阅读说明：本技术 钢琴弦槌芯毡的自动打磨装置 (Automatic polishing device for core felt of piano hammer head ) 是由 何玉坚 林鸣亚 冯锦豪 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种钢琴弦槌芯毡的自动打磨装置,包括底座、芯毡驱动机构、侧边打磨装置和平面打磨机构；芯毡驱动机构安装在底座上,以驱动芯毡沿前后方向移动；侧边打磨装置包括固定在底座上的支架和安装在支架上的一对侧边打磨装置,两个侧边打磨装置相对设置,用以打磨芯毡的左右两侧；平面打磨机构包括一打磨机,打磨机安装在芯毡驱动机构的上方且位于侧边打磨装置的后方,用于打磨芯毡的后段平面。通过芯毡驱动机构、侧边打磨装置和平面打磨机构的配合对芯毡的两侧边和后段平面进行打磨,自动化程度高,可缩短产品加工时间,减轻工人劳动强度,提高了芯毡修磨整形的生产效率,利于提升加工精度。(The invention discloses an automatic polishing device for a core felt of a piano hammer head, which comprises a base, a core felt driving mechanism, a side edge polishing device and a plane polishing mechanism, wherein the base is provided with a base seat; the core felt driving mechanism is arranged on the base to drive the core felt to move along the front-back direction; the side edge polishing devices comprise a bracket fixed on the base and a pair of side edge polishing devices arranged on the bracket, and the two side edge polishing devices are oppositely arranged and used for polishing the left side and the right side of the core felt; the plane grinding mechanism comprises a grinding machine, and the grinding machine is arranged above the core felt driving mechanism and behind the side grinding device and used for grinding the rear section plane of the core felt. The two side edges and the rear section plane of the core felt are polished through the matching of the core felt driving mechanism, the side edge polishing device and the plane polishing mechanism, the degree of automation is high, the product processing time can be shortened, the labor intensity of workers is reduced, the production efficiency of core felt polishing and shaping is improved, and the processing precision is favorably improved.)

1. An automatic polishing device for a core felt of a piano hammer head is characterized by comprising a base, a core felt driving mechanism, a side edge polishing device and a plane polishing mechanism;

the core felt driving mechanism is arranged on the base to drive the core felt to move along the front-back direction;

the side edge polishing devices comprise a bracket fixed on the base and a pair of side edge polishing devices arranged on the bracket, and the two side edge polishing devices are oppositely arranged and used for polishing the left side and the right side of the core felt;

the plane grinding mechanism comprises a grinding machine, and the grinding machine is arranged above the core felt driving mechanism and behind the side grinding device and used for grinding the rear section plane of the core felt.

2. The automatic sanding device for hammer core felt of piano of claim 1, wherein the core felt driving mechanism comprises a mount, a core felt positioning means and a linear driving means; the mounting seat is fixed on the base and is provided with a slide rail extending along the front-back direction; the core felt positioning device is slidably arranged on the slide rail and used for fixing the core felt; the linear driving device is arranged on the mounting seat and is connected with the core felt positioning device in a driving way.

3. The automatic grinding device of core felt for piano hammer of claim 2, wherein the core felt positioning means comprises a moving plate and a core felt fixing strip mounted on the moving plate, the top surface of the core felt fixing strip being provided with a plurality of pins arranged vertically.

4. The automatic sanding device for hammer core felt of piano of claim 3, wherein the core felt driving mechanism further comprises a pressing mechanism; the pressing mechanism comprises a fixed frame, a pressing cylinder and a felt pressing piece; the fixing frame is arranged on one side of the core felt driving mechanism and is positioned in front of the side edge polishing device; the downward pressing cylinder is arranged on the fixing frame and is positioned above the core felt driving mechanism, and the downward pressing cylinder is provided with a piston rod protruding downwards; the felt presser is fixed to the lower end of the piston rod for pressing the top surface of the hammer felt.

5. The automatic sanding device for core felt of piano hammers according to claim 3, wherein the moving plate is provided with inclined support plates at opposite sides of the core felt fixing strip, and rollers abutting against the inclined support plates are provided at the lower side of the sander.

6. The automatic grinding device for the core felt of a piano hammer according to claim 2, wherein two side grinding devices are disposed opposite to each other in the front-rear direction, each side grinding device comprising a lifting bracket, a first lifting driving mechanism and an abrasive belt machine; the lifting bracket can be movably arranged on the bracket up and down; the lifting driving mechanism is arranged on the lifting support and is connected with the lifting support in a driving way; the abrasive band machine is installed in one side of lifting support for the side of core felt is polished.

7. The automatic grinding apparatus for the felt of hammer core of piano as claimed in claim 6, wherein the belt sander has a rotating end which is journaled to the elevating bracket through a rotating shaft; the side edge polishing device also comprises a rotary driving mechanism, and the rotary driving mechanism comprises a fixing plate and a second lifting driving mechanism; the fixed plate is installed on one side of the lifting support, and the second lifting driving mechanism is installed on the fixed plate and connected with one side of the abrasive belt machine so as to drive the abrasive belt machine to rotate around the rotating shaft.

8. The automatic sanding device for felt of hammer core of piano of claim 7, wherein the fixed plate is provided with elevating slide rails; the second lifting driving mechanism is connected with the abrasive belt machine through a lifting connecting piece, and one side of the lifting connecting piece, which is close to the fixed plate, is provided with a sliding seat matched with a lifting sliding rail.

9. The automatic sanding device for felt of piano hammer core according to claim 8, wherein a connecting plate is provided at one side of the belt sander, the connecting plate is provided with a strip-shaped hole, and a pulley is installed at the lower end of the lifting connecting member and is in sliding fit with the strip-shaped hole.

10. The automatic grinding apparatus for the core felt of a piano hammer according to claim 1, wherein the grinding machine further comprises a casing and a grinding wheel mounted on the casing, the grinding wheel being exposed outwardly from the front and lower ends of the casing for grinding the rear end plane of the core felt; the plane polishing mechanism also comprises a mounting frame and a telescopic cylinder; the mounting bracket includes horizontal first dwang and the second dwang that sets up, and the rear end of casing is connected to first dwang, and the second dwang is located the place ahead of first dwang, and telescopic cylinder installs on the second dwang and is connected with the casing front end to the drive polisher pendulum changes.

Technical Field

The invention relates to the technical field of piano processing equipment, in particular to an automatic polishing device and a polishing method for a core felt of a piano hammer head.

Background

Hammers are important parts in a piano, and are used for striking strings, causing the strings to vibrate, and transmitting vibration energy to a soundboard playing a resonance role through string codes, and the vibration of the soundboard generates density waves in air, so that the sound of the piano heard by people is emitted. The hammer head is formed by gluing a wood core, a core felt and a white felt. As shown in fig. 1, in the processing process of the core felt, two side inclined planes 101 and a rear section plane 102 need to be cut on a long core felt, the existing processing mode of the core felt is to cut on the core felt by manually using a cutter and a tooling scale, the manual manufacturing mode can make the overall dimension of the core felt difficult to control accurately, the dimension deviation between different core felts is large, the standardization of a product is not facilitated, and the product quality is influenced.

Therefore, it is necessary to provide a new core mat processing apparatus to solve the above problems.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides the automatic polishing device for the core felt of the piano hammer head, so that the inclined planes at two sides and the rear section plane of the core felt are polished, and the production efficiency and the processing precision of the core felt are improved.

In order to achieve the above purpose, the invention provides the following technical scheme:

an automatic polishing device for a core felt of a piano hammer head comprises a base, a core felt driving mechanism, a side edge polishing device and a plane polishing mechanism;

the core felt driving mechanism is arranged on the base to drive the core felt to move along the front-back direction;

the side edge polishing devices comprise a bracket fixed on the base and a pair of side edge polishing devices arranged on the bracket, and the two side edge polishing devices are oppositely arranged and used for polishing the left side and the right side of the core felt;

the plane grinding mechanism comprises a grinding machine, and the grinding machine is arranged above the core felt driving mechanism and behind the side grinding device and is used for grinding the rear section plane of the core felt.

As a preferred scheme, the core felt driving mechanism comprises a mounting seat, a core felt positioning device and a linear driving device; the mounting seat is fixed on the base and is provided with a slide rail extending along the front-back direction; the core felt positioning device is slidably arranged on the slide rail and used for fixing the core felt; the linear driving device is arranged on the mounting seat and is connected with the core felt positioning device in a driving way.

As a preferred scheme, the core felt positioning device comprises a moving plate and a core felt fixing strip arranged on the moving plate, and a plurality of contact pins vertically arranged are arranged on the top surface of the core felt fixing strip.

As a preferable scheme, the core felt driving mechanism further comprises a pressing mechanism; the pressing mechanism comprises a fixed frame, a pressing cylinder and a felt pressing piece; the fixing frame is arranged on one side of the core felt driving mechanism and is positioned in front of the side edge polishing device; the downward pressing cylinder is arranged on the fixing frame and is positioned above the core felt driving mechanism, and the downward pressing cylinder is provided with a piston rod protruding downwards; the felt presser is fixed to the lower end of the piston rod for pressing the top surface of the hammer felt.

Preferably, the movable plate is provided with inclined support plates at two opposite sides of the core felt fixing strip, and rollers abutting against the inclined support plates are arranged at the lower side of the grinding machine.

As a preferred scheme, two side edge grinding devices are oppositely arranged in front and back, and each side edge grinding device comprises a lifting support, a first lifting driving mechanism and an abrasive belt machine; the lifting bracket can be movably arranged on the bracket up and down; the lifting driving mechanism is arranged on the lifting support and is connected with the lifting support in a driving way; the abrasive band machine is installed in one side of lifting support for the side of core felt is polished.

As a preferred scheme, the belt sander is provided with a rotating end, and the rotating end is coupled with the lifting bracket through a rotating shaft; the side grinding device also comprises a rotary driving mechanism, and the rotary driving mechanism comprises a fixing plate and a second lifting driving mechanism; the fixed plate is installed on one side of the lifting support, and the second lifting driving mechanism is installed on the fixed plate and connected with one side of the abrasive belt machine so as to drive the abrasive belt machine to rotate around the rotating shaft.

As a preferred scheme, a lifting slide rail is arranged on the fixing plate; the second lifting driving mechanism is connected with the abrasive belt machine through a lifting connecting piece, and one side of the lifting connecting piece, which is close to the fixed plate, is provided with a sliding seat matched with a lifting sliding rail.

As a preferred scheme, one side of the belt sander is provided with a connecting plate, the connecting plate is provided with a strip-shaped hole, the lower end of the lifting connecting piece is provided with a pulley, and the pulley is in sliding fit with the strip-shaped hole.

As a preferable scheme, the grinding machine comprises a casing and a grinding wheel arranged on the casing, wherein the grinding wheel is exposed outwards from the front lower end of the casing and is used for grinding the rear section plane of the core felt; the plane polishing mechanism also comprises a mounting frame and a telescopic cylinder; the mounting bracket includes horizontal first dwang and the second dwang that sets up, and the rear end of casing is connected to first dwang, and the second dwang is located the place ahead of first dwang, and telescopic cylinder installs on the second dwang and is connected with the casing front end to the drive polisher pendulum changes.

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

the invention provides an automatic polishing device for a core felt of a piano hammer head, which comprises a base, a core felt driving mechanism, a side edge polishing device and a plane polishing mechanism, wherein the side edge and the rear section plane of the core felt can be efficiently polished through the matching of the core felt driving mechanism, the side edge polishing device and the plane polishing mechanism, the automation degree is high, the product processing time is shortened, the labor intensity of workers is reduced, the production efficiency of polishing and shaping the core felt is improved, and the processing precision is favorably improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a perspective view of a core mat;

FIG. 2 is a perspective view of an automatic grinding device for a core felt of a piano hammer of the present invention;

FIG. 3 is a side view of the automatic grinding device for a core felt of a piano hammer of the present invention;

FIG. 4 is a rear view of the automatic grinding apparatus for a core felt of a piano hammer of the present invention;

FIG. 5 is a perspective view of a core mat drive mechanism of the present invention;

FIG. 6 is a cross-sectional view of the core mat drive mechanism of the present invention;

FIG. 7 is a perspective view of the pinch roller mechanism of the present invention;

FIG. 8 is a perspective view of the side grinding apparatus of the present invention;

FIG. 9 is a front view of the side grinding apparatus of the present invention;

FIG. 10 is a cross-sectional view of FIG. 9 taken along the line A-A;

FIG. 11 is a perspective view of the flat grinding mechanism of the present invention;

in the figure:

1. a base; 2. a core felt drive mechanism; 21. a mounting seat; 211. a slide rail; 22. moving the plate; 23. a core felt fixing strip; 24. A linear drive device; 241. a first servo motor; 242. a first lead screw; 243. a first lead screw nut; 25. a hold-down mechanism; 251. a fixed mount; 252. pressing down the air cylinder; 253. a felt pressing member; 26. inclining the support plate; 3. a side edge polishing device; 31. a support; 32. a sander; 321. a lifting support; 322. a first elevation drive mechanism; 3221. a second servo motor; 3222. a second lead screw; 3223. a second feed screw nut; 323. an abrasive belt machine; 3231. a connecting plate; 3232. a strip-shaped hole; 324. A lifting connecting piece; 325. a second elevation drive mechanism; 326. a fixing plate; 327. a rotating shaft; 4. a flat surface grinding mechanism; 41. a mounting frame; 411. a first rotating lever; 412. a second rotating lever; 42. a sander; 421. a grinding wheel; 43. a telescopic cylinder; 44. an extension arm; 441. a roller; 5. a pinch roller mechanism; 51. mounting a plate; 52. a lifting cylinder; 53. a transverse extension plate; 54. a pinch roller; 100. a core felt; 101. a bevel; 102. the back section is plane.

Detailed Description

For a better understanding of the objects, structure, features, and functions of the invention, reference should be made to the drawings and detailed description that follow. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale. Moreover, the described embodiments are only some, and not all, embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of the protection of the invention.

Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in the present disclosure do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", "front", "rear", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

Examples

Referring to fig. 2 to 4, the present embodiment provides an automatic grinding device for core felt of piano hammer, comprising a base 1, a core felt driving mechanism 2, a side grinding device 3 and a plane grinding mechanism 4; wherein, the core felt driving mechanism 2 is installed on the base 1 to drive the core felt 100 to move in the front-back direction; the side edge polishing device 3 comprises a bracket 31 fixed on the base 1 and a pair of side edge polishing devices 42 arranged on the bracket 31, wherein the two side edge polishing devices 42 are oppositely arranged and used for polishing the left side and the right side of the core felt; the plane grinding mechanism 4 comprises a grinder 42, and the grinder 42 is arranged above the core felt driving mechanism 2 and behind the side grinding device 3 and is used for grinding the rear section plane of the core felt.

As shown in fig. 5 to 6, the core felt driving mechanism 2 includes a mount 21, a core felt positioning means, and a linear driving means 24; wherein, the mounting seat 21 is fixed on the base 1 and is provided with a slide rail 211 extending along the front-back direction; the core felt positioning device is slidably arranged on the slide rail 211 and used for fixing the core felt; the linear driving device 24 is arranged on the mounting seat 21 and is connected with the core felt positioning device in a driving way, so that the core felt is driven to move along the front-back direction.

As shown in fig. 5-6, the core felt positioning device comprises a moving plate 22 and a core felt fixing strip 23 mounted on the moving plate 22, the moving plate 22 is mounted on the slide rail 211 and connected to the linear driving device 24, and a plurality of pins arranged at intervals are arranged on the top surface of the core felt fixing strip 23 for limiting the core felt. Because the core felt fixing strip 23 has the characteristic of light weight, huge friction force is generated between the grinding wheel and the surface of the core felt in the grinding process, the core felt is easy to deviate from the correct position, the processing precision is influenced, the core felt can be prevented from sliding relative to the core felt fixing strip 23 by inserting the contact pin into the core felt from bottom to top, and the processing quality is ensured.

As shown in fig. 5-6, the linear driving device 24 includes a first servo motor 241, a first lead screw 242, and a first lead screw nut 243; the first servo motor 241 is installed on the installation base 21, and a rotating shaft thereof is connected with one end of the first screw rod 242; the first lead screw nut 243 is screw-engaged with the first lead screw 242 and fixed to the lower end of the moving plate 22. During polishing, the first servo motor drives the first lead screw 242 to rotate, so that the first lead screw nut 243 moves back and forth, thereby driving the core felt positioning device.

The core mat drive mechanism 2 further includes a hold-down mechanism 25. The pressing mechanism 25 comprises a fixing frame 251, a downward pressing air cylinder 252 and a felt pressing piece 253; the fixing frame 251 is arranged at one side of the core felt driving mechanism 2 and is positioned in front of the side edge polishing device 3; the downward pressing air cylinder 252 is arranged on the fixing frame 251 and is positioned above the core felt driving mechanism 2, and the downward pressing air cylinder 252 is provided with a piston rod protruding downwards; the felt pressing piece 253 is fixed at the lower end of the piston rod and is vertically aligned with the core felt fixing strip 23, when the core felt positioning device is located at the initial position, the core felt is placed on the core felt fixing strip 23, then the pressing cylinder is started, and the felt pressing piece 253 is driven to press the core felt downwards, so that the contact pin on the core felt fixing strip 23 is fully inserted into the core felt, the position of the core felt is fixed, and the polishing precision is guaranteed.

In the embodiment shown in fig. 3 and 7, the grinding device further includes a plurality of pinch roller mechanisms 5 arranged at intervals in the front-back direction, and each pinch roller mechanism 5 includes a mounting plate 51, a lifting cylinder 52, a transverse extension plate 53 and a pinch roller; the mounting plate 51 is fixed on the base 1 and positioned at one side of the core felt driving mechanism 2, and the lifting cylinder 52 is fixed on the mounting plate 51 and drives the transverse extension plate 53 to ascend and descend; transversely extend to and extend to directly over core felt positioner, and clamp plate lower extreme movable mounting has three pinch roller 54, is used for the both sides and the top surface of crimping core felt respectively, and in the process of polishing, lift cylinder 52 drive pinch roller descends, and crimping core felt further prevents that core felt from breaking away from felt hold-down piece 253.

As shown in fig. 8-10, two side grinding devices 3 are respectively fixed on the front and rear sides of the bracket, and each side grinding device 3 includes a lifting bracket 321, a first lifting driving mechanism 322, and an abrasive belt machine 323; the lifting bracket 321 is movably mounted on the bracket 31 up and down; the lifting driving mechanism is installed on the lifting support 321 and is in driving connection with the lifting support 321 to drive the lifting support 321 to lift; the belt sander 323 is mounted on one side of the lifting bracket 321 for sanding the side of the core mat. In the rear view, the two belt sander are arranged in a staggered manner, the lifting support 321 descends during polishing, and when the core felt passes below the belt sander, the sanding belt on the belt sander 323 rotates to rub the core felt, so that the inclined plane of the core felt 100 is polished. The linear movement of the core felt is matched, so that consistency of side edge polishing can be guaranteed, and the processing precision is guaranteed.

Further, the belt sander 323 has a rotating end, which is coupled to the lifting bracket 321 through a rotating shaft 327; the grinding mechanism 42 also includes a rotary drive mechanism for adjusting the angle of the belt sander. The rotation driving mechanism includes a fixing plate 326 and a second elevation driving mechanism 325; a fixed plate 326 is installed at one side of the elevating bracket 321, and a second elevating driving mechanism 325 is installed at the fixed plate 326 and connected to one side of the belt sander 323 to drive the belt sander 323 to rotate about a rotation shaft 327. So set up, adjustable abrasive band machine 323's gradient adapts to different core felts. The fixed plate 326 is provided with a lifting slide rail 211; the second lifting driving mechanism 325 is connected to the belt sander 323 through a lifting connecting member 324, and one side of the lifting connecting member 324 close to the fixing plate 326 is connected to a slide seat provided with a lifting slide rail 211. The stability of the lifting connecting piece 324 can be improved by installing the lifting slide rail 211, the belt sander is prevented from shaking, and the polishing quality of the belt sander is guaranteed. In addition, one side of abrasive band machine sets up a connecting plate 3231, and a bar hole 3232 is seted up to connecting plate 3231, and a pulley is installed to the lower extreme of lift connecting piece 324, and pulley and bar hole 3232 sliding fit can make the linking of lift connecting piece 324 and abrasive band machine 323 more nimble.

In this embodiment, the first and second lifting/lowering driving mechanisms 325 are a structure in which a servo motor is engaged with a screw rod. The first lifting driving mechanism 322 comprises a second servo motor 3221 installed on the fixing frame 251, a second lead screw 3222 connected with a rotating rod of the second servo motor 3221, and a second lead screw nut 3223 in threaded connection with the second lead screw 3222, and the second lead screw nut 3223 is fixedly connected with the lifting support 321; the second elevation driving mechanism 325 includes a third servo motor 3251, a third screw rod 3252 and a third screw nut 3253, the third servo motor is installed at a side of the elevation support 321, a rotating shaft of the third servo motor is exposed downward, the third screw rod is vertically arranged and connected to a lower end of the rotating shaft of the third servo motor 3251, and the third screw rod nut is in threaded connection with the third screw rod and fixed to an upper end of the elevation connection member 324.

As shown in fig. 11, the grinding machine 42 includes a housing and a grinding wheel 421 mounted on the housing, the grinding wheel 421 being exposed outward from a front lower end of the housing for grinding a rear end of the core mat; the plane grinding mechanism 4 further comprises a mounting frame 41 and a telescopic cylinder 43; the mounting frame 41 includes a first rotating rod 411 and a second rotating rod 412 which are transversely arranged, the first rotating rod 411 is connected with the rear end of the housing, the second rotating rod 412 is positioned in front of the first rotating rod 411, and the telescopic cylinder 43 is installed on the second rotating rod 412 and connected with the front end of the housing so as to drive the sander 42 to swing. When the core mat moves backward, the telescopic cylinder 43 drives the grinding machine 42 so that the grinding wheel 421 descends and contacts the rear end of the upper surface of the core mat to grind the core mat 100.

Further, the inclined support plates 26 are installed on the two opposite sides of the core felt fixing strip 23 of the moving plate 22, the extending arms 44 extending downwards are arranged on the two opposite sides of the casing of the grinding machine 42, the rollers 441 are installed at the lower ends of the extending arms 44, the rollers 441 are in sliding connection with the corresponding inclined support plates 26, the inclined support plates 26 are arranged to play a limiting role, the grinding machine 42 is prevented from being turned downwards excessively, and machining accuracy is guaranteed.

In this embodiment, the automatic polishing device for the core felt of the piano hammer has the following processing modes:

1. starting a power supply air source, wherein the core felt positioning device is positioned at an initial position;

2. placing the core mat on the core mat fixing strip 23;

3. starting the pressing mechanism 25, and pressing the core felt 100 downwards to ensure that the core felt is fully attached to the upper side surface of the core felt fixing strip 23;

4. the core felt driving mechanism 2 drives the core felt to gradually move backwards, and the two side edge polishing devices 3 sequentially act to polish the left side surface and the right side surface of the core felt;

5. the core felt driving mechanism 2 drives the core felt to move backwards continuously, the plane polishing mechanism 4 is started, and the polisher 42 moves downwards and polishes the rear section plane of the core felt;

6. after polishing, the core felt positioning device moves forwards and resets, so that the core felt can be taken down, and polishing is completed.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the invention as defined by the appended claims. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.