阅读说明：本技术 一种机械领域的机械配件加工装置及加工方法 (Machining device and machining method for mechanical parts in mechanical field ) 是由 匡自然 于 2021-09-07 设计创作，主要内容包括：本发明公开了一种机械领域的机械配件加工装置及加工方法,包括基座和安装在基座上的砂轮机,所述基座上设置有无需管类板材提前测量划线并能够实时任意长度切割使用的功能定位夹具机构,此机械领域的机械配件加工装置及加工方法,区别于现有技术,通过设置的功能定位夹具机构,能够在对管类板材进行切割时无需提前定长测量划线,可通过功能定位夹具机构的使用,以在管类板材固定状态下实时量取相应长度的管类板材,进而方便管类板材的实时任意长度切割加工使用,且不需要对板材进行频繁的移动定位,有效提高了机械加工过程中管类板材的切割加工效率。(The invention discloses a machining device and a machining method for mechanical parts in the mechanical field, and the machining device and the machining method for the mechanical parts in the mechanical field comprise a base and a grinding machine arranged on the base, wherein a functional positioning fixture mechanism which does not need to measure and scribe a pipe plate in advance and can be used for cutting the pipe plate in any length in real time is arranged on the base.)

1. The utility model provides a machinery's machine parts processingequipment, includes base (1) and install abrasive machine (2) on base (1), its characterized in that: the base (1) is provided with a functional positioning clamp mechanism (3) which does not need to measure and mark the pipe plate in advance and can cut the pipe plate to any length in real time.

2. A machine-related machine part machining apparatus according to claim 1, wherein: function positioning fixture mechanism (3) are including demountable installation solid fixed splint (4) on base (1), be provided with on base (1) and be used for cooperation solid fixed splint (4) to guarantee that the movable splint part (5) that the effective location of pipe class panel used, be provided with on movable splint part (5) and be used for the real-time fixed length cutting of pipe class panel to use fixed length aversion driver part (6).

3. A machine-related machine part machining apparatus according to claim 2, wherein: movable clamp plate part (5) are including function seat (7) of demountable installation on base (1), the screw thread runs through drive shift screw rod (8) on function seat (7), drive shift screw rod (8) and fixed length aversion driver part (6) cooperation are used, and drive shift screw rod (8) tip and rotate through the bearing and install aversion splint (9), install on aversion splint (9) and be used for aversion splint (9) directional stable guide (10) that remove and use, and aversion splint (9) and solid fixed splint (4) all cooperate fixed length aversion driver part (6) to use.

4. A machine-related machine part machining apparatus according to claim 3, wherein: fixed length shifts driver part (6) and includes and rotate through the bearing and install main shaft (11) of bearing on shifting splint (9), all set up function through groove (12) that run through on shifting splint (9) and solid fixed splint (4), all install installation axle (13) through the bearing rotation in function through groove (12), the installation axle (13) outside all is fixed with direction drive gyro wheel (14), installation axle (13) on shifting splint (9) extend to shifting splint (9) top, and be provided with on shifting splint (9) and be used for driving two installation axles (13) synchronous and with the auto-lock transmission member (15) that the drive used that deflect, it is used for cooperating transmission member (15) to guarantee fixed length driving piece (16) that direction drive gyro wheel (14) effectively lead the drive and use to bear main shaft (11) to be provided with connecting piece (17) that are used for driving to shift screw rod (8) real-time rotation drive and use to bear main shaft (11) on ).

5. A machine-related machine part machining apparatus according to claim 4, wherein: connecting piece (17) including fix on bearing main shaft (11) in order to conveniently bear grip (18) that main shaft (11) real-time rotary drive used, be fixed with mount pad (19) on aversion splint (9), run through being fixed with connecting axle (20) through the bearing on mount pad (19), be fixed with drive bevel gear (21) on bearing main shaft (11), the corresponding tip of connecting axle (20) is fixed with driven bevel gear (22) with drive bevel gear (21) interlock, and connecting axle (20) other end is fixed with driving gear (23), drive aversion screw (8) go up fixed driven gear (24) with driving gear (23) interlock.

6. A machine-related machining device according to claim 5, characterized in that: driving medium (15) are including fixing synchronizing gear (25) in two installation axle (13) outsides on aversion splint (9) respectively, two synchronizing gear (25) outside cover is equipped with synchronous chain (26), and two synchronizing gear (25) are connected through synchronous chain (26) transmission, arbitrary installation axle (13) end fixing has auto-lock worm wheel (27), be close to the position of auto-lock worm wheel (27) on aversion splint (9) and install fixing base (28), run through self-lock worm (29) of installing and auto-lock worm wheel (27) interlock through the bearing on fixing base (28), auto-lock worm (29) are used with fixed length driving piece (16) cooperation.

7. A machine-related machining device according to claim 6, characterized in that: fixed length driving piece (16) include and rotate the cover through the bearing and establish the bearing sleeve (30) that bear main shaft (11) outside, bear sleeve (30) outside and be fixed with drive bevel gear (31), be fixed with on aversion splint (9) and bear seat (36), bear and run through the bearing on seat (36) and install functional shaft (37), functional shaft (37) end fixing has transmission bevel gear (32) with drive bevel gear (31) interlock, and functional shaft (37) other end is fixed with drive gear (38), auto-lock worm (29) end fixing has drive gear (39) with drive gear (38) interlock, bear sleeve (30) outside and be fixed with drive carousel (33), continuous scale groove (34) have been seted up to drive carousel (33) side position.

8. A machine-related machining device according to claim 7, characterized in that: a plurality of holding handles (35) are fixed at the side edge positions of the driving turntable (33) at equal intervals.

9. The method for machining a mechanical accessory in the field of machinery as claimed in claim 8, comprising the steps of:

s1: placing a tubular plate on a base (1) and at a position between a fixed clamping plate (4) and a shifting clamping plate (9), driving a bearing main shaft (11) to rotate by rotating a holding piece (18) and matching with a driving bevel gear (21), a driven bevel gear (22), a driving gear (23) and a driven gear (24) so as to drive a driving shifting screw (8) to rotate, driving the shifting clamping plate (9) to be close to the fixed clamping plate (4) by matching with a functional seat (7), and enabling a guide driving roller (14) to be in contact with the plate in a self-locking state to fix the position;

s2: the rotating disc (33) is driven to rotate by holding the handle (35), the guide driving roller (14) is driven to rotate continuously, the plate is driven to move to an initial cutting position, cutting machining is started, and in the cutting machining process, the guide driving roller (14) locks and fixes the position of the plate through the self-locking worm (29) and the self-locking worm (29), so that stable cutting machining is guaranteed;

s3: continuously rotating the driving turntable (33), correspondingly rotating the driving turntable (33) to a corresponding position according to the length of the plate to be cut in real time, and continuously cutting after loosening the driving turntable (33);

s4: and repeating the step of S3 until the cutting processing of any length of the single tube plate is completed.

Technical Field

The invention relates to the technical field of machining equipment, in particular to a machining device and a machining method for mechanical parts in the mechanical field.

Background

The cutting machine, also called abrasive wheel saw, is suitable for building, hardware, petrochemical, mechanical metallurgy and hydroelectric installation, and is a common device for cutting metal square flat tubes, square flat steel, I-shaped steel, channel steel, carbon steel, element tubes and other materials.

The conventional in-process that cuts panel, need measure the length of panel in advance to mark, in order to carry out fixed length cutting, and in lasting cutting process, need frequently loosen the location of panel, in order to remove it to corresponding marking off position, and carry out fixed length cutting after tightly positioning fixedly, whole process is extremely troublesome, especially when one man operation man-hour, and the power consumption consuming time for this reason, we provide a machine parts processingequipment and processing method in machinery field.

Disclosure of Invention

The invention aims to provide a machining device and a machining method for mechanical parts in the field of machinery, and the machining device and the machining method are used for solving the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides a machinery accessory processingequipment in machinery field, includes the base and installs the abrasive machine on the base, be provided with on the base and need not the pipe class panel and measure in advance and rule and can real-time arbitrary length cutting function positioning fixture mechanism who uses.

Preferably, function positioning fixture mechanism includes the solid fixed splint of demountable installation on the base, be provided with on the base and be used for cooperating solid fixed splint to guarantee the movable splint part that the effective location of pipe class panel used, be provided with the fixed length displacement drive part that is used for the real-time fixed length cutting of pipe class panel to use on the movable splint part.

Preferably, the movable clamp plate component comprises a function seat which can be detachably installed on the base, a driving displacement screw penetrates through the thread on the function seat, the driving displacement screw is matched with the fixed-length displacement driving component for use, the end part of the driving displacement screw is provided with a displacement clamp plate through the rotation of a bearing, a guide part used for the directional stable movement of the displacement clamp plate is installed on the displacement clamp plate, and the displacement clamp plate and the fixed clamp plate are matched with the fixed-length displacement driving component for use.

Preferably, the fixed length aversion driver part includes and rotates the main shaft that bears who installs on the splint that shifts through the bearing, all set up the function that runs through on aversion splint and the solid fixed splint and lead to the groove, the function leads to the inslot all and rotates through the bearing and install the installation axle, the installation off-axial side all is fixed with direction drive gyro wheel, the installation axle on the aversion splint extends to aversion splint top, and is provided with on the aversion splint and is used for driving two installation synchronous and syntropy auto-lock deflection drive driving medium that use of axle, it guarantees the fixed length driving piece that the effective direction drive of direction drive gyro wheel used to bear the main epaxial cooperation driving piece that is provided with, and bears the main connecting piece that is provided with to be used for driving the real-time rotary drive of aversion screw rod and uses.

Preferably, the connecting piece is including fixing on bearing the weight of the main shaft in order to conveniently bear the weight of the grip that the real-time rotary drive of main shaft used, be fixed with the mount pad on the aversion splint, run through the bearing on the mount pad and be fixed with the connecting axle, be fixed with drive bevel gear on bearing the main shaft, the corresponding tip of connecting axle is fixed with the driven bevel gear with drive bevel gear interlock, and the connecting axle other end is fixed with the driving gear, the last driven gear with the driving gear interlock of fixing of drive aversion screw rod.

Preferably, the driving medium is including fixing the synchronizing gear in two installation axle outsides on the splint that shifts respectively, two synchronizing gear outside cover is equipped with synchronous chain, and two synchronizing gear pass through synchronous chain transmission and connect, arbitrary installation axle end fixing has auto-lock worm wheel, the position that is close to auto-lock worm wheel on the splint that shifts installs the fixing base, run through the auto-lock worm of installing with auto-lock worm wheel interlock through the bearing on the fixing base, auto-lock worm uses with the cooperation of fixed length driving piece.

Preferably, the fixed length driving piece includes that it establishes the sleeve that bears the weight of in the main shaft outside to rotate the cover through the bearing, it is fixed with drive bevel gear to bear the sleeve outside, be fixed with on the aversion splint and bear the weight of the seat, bear and run through the bearing and install the function axle on the seat, function axle end fixing has the transmission bevel gear with the interlock of drive bevel gear, and the function axle other end is fixed with drive gear, auto-lock worm end fixing has the drive gear with the interlock of drive gear, it is fixed with the drive carousel to bear the sleeve outside, continuous scale groove has been seted up to drive carousel side position.

Preferably, a plurality of holding handles are fixed at equal intervals at the side positions of the driving turntable.

A machining method of mechanical parts in the field of machinery comprises the following steps:

s1: placing a tubular plate on the base and at a position between the fixed clamping plate and the shifting clamping plate, rotating the holding part to drive the bearing spindle to rotate, and driving the driving bevel gear, the driven bevel gear, the driving gear and the driven gear to drive the driving shifting screw to rotate, driving the shifting clamping plate to be close to the fixed clamping plate by matching with the function seat, and fixing the position by driving the guide roller to be in contact with the plate in a self-locking state;

s2: the rotating disc is driven to rotate by holding the handle, the guide driving roller is driven to rotate continuously, the plate is driven to move to an initial cutting position, cutting machining is started, and in the cutting machining process, the guide driving roller locks and fixes the position of the plate through the self-locking worm and the self-locking worm, so that stable cutting machining is guaranteed;

s3: continuously rotating the driving turntable, correspondingly rotating the driving turntable to a corresponding position according to the length of the plate to be cut in real time, and continuously cutting after loosening the driving turntable;

s4: and repeating the step of S3 until the cutting processing of any length of the single tube plate is completed.

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

compared with the prior art, the pipe plate cutting machine is not required to measure and line in advance when cutting a pipe plate by the aid of the arranged functional positioning fixture mechanism, the pipe plate with the corresponding length can be measured in real time in a fixed state by the aid of the functional positioning fixture mechanism, so that the pipe plate can be conveniently cut and processed to any length in real time, the plate is not required to be frequently moved and positioned, and cutting efficiency of the pipe plate in a machining process is effectively improved.

Drawings

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

FIG. 2 is a schematic view of another orientation of the present invention shown in FIG. 1;

FIG. 3 is a schematic view of another embodiment of the present invention;

FIG. 4 is a schematic view of another embodiment of the present invention;

FIG. 5 is a schematic view of the structure A of the present invention;

FIG. 6 is a schematic view of the structure of the present invention B;

FIG. 7 is a schematic view of the structure C of the present invention.

In the figure: 1-a base; 2-a grinder; 3-a functional positioning fixture mechanism; 4-fixing the splint; 5-a movable cleat component; 6-fixed length displacement drive means; 7-a functional seat; 8-driving the displacement screw; 9-shifting the splint; 10-a guide; 11-a load-bearing spindle; 12-functional through grooves; 13-mounting the shaft; 14-guide drive rollers; 15-a transmission member; 16-a fixed length driving element; 17-a connector; 18-a grip; 19-a mounting seat; 20-a connecting shaft; 21-drive bevel gear; 22-driven bevel gear; 23-a drive gear; 24-a driven gear; 25-a synchronizing gear; 26-a synchronization chain; 27-a self-locking worm gear; 28-a fixed seat; 29-a self-locking worm; 30-a carrier sleeve; 31-drive bevel gear; 32-drive bevel gear; 33-driving the turntable; 34-scale groove; 35-a grip handle; 36-a carrier seat; 37-functional axis; 38-a drive gear; 39-drive gear.

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.

Referring to fig. 1-7, the present invention provides a technical solution: a mechanical part processing device in the mechanical field comprises a base 1 and a grinding wheel machine 2 installed on the base 1, wherein the base 1 and the grinding wheel machine 2 are designed by adopting conventional structures in the prior art, and are not described in detail herein;

the utility model discloses a pipe type plate cutting machine, including base 1, be provided with on the base and need not pipe type plate and measure in advance and rule and can real-time arbitrary length cutting use function positioning fixture mechanism 3, and then in real-time use, in order to be different from prior art, through the function positioning fixture mechanism 3 who sets up, can need not in advance fixed length measurement and rule when cutting pipe type plate, the use of accessible function positioning fixture mechanism 3, with the pipe type plate of corresponding length is got to real-time volume under pipe type plate fixed state, and then make things convenient for the real-time arbitrary length cutting processing use of pipe type plate, and need not carry out frequent removal location to panel, the cutting machining efficiency of pipe type plate in the machining process has effectively been improved.

Function positioning fixture mechanism 3 includes demountable installation and fixes splint 4 on base 1, be provided with on base 1 and be used for cooperating solid splint 4 to guarantee the movable splint part 5 that the effective location of pipe class panel used, be provided with the fixed length that is used for the real-time fixed length cutting of pipe class panel to use on the movable splint part 5 and shift drive part 6, and then in real-time use, use through the cooperation of solid splint 4 with movable splint part 5 to guarantee the normal effective location of panel, and in its locate process, through the use of fixed length shift drive part 6, can last the positioned state under it, remove with real-time drive panel fixed length, need not measure the marking off to panel in advance, in lasting the cutting process of fixing a position, can directly cut out the panel of required length.

The movable splint component 5 comprises a functional seat 7 which is detachably arranged on the base 1, a driving displacement screw 8 penetrates through the functional seat 7 in a threaded manner, the driving displacement screw 8 is matched with the fixed-length displacement driving component 6 for use, and the end of the driving shift screw 8 is rotatably provided with a shift clamping plate 9 through a bearing, a guide piece 10 used for the directional and stable movement of the shift clamping plate 9 is arranged on the shift clamping plate 9, the guide piece 10 adopts the conventional guide structure design on the grinder 2 in the prior art, not described in detail, and the shifting clamp 9 and the fixing clamp 4 are used together with the fixed-length shifting driving part 6, and then in the real-time use process, through the use of the fixed-length displacement driving component 6, the driving displacement screw 8 is driven to continuously rotate, thereby driving the shifting splint 9 to move continuously and matching with the fixed splint 4 to effectively position the plate.

The fixed-length displacement driving part 6 comprises a bearing main shaft 11 which is rotatably installed on a displacement clamping plate 9 through a bearing, the bearing main shaft 11 is of a circular shaft structure, but is not limited to, a through function through groove 12 is formed in each of the displacement clamping plate 9 and the fixed clamping plate 4, an installation shaft 13 is rotatably installed in each function through groove 12 through a bearing, the installation shaft 13 is of a circular shaft structure, but is not limited to, a guide driving roller 14 is fixed on the outer side of each installation shaft 13, the guide driving roller 14 is in contact positioning with a plate in the actual positioning process of the plate, the installation shaft 13 on the displacement clamping plate 9 extends to the top of the displacement clamping plate 9, a transmission part 15 which is used for driving the two installation shafts 13 to synchronously and automatically lock and deflect for use is arranged on the displacement clamping plate 9, and a fixed-length driving part 16 which is used for matching with the transmission part 15 to ensure the guide driving roller 14 to effectively guide and drive use is arranged on the bearing main shaft 11, and bear and be provided with on the main shaft 11 and be used for driving the connecting piece 17 that the real-time rotary drive of aversion screw rod 8 used, and then in real-time use, through the connecting piece 17 that sets up, in order to make things convenient for the real-time rotary drive of drive aversion screw rod 8, thereby make things convenient for the real-time aversion of aversion splint 9 to press from both sides and get the location use, and the use of the driving medium 15 that possesses real-time auto-lock ability, in order to guarantee corresponding direction drive gyro wheel 14's stable locking, and then when making things convenient for panel stable location cutting, the use of cooperation fixed length driving piece 16, can also pass through the real-time drive of direction drive gyro wheel 14, in order to order about the corresponding fixed length of panel and shift, guarantee to last the positioning process, use with effective real-time fixed length cutting of making things convenient for.

The connecting piece 17 comprises a holding piece 18 fixed on the bearing spindle 11 to facilitate real-time rotation driving of the bearing spindle 11, the holding piece 18 is preferably but not limited to a hand wheel to ensure real-time rotation driving of the bearing spindle 11, the shifting clamp plate 9 is fixed with a mounting seat 19, the mounting seat 19 is of a polygonal arc seat structure but not limited to a polygonal arc seat structure, a connecting shaft 20 is fixedly penetrated through the mounting seat 19 through a bearing, the connecting shaft 20 is of a circular shaft structure but not limited to a circular shaft structure, a driving bevel gear 21 is fixed on the bearing spindle 11, a driven bevel gear 22 meshed with the driving bevel gear 21 is fixed at the corresponding end of the connecting shaft 20, a driving gear 23 is fixed at the other end of the connecting shaft 20, a driven gear 24 meshed with the driving gear 23 is fixed on the driving shifting screw 8, and further, in the real-time use process, the bearing spindle 11 is conveniently rotated through the holding piece 18, then through the cooperation of initiative bevel gear 21 and driven bevel gear 22, order about connecting axle 20 and continuously rotate, then through the cooperation of driving gear 23 with driven gear 24 to order about the drive and shift screw 8 and rotate in real time, and then cooperate the use of function seat 7, in order to order about the drive and shift screw 8 and effectively shift, guarantee to shift splint 9 and the fixed plate of the effective cooperation of fixed splint 4.

The transmission member 15 includes two synchronous gears 25 respectively fixed on the outer sides of the two mounting shafts 13 on the shifting clamp plate 9, a synchronous chain 26 is sleeved on the outer sides of the two synchronous gears 25, the two synchronous gears 25 are in transmission connection through the synchronous chain 26, a self-locking worm wheel 27 is fixed on any end portion of the mounting shaft 13, correspondingly, a fixing seat 28 is installed on the shifting clamp plate 9 at a position close to the self-locking worm wheel 27, the fixing seat 28 is in a polygonal arc seat structure, but not limited to, a self-locking worm 29 meshed with the self-locking worm wheel 27 is installed on the fixing seat 28 through a bearing in a penetrating manner, the self-locking worm 29 is used in cooperation with the fixed length driving member 16, and in the real-time use process, when the fixed length driving member 16 is used in cooperation with the bearing main shaft 11, the self-locking worm 29 is driven to continuously rotate, and then the self-locking worm wheel 27 used in cooperation is driven to continuously drive the self-locking rotation of any mounting shaft 13, thereby drive direction drive roller 14 and continue to rotate, order to drive the panel that is in the positioned state and remove to through the fixed length drive of fixed length driving piece 16, thereby the cutting process of convenient real-time arbitrary length panel uses.

The fixed-length driving member 16 includes a bearing sleeve 30 rotatably sleeved on the outer side of the bearing spindle 11 through a bearing, the bearing sleeve 30 is in a circular cylinder structure, but not limited to, a driving bevel gear 31 is fixed on the outer side of the bearing sleeve 30, a bearing seat 36 is fixed on the shifting clamp plate 9, a functional shaft 37 is mounted on the bearing seat 36 through a bearing in a penetrating manner, a transmission bevel gear 32 engaged with the driving bevel gear 31 is fixed on the end portion of the functional shaft 37, a driving gear 38 is fixed on the other end of the functional shaft 37, a transmission gear 39 engaged with the driving gear 38 is fixed on the end portion of the self-locking worm 29, a driving turntable 33 is fixed on the outer side of the bearing sleeve 30, the driving turntable 33 is in a circular disc structure, but not limited to, a continuous scale groove 34 is formed in the side position of the driving turntable 33, specifically, the driving turntable 33 rotates one circle, and the driving roller 14 is guided to drive the plate to move for a fixed distance, further, its minimum division value can be 1 centimetre, and the round can be 10 centimetres, but not the limitation, also can be for the design of other models, guarantee to satisfy the use precision can, and then in the in-service use process, through the real-time use of drive carousel 33, and then make things convenient for the real-time rotary drive of auto-lock worm 29, guarantee to make things convenient for the real-time fixed length cutting of panel to use.

The equidistance of drive carousel 33 side position is fixed with a plurality of handles 35 that grip to through the setting of gripping handle 35, effectively make things convenient for the real-time rotation of drive carousel 33, and then make things convenient for the real-time fixed length cutting of panel to use.

A machining method of mechanical parts in the field of machinery comprises the following steps:

s1: placing a tubular plate on the base 1 at a position between the fixed clamping plate 4 and the shifting clamping plate 9, rotating the holding part 18 to drive the bearing spindle 11 to rotate, and matching with the driving bevel gear 21, the driven bevel gear 22, the driving gear 23 and the driven gear 24 to drive the shifting screw 8 to rotate, matching with the function seat 7 to drive the shifting clamping plate 9 to be close to the fixed clamping plate 4, and enabling the guide driving roller 14 in a self-locking state to be in contact with the plate to fix the position;

s2: the rotating disc 33 is driven to rotate by the holding handle 35, the guide driving roller 14 is driven to rotate continuously, the plate is driven to move to an initial cutting position, cutting machining is started, and in the cutting machining process, the guide driving roller 14 is locked and fixed in position through the self-locking worm 29 and the self-locking worm 29, so that stable cutting machining use is guaranteed;

s3: continuously rotating and driving the turntable 33, correspondingly rotating and driving the turntable 33 to a corresponding position according to the length of the plate to be cut in real time, and continuously cutting after loosening the driving turntable 33;

s4: and repeating the step of S3 until the cutting processing of any length of the single tube plate is completed.

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.

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.