METHOD FOR FABRICATING A STRING, IN PARTICULAR A STRING FOR A BOWED MUSICAL INSTRUMENT, AND AN APPARATUS FOR CARRYING OUT THE SAME

Abstract

Method for fabricating a string, in particular a string for a bowed musical instrument, said string having a core with at least one winding strand helically wound thereon, thereby forming a string with at least one core and at least one winding layer, the method comprising: placing a core axially along a path, spinning the core about its central axis and helically winding at least one winding strand around the string, preferably without overlaps between adjacent windings and/or large gaps between adjacent windings, of more than about 12% of the width of the individual winding strand, between adjacent windings, wherein for increasing compactness of the string a friction force is applied to the at least one winding strand by a compactness increasing module at a spinning point, said spinning point being defined as the point where the at least one winding strand is being wound on to the string, consisting of at least one core, and a compression force is applied to the at least one winding strand and the string by the compactness increasing module, when helically winding the at least one winding strand around the string.

Claims

1. Method for fabricating a string, in particular a string for a bowed musical instrument, said string having a core with at least one winding strand helically wound thereon, thereby forming a string with at least one core and at least one winding layer, the method comprising: placing a core axially along a path, spinning the core about its central axis and helically winding at least one winding strand around the string, preferably without overlaps between adjacent windings and/or large gaps between adjacent windings, of more than about 12% of the width of the individual winding strand, between adjacent windings, wherein for increasing compactness of the string a friction force is applied to the at least one winding strand by a compactness increasing module at a spinning point, said spinning point being defined as the point where the at least one winding strand is being wound on to the string, consisting of at least one core, and a compression force is applied to the at least one winding strand and the string by the compactness increasing module, when helically winding the at least one winding strand around the string.

2. The method of claim 1, wherein during spinning the compactness increasing module is moved, such that it follows the spinning point.

3. The method of claim 1, wherein the compression force and/or the friction force is/are controlled.

4. The method of claim 1, wherein at least one winding strand is wound around the string during the spinning step.

5. The method of claim 1, wherein the compactness increasing module comprises two contact plates (1, 2) and the applied friction force is the result of bringing at least one of the two contact plates in contact with the at least one winding strand therebetween during spinning and the compression force is applied by exerting a force on the at least one winding strand and the string by at least one of the two contact plates (1, 2).

6. The method of any one of the claim 1, wherein the compactness increasing module comprises between one and six contact plates (1, 2), said contact plates being arranged in pairs in series along the length of the core/string, each pair consisting of one top contact plate and one bottom contact plate and if the number of contact plates is odd, one or more of the pairs will lack either a top plate or a bottom plate, and the row of bottom contact plates will be shifted slightly along the length of the string, relative to the top row of contact plates.

7. The method of claim 5, wherein the one or at least one pair of contact plates is arranged such that it spans an angle 0 in a plane that is perpendicular to the length direction of the core, preferably with a being less than 30, more preferably less than 15 and most preferably less than 8.

8. The method of claim 5, wherein the or at least one pair of contact plates is arranged such that it spans an angle 0 in a plane including the length direction of the core, preferably with being less than 30, more preferably less than 15 and most preferably less than 8.

9. The method of claim 1, wherein the compactness increasing module comprises only one contact plate, said contact plate being shaped as an open ring, and the ring is arranged such that the core with or without one or more winding strands wound thereon passes through the ring.

10. String fabricating apparatus for fabricating a string, in particular a string for a bowed musical instrument, said string having a core with at least one winding strand helically wound thereon, thereby forming at least one winding layer, the apparatus comprising: means for spinning a fixed core of a string, in particular a string for a bowed musical instrument, and for helically winding at least one winding strand on to said core as the core spins, thereby forming a string with at least one core and at least one winding layer, and a compactness increasing module configured to be in contact with the winding strand or a current uppermost winding strand at a spinning point when the winding strand or the current uppermost winding strand is wound onto the string, consisting of at least one core, the spinning point being defined as the point where the at least one winding strand is being wound on to the string, such that a friction force is introduced at the spinning point between the compactness increasing module and the at least one winding strand during spinning, and a compression force leading to increased compression of the at least one winding strand and the string.

11. The apparatus according to claim 10, wherein the compactness increasing module is mounted on a carriage that is movable parallel to the length of the fixed core.

12. The apparatus according to claim 11, wherein the carriage is configured to also support the at least one winding strand.

13. The apparatus according to claim 10, wherein the compactness increasing module comprises a compression force controlling means for adjusting the amount of compression force introduced.

14. The apparatus according to claim 10, wherein the compactness increasing module also comprises a friction force controlling means for adjusting the amount of friction force introduced.

15. The apparatus according to claim 10, wherein the compactness increasing module comprises two contact plates (1 and 2), one thereof being a lower contact plate and the other thereof being an upper contact plate, the lower of the two contact plates being mounted on the carriage such that it is below the fixed core, preferably with no downward force exerted on the lower contact plate by the core/string before the upper contact plate presses down on the core/string, with the winding strand being wound thereon in direct contact with the lower contact plate, less than one full winding turn after winding onto the string, and the upper contact plate being attached to the carriage such that it is above the fixed core and the upperside of the core with the at least one winding strand being wound thereon being in direct contact with the upper contact plate during spinning.

16. The apparatus according to claim 10, wherein the compactness increasing module comprises between one and six contact plates (1, 2), said contact plates being arranged in pairs in series along the length of the core, each pair consisting of one top contact plate and one bottom contact plate and if the number of contact plates is odd, one or more of the pairs will lack either a top plate or a bottom plate, and the row of bottom contact plates will be shifted slightly along the length of the string, relative to the top row of contact plates.

17. The apparatus according to claim 15, wherein the or at least one pair of contact plates is angled with respect to one another.

18. The apparatus according to claim 17, wherein the at least one pair of contact plates (1 and 2) spans an angle 0 in a plane that is perpendicular to the length direction of the core.

19. The apparatus according to claim 17, wherein the at least one pair of contact plates (1 and 2) spans an angle 0 in a plane including the length direction of the core.

20. The apparatus (100) according to claim 15, wherein the contact surface of the contact plate or of at least one contact plate is coated with a surface coating.

21. The apparatus according to claim 10, wherein the compactness increasing module comprises only one contact element, preferably being coated on a contact surface, said contact element being shaped as an open ring arranged such that a core passes through it.

22. The apparatus according to claim 21, wherein the compactness increasing module is configured such that the radius of the ring can be increased or decreased.

Description

[0041] Further features and advantages of the present invention will be clear from the accompanying claims and the following description of special embodiments in combination with the schematic drawings, wherein

[0042] FIGS. 1A to 1E show steps of a method of fabricating a string, in particular a string for a bowed musical instrument, said string having a core with at least one winding strand helically wound thereon according to a first special embodiment of the invention;

[0043] FIGS. 2A to 2E show steps of a method of fabricating a string, in particular a string for a bowed musical instrument, string having a core with at least one winding strand helically wound thereon according to a second special embodiment of the invention;

[0044] FIG. 3 a modification of the step shown in FIG. 1D according to a special embodiment of the present invention;

[0045] FIG. 4 a modification of the step shown in FIG. 1D according to a special embodiment of the present invention;

[0046] FIG. 5 a modification of the step shown in FIG. 1D according to a special embodiment of the present invention;

[0047] FIG. 6 a modification of the step shown in FIG. 1D according to a special embodiment of the present invention; and

[0048] FIG. 7 a modification of the step shown in FIG. 1D according to a special embodiment of the present invention.

[0049] For example FIG. 1 (FIGS. 1A to 1E) shows a string fabricating apparatus 100 (FIG. 1A: upper left: front view; upper middle: side view; lower middle: top view) for fabricating a string, in particular a string for a bowed musical instrument, said string 110 having a core 3 with one winding strand 4 helically wound thereon according to a special embodiment of the present invention. Said apparatus 1100 comprises means (not shown) for rotating the core 3, which is fixed, i.e. not moving, and for helically winding the winding strand 4 on said core 3 as the core rotates and a compactness increasing module 120 is configured to be in contact with the winding strand 4 at a spinning point 7 when the winding strand 4 is wound onto the core 3. The spinning point being defined as the point where the winding strand 4 is being wound on to the core 3, such that a friction force is introduced at the spinning point 7, the friction force being applied to increase the friction between the compactness increasing module 120 and the winding strand 4, and a compression force being applied to compress the winding strand 4 and the core 3.

[0050] The compression increasing module 120 is mounted on a carriage (not shown) that is movable parallel to the length of the fixed core 3 and comprises two contact plates 1 and 2. The lower of the two contact plates 2 is mounted on the carriage such that it is below the fixed core 3 and the underside of the core, with the winding strand 4 being wound thereon being in direct contact with the lower contact plate 2, preferably with no downward force exerted on the contact plate 2 by the core 3 with the winding strand 4 being wound thereon. The one upper contact plate 1 is mounted on the carriage such that it is above the fixed core 3 and the upperside of the core 3 with the winding strand 4 being wound thereon is in direct contact with the upper contact plate 1 during winding. The carriage is configured to also support the winding strand 4.

[0051] Furthermore, the compactness increasing module 120 comprises a force controlling means for adjusting the amount of compression force applied. Said force controlling means is also configured to adjust the friction force applied.

[0052] An arm (not shown) is carrying the upper contact plate 1 of the compactness increasing module 120.

[0053] The compactness increasing module 120 increases the compactness of the string 110, as the string is being spun, by increasing the compression force and friction. The friction is introduced at the contact point between the contact plates 1 and 2 and the winding strand 4, and the compression force comes from the arm carrying the upper plate 1 of the compactness increasing module 120, pressing down on the string 110, compressing the core 3 and winding strand 4 between the upper contact plate 1 and the lower contact plate 2.

[0054] The compression force being exerted by the compactness increasing module 120 onto the winding strand 4 and string 110 can be adjusted by the force controlling means. In the simplest case, the force controlling means may be a mechanism, consisting of a system of adding or removing mass from the movable arm of the compactness increasing module 120. Increasing the mass of the arm will increase the downward force exerted by the arm on the string 110. However, it may also be a force controlling means based on, for example, force from a variable spring constant, pneumatics, hydraulics, magnetism, or an application of the reverse piezoelectric effect. It is important to be able to adjust the force exerted on the string 110 from the compactness increasing module 120, because several different layers with several different materials may be wound onto the same string 110. The materials are carefully selected based on density and dimensions, in order for the final music string to have a desired thickness and tension on the instrument. Different materials and material dimensions require different compressions forces, thus making the adjustability of the force critical to obtain the optimal effect of the compactness increasing module 120. A force in the range for example between 0 newton and 25 newtons is sufficient for most applications of the compactness increasing module 120.

[0055] The frictional force being exerted by the compactness increasing module 120 onto the winding strand can be adjusted by the compression force as well. However, the friction has another controlling component, namely the choice of material for the contact plates. Different materials have different coefficients of friction, which introduces another parameter for adjusting the frictional force exerted by the compactness increasing module. It should be noted that the choice of material is limited by the hardness of the winding strand material. If the contact plate material is softer than the winding strand material, the contact plates will be easily scratched and damaged by the winding strand, which will reduce the effect of the compactness increasing module. A suitable material for the contact plates is for example ceramic or steel, particularly hardened or tool steel, either blank or with a suitable coating. Examples of coatings 6 (see for example FIGS. 2A to 2E) for the contact plates include carbon-based coatings, titanium nitride and chromium nitride. Most suitable coatings will be applied using physical or chemical vapor deposition (PVD or CVD). Also, the upper and lower contact plates may be coated with different coatings, or coatings consisting of more than one coating layer. Basically, any material with a suitable frictional coefficient, in particular a material with a low coefficient of friction, and with a hardness above that of the winding strand material will be sufficient. At all times the hardness of the contact plates will exceed that of the winding strand material being wound onto the string. By the correct choice of materials and coating, the frictional coefficient can be tuned to the desired value.

[0056] The FIGS. 1A to 1E show steps of a method for fabricating a string, in particular a string for a bowed musical instrument, said string having a core with a winding strand helically wound thereon. In step 1 (FIG. 1A), a few windings of the winding strand 4 have been wound onto the core 3/string 110. This is to fasten the winding strand to the core 3/string 110. The contact plates 1 and 2 are not in contact with the core 3/string 110. In step 2 (FIG. 1B), the compactness increasing module 120 has been moved into place, and it is ready to apply increased frictional force and compression force to the winding strand 4 (the upper 1 and lower plates 2 of the compactness increasing module 120 are not yet in contact with the core 3/winding strand 4). In the step 3 (FIG. 1C), the compactness increasing module 120 has moved into contact with the core 3/string 110, but is still at the beginning (left side in FIG. 1C) of the core 3/string 110. Step 4 (FIG. 1D) illustrates the string 110 in the process of being wound, with the string 110 rotating, where the compactness increasing module 120 moves parallel to the string, following the spinning point 7 of the string 110 and winding strand 4. In step 5 (FIG. 1E), the compactness increasing module 120 has been released from the string 110, and the core 3/winding strand 4/string 110 has reached the desired level of compactness.

[0057] The apparatus 100 shown in FIGS. 2A to 2E is different from the apparatus 100 shown in FIGS. 1A to 1E in that the contact plates 1 and 2 each comprise a coating 5 and 6 respectively, facing towards the core 3/string 110. By way of said apparatus a method for fabricating a string, in particular a string for a bowed musical instrument, said string having a core with at least one winding strand helically wound thereon as described before can be carried out.

[0058] FIG. 3 shows a further strand fabricating apparatus 100 for fabricating a string, in particular a string for a bowed musical instrument, said string 110 having a core 3 with (at least) one winding strand for helically wound thereon. Said apparatus differs from the apparatus 100 shown in FIGS. 1A to 1E in that the contact plates 1 and 2 are not parallel to each other but span an angle in a plane that is perpendicular to the length direction of the core 3.

[0059] In particular, FIG. 3 shows step 4 of above mentioned method.

[0060] The string fabricating apparatus 100 shown in FIG. 4 is different from the apparatus shown in FIGS. 1A to 1E in that the contact plates 1 and 2 are not parallel to each other but span an angle in a plane including the length direction of the core 3. It also shows step 4 of above mentioned method.

[0061] FIG. 5 shows a string fabricating apparatus 100 that differs from the apparatus shown in FIGS. 1A to 1E in that it comprises two pairs of contact plates 1 and 2 arranged side-by-side in the length direction of the core 3. It also shows step 4 of above mentioned method.

[0062] FIG. 6 shows step 4 of the method described in connection with FIGS. 1A to 1E. However, instead of one winding strand 4, three parallel winding strands 4 are simultaneously wound around the core 3.

[0063] In general, the compactness increasing module can be designed in a variety of ways, which all achieve the desired effect. The design described earlier, with the string wedged between one upper contact plate and one lower contact plate is simply one configuration. The same configuration can also be imagined with both contact plates being on movable arms, or the lower contact plate being on a movable arm with the upper contact plate being stationary. Also, the contact plate pair can be rotated between 0 and 90 degrees, such that the winding strand is at a non-right angle to the plates. It is also not required for the two contact plates to be parallel to one another. The contact plates can be at an angle between 0 and 90 degrees to one another, where an angle of 0 degrees means the contact plates are parallel to one another, and 90 degrees means the contact plates are perpendicular to one another. An angle less than 30 should be especially suitable, preferentially an angle less than 15, most preferably less than 8.

[0064] Another configuration of the invention is the compactness increasing module with between one and six contact plates, being arranged in pairs in series along the axis of the string, each pair consisting of one upper plate and one lower plate. If the number of contact plates is odd, one or more of the pairs will lack either an upper contact plate or a lower contact plate, or the upper and lower contact plates will be shifted, relative to each other, such that there is not a lower contact plate aligned directly below each top plate. Each pair can be either placed directly adjacent to its neighboring pair, or there may be a gap between the pairs. Also, each pair may be rotated to a desired configuration, as described above.

[0065] Yet another configuration according to an embodiment of the invention is a circular one. The compactness increasing module 120 (see FIG. 7) may be designed such that it has a ring-shaped contact element. The ring 13 has an opening 14, which allows for the winding strand 4 to reach the core 3/string 110. The opening 14 may be for example between and th of the circumference of the circle. The core 3 passes through the ring 13. The compactness increasing module 120 has a contact region with the string 110, defined by the outer circumference of the string 110, the inner circumference of the ring 13, and the size of the opening 14 of the ring 13. The radius of the ring 13 can be increased or decreased by the use of, for example, piezoelectric actuators 12, placed on the outer circumference and/or the inner circumference of the ring 13. Because of a larger contact region between the compactness increasing module 120 and the winding strand 4, this configuration allows for a much larger frictional force being exerted on the winding strand 4 and string 110, but allows for only a smaller compression force, as there is no opposite part of the module to apply an equal but opposite force to the string. The compactness increasing module is mounted on a movable arm (not shown), which moves perpendicular to the string, with the string entering the center of the ring 13 via the ring opening 14. Alternatively, the compactness increasing module 120 may be mounted on a carriage (not shown), and the core 3 is passed through the ring 13, when it is being attached to hooks.

[0066] The compactness increasing module may be able to act on each winding layer as it is being wound onto the string, meaning that, in a finished string, which comprises a core and upwards of six different winding layers, the compactness increasing module can have acted on each individual layer, meaning that all layers may have been wound onto the string under increased compression force and increased frictional force. This differentiates the compactness increasing module at least according to a special embodiment of the present invention from the apparatus in GB2073469, which is described as a string modification apparatus, meaning it is able to modify an already playable string, as opposed to the compactness increasing module, which is an integrated part of the string production machinery and process.

[0067] Another distinction between at least a special embodiment of the present invention and the apparatus described in GB2073469 is that the apparatus is only able to modify the outermost layer of the string, and only if said outer layer has a substantially round cross-section. This introduces an additional manufacturing step to string production, or, at least limits the winding speed, as the apparatus is described as acting on the slowly moving string. This means that the compactness increasing module, which acts instantaneously on the string during spinning, causes little or no added production time or cost. Also, the compactness increasing module is able to apply compression and additional friction to any winding material, regardless of cross-sectional profile.

[0068] Furthermore, at least in a preferred embodiment, the contact surface between the winding material and the compression increasing module is completely different from the contact surface of the apparatus. In the apparatus, the contact point between the apparatus and the string is two rollers, which roll along the winding of the string, creating the desired effect. In the compactness increasing module, the contact surface between the module and the winding strand are, for example, rectangular plates, which are fixed in place and do not rotate. The fixed plates are a critical feature, as these can introduce a substantially larger frictional force than rollers can. Especially the difference in the contact surfaces is important for the distinction between the compactness increasing module and the invention of GB2073469, as the purpose of the compactness increasing module is not to flatten the outer layer, but to improve the compactness, and thus the response and acoustical output of the string, rather than noise reduction when rubbed axially by the fingers of the player, as is claimed for the apparatus in GB2073469. The, for example, rectangular plates should have an area between five and 200 square millimeters and minimum thickness of 0.1 millimeter. The two sides of the, for example, rectangular plates may be equal in length. The overall shape of the plates is not critical, as long as the shape allows for a sufficient contact point.

[0069] Depending on which end of the string 110 the winding is initiated and the direction of rotation of the string 110, either the upper contact plate or the lower contact plate of the compactness increasing module 120 is in contact with the spinning point. The contact plate of the compactness increasing module 120, which is not in contact with the spinning point 7, will be in contact with the winding strand 4, immediately after it has been wound onto the string, on the opposite side of the string 110. At least one of either the upper contact plate or the lower contact plate of the compactness increasing module 120 must be attached to the arm, which can move up and down perpendicular to the string, such that the compactness increasing module 120 can be attached and detached from the string 110.

[0070] It should be noted that the invention is not limited to the exact specifications stated in this application, as a person skilled in the art of string production and/or machine construction should be able to make obvious changes and improvements to both design and operation of the compactness increasing module.

[0071] FIGS. 3 to 7 are marked here as relating to a modification of only step 4 shown in FIG. 1D. However, of course there may be further modifications to the entire process shown in FIGS. 1A to 1E. In addition, the step shown in FIGS. 3 to 7 could be steps of a method different from the method shown in FIGS. 1A to 1E. The modifications made to the compactness increasing module shown in FIGS. 3 to 7 may be applied to all steps shown in FIGS. 1A to 1E and 2A to 2E.

[0072] The features in the foregoing description, in the claims and/or in the accompanying drawings may, both and in any combination thereof, be material for realizing the invention in diverse forms thereof.

REFERENCE SIGN LIST

[0073] 1, 2 contact plates [0074] 3 core [0075] 4 winding strand [0076] 5 coating [0077] 6 coating [0078] 7 spinning point [0079] 12 bending actuator [0080] 100 apparatus [0081] 110 string [0082] 120 compactness increasing module [0083] 13 ring [0084] 14 opening [0085] angle [0086] angle