral surface of the inner cylinder 3. Further, it is welded at a position parallel to the rotation axis of the inner cylinder 3 and rotated by 120 degrees about the rotation axis. The root of the rib 5 on the inner cylinder 3 side is welded on the entire circumference.

  Next, a process of forming the boss 2 by joining the outer cylinder 4 to the outer end portion 10 of the rib 5 joined to the inner cylinder 3 by welding will be described. As shown in FIG. 2, the outer cylinder 4 is divided into three in this case by the same number as the number of ribs 5 and is welded to each rib 5. For this reason, the plate material of the wrought material made of pure titanium is cut so as to be equally divided into three, three divided pieces 41 having the same shape are formed, and a groove perpendicular to the rotation direction of the divided pieces 41 is formed. Surface 9 is formed.

  Further, these divided pieces 41 are press-molded at room temperature so as to bend in a direction perpendicular to the rotation axis, and thereafter, these divided pieces 41 are formed on the outer end portion 10 of the rib 5 as shown in FIG. The groove face 9 of the divided piece 41 is arranged so as to be in the same direction as the rotation direction of the rotation shaft, and is bridged between the adjacent ribs 5 and ribs 5. 5, one end face 9 of the split piece 41 and an end face (a flat end face that is not a slot face) 11 of another split piece 41 adjacent to the split piece 41 are mutually connected to the rib 5. Welding is performed in a state of being in contact with and arranged in the vicinity of the outer end 10, positioning and welding processes can be facilitated, and the groove surface 9, the end surface 11 and the rib 5 of each divided piece 41 are formed once. It has the effect of being joined by welding.

  Next, the process of forming the blade 7 and the process of completing the blade 1 by welding the blade 7 to the boss 2 will be described.

  A smooth plate material of a wrought material made of pure titanium is cut into the size of a blade 7 and a three-dimensional curved surface is formed by press molding at room temperature. As shown in FIG. The blades 7 are joined and assembled by welding.

  In this case, when the three-dimensional curved surface of the blade 7 is formed, a smooth plate material is press-molded at room temperature, so that the distortion correction and surface polishing steps can be omitted. Note that a rolled flat plate and a pipe material may be used as the wrought material.

  In the case of forming the blades 7 having different pitches on the same boss 2, the propeller 1 of the present invention is a mold having a different pitch as in the case of the propeller 1 manufactured by casting, as long as the circumscribed circle diameters of the same blades are formed. Etc. are not required, and can contribute to high-mix low-volume production.

  As a result of the installation test of the propeller 1 described above to the outboard motor main body at the rear of the hull, the weight of the entire shaft system was greatly reduced, and high-speed rotation became possible as the load on the stern bearing decreased. Further, the cavitation resistance and erosion resistance are greatly improved, and the secular change of the surface of the blade 7 of the propeller 1 is small.

  In general, the downstream side (reverse side) of the propeller 1 is prone to cavitation and erosion, but in the case of the blade 7 formed by the pure titanium or titanium alloy wrought material of the present invention, Temporarily, the titanium oxide film can be formed on the surface of the blade 7 by heating at least the downstream (reverse side) surface 13 of the propeller 1 to about 300 to 600 ° C. by high-frequency heating or the like. Therefore, by forming the titanium oxide film in this way, the wear resistance is drastically improved, which can greatly contribute to cavitation resistance and erosion resistance.

  Further, when the surface of the blade 7 is heated to about 300 to 600 ° C. by high frequency heating or the like, a titanium oxide film is formed on the surface, and the film exhibits silver, gold, purple or blue depending on the heating temperature, By using this method, it is possible to form a good pattern or character in terms of design by combining characters, figures and colors.

DESCRIPTION OF SYMBOLS 1 Propeller 2 Boss 3 Inner cylinder 4 Outer cylinder 41 Divided piece 5 Rib 6 Exhaust passage 7 Blade 8 Bushing 9, 91 Groove surface 10 Outer end 11 End surface 12 Outer peripheral side 13 Downstream surface

Claims (5)

In an outboard motor propeller having a boss in which an inner cylinder and an outer cylinder are connected by a plurality of ribs and a plurality of blades on the outer peripheral side of the boss, the inner cylinder, the rib, the outer cylinder, and the blade are made of pure titanium or A propeller for an outboard motor, which is formed of a wrought material made of a titanium alloy, and an inner cylinder, a rib, an outer cylinder, and a blade are joined by welding. The propeller for an outboard motor according to claim 1, wherein the outer cylinder is obtained by joining divided pieces evenly divided along the axis of the outer cylinder by welding. The outboard motor propeller according to claim 2, wherein the number of the divided pieces is the same as the number of ribs. The outboard motor propeller according to claim 2 or 3, wherein the joining portion of the divided pieces is in the vicinity of the rib. The propeller for an outboard motor according to any one of claims 1 to 4, wherein the blades are formed by press-molding a smooth rolled plate.

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