阅读说明：本技术 一种基于模具生产压力臂的方法及流程 (Method and process for producing pressure arm based on mold ) 是由 文划明 于 2021-06-23 设计创作，主要内容包括：本发明公开了一种基于模具生产压力臂的方法及流程,包括底板,所述底板的顶部固定连接有冷却箱体,底板顶部的四周均固定连接有支撑立柱,支撑立柱的顶部固定连接有平台,平台的顶部设置有升降机构。本发明通过设置底模与上模用于压力臂的浇注,通过设置冷却箱体用于对底模和上模进行冷却降温的效果,提升压力臂的铸造效率,通过设置升降机构,能够带动底模和上模向冷却箱体的内腔运动,方便进行冷却的效果,其中伺服电机能够在正反向旋转的情况下带动底模和上模进入冷却箱体和从冷却箱体的内腔升起,解决了通过冷却液进行冷却的方式虽然冷却较快,但是生产所使用的模具不便于放入冷却液中,因此不利于生产工作的问题。(The invention discloses a method and a process for producing a pressure arm based on a mold, which comprises a bottom plate, wherein the top of the bottom plate is fixedly connected with a cooling box body, the periphery of the top of the bottom plate is fixedly connected with supporting upright posts, the tops of the supporting upright posts are fixedly connected with a platform, and the top of the platform is provided with a lifting mechanism. According to the invention, the bottom die and the upper die are arranged for pouring the pressure arm, the cooling box body is arranged for cooling the bottom die and the upper die, so that the casting efficiency of the pressure arm is improved, the lifting mechanism is arranged, the bottom die and the upper die can be driven to move towards the inner cavity of the cooling box body, and the cooling effect is convenient to carry out, wherein the servo motor can drive the bottom die and the upper die to enter the cooling box body and lift from the inner cavity of the cooling box body under the condition of forward and reverse rotation, so that the problem that the cooling is fast in a cooling mode through cooling liquid, but a die used for production is inconvenient to place in the cooling liquid, so that the production work is not facilitated is solved.)

1. The utility model provides a based on mould production pressure arm, includes bottom plate (1), its characterized in that: the cooling box body (2) is fixedly connected to the top of the bottom plate (1), the supporting columns (3) are fixedly connected to the periphery of the top of the bottom plate (1), the platforms (4) are fixedly connected to the tops of the supporting columns (3), the lifting mechanism (5) is arranged on the top of each platform (4), each lifting mechanism (5) comprises two supporting rods (501), the bottom of each supporting rod (501) penetrates through each platform (4), the number of the supporting rods (501) is two, a servo motor (502) is fixedly connected between the two supporting rods (501), a threaded rod (503) is fixedly connected to an output shaft of each servo motor (502), the threaded rod (503) penetrates through each platform (4) and is in threaded connection with each platform (4), the bottom of each threaded rod (503) is movably connected with a top plate (504) through a bearing, and the bottom of each supporting rod (501) is fixedly connected with the top plate (504), equal fixedly connected with gangbar (505) all around of roof (504) bottom, the bottom fixedly connected with fixed block (506) of gangbar (505), one side fixedly connected with backup pad (507) of fixed block (506), the top fixedly connected with die block (6) of backup pad (507), the top swing joint of die block (6) has last mould (7).

2. The mold-based production pressure arm of claim 1, wherein: fixedly connected with die sinking mechanism (8) are located at the center of roof (504) bottom, die sinking mechanism (8) include crossbeam (801), first spacing slide (802) have been seted up to the bottom of crossbeam (801), the inner chamber sliding connection of first spacing slide (802) has first spacing slide bar (803), the quantity of first spacing slide bar (803) is two, the bottom and last mould (7) fixed connection of first spacing slide bar (803).

3. The mold-based production pressure arm of claim 2, wherein: second limiting slide rails (804) are arranged on two sides of an inner cavity of the first limiting slide rail (802), a second limiting slide bar (805) is connected to the inner cavity of the second limiting slide rail (804) in a sliding mode, and one side, away from the inner cavity of the second limiting slide rail (804), of the second limiting slide bar (805) is fixedly connected with the first limiting slide bar (803).

4. The mold-based production pressure arm of claim 1, wherein: positioning sliding grooves (9) are formed in the two sides of the top of the bottom die (6), positioning sliding blocks (10) are fixedly connected to the two sides of the bottom of the upper die (7), and the positioning sliding blocks (10) are connected with the inner cavities of the positioning sliding grooves (9) in a sliding mode.

5. The mold-based production pressure arm of claim 1, wherein: spacing spout (11) have all been seted up to the front end and the rear end of cooling box (2) inner chamber both sides, the one end that backup pad (507) were kept away from in fixed block (506) extends to the inner chamber of spacing spout (11) and with the inner chamber sliding connection of spacing spout (11).

6. The mold-based production pressure arm of claim 1, wherein: go up the left side fixedly connected with handle at mould (7) top, the right side intercommunication at last mould (7) top has annotates the liquid pipe.

7. The mold-based production pressure arm of claim 1, wherein: the front side of the cooling box body (2) is communicated with a liquid inlet pipe, the lower end of the right side of the cooling box body (2) is communicated with a liquid discharge pipe, and a valve is arranged on the surface of the liquid discharge pipe.

8. The method and process of any one of claims 1-7, wherein the method comprises the steps of: the production method and the process comprise the following steps:

A. molten iron is injected into the upper die (7) and the bottom die (6) through the liquid injection pipe, an output shaft of the servo motor (502) drives the threaded rod (503) to rotate, the threaded rod (503) moves downwards while rotating, the bottom die (6) and the upper die (7) on the top of the supporting plate (507) move towards the inner cavity of the cooling box body (2) together along with the upper die, and contact with cooling liquid in the inner cavity of the cooling box body (2) to cool;

B. after the temperature reduction is finished, the servo motor (502) is controlled to rotate reversely, an output shaft of the servo motor (502) drives the threaded rod (503) to rotate reversely, and the support plate (507) can drive the bottom die (6) and the upper die (7) to move upwards from the inner cavity of the cooling box body (2);

C. the upper die (7) is pulled to move to the left side through a handle at the top of the upper die (7), the upper die (7) drives the first limiting slide rod (803) to move, and the first limiting slide rod (803) slides to the left in the inner cavity of the first limiting slide way (802), so that the upper die (7) and the bottom die (6) are opened and closed;

D. and after the upper die (7) and the bottom die (6) are opened and closed, the pressure arm for forming the inner cavity of the bottom die (6) is taken out, then the upper die (7) is pushed to one side of the bottom die (6) until the upper die (7) and the bottom die (6) are overlapped, and then the pouring work can be carried out again.

Technical Field

The invention relates to the technical field of pressure arm production, in particular to a method and a process for producing a pressure arm based on a mold.

Background

In the air pressure disc brake, the rotating shaft assembly completes the brake function of the brake, the pressure arm is a key part of the rotating shaft assembly, the function of the pressure arm is equivalent to a force increasing lever, and the working principle is as follows: brake chamber push rod vertical action when the pressure arm ball socket, the pressure arm can rotate round the cylindrical center of fulcrum of pivot mechanism, the pressure arm has one section displacement in the braking direction when rotatory, the ascending displacement with the braking direction of lieing in of pressure arm in ball socket direction becomes a fixed proportion, namely lever ratio or reinforcement ratio, the reinforcement ratio is a constant usually, the displacement of pressure arm in the braking direction is transmitted for the base, then transmit the friction disc respectively by the base, eliminate the clearance between friction disc and the brake disc, outer friction disc also laminates with the brake disc, thereby inside and outside friction disc cohesion post brake disc, with this braking effect that realizes.

The pressure arm needs to be produced by using a mold, but when the pressure arm is produced by using the mold, the time consumption is long in a natural cooling mode due to the fact that the temperature of poured molten iron is high, and the cooling is fast in a cooling mode through cooling liquid, but the mold used for production is not convenient to place in the cooling liquid, so that the production work is not facilitated, and therefore a method and a flow for producing the pressure arm based on the mold are provided.

Disclosure of Invention

The invention aims to provide a method and a process for producing a pressure arm based on a mold, which have the advantage of convenience in cooling, and solve the problems that the pressure arm needs to be produced by using the mold, but the time consumption is long in a natural cooling mode due to the fact that the temperature of poured molten iron is high when the mold is used for producing the pressure arm, and the cooling is fast in a cooling mode by using cooling liquid, but the mold used for production is not convenient to place in the cooling liquid, so that the production work is not facilitated.

In order to achieve the purpose, the invention provides the following technical scheme: a pressure arm based on mold production comprises a bottom plate, wherein the top of the bottom plate is fixedly connected with a cooling box body, the periphery of the top of the bottom plate is fixedly connected with supporting stand columns, the top of each supporting stand column is fixedly connected with a platform, the top of each platform is provided with a lifting mechanism, each lifting mechanism comprises a supporting rod, the bottom of each supporting rod penetrates through the corresponding platform, the number of the supporting rods is two, a servo motor is fixedly connected between the two supporting rods, an output shaft of each servo motor is fixedly connected with a threaded rod, the threaded rod penetrates through the corresponding platform and is in threaded connection with the corresponding platform, the bottom of each threaded rod is movably connected with a top plate through a bearing, the bottom of each supporting rod is fixedly connected with the top plate, the periphery of the bottom of each top plate is fixedly connected with a linkage rod, the bottom of each linkage rod is fixedly connected with a fixed block, one side of each fixed block is fixedly connected with a supporting plate, the top fixedly connected with die block of backup pad, the top swing joint of die block has the mould.

Preferably, the fixedly connected with die sinking mechanism is located at the center of roof bottom, die sinking mechanism includes the crossbeam, first spacing slide has been seted up to the bottom of crossbeam, the inner chamber sliding connection of first spacing slide has first spacing slide bar, the quantity of first spacing slide bar is two, the bottom and the last mould fixed connection of first spacing slide bar through setting up die sinking mechanism, have played the effect that conveniently opens and shuts last mould and die block, the off-the-shelf taking out of being convenient for.

Preferably, the two sides of the inner cavity of the first limit slide way are provided with second limit slide ways, the inner cavity of each second limit slide way is connected with a second limit slide bar in a sliding manner, one side, away from the inner cavity of each second limit slide way, of each second limit slide bar is fixedly connected with the corresponding first limit slide bar, and the effect of limiting and fixing the first limit slide bars is achieved by arranging the second limit slide ways and the second limit slide bars.

Preferably, the location spout has all been seted up to the both sides at die block top, the equal fixedly connected with location slider in both sides of going up the mould bottom, the location slider and the inner chamber sliding connection of location spout have played the spacing effect to last mould through setting up location spout and location slider, avoid going up the situation that the movement track of mould squinted.

Preferably, spacing spout has all been seted up to the front end and the rear end of cooling box inner chamber both sides, the one end that the backup pad was kept away from to the fixed block extend to the inner chamber of spacing spout and with the inner chamber sliding connection of spacing spout, through setting up fixed block and spacing spout, played the spacing effect to the backup pad, ensure that the skew can not appear in the movement track of die block and last mould.

Preferably, go up the left side fixedly connected with handle at mould top, the right side intercommunication at last mould top has annotates the liquid pipe, through setting up the handle and annotating the liquid pipe, has played the effect of being convenient for the pulling go up the mould and make things convenient for the pouring respectively.

Preferably, the front side of the cooling box body is communicated with a liquid inlet pipe, the lower end of the right side of the cooling box body is communicated with a liquid discharge pipe, a valve is arranged on the surface of the liquid discharge pipe, and the liquid inlet pipe and the liquid discharge pipe are arranged, so that the effect of circulating cooling liquid in the inner cavity of the cooling box body is achieved, and the cooling effect is ensured.

Preferably, the production method and the process comprise the following steps:

A. molten iron is injected into the upper die and the bottom die through the liquid injection pipe, an output shaft of the servo motor drives the threaded rod to rotate, the threaded rod moves downwards while rotating, and the bottom die and the upper die at the top of the supporting plate move towards the inner cavity of the cooling box body together and contact with cooling liquid in the inner cavity of the cooling box body to cool;

B. after the temperature reduction is finished, the servo motor is controlled to rotate reversely, an output shaft of the servo motor drives the threaded rod to rotate reversely, and the bottom die and the upper die are driven by the supporting plate to move upwards from the inner cavity of the cooling box body;

C. the upper die is pulled to move to the left by a handle at the top of the upper die, the upper die drives the first limiting slide rod to move, and the first limiting slide rod slides leftwards in an inner cavity of the first limiting slide way, so that the upper die and the bottom die are opened and closed;

D. and after the upper die and the bottom die are opened and closed, taking out the pressure arm formed in the inner cavity of the bottom die, and then pushing the upper die to one side of the bottom die until the upper die and the bottom die are overlapped, so that the pouring work can be carried out again.

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

1. according to the invention, the bottom die and the upper die are arranged for pouring the pressure arm, the cooling box body is arranged for cooling the bottom die and the upper die, so that the casting efficiency of the pressure arm is improved, the lifting mechanism is arranged so as to drive the bottom die and the upper die to move towards the inner cavity of the cooling box body, and the cooling effect is convenient to carry out, wherein the servo motor can drive the bottom die and the upper die to enter the cooling box body and lift from the inner cavity of the cooling box body under the condition of forward and reverse rotation, so that the problem that the pressure arm needs to be produced by using a die, but the time consumption is long in a natural cooling mode due to higher temperature of poured molten iron when the die is used for producing the pressure arm, and the cooling mode by using the cooling liquid is fast, but the die used for production is inconvenient to put into the cooling liquid, so that the production work is not facilitated is solved.

2. The invention has the advantages that the supporting upright post and the platform are arranged to play a role in supporting and fixing the lifting mechanism and the die sinking mechanism, the die sinking mechanism is arranged to play a role in conveniently opening and closing the upper die and the bottom die and bring convenience for taking out finished products, the positioning slide groove and the positioning slide block are arranged to play a role in limiting the upper die and avoid the situation that the movement track of the upper die deviates, the fixing block and the limiting slide groove are arranged to play a role in limiting the supporting plate and ensure that the movement tracks of the bottom die and the upper die do not deviate, the second limiting slide way and the second limiting slide bar are arranged to play a role in limiting and fixing the first limiting slide bar, the handle and the liquid injection pipe are arranged to respectively play roles in conveniently pulling the upper die and conveniently pouring, and the liquid inlet pipe and the liquid outlet pipe are arranged to play a role in circulating cooling liquid in the inner cavity of the cooling box, ensure the cooling effect, through setting up the bracing piece, played spacing and fixed effect to servo motor.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the lifting mechanism of the present invention;

FIG. 3 is a schematic view of a bottom mold according to the present invention;

FIG. 4 is a schematic bottom view of the upper mold of the present invention;

fig. 5 is a schematic bottom view of the mold opening mechanism of the present invention.

In the figure: 1. a base plate; 2. cooling the box body; 3. supporting the upright post; 4. a platform; 5. a lifting mechanism; 501. a support bar; 502. a servo motor; 503. a threaded rod; 504. a top plate; 505. a linkage rod; 506. a fixed block; 507. a support plate; 6. bottom die; 7. an upper die; 8. a mold opening mechanism; 801. a cross beam; 802. a first limiting slideway; 803. a first limit slide bar; 804. a second limiting slideway; 805. a second limit slide bar; 9. positioning the chute; 10. positioning the sliding block; 11. and a limiting sliding groove.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The bottom plate 1, the cooling box 2, the supporting upright 3, the platform 4, the lifting mechanism 5, the supporting rod 501, the servo motor 502, the threaded rod 503, the top plate 504, the linkage rod 505, the fixing block 506, the supporting plate 507, the bottom die 6, the upper die 7, the die opening mechanism 8, the cross beam 801, the first limiting slide way 802, the first limiting slide way 803, the second limiting slide way 804, the second limiting slide way 805, the positioning slide way 9, the positioning slide block 10 and the limiting slide way 11 are all universal standard parts or parts known by those skilled in the art, and the structure and principle of the invention are known by technical manuals or conventional experimental methods.

Referring to fig. 1-5, a pressure arm based on mold production comprises a bottom plate 1, a cooling box 2 is fixedly connected to the top of the bottom plate 1, supporting columns 3 are fixedly connected to the periphery of the top of the bottom plate 1, a platform 4 is fixedly connected to the top of the supporting columns 3, a lifting mechanism 5 is arranged on the top of the platform 4, the lifting mechanism 5 comprises supporting rods 501, the bottom of each supporting rod 501 penetrates through the platform 4, the number of the supporting rods 501 is two, a servo motor 502 is fixedly connected between the two supporting rods 501, a threaded rod 503 is fixedly connected to an output shaft of the servo motor 502, the threaded rod 503 penetrates through the platform 4 and is in threaded connection with the platform 4, a top plate 504 is movably connected to the bottom of each threaded rod 503 through a bearing, the bottom of each supporting rod 501 is fixedly connected with the top plate 504, linkage rods 505 are fixedly connected to the periphery of the bottom of the top plate 504, and fixed blocks 506 are fixedly connected to the bottoms of the linkage rods 505, one side of the fixed block 506 is fixedly connected with a supporting plate 507, the top of the supporting plate 507 is fixedly connected with a bottom die 6, the top of the bottom die 6 is movably connected with an upper die 7, the bottom die 6 and the upper die 7 are used for pouring pressure arms, the cooling box body 2 is used for cooling the bottom die 6 and the upper die 7, the casting efficiency of the pressure arms is improved, the lifting mechanism 5 is arranged, the bottom die 6 and the upper die 7 can be driven to move towards the inner cavity of the cooling box body 2, the cooling effect is convenient to carry out, the servo motor 502 can drive the bottom die 6 and the upper die 7 to enter the cooling box body 2 and lift from the inner cavity of the cooling box body 2 under the condition of forward and reverse rotation, the problem that the pressure arms need to be produced by using a die is solved, but when the die is used for producing the pressure arms, the temperature of poured molten iron is higher, the consumed time is longer in a natural cooling mode, and the cooling mode by cooling liquid is quicker, but the mould used in the production is not convenient to put into the cooling liquid, thereby being not beneficial to the production work.

In this embodiment, specifically, a die sinking mechanism 8 is fixedly connected to the center of the bottom of the top plate 504, the die sinking mechanism 8 includes a cross beam 801, a first limiting slide 802 is disposed at the bottom of the cross beam 801, an inner cavity of the first limiting slide 802 is slidably connected to a first limiting slide 803, the number of the first limiting slide 803 is two, and the bottom of the first limiting slide 803 is fixedly connected to the upper die 7.

In this embodiment, specifically, the two sides of the inner cavity of the first limiting slide way 802 are both provided with a second limiting slide way 804, the inner cavity of the second limiting slide way 804 is slidably connected with a second limiting slide bar 805, and one side of the second limiting slide bar 805 away from the inner cavity of the second limiting slide way 804 is fixedly connected with the first limiting slide bar 803.

In this embodiment, specifically, the positioning sliding grooves 9 are formed in both sides of the top of the bottom die 6, the positioning sliding blocks 10 are fixedly connected to both sides of the bottom of the upper die 7, and the positioning sliding blocks 10 are slidably connected to the inner cavities of the positioning sliding grooves 9.

In this embodiment, specifically, the front end and the rear end of the two sides of the inner cavity of the cooling box 2 are both provided with the limiting sliding grooves 11, and one end of the fixing block 506, which is far away from the supporting plate 507, extends to the inner cavity of the limiting sliding grooves 11 and is in sliding connection with the inner cavity of the limiting sliding grooves 11.

In this embodiment, specifically, the left side of the top of the upper die 7 is fixedly connected with a handle, and the right side of the top of the upper die 7 is communicated with a liquid injection pipe.

In this embodiment, specifically, the front side of the cooling box 2 is communicated with a liquid inlet pipe, the lower end of the right side of the cooling box 2 is communicated with a liquid outlet pipe, and a valve is arranged on the surface of the liquid outlet pipe.

In this embodiment, the production method and the process specifically include the following steps:

A. molten iron is injected into the upper die 7 and the bottom die 6 through the liquid injection pipe, an output shaft of the servo motor 502 drives the threaded rod 503 to rotate, the threaded rod 503 moves downwards while rotating, and the bottom die 6 and the upper die 7 on the top of the supporting plate 507 move towards the inner cavity of the cooling box body 2 along with the upper die and contact with cooling liquid in the inner cavity of the cooling box body 2 to cool;

B. after the temperature reduction is finished, the servo motor 502 is controlled to rotate reversely, an output shaft of the servo motor 502 drives the threaded rod 503 to rotate reversely, and the support plate 507 drives the bottom die 6 and the upper die 7 to move upwards from the inner cavity of the cooling box body 2;

C. the upper die 7 is pulled to move to the left by a handle at the top of the upper die 7, the upper die 7 drives the first limiting slide rod 803 to move, and the first limiting slide rod 803 slides to the left in the inner cavity of the first limiting slide way 802, so that the upper die 7 and the bottom die 6 are opened and closed;

D. and after the upper die 7 and the bottom die 6 are opened and closed, taking out the pressure arm formed in the inner cavity of the bottom die 6, and then pushing the upper die 7 to one side of the bottom die 6 until the upper die 7 and the bottom die 6 are overlapped, so that the pouring work can be carried out again.

When the cooling device is used, molten iron is injected into the upper die 7 and the bottom die 6 through the liquid injection pipe, the output shaft of the servo motor 502 drives the threaded rod 503 to rotate and move downwards while the threaded rod 503 rotates, the bottom die 6 and the upper die 7 on the top of the supporting plate 507 move along with the inner cavity of the cooling box body 2 and contact with cooling liquid in the inner cavity of the cooling box body 2 to cool, the servo motor 502 is controlled to rotate reversely after cooling is finished, the output shaft of the servo motor 502 drives the threaded rod 503 to rotate reversely, the supporting plate 507 drives the bottom die 6 and the upper die 7 to move upwards from the inner cavity of the cooling box body 2, the upper die 7 is pulled to move towards the left side through the handle on the top of the upper die 7, the upper die 7 drives the first limiting slide rod 803 to move, the first limiting slide rod 803 slides towards the left in the inner cavity of the first limiting slide way 802, so that the upper die 7 and the bottom die 6 are opened, and the pressure arm formed in the inner cavity of the bottom die 6 is taken out after the upper die 7 and the bottom die 6 are opened, then will go up mould 7 and promote to one side of die block 6, until going up mould 7 and die block 6 coincidence, can carry out the pouring work once more, solved the pressure arm and need use the mould to produce, but because the molten iron temperature of pouring is higher when using mould production pressure arm, it is long consuming time through natural cooling's mode, and carry out refrigerated mode through the coolant liquid and though cool off sooner, but the mould that the production used is not convenient for put into the coolant liquid, consequently is unfavorable for the problem of production work.

The standard parts used in the present application document can be purchased from the market, and can be customized according to the description of the specification and the accompanying drawings, the specific connection mode of each part adopts the conventional means of mature bolt, rivet, welding and the like in the prior art, the machines, parts and equipment adopt the conventional models in the prior art, the control mode is automatically controlled by a controller, the control circuit of the controller can be realized by simple programming of technicians in the field, the control circuit belongs to the common knowledge in the field, and the present application document is mainly used for protecting mechanical devices, so the control mode and the circuit connection are not explained in detail in the present application.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are to be construed broadly, e.g., "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.