阅读说明：本技术 一种分体式复合材料螺旋桨的制作方法及产品 (Manufacturing method and product of split type composite propeller ) 是由 郑子衡 于 2020-07-17 设计创作，主要内容包括：本发明公开了一种分体式复合材料螺旋桨的制作方法及产品,包括：1)桨毂制作步骤：1-1)桨毂预型步骤：按照预定方法铺覆预浸料片,得到桨毂预形体；1-2)桨毂成型步骤：将桨毂预形体放入桨毂成型模具中,加热加压,得到桨毂；2)桨叶制作步骤：2-1)桨叶预型步骤：按照预定方法铺覆预浸料片,得到桨叶预形体；2-2)桨叶成型步骤：将桨叶预形体放入桨叶成型模具中,加热加压,得到桨叶；3)粘接步骤：分别在桨叶的贴合面和桨毂的第一凹陷部涂胶,然后将两个以上的桨叶的贴合面与桨毂的第一凹陷部一一对接后进行固定,最后经过烘烤后,得到产品。本发明具有制作方便、生产效率高和连接稳定性好的特点。(The invention discloses a manufacturing method and a product of a split type composite propeller, wherein the method comprises the following steps: 1) the method comprises the following steps: 1-1) hub preforming step: paving a prepreg according to a preset method to obtain a hub preform; 1-2) hub forming step: placing the hub preform into a hub forming die, and heating and pressurizing to obtain a hub; 2) the paddle manufacturing steps are as follows: 2-1) a blade preforming step: paving a prepreg according to a preset method to obtain a blade preform; 2-2) blade forming: placing the blade preform into a blade forming die, and heating and pressurizing to obtain a blade; 3) bonding: gluing the binding surfaces of the blades and the first sunken parts of the propeller hub respectively, then butting the binding surfaces of more than two blades and the first sunken parts of the propeller hub one by one and fixing, and finally baking to obtain the product. The invention has the characteristics of convenient manufacture, high production efficiency and good connection stability.)

1. A manufacturing method of a split type composite propeller is characterized by comprising the following steps:

1) the method comprises the following steps:

1-1) hub preforming step: paving a prepreg according to a preset method to obtain a hub preform;

1-2) hub forming step: placing the propeller hub preform into a propeller hub forming die, heating and pressurizing after die assembly, and demolding after curing and forming to obtain the propeller hub; at least two first concave parts are uniformly formed on the outer wall of the propeller hub in the circumferential direction;

2) the paddle manufacturing steps are as follows:

2-1) a blade preforming step: paving a prepreg according to a preset method to obtain a blade preform;

2-2) blade forming: placing the blade preform into a blade forming mold, heating and pressurizing after mold closing, curing and forming, and demolding to obtain the blade; the paddle comprises a paddle connecting part and a spiral blade extending outwards from one end of the paddle connecting part, and the paddle connecting part is provided with a binding surface matched with the first concave part;

3) bonding: gluing the binding surfaces of the blades and the first sunken parts of the propeller hub respectively, then butting the binding surfaces of more than two blades and the first sunken parts of the propeller hub one by one and fixing, and finally baking to obtain the product.

2. The method for manufacturing the split type composite propeller according to claim 1, wherein in the blade preforming step, a prepreg sheet is laid on a blade preforming mold; the blade preforming die comprises a preforming die main body and a sliding block; the preforming die main body comprises a base, a first spiral groove is formed in the base, and a first sliding groove is formed in one side, located on the first spiral groove, of the base; the sliding block is slidably arranged in the first sliding groove; a second concave part is arranged on the side surface, adjacent to the first spiral groove, of the sliding block; and the second concave part and the first spiral groove are enclosed to form a first accommodating cavity matched with the outer contour of the paddle.

3. The method for manufacturing the split composite propeller of claim 2, wherein the first spiral groove is communicated with a middle portion of the second depression, wherein the second depression has a second lower depression located below the first spiral groove in a vertical direction and a second upper depression located above the first spiral groove in the vertical direction.

4. The method for manufacturing the split composite propeller of claim 3, wherein in the blade preforming step, the process of laying the prepreg is as follows: firstly, cutting a prepreg into designed specification sizes, and numbering and arranging the prepreg according to a laminating sequence; then the sliding block is moved away, and a plurality of layers of first prepregs are laid in the first spiral groove, wherein one part of the first prepregs is located in the first spiral groove, and the other part of the first prepregs extends to the position, corresponding to the second lower concave part, on the side wall of the base; and then, paving a plurality of layers of second prepregs in the second concave part of the sliding block, inserting the sliding block into the first sliding groove to be butted with the first spiral groove, and paving a plurality of layers of third prepregs in the first spiral groove, wherein one part of the third prepregs is positioned in the first spiral groove, and the other part of the third prepregs extends into the second upper concave part to form the blade preform.

5. The manufacturing method of the split type composite propeller of claim 1, wherein in the blade forming step, the blade forming mold comprises:

the lower blade forming die comprises a lower blade forming template, and a first accommodating groove is formed in the lower blade forming template;

the paddle cavity assembly comprises a first paddle cavity core and a second paddle cavity core which are respectively arranged in the first accommodating groove, and the second paddle cavity core is detachably matched with the first paddle cavity core; a second spiral groove is formed in the first blade mold core; a third concave part is arranged on the side surface, adjacent to the second spiral groove, of the second blade mold core;

the mould is gone up in the paddle shaping, the mould includes paddle shaping cope match-plate pattern in the paddle shaping, be equipped with the second holding tank on the paddle shaping cope match-plate pattern, the second holding tank with first holding tank encloses to form the chamber that holds that is used for accomodating paddle mould benevolence subassembly after closing, the second holding tank the second spiral groove with the third depressed part is injectd jointly and is had the identical paddle die cavity of external profile with the paddle.

6. The method for manufacturing the split composite propeller of claim 1, wherein in the hub forming step, the hub forming mold comprises:

the hub forming lower die comprises a hub forming lower template, and a third accommodating groove is formed in the hub forming lower template;

the hub die core assembly comprises more than two hub die cores and a lower die insert which are respectively arranged in the third accommodating groove, and the more than two hub die cores are separably matched; the inner side surface of the hub mould core is provided with a groove, and the inner wall of the groove is provided with a third protruding part; the grooves of more than two hub die cores are enclosed to form a hub accommodating cavity with an opening at the bottom, and the size and the shape of the hub accommodating cavity are matched with the external contour of the hub; the lower die insert is arranged in the middle of an opening at the bottom of the propeller hub accommodating cavity, and the lower die insert and the propeller hub accommodating cavity jointly define a propeller hub cavity;

the hub forming upper die comprises a hub forming upper die plate, a fourth accommodating groove is formed in the hub forming upper die plate, and the fourth accommodating groove and the third accommodating groove are enclosed to form an accommodating cavity for accommodating a hub die core assembly.

7. The manufacturing method of the split type composite propeller according to claim 1, wherein in the propeller hub molding step, a hot press is adopted to cure a propeller hub molding die, the die assembly pressure is 8MPa-12MPa, and the curing temperature of the prepreg sheet is 120 ℃ to 150 ℃;

in the blade forming step, a hot press is adopted to cure a blade forming die, the die assembly pressure is 8MPa-12MPa, and the curing temperature of the prepreg sheet is 120-150 ℃;

in the bonding step, baking is carried out through an oven, wherein the baking temperature is as follows: 100-150 ℃; the baking time is as follows: 1-2H.

8. A split composite propeller, characterized in that the split composite propeller is manufactured according to the manufacturing method of any one of claims 1 to 7.

9. The split composite propeller of claim 8, wherein a stop block is arranged on the propeller hub at a position between each two adjacent first recesses; the limiting blocks comprise a first limiting block and a second limiting block which are respectively arranged on the propeller hub body, and the first limiting block and the second limiting block are arranged in a staggered mode in the horizontal direction and the vertical direction; the first limiting block is positioned at the end part of the propeller hub and is provided with a first inclined side wall and a first vertical side wall, and the blade connecting part is provided with an upper inclined side wall and an upper vertical side wall; the first inclined side wall of the first limiting block is fixedly connected with the upper inclined side wall of one adjacent paddle connecting part through an adhesive layer, and the first vertical side wall of the first limiting block is fixedly connected with the upper vertical side wall of the other adjacent paddle connecting part through an adhesive layer; the second limiting block is positioned at the middle lower part of the propeller hub body and is provided with a second inclined side wall and a second vertical side wall, and the blade connecting part is correspondingly provided with a lower inclined side wall and a lower vertical side wall; the second inclined side wall of the second limiting block is fixedly connected with the lower inclined side wall of one adjacent paddle connecting portion through an adhesive layer, and the second vertical side wall of the second limiting block is fixedly connected with the lower vertical side wall of the other adjacent paddle connecting portion through an adhesive layer.

10. The split composite propeller of claim 9, wherein the inner bottom wall of the first recess is an inclined arc-shaped surface, and the abutting surface of the blade connecting portion is an inclined arc-shaped surface, and the abutting surface of the blade is fixedly connected with the inner bottom wall of the first recess through an adhesive layer; the thickness of the paddle is optionally gradually reduced from the paddle root to the paddle tip; the propeller hub body is of a bullet head type structure and comprises a bullet part and a bullet head part, wherein the bullet head part is formed by extending one end surface of the bullet part outwards and has a gradually reduced diameter; and the middle part of the bullet head type structure is provided with an axially through mounting hole.

Technical Field

The invention relates to a manufacturing method of a propeller, in particular to a manufacturing method of a split type composite propeller and a product.

Background

The propeller is a device for converting the rotating power of an engine into propelling force by rotating blades in air or water, and can be a marine propeller with two or more blades connected with a propeller hub, and the backward surface of each blade is a helicoid or a surface similar to the helicoid. At present, propellers comprise conventional metal propellers and composite propellers, and compared with the conventional metal propellers, the composite propellers have the advantages of light weight, high efficiency, low vibration, seawater corrosion resistance, easiness in maintenance and the like.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the manufacturing method of the split type composite propeller, which has the characteristics of convenience in manufacturing, high production efficiency and good connection stability.

The invention also aims to provide the split type composite material propeller obtained by the manufacturing method, which has the characteristics of light weight, simple structure and good connection stability.

One of the purposes of the invention is realized by adopting the following technical scheme:

a manufacturing method of a split type composite propeller is characterized by comprising the following steps:

1) the method comprises the following steps:

1-1) hub preforming step: paving a prepreg according to a preset method to obtain a hub preform;

1-2) hub forming step: placing the propeller hub preform into a propeller hub forming die, heating and pressurizing after die assembly, and demolding after curing and forming to obtain the propeller hub; at least two first concave parts are uniformly formed on the outer wall of the propeller hub in the circumferential direction;

2) the paddle manufacturing steps are as follows:

2-1) a blade preforming step: paving a prepreg according to a preset method to obtain a blade preform;

2-2) blade forming: placing the blade preform into a blade forming mold, heating and pressurizing after mold closing, curing and forming, and demolding to obtain the blade; the paddle comprises a paddle connecting part and a spiral blade extending outwards from one end of the paddle connecting part, and the paddle connecting part is provided with a binding surface matched with the first concave part;

3) bonding: gluing the binding surfaces of the blades and the first sunken parts of the propeller hub respectively, then butting the binding surfaces of more than two blades and the first sunken parts of the propeller hub one by one and fixing, and finally baking to obtain the product.

In an alternative embodiment, in the blade preforming step, a prepreg sheet is laid on a blade preforming mold; the blade preforming die comprises a preforming die main body and a sliding block; the preforming die main body comprises a base, a first spiral groove is formed in the base, and a first sliding groove is formed in one side, located on the first spiral groove, of the base; the sliding block is slidably arranged in the first sliding groove; a second concave part is arranged on the side surface, adjacent to the first spiral groove, of the sliding block; and the second concave part and the first spiral groove are enclosed to form a first accommodating cavity matched with the outer contour of the paddle.

In an alternative embodiment, the first spiral groove communicates with a middle portion of the second recess, wherein the second recess has a second lower recess located vertically below the first spiral groove and a second upper recess located vertically above the first spiral groove.

In an alternative embodiment, the process of laying down the prepreg in the blade preforming step is as follows: firstly, cutting a prepreg into designed specification sizes, and numbering and arranging the prepreg according to a laminating sequence; then the sliding block is moved away, and a plurality of layers of first prepregs are laid in the first spiral groove, wherein one part of the first prepregs is located in the first spiral groove, and the other part of the first prepregs extends to the position, corresponding to the second lower concave part, on the side wall of the base; and then, paving a plurality of layers of second prepregs in the second concave part of the sliding block, inserting the sliding block into the first sliding groove to be butted with the first spiral groove, and paving a plurality of layers of third prepregs in the first spiral groove, wherein one part of the third prepregs is positioned in the first spiral groove, and the other part of the third prepregs extends into the second upper concave part to form the blade preform.

In an alternative embodiment, in the blade forming step, the blade forming mold includes:

the lower blade forming die comprises a lower blade forming template, and a first accommodating groove is formed in the lower blade forming template;

the paddle cavity assembly comprises a first paddle cavity core and a second paddle cavity core which are respectively arranged in the first accommodating groove, and the second paddle cavity core is detachably matched with the first paddle cavity core; a second spiral groove is formed in the first blade mold core; a third concave part is arranged on the side surface, adjacent to the second spiral groove, of the second blade mold core;

the mould is gone up in the paddle shaping, the mould includes paddle shaping cope match-plate pattern in the paddle shaping, be equipped with the second holding tank on the paddle shaping cope match-plate pattern, the second holding tank with first holding tank encloses to form the chamber that holds that is used for accomodating paddle mould benevolence subassembly after closing, the second holding tank the second spiral groove with the third depressed part is injectd jointly and is had the identical paddle die cavity of external profile with the paddle.

In an alternative embodiment, in the hub forming step, the hub forming die comprises:

the hub forming lower die comprises a hub forming lower template, and a third accommodating groove is formed in the hub forming lower template;

the hub die core assembly comprises more than two hub die cores and a lower die insert which are respectively arranged in the third accommodating groove, and the more than two hub die cores are separably matched; the inner side surface of the hub mould core is provided with a groove, and the inner wall of the groove is provided with a third protruding part; the grooves of more than two hub die cores are enclosed to form a hub accommodating cavity with an opening at the bottom, and the size and the shape of the hub accommodating cavity are matched with the external contour of the hub; the lower die insert is arranged in the middle of an opening at the bottom of the propeller hub accommodating cavity, and the lower die insert and the propeller hub accommodating cavity jointly define a propeller hub cavity;

the hub forming upper die comprises a hub forming upper die plate, a fourth accommodating groove is formed in the hub forming upper die plate, and the fourth accommodating groove and the third accommodating groove are enclosed to form an accommodating cavity for accommodating a hub die core assembly.

In an optional embodiment, in the hub molding step, a hot press is used for curing a hub molding die, the die assembly pressure is 8-12 MPa, and the curing temperature of the prepreg sheet is 120-150 ℃;

in the blade forming step, a hot press is adopted to cure a blade forming die, the die assembly pressure is 8MPa-12MPa, and the curing temperature of the prepreg sheet is 120-150 ℃;

in the bonding step, baking is carried out through an oven, wherein the baking temperature is as follows: 100-150 ℃; the baking time is as follows: 1-2H.

The second purpose of the invention is realized by adopting the following technical scheme:

the invention relates to a split composite propeller, which is a product obtained by adopting the manufacturing method for one of the purposes of the invention.

In an alternative embodiment, a limiting block is arranged on the hub at a position between every two adjacent first concave parts; the limiting blocks comprise a first limiting block and a second limiting block which are respectively arranged on the propeller hub body, and the first limiting block and the second limiting block are arranged in a staggered mode in the horizontal direction and the vertical direction; the first limiting block is positioned at the end part of the propeller hub and is provided with a first inclined side wall and a first vertical side wall, and the blade connecting part is provided with an upper inclined side wall and an upper vertical side wall; the first inclined side wall of the first limiting block is fixedly connected with the upper inclined side wall of one adjacent paddle connecting part through an adhesive layer, and the first vertical side wall of the first limiting block is fixedly connected with the upper vertical side wall of the other adjacent paddle connecting part through an adhesive layer; the second limiting block is positioned at the middle lower part of the propeller hub body and is provided with a second inclined side wall and a second vertical side wall, and the blade connecting part is correspondingly provided with a lower inclined side wall and a lower vertical side wall; the second inclined side wall of the second limiting block is fixedly connected with the lower inclined side wall of one adjacent paddle connecting portion through an adhesive layer, and the second vertical side wall of the second limiting block is fixedly connected with the lower vertical side wall of the other adjacent paddle connecting portion through an adhesive layer.

In an optional embodiment, the inner bottom wall of the first recess is an inclined arc-shaped surface, and correspondingly, the attachment surface of the blade connecting portion is an inclined arc-shaped surface, and the attachment surface of the blade and the inner bottom wall of the first recess are fixedly connected through an adhesive layer; the thickness of the paddle is optionally gradually reduced from the paddle root to the paddle tip; the propeller hub body is of a bullet head type structure and comprises a bullet part and a bullet head part, wherein the bullet head part is formed by extending one end surface of the bullet part outwards and has a gradually reduced diameter; and the middle part of the bullet head type structure is provided with an axially through mounting hole.

Compared with the prior art, the invention has the beneficial effects that:

1. the manufacturing method of the invention adopts the composite material prepreg to manufacture the blade and the hub respectively, then the glue is coated on the binding surface of the blade and the first sunken part of the hub respectively, then the binding surfaces of more than two blades are fixed after being in one-to-one butt joint with the first sunken parts of the hub, and finally the product is obtained after baking. In addition, the split composite propeller obtained by the manufacturing method has the characteristics of light weight, simple structure, good connection stability and convenience in processing.

2. The manufacturing method adopts a blade preforming mold with a brand-new design, and comprises a preforming mold main body and a sliding block, wherein a first spiral groove is formed in a base, and a first sliding groove is formed in one side, located on the first spiral groove, of the base; the sliding block is slidably arranged in the first sliding groove; a second concave part is arranged on the side surface of the sliding block adjacent to the first spiral groove; the second concave part and the first spiral groove are enclosed to form a first accommodating cavity matched with the outer contour of the paddle. In the step of preforming, the prepreg is laid down as follows: firstly, cutting a prepreg into designed specification sizes, and numbering and arranging the prepreg according to a laminating sequence; then the sliding block is moved away, and a plurality of layers of first prepregs are laid in the first spiral groove, wherein one part of the first prepregs is located in the first spiral groove, and the other part of the first prepregs extends to the position, corresponding to the second lower concave part, on the side wall of the base; then, paving a plurality of layers of second prepregs in a second concave part of the sliding block, inserting the sliding block into the first sliding groove to be butted with the first spiral groove, and paving a plurality of layers of third prepregs in the first spiral groove, wherein one part of the third prepregs is positioned in the first spiral groove, and the other part of the third prepregs extends into the second upper concave part to form a blade preform; design like this for the joint strength between paddle connecting portion and the helical blade is better, has the preparation convenience, lays the efficient and paddle preforming of layer of characteristics of high quality that the preparation obtained.

3. According to the invention, the limiting blocks are arranged on the propeller hub body between every two adjacent first concave parts, so that a better positioning effect can be achieved in the processing process, the blades are prevented from moving in a staggered manner, and the connection stability of products is improved. Furthermore, the limiting block comprises a first limiting block and a second limiting block which are respectively arranged on the propeller hub body, and the first limiting block and the second limiting block are arranged in a staggered mode in the horizontal direction and the vertical direction, so that the positioning effect can be further improved; furthermore, the first inclined side wall of the first limiting block is fixedly connected with the upper inclined side wall of one adjacent blade connecting part through an adhesive layer, and the first vertical side wall of the first limiting block is fixedly connected with the upper vertical side wall of the other adjacent blade connecting part through an adhesive layer; the second inclined side wall of the second limiting block is fixedly connected with the lower inclined side wall of one adjacent blade connecting part through an adhesive layer, and the second vertical side wall of the second limiting block is fixedly connected with the lower vertical side wall of the other adjacent blade connecting part through an adhesive layer; the positioning effect can be further improved, alignment between the blades is facilitated, the bonding area is increased, and the connection stability of the product is improved.

Drawings

FIG. 1 is a perspective view of a split composite propeller of an embodiment;

FIG. 2 is an exploded view of the split composite propeller of the embodiment;

FIG. 3 is a perspective view of the split composite propeller of the embodiment with one blade omitted;

FIG. 4 is a perspective view of the split composite propeller of the embodiment with one hub omitted;

FIG. 5 is a perspective view of a blade preform mold of an embodiment;

FIG. 6 is a perspective view of a blade preform mold with blades according to an embodiment;

FIG. 7 is an exploded view of a blade preform mold with blades according to an embodiment;

FIG. 8 is a perspective view of a preform mold body of the embodiment;

FIG. 9 is a perspective view of a slider of an embodiment;

fig. 10 is a perspective view of a blade forming mold of the embodiment;

fig. 11 is an exploded view of the blade forming mold of the embodiment;

fig. 12 is a perspective view of a lower blade molding die and a blade core assembly according to an embodiment;

fig. 13 is a perspective view of a blade forming lower die of the embodiment;

fig. 14 is a perspective view of an upper mold for molding a blade and a cavity assembly for molding a blade according to an embodiment;

FIG. 15 is a perspective view of an upper blade-forming die of an embodiment;

fig. 16 is a perspective view of an embodiment of a blade core assembly;

FIG. 17 is a perspective view of an embodiment hub forming die;

FIG. 18 is an exploded view of the hub forming die of the embodiment;

FIG. 19 is a perspective view of an embodiment of a hub forming lower die and hub core insert assembly;

FIG. 20 is a perspective view of an exemplary lower hub molding die;

FIG. 21 is a perspective view of an upper hub forming die of an embodiment;

figure 22 is a perspective view of an embodiment of a hub core assembly;

figure 23 is a perspective view of an embodiment hub core insert;

in the figure:

110. a hub; 111. a hub body; 112. a first recess; 113. a limiting block; 1131. a first stopper; 1132. a second limiting block; 120. a paddle; 121. a blade body; 1211. a paddle connecting portion; 1212. a helical blade;

210. preforming the mold body; 211. a base; 212. a first spiral groove; 213. a chute; 2131. a first chute; 2132. a second chute; 214. a limiting column; 220. a slider; 221. a slider body; 222. a first protrusion; 230. a second recess;

310. a blade forming lower die; 311. forming a lower template by using a paddle; 312. a first accommodating groove; 320. a blade core assembly; 321. a first blade core; 3211. a second spiral groove; 322. a second blade insert; 3221. a second blade core body; 3222. a second protrusion; 3223. a third recessed portion; 330. forming an upper die for the blade; 331. forming an upper template by the blades; 332. a second accommodating groove;

410. forming a lower die of the propeller hub; 411. forming a lower template by the propeller hub; 412. a third accommodating groove; 420. a hub core assembly; 421. a hub core insert; 4211. a groove; 4212. a third projection; 422. a lower die insert; 430. an upper mould for forming the propeller hub; 431. forming an upper template by the propeller hub; 432. and a fourth accommodating groove.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict. Except as specifically noted, the materials and equipment used in this example are commercially available. Examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. In the description of the present application, "a plurality" means two or more unless specifically stated otherwise.

In the description of the present application, it should be noted that unless otherwise specifically stated or limited, the terms "connected," "communicating," and "connected" are to be construed broadly, e.g., as meaning a fixed connection, a connection through an intervening medium, a connection between two elements, or an interaction between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

The terms "first," "second," and the like in the description and in the claims of the present application and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.