阅读说明：本技术 一种可调节抛光压力的抛光机床 (Polishing machine tool capable of adjusting polishing pressure ) 是由 沙洁云 徐天楠 于 2021-10-13 设计创作，主要内容包括：本发明涉及抛光技术领域,具体的说是一种可调节抛光压力的抛光机床,包括,所述底板上表面一侧固定连接有打磨组件,所述底板上表面固定连接有第二电机,所述第二电机输出固定连接有第三滑轮,所述底板上表面固定连接有支撑架,所述支撑架内部活动安装有转动锟,所述转动锟一端设有第四滑轮,所述第四滑轮通过传动带活动连接第三滑轮,所述底板上表面固定连接有支撑组件。通过底板上表面固定连接有第二电机,使得第二电机可以带动第三滑轮进行转动,通过第四滑轮通过传动带活动连接第三滑轮,使得第二电机可以带动转动锟进行转动,可以带动钢管进行转动抛光,通过底板上表面一侧固定连接有打磨组件,可以对钢管进行自动限位打磨抛光。(The invention relates to the technical field of polishing, in particular to a polishing machine tool capable of adjusting polishing pressure, which comprises a polishing assembly fixedly connected to one side of the upper surface of a bottom plate, a second motor fixedly connected to the upper surface of the bottom plate, a third pulley fixedly connected to the output of the second motor, a support frame fixedly connected to the upper surface of the bottom plate, a rotating roller movably mounted in the support frame, a fourth pulley arranged at one end of the rotating roller, a third pulley movably connected to the fourth pulley through a transmission belt, and a support assembly fixedly connected to the upper surface of the bottom plate. The second motor is fixedly connected to the upper surface of the bottom plate, so that the second motor can drive the third pulley to rotate, the fourth pulley is movably connected with the third pulley through a transmission belt, the second motor can drive the rotating roller to rotate, the steel pipe can be driven to rotate and polish, and the steel pipe can be automatically limited to polish by the aid of the polishing component fixedly connected to one side of the upper surface of the bottom plate.)

1. A polishing machine tool capable of adjusting polishing pressure, comprising a base plate (1), characterized in that: the polishing machine is characterized in that a polishing assembly (2) is fixedly connected to one side of the upper surface of the bottom plate (1), a second motor (6) is fixedly connected to the upper surface of the bottom plate (1), a third pulley (7) is fixedly connected to the output of the second motor (6), a support frame (4) is fixedly connected to the upper surface of the bottom plate (1), a rotating roller (5) is movably mounted inside the support frame (4), a fourth pulley (8) is arranged at one end of the rotating roller (5), the fourth pulley (8) is movably connected with the third pulley (7) through a transmission belt, a support assembly (3) is fixedly connected to the upper surface of the bottom plate (1), the polishing assembly (2) comprises a first electric push rod (203), the first electric push rod (203) is fixedly mounted on the upper surface of the bottom plate (1), and a support cabinet (201) is fixedly connected to the output end of the first electric push rod (203), the surface of one side of the supporting cabinet (201) is fixedly connected with a connecting cabinet (216) through an inclined plate (208), one side of the connecting cabinet (216) far away from the supporting cabinet (201) is fixedly connected with a limiting cylinder (211), a second rotating rod (212) is movably connected inside the limiting cylinder (211), the other end of the second rotating rod (212) is fixedly connected with a pressure adjusting component (210), the pressure regulating component (210) comprises a latch (2103), one side of the latch (2103) is fixedly connected with a second rotating rod (212), a second movable rod (2105) is movably arranged in the edge of the latch (2103) through a spring, a second roller (2104) is movably arranged in the second movable rod (2105), the latch (2103) and the second roller (2104) are respectively movably connected with a same movable ring (2102), the edge of the movable ring (2102) is movably provided with a polishing ring (2101) through a spring.

2. A polishing machine tool capable of adjusting polishing pressure according to claim 1, wherein: the supporting component (3) comprises a second electric push rod (301), the second electric push rod (301) is fixedly installed on the upper surface of the bottom plate (1), the output end of the second electric push rod (301) is fixedly connected with a push plate (302), and the lower surface of the push plate (302) is movably connected with the bottom plate (1).

3. A polishing machine tool capable of adjusting polishing pressure according to claim 2, wherein: fixed surface installs a plurality of third electric putter (303) on push pedal (302), third electric putter (303) output end fixedly connected with backup pad (304), one side that backup pad (304) are close to subassembly (2) of polishing is equipped with chute (305), every inside respectively movable mounting of chute (305) has fourth gyro wheel (306).

4. A polishing machine tool capable of adjusting polishing pressure according to claim 1, wherein: the upper surface of the bottom plate (1) is fixedly connected with two sliding rods (204), and the supporting cabinet (201) is connected with the bottom plate (1) through the two sliding rods (204) in a sliding mode.

5. A polishing machine tool capable of adjusting polishing pressure according to claim 4, wherein: support cabinet (201) one side fixedly connected with connecting plate (202), fixed surface is connected with first motor (207) on support cabinet (201), first motor (207) output end fixedly connected with first bull stick (206), first bull stick (206) other end swing joint connecting plate (202), first bull stick (206) outside fixedly connected with first pulley (205).

6. A polishing machine tool capable of adjusting polishing pressure according to claim 5, wherein: the outer side of the second rotating rod (212) is fixedly connected with two limiting discs (215), a plurality of third rollers (214) are movably mounted at the edges of the limiting discs (215), and the third rollers (214) are movably connected with the inner wall of the limiting barrel (211).

7. A polishing machine tool capable of adjusting polishing pressure according to claim 6, wherein: second bull stick (212) one end fixedly connected with second pulley (213), second pulley (213) have first pulley (205) through drive belt swing joint, spacing section of thick bamboo (211) outside fixed mounting has positioning switch subassembly (209).

8. A polishing machine tool capable of adjusting polishing pressure according to claim 7, wherein: positioning switch subassembly (209) is including slide rail (2091), slide rail (2091) have slider (2092) through brush electric connection, slider (2092) keep away from the inside first movable rod (2093) of having through spring movable mounting in one side of slide rail (2091), one side inside movable mounting that slider (2092) were kept away from in first movable rod (2093) has first gyro wheel (2094), slider (2092) both sides fixedly connected with dead lever (2095), every dead lever (2095) pass slide rail (2091) one side swing joint respectively and have fixation nut (2096).

Technical Field

The invention relates to the technical field of polishing, in particular to a polishing machine tool capable of adjusting polishing pressure.

Background

Polishing refers to a processing method for reducing the roughness of the surface of a workpiece by using mechanical, chemical or electrochemical action to obtain a bright and flat surface; the method comprises the following steps of modifying the surface of a workpiece by using a polishing tool and abrasive particles or other polishing media; polishing does not improve the dimensional or geometric accuracy of the workpiece, but aims to obtain a smooth surface or mirror surface gloss, sometimes also for eliminating gloss (matting);

however, when a steel pipe is polished by a traditional polishing machine tool, the steel pipe needs to be polished for multiple times in the machine tool, and an operator needs to operate a plurality of grinding wheels to enable the grinding wheels to be in contact with the steel pipe, so that the steel pipe is polished, the operation is very complicated, and meanwhile, the distance between the grinding wheels and the steel pipe is controlled by a handle and has certain operation difficulty and is not easy to get into hand.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a polishing machine tool capable of adjusting polishing pressure, which solves the problems that when a traditional polishing machine tool is used for polishing a steel pipe, multiple times of polishing needs to be carried out in the machine tool, and an operator needs to operate a plurality of grinding wheels to enable the grinding wheels to be in contact with the steel pipe.

(II) technical scheme

In order to achieve the purpose, the invention adopts the technical scheme that:

the utility model provides an adjustable polishing pressure's polishing machine tool, includes the bottom plate, bottom plate upper surface one side fixedly connected with subassembly of polishing, bottom plate upper surface fixedly connected with second motor, second motor output fixedly connected with third pulley, fixed surface is connected with the support frame on the bottom plate, the inside movable mounting of support frame has rotation kun, rotation kun one end is equipped with the fourth pulley, the fourth pulley passes through drive belt swing joint third pulley, fixed surface is connected with supporting component on the bottom plate.

Preferably, the supporting component comprises a second electric push rod, the second electric push rod is fixedly installed on the upper surface of the bottom plate, the output end of the second electric push rod is fixedly connected with a push plate, and the lower surface of the push plate is movably connected with the bottom plate.

Preferably, a plurality of third electric push rods are fixedly mounted on the upper surface of the push plate, a supporting plate is fixedly connected to the output end of each third electric push rod, inclined grooves are formed in one side, close to the polishing assembly, of the supporting plate, and a fourth roller is movably mounted inside each inclined groove.

Preferably, the polishing assembly comprises a first electric push rod, the upper surface of the base plate is fixedly mounted on the first electric push rod, the output end of the first electric push rod is fixedly connected with a supporting cabinet, the upper surface of the base plate is fixedly connected with two sliding rods, and the supporting cabinet is connected with the base plate through the two sliding rods in a sliding manner.

Preferably, one side of the supporting cabinet is fixedly connected with a connecting plate, the upper surface of the supporting cabinet is fixedly connected with a first motor, the output end of the first motor is fixedly connected with a first rotating rod, the other end of the first rotating rod is movably connected with the connecting plate, and the outside of the first rotating rod is fixedly connected with a first pulley.

Preferably, the supporting cabinet is connected to one side surface through swash plate fixedly connected with and connects the cabinet, connect the cabinet and keep away from the spacing section of thick bamboo of one side fixedly connected with of supporting cabinet, the inside swing joint of spacing section of thick bamboo has the second bull stick, two spacing dishes of second bull stick outside fixedly connected with, spacing dish edge movable mounting has a plurality of third gyro wheels, the spacing section of thick bamboo inner wall of third gyro wheel swing joint.

Preferably, one end of the second rotating rod is fixedly connected with a second pulley, the second pulley is movably connected with a first pulley through a transmission belt, the other end of the second rotating rod is fixedly connected with a pressure adjusting assembly, and a positioning switch assembly is fixedly mounted outside the limiting cylinder.

Preferably, the pressure regulating assembly comprises a latch, a second rotating rod is fixedly connected to one side of the latch, a second movable rod is movably mounted inside the edge of the latch through a spring, a second roller is movably mounted inside the second movable rod, the latch and the second roller are respectively movably connected with a same movable ring, and a polishing ring is movably mounted at the edge of the movable ring through a spring

Preferably, the positioning switch assembly comprises a slide rail, the slide rail is electrically connected with a slide block through an electric brush, a first movable rod is movably mounted inside one side of the slide block away from the slide rail through a spring, a first idler wheel is movably mounted inside one side of the first movable rod away from the slide block, fixing rods are fixedly connected to two sides of the slide block, and each fixing rod penetrates through one side of the slide rail and is movably connected with a fixing nut.

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

the steel pipe polishing device can move through the second electric push rod, the third electric push rods can push the supporting plate to move through the plurality of third electric push rods fixedly mounted on the upper surface of the push plate, the inclined grooves are formed in one side, close to the polishing assembly, of the supporting plate, the fourth idler wheels are movably mounted in each inclined groove, the first idler wheels can movably support the steel pipe, and when the steel pipe rotates, the first idler wheels are obliquely mounted, so that the steel pipe can be moved radially;

the supporting cabinet can be moved through the first electric push rod, so that the polishing assembly can be matched with other parts to clamp and fix a steel pipe, the first motor can drive the first pulley to rotate, one end of the second rotating rod is fixedly connected with the second pulley, the second pulley is movably connected with the first pulley through a transmission belt, so that the second rotating rod rotates, one side of the latch is fixedly connected with the second rotating rod, so that the latch can rotate, the second movable rod is movably arranged in the edge of the latch through a spring, and the latch and the second roller are respectively movably connected with a movable ring, so that the latch can drive the second movable ring to rotate;

the polishing ring is movably arranged on the edge of the movable ring through the spring, so that the polishing ring of the pressure adjusting assembly can carry out elastic polishing when the polishing ring carries out polishing on the steel pipe, thereby adjusting the pressure on the steel pipe, a first movable rod is movably arranged in one side of the slide block far away from the slide rail through a spring, and a first roller is movably arranged in one side of the first movable rod away from the sliding block, the first roller and the polishing ring are simultaneously contacted with the steel pipe, when the steel pipe is extruded, the first movable rod retracts, the sliding block is electrically connected with the sliding rail through the electric brush, so that the first movable rod contacts with the switch inside the sliding block when retracting, thereby controlling the first electric push rod to stop moving, so that the invention can adjust the pressure through the first electric push rod, by positioning the switch assembly, the pressure applied by the pressure-applying mechanism stops being applied after reaching a certain degree, and manual adjustment by workers is not needed.

Drawings

FIG. 1 is a schematic view of the overall structure of a polishing machine capable of adjusting polishing pressure according to the present invention;

FIG. 2 is a schematic view of another angle structure of a polishing machine capable of adjusting polishing pressure according to the present invention;

FIG. 3 is a schematic structural diagram of a supporting assembly of a polishing machine capable of adjusting polishing pressure according to the present invention;

FIG. 4 is a schematic diagram of a grinding assembly of the polishing machine capable of adjusting polishing pressure according to the present invention;

FIG. 5 is a schematic diagram of a pressure adjustment assembly of a polishing machine capable of adjusting polishing pressure according to the present invention;

FIG. 6 is a schematic view of a second rotating rod of the polishing machine with adjustable polishing pressure according to the present invention;

FIG. 7 is a schematic structural diagram of a positioning switch assembly of a polishing machine capable of adjusting polishing pressure according to the present invention;

FIG. 8 is a schematic diagram of a slider structure of a polishing machine capable of adjusting polishing pressure according to the present invention.

In the figure: 1. a base plate; 2. polishing the assembly; 201. a support cabinet; 202. a connecting plate; 203. a first electric push rod; 204. a slide bar; 205. a first pulley; 206. a first rotating lever; 207. a first motor; 208. a sloping plate; 209. a positioning switch assembly; 2091. a slide rail; 2092. a slider; 2093. a first movable bar; 2094. a first roller; 2095. fixing the rod; 2096. fixing a nut; 210. a pressure regulating assembly; 2101. polishing the ring; 2102. a movable ring; 2103. clamping teeth; 2104. a second roller; 2105. a second movable bar; 211. a limiting cylinder; 212. a second rotating rod; 213. a second pulley; 214. a third roller; 215. a limiting disc; 216. a connecting cabinet; 3. a support assembly; 301. a second electric push rod; 302. pushing the plate; 303. a third electric push rod; 304. a support plate; 305. a chute; 306. a fourth roller; 4. a support frame; 5. rotating the roller; 6. a second motor; 7. a third pulley; 8. and a fourth pulley.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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.

Examples

As shown in fig. 1-8, a polishing machine tool capable of adjusting polishing pressure comprises a bottom plate 1, a polishing assembly 2 is fixedly connected to one side of the upper surface of the bottom plate 1, a second motor 6 is fixedly connected to the upper surface of the bottom plate 1, a third pulley 7 is fixedly connected to the output of the second motor 6, a support frame 4 is fixedly connected to the upper surface of the bottom plate 1, a rotating roller 5 is movably installed inside the support frame 4, a fourth pulley 8 is arranged at one end of the rotating roller 5, the fourth pulley 8 is movably connected to the third pulley 7 through a transmission belt, and a support assembly 3 is fixedly connected to the upper surface of the bottom plate 1.

Through the technical scheme, the second motor 6 is fixedly connected with the upper surface of the bottom plate 1, and the output of the second motor 6 is fixedly connected with the third pulley 7, so that the second motor 6 can drive the third pulley 7 to rotate, the fourth pulley 8 is movably connected with the third pulley 7 through a transmission belt, so that the second motor 6 can drive the rotating roller 5 to rotate, when the steel pipe is limited, can drive the steel pipe to rotate and polish, a polishing component 2 is fixedly connected with one side of the upper surface of the bottom plate 1, the automatic limiting polishing device can automatically limit, polish and polish steel pipes, is different from a traditional polishing machine tool, can automatically attach and polish through the polishing assembly 2, does not need manual adjustment of workers, reduces the operation difficulty of the polishing machine tool, and can support and adjust steel pipes with different diameters through the supporting assembly 3.

In this embodiment, the supporting component 3 includes the second electric putter 301, the second electric putter 301 is fixedly installed on the upper surface of the bottom plate 1, the output end of the second electric putter 301 is fixedly connected with the push plate 302, the lower surface of the push plate 302 is movably connected with the bottom plate 1, the upper surface of the push plate 302 is fixedly installed with a plurality of third electric putters 303, the output end of the third electric putter 303 is fixedly connected with the supporting plate 304, one side of the supporting plate 304, which is close to the polishing component 2, is provided with the inclined slots 305, and the inside of each inclined slot 305 is movably installed with the fourth roller 306. Can push pedal 302 remove through second electric putter 301, fixed surface installs a plurality of third electric putter 303 through push pedal 302, make third electric putter 303 can promote backup pad 304 and remove, one side that is close to grinding assembly 2 through backup pad 304 is equipped with chute 305, the inside movable mounting respectively of each chute 305 has fourth gyro wheel 306, make first gyro wheel 2094 can carry out the activity to the steel pipe and support, and when the steel pipe rotated, because the first gyro wheel 2094 of slope installation, make and carry out radial movement to the steel pipe.

In this embodiment, the polishing assembly 2 includes a first electric push rod 203, the first electric push rod 203 is fixedly installed on the upper surface of the base plate 1, the output end of the first electric push rod 203 is fixedly connected with a supporting cabinet 201, the upper surface of the base plate 1 is fixedly connected with two sliding rods 204, and the supporting cabinet 201 is slidably connected to the base plate 1 through the two sliding rods 204. The supporting cabinet 201 can be moved by the first electric push rod 203, so that the grinding assembly 2 can be matched with other components to clamp and fix the steel pipe.

In this embodiment, a connection board 202 is fixedly connected to one side of a supporting cabinet 201, a first motor 207 is fixedly connected to the upper surface of the supporting cabinet 201, a first rotating rod 206 is fixedly connected to the output end of the first motor 207, the other end of the first rotating rod 206 is movably connected to the connection board 202, a first pulley 205 is fixedly connected to the outside of the first rotating rod 206, a connection cabinet 216 is fixedly connected to one side surface of the supporting cabinet 201 through an inclined board 208, a limiting cylinder 211 is fixedly connected to one side of the connection cabinet 216 away from the supporting cabinet 201, a second rotating rod 212 is movably connected to the inside of the limiting cylinder 211, two limiting discs 215 are fixedly connected to the outside of the second rotating rod 212, a plurality of third rollers 214 are movably installed at the edge of the limiting discs 215, the third rollers 214 are movably connected to the inner wall of the limiting cylinder 211, a second pulley 213 is fixedly connected to one end of the second rotating rod 212, the first pulley 205 is movably connected to the second pulley 213 through a transmission belt, and a pressure adjusting assembly 210 is fixedly connected to the other end of the second rotating rod 212, the exterior of the limit cylinder 211 is fixedly provided with a positioning switch component 209. Can drive first pulley 205 through first motor 207 and rotate, through second bull stick 212 one end fixedly connected with second pulley 213, and second pulley 213 has first pulley 205 through drive belt swing joint, make second bull stick 212 rotate, through second bull stick 212 other end fixedly connected with pressure regulating assembly 210, can polish and adjust pressure the steel pipe, there is positioning switch subassembly 209 through the outside fixed mounting of a spacing section of thick bamboo 211, make polishing subassembly 2 spacing to the steel pipe, when exerting pressure, to a certain position stop movement.

In this embodiment, the pressure adjustment assembly 210 includes a latch 2103, a second rotating rod 212 is fixedly connected to one side of the latch 2103, a second movable rod 2105 is movably installed inside the edge of the latch 2103 through a spring, a second roller 2104 is movably installed inside the second movable rod 2105, a movable ring 2102 is respectively movably connected to the latch 2103 and the second roller 2104, and a polishing ring 2101 is movably installed on the edge of the movable ring 2102 through a spring. Through latch 2103 one side fixed connection second bull stick 212, make latch 2103 can rotate, there is second movable rod 2105 through spring movable mounting inside the latch 2103 edge, and latch 2103 and second gyro wheel 2104 swing joint respectively have same activity ring 2102, make latch 2103 can drive second activity ring 2102 and rotate, there is polishing ring 2101 through spring movable mounting at activity ring 2102 edge, make polishing ring 2101 of pressure adjusting component 210 when polishing the steel pipe, can carry out elasticity and polish, thereby the adjustment is to the pressure of steel pipe.

In this embodiment, switch module 209 fixes a position including slide rail 2091, slide rail 2091 has slider 2092 through brush electric connection, slider 2092 keeps away from slide rail 2091 one side inside through spring movable mounting have first movable rod 2093, first movable rod 2093 keeps away from the inside movable mounting of one side of slider 2092 has first gyro wheel 2094, slider 2092 both sides fixedly connected with dead lever 2095, every dead lever 2095 passes slide rail 2091 one side swing joint respectively and has fixation nut 2096. A first movable rod 2093 is movably arranged in one side, far away from the sliding rail 2091, of the sliding block 2092 through a spring, a first roller 2094 is movably arranged in one side, far away from the sliding block 2092, of the first movable rod 2093, the first roller 2094 and the polishing ring 2101 are in contact with a steel pipe at the same time, when the steel pipe is extruded, the first movable rod 2093 retracts, the sliding block 2092 is electrically connected with the sliding rail 2091 through an electric brush, so that the first movable rod 2093 is in contact with an internal switch of the sliding block 2092 when retracting, the first electric push rod 203 is controlled to stop moving, pressure can be adjusted through the first electric push rod 203, and after the pressure applied by the pressure adjusting device reaches a certain degree, the pressure is stopped to be applied continuously through the positioning switch component 209, and manual adjustment by workers is not needed.

The working principle of the polishing machine tool capable of adjusting polishing pressure is as follows:

when the steel pipe polishing device is used, firstly, the push plate 302 can move through the second electric push rod 301, a plurality of third electric push rods 303 are fixedly arranged on the upper surface of the push plate 302, so that the third electric push rods 303 can push the support plate 304 to move, the inclined grooves 305 are arranged on one side, close to the polishing component 2, of the support plate 304, the fourth idler wheels 306 are movably arranged in each inclined groove 305, so that the first idler wheels 2094 can movably support the steel pipe, when the steel pipe rotates, the first idler wheels 2094 are obliquely arranged to radially move the steel pipe, the support cabinet 201 can be moved through the first electric push rods 203, so that the polishing component 2 can clamp and fix the steel pipe by matching with other parts, the first motor 207 can drive the first pulley 205 to rotate, the second pulley 213 is fixedly connected to one end of the second rotating rod 212, and the second pulley 213 is movably connected to the first pulley 205 through a transmission belt, the second rotating rod 212 is enabled to rotate, the second rotating rod 212 is fixedly connected with one side of the latch 2103, the latch 2103 can rotate, the second movable rod 2105 is movably installed inside the edge of the latch 2103 through a spring, the latch 2103 and the second roller 2104 are respectively and movably connected with a movable ring 2102, the latch 2103 can drive the second movable ring 2102 to rotate, the polishing ring 2101 is movably installed on the edge of the movable ring 2102 through the spring, the polishing ring 2101 of the pressure adjusting assembly 210 can perform elastic polishing when polishing and polishing a steel pipe, so that the pressure on the steel pipe is adjusted, the first movable rod 2093 is movably installed inside one side, far away from the sliding rail 2091, of the first movable rod 2093 through the spring, the first roller 2094 is movably installed inside one side, far away from the sliding rail 2092, the first roller 2094 and the polishing ring 2101 are simultaneously contacted with the steel pipe, when the steel pipe is extruded, the first movable rod 2093 retracts, the sliding block 2092 is electrically connected to the sliding rail 2091 through the electric brush, so that the first movable rod 2093 contacts with an internal switch of the sliding block 2092 when retracting, the first electric push rod 203 is controlled to stop moving, pressure can be adjusted through the first electric push rod 203, and pressure applied by the automatic pressure adjusting device stops being continuously applied after reaching a certain degree through the positioning switch assembly 209, and manual adjustment by workers is not needed.

The specific specifications of the first motor 207 and the second motor 6 are HF-SP102K, and the specific specifications of the first electric putter 203 and the second electric putter 301 are F10-300 BC.

Will be clear to a person skilled in the art, and the principle thereof will not be described in detail here

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.