US3683845A - Domes for electric bells - Google Patents

Domes for electric bells Download PDF

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Publication number
US3683845A
US3683845A US22637A US3683845DA US3683845A US 3683845 A US3683845 A US 3683845A US 22637 A US22637 A US 22637A US 3683845D A US3683845D A US 3683845DA US 3683845 A US3683845 A US 3683845A
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United States
Prior art keywords
bell
bell member
thickness
thicknesses
shape
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Expired - Lifetime
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US22637A
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English (en)
Inventor
John Doggart
Paul Rogerson Gleave
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V&E Friedland Ltd
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V&E Friedland Ltd
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K1/00—Devices in which sound is produced by striking a resonating body, e.g. bells, chimes or gongs
    • G10K1/06—Devices in which sound is produced by striking a resonating body, e.g. bells, chimes or gongs the resonating devices having the shape of a bell, plate, rod, or tube
    • G10K1/08—Details or accessories of general applicability
    • G10K1/10—Sounding members; Mounting thereof; Clappers or other strikers
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K1/00—Devices in which sound is produced by striking a resonating body, e.g. bells, chimes or gongs
    • G10K1/06—Devices in which sound is produced by striking a resonating body, e.g. bells, chimes or gongs the resonating devices having the shape of a bell, plate, rod, or tube
    • G10K1/062—Devices in which sound is produced by striking a resonating body, e.g. bells, chimes or gongs the resonating devices having the shape of a bell, plate, rod, or tube electrically operated
    • G10K1/063—Devices in which sound is produced by striking a resonating body, e.g. bells, chimes or gongs the resonating devices having the shape of a bell, plate, rod, or tube electrically operated the sounding member being a bell
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4957—Sound device making

Definitions

  • the present invention is directed to improving the tonal quality of an electric bell. It has now been found that if the thickness of the bell member is varied from place to place it is possible not only to obtain a louder sound from the bell member than that obtained from a uniformly thick bell member, of the same diameter, for
  • the bell member comprises principally a base and a surrounding skirt, in which the thickness of the base and the thickness of the skirt are predetermined in accord with a desired vibration mode of the bell member.
  • the bell member comprises a generally flat base particularly described joined by a shoulder to a surrounding skirt, wherein the same striking force but that the subjective quality of the sound is enhanced. It is possible to vary the thickness of the bell member to give prominence to harmonics which give either a pleasing or strident tone as required.
  • a typical church bell would have a height about three-quarters of the diameter at the mouth of the bell and a diameter at its shoulder of one half the diameter at the mouth; the height of a typical bell member for an electric bell is less than half that of the diameter of the mouth, and is preferably between one fifth and one third of the diameter of its mouth. Also the diameter at the shoulder would normally be rather more than half the diameter at the mouth. It is therefore apparent that in general quite different considerations apply in determining the manner in which the thickness of the bell member should vary.
  • an electric bell comprises an electrically operable striker and a bell member of which the thickness varies in a predetermined manner from place to place in accord with desired tonal characteristics of the bell.
  • the thicknesses of selected parts of the member it would be preferable for the thicknesses of selected parts of the member to be predetermined in accord with a desired vibration mode of resonant frequency m," where m is the number of circumferential waves and n is the number of nodal circles in the vibration bell member is thinner in a region at the edge of the skirt forming a mouth for the bell than it is at the shoulder.
  • the thickness of the base of the bell member may increase towards the shoulder.
  • the striker may be arranged to strike the bell member in the said thinner region.
  • the thickness of the bell member may vary circumferentially. This variation may be cyclic.
  • One possibility is an arrangement in which the outside dimension of the section through the bell member is circular but the inside dimension corresponds to a regular polygon.
  • FIG. 1 illustrates an electric bell
  • FIG. 2 is a diagram illustrating the effect of circumferential waves on a bell dome
  • FIGS. 3 and 4 illustrate the significance of nodal circles in a vibrating dome
  • FIG. 5 illustrates two shapes of a bell member or dome, one shape being optimised, the other being selected for analysis;
  • FIG. 6 is a graph showing the variation of the fundamental natural frequencies of the analyzed bell dome of FIG. 5 with the number of circumferential waves;
  • FIG. 7 is a further graph illustrating the relation between the thicknesses of the base and skirt of the analyzed bell dome of FIG. 5;
  • FIG. 8 is a graph illustrating the effect of plate thickness on the natural frequency of the analyzed bell dome of FIG. 5.
  • FIG. 9 illustrates a bell member of which the thickness varies circumferentially.
  • FIG. 1 shows a generally circular section bell member 10 in the form of a flattened dome having a base 11.
  • the mouth 13 of the dome is formed at the outer extremity of the rim 14 on an outwardly flared skirt 15 joined by a shoulder 12 to the base 11.
  • the base 11 is attached at the center of its base by means of a screw 16 to the housing of an electrically operable striker mechanism 17 operating a striker 18 to strike the dome on the rim 14.
  • nodal meridians which run up and down the bell at different azimuths and the other is a system of circles which lie at difierent diameters.
  • the former are called nodal meridians, the latter are called nodal circles.
  • FIG. 2 there is shown a circle 1 denoting the rim of the skirt of a bell dome. If the rim is struck at a point H, the point vibrates in and out between points H1 and H2. Nodal points are formed at four points A, B, C and D while quadrantal points of which point H is one oscillate between points E1 and E2; F l and F2; G1 and G2; and H1 and H2 respectively. It will be apparent that the displacement of the rim from the rest position is sinusoidal around the rim and accordingly one cycle of inward and outward deflection is conveniently called a circumferential wave.
  • FIG. 2 illustrates a mode of vibration containing two such waves.
  • FIGS. 3 and 4 show an idealized half-section of a bell dome having a flat base 2 and a skirt 3. Also shown greatly exaggerated is the vibration of the small element of the dome represented by the Figures, the position of the skirt and base in vibration being denoted 2a and 3a respectively.
  • the vibration of the element has a node at the point 4.
  • the locus of the node as successive elements of the bell member are considered is a circle centered on the axis of the dome. For this reason it may be termed a nodal circle.
  • FIG. 4 there are two nodes 5 and 6 associated with a respective one of two nodal circles at different diameters of the dome.
  • any vibration mode may be described by a resonant frequency f, where f is the frequency of vibration, m is the number of circumferential waves and n is the number of nodal circles.
  • the finite element method requires that the structure be divided into a number of finite elements, the stiffness and mass matrices which can be determined in local co-ordinates. From these matrices the stiffness and mass matrices for the complete structure can be determined.
  • the present invention is concerned with the practical application of the knowledge that selective variation in thickness of the dome can be used to improve the vibrational characteristics of the dome.
  • such programs are in the general case extremely complex and from the point of view of the designer it is convenient to assume an idealized shape such as a truncated cone for the bell member or dome, to examine how the vibrational characteristics of such a dome vary with change of thickness of selected parts of the dome and then to choose those thicknesses in accord with the desired frequency and sound output of the dome.
  • FIG. 5 shows a dome 51 having a skirt 52 and a base 53.
  • the base has a thickness. t,
  • the skirt has an initial thickness of Z and tapers to a thickness t,, the inner angle of the taper being a and the outer cone angle being B.
  • the height of the skirt is W
  • the length of the rim is y
  • the radius of the dome is R.
  • the shape of dome just described is an optimized shape, in which the thickness of the skirt is not constant.
  • Table 1 refers to the results of varying t
  • t Also shown in FIG. 5 is a shape of dome selected for analysis, in which the skirt is of constant thickness t,,, as shown by the lines 54.
  • the results of analyzing the latter shape of dome are shown in Tables 2A to 2D.
  • Mode Ms0, NpO... M50, NpO N50, MsO, Np0 NsO, M50, Npl. m 0 MHZ.) 825 2, 445 3,344 4,857.
  • dome of FIG. 5 having a skirt of constant thickness
  • the dome should have a resonant 2,100 Hz.
  • Tables 2A, 2B, 2C and 2D to illustrate the various vibrational modes associated with selected values of the base thickness and skirt thickness.
  • Table 2A is associated with base thickness and skirt thickness equal to 0.1 inches
  • Table 28 with a base thickness of 0.1 inch and a skirt thickness of 0.15 inches
  • Table 2C with a base thickness of 0.08 inches and a skirt thickness of 0.1 inches
  • Table 2D with a plate thickness of 0.08 inches and a skirt thickness of 0.15 inches.
  • M, N and T correspond to displacements in the meridional, normal and tangential directions respectively; the appropriate letter (M,
  • frequency f equal to design problem may be Nor T) is followed by either the letter p indicating that the largest displacement is in the (base) plate or the letter s indicating that the largest displacement is in the skirt and finally the number after p or s indicates the number of nodal circles associated with displacements in the plate or skirt.
  • the principal features of vibration include more than one type of displacement. Accordingly the most significant type is listed first, the next most important displacement is listed second and so on. The Tables do not illustrate every type of mode 7 since this would be a task difficult both experimentally and by calculation and is in any event unnecessary for present purposes.
  • the thicknesses of the base and skirt in accord with the required vibrational characteristics of the bell member or dome.
  • the lowest natural frequency for the respective type of dome with n equal a to 4 is 2,859 Hz.
  • the mode shape is characterized by a normal N displacement of the skirt s with zero nodal circles, meridional displacement of the skirt with zero nodal circles and a nonnal displacement of the base plate with one nodal circle.
  • FIG. 6 is a graph illustrating the variation of the natural frequency for the mode with one nodal circle (n equal to 1) as a function of m the number of circumferential waves for the types of dome (A and B) associated with Table 2A and 2B.
  • FIG. 7 shows the required relationship between the thickness of the plate t, and the thickness of the skirt t, such that the fundamental mode with three circumferential waves will have a natural frequency of 2,100 Hz as required.
  • the mode shape is similar to that shown in FIG. 3. However for a plate thickness of about 0.031 inches another mode of vibration occurs as is shown in FIG. 8 which is a graph illustrating resonant frequency against base-plate thickness.
  • FIG. 7 shows how to select the skirt thickness and plate thickness to give the required shape of bell member. Indeed, the results plotted on FIG. 7 can be used to design a bell with f equal to 2,100 Hz by inspection.
  • V is approximately equalto 24.4t,, 28.8t, cubic inches; superposition of the line corresponding to this equation on FIG. 7 indicates that V is an absolute minimum when the thickness of the base is zero.
  • the minimum thickness of the base is specified such as 0.05 inches the minimum value of the volume corresponds to a thickness of the skirt of 0.141 inches and is in fact 5.28 cubic inches.
  • FIG. 9 illustrates another type of variation of the thickness of a bell member 81.
  • the outside of a section through the member is a circle 82 whereas the inside is shaped as a regular polygon.
  • the order of the polygon may be selected in accord with the number of desired circumferential circles in the vibration mode.
  • An electric bell comprising: an electrically operable striker; and a bell member of which the thickness varies in a preselected manner from place to place in accord with the desired tonal characteristics of the bell, the thickness of the bell member varying circumferentially, the circumferential variation being cyclic, the outside dimension of a section through the bell member being circular, and the inside dimension of the section corresponding to a regular polygon.
  • a method of making a bell member for an electric bell comprising; selecting an idealized shape for the bell member; calculating the resonant frequencies associated with different combinations of thicknesses of selected parts of the bell member; determining the thicknesses of those parts in accord with the desired vibrational mode and resonant frequency or frequencies of the bell member; and forming the bell member according to said selected shape and said determined thicknesses.
  • a method wherein the desired resonant frequency is satisfied by a range of values for the thicknesses of selected parts of the bell member and the actual thicknesses are determined in accord with a constraint on the volume of the bell S PR r nethQd of making a bell member for an electric bell, comprising: selecting an idealized shape for the bell member, said shape consisting of geometrically substantially regular parts; calculating the vibration mode of the bell in respect of a plurality of sets of values of thickness of selected parts of the bell member; selecting a particular vibration mode for the bell, thereby predetermining the thicknesses of said .parts in accord with said calculations; and forming the bell member according to said selected shape and said determined thicknesses.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)
  • Braking Arrangements (AREA)
  • Folding Of Thin Sheet-Like Materials, Special Discharging Devices, And Others (AREA)
US22637A 1969-03-28 1970-03-25 Domes for electric bells Expired - Lifetime US3683845A (en)

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Application Number Priority Date Filing Date Title
GB1652169 1969-03-28

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US (1) US3683845A (enrdf_load_stackoverflow)
AU (1) AU1295370A (enrdf_load_stackoverflow)
DE (1) DE2014823A1 (enrdf_load_stackoverflow)
FR (1) FR2040033A5 (enrdf_load_stackoverflow)
GB (1) GB1258770A (enrdf_load_stackoverflow)
NL (1) NL7004421A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6915756B1 (en) * 1999-10-22 2005-07-12 Australian Bell Pty Ltd. Bells
US20090049913A1 (en) * 2007-08-20 2009-02-26 Seoul National University Industry Foundation Method of beat tuning in a slightly asymmetric ring-type structure
US10777182B2 (en) * 2018-10-23 2020-09-15 John Taylor Bell Foundry (Loughborough) Limited Bell and a method of designing a bell

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US60083A (en) * 1866-11-27 Improved car bell
US386632A (en) * 1888-07-24 Yictoe alphonse germain
US393818A (en) * 1888-12-04 Door-bell
US483149A (en) * 1892-09-27 Gong-bell
US561421A (en) * 1896-06-02 Paul minnis
GB189717500A (en) * 1897-07-26 1898-05-07 Harry Mather Improvements in Bells, and in Means for Actuating the same.
US731551A (en) * 1901-10-25 1903-06-23 John T Duff Bell.
US1091548A (en) * 1909-11-10 1914-03-31 Railroad Supply Company Electromagnetic bell.
US1229549A (en) * 1914-05-18 1917-06-12 Chicago Railway Signal And Supply Company Signal-bell for railroad service.
US3424124A (en) * 1966-05-19 1969-01-28 W L Jenkins Co The Bell gong shell mounting construction
US3451057A (en) * 1967-05-08 1969-06-17 Walter Zober Bell,yoke and coil assembly for reciprocating signal devices

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US60083A (en) * 1866-11-27 Improved car bell
US386632A (en) * 1888-07-24 Yictoe alphonse germain
US393818A (en) * 1888-12-04 Door-bell
US483149A (en) * 1892-09-27 Gong-bell
US561421A (en) * 1896-06-02 Paul minnis
GB189717500A (en) * 1897-07-26 1898-05-07 Harry Mather Improvements in Bells, and in Means for Actuating the same.
US731551A (en) * 1901-10-25 1903-06-23 John T Duff Bell.
US1091548A (en) * 1909-11-10 1914-03-31 Railroad Supply Company Electromagnetic bell.
US1229549A (en) * 1914-05-18 1917-06-12 Chicago Railway Signal And Supply Company Signal-bell for railroad service.
US3424124A (en) * 1966-05-19 1969-01-28 W L Jenkins Co The Bell gong shell mounting construction
US3451057A (en) * 1967-05-08 1969-06-17 Walter Zober Bell,yoke and coil assembly for reciprocating signal devices

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6915756B1 (en) * 1999-10-22 2005-07-12 Australian Bell Pty Ltd. Bells
US20090049913A1 (en) * 2007-08-20 2009-02-26 Seoul National University Industry Foundation Method of beat tuning in a slightly asymmetric ring-type structure
US10777182B2 (en) * 2018-10-23 2020-09-15 John Taylor Bell Foundry (Loughborough) Limited Bell and a method of designing a bell

Also Published As

Publication number Publication date
DE2014823A1 (de) 1971-02-25
AU1295370A (en) 1971-09-30
NL7004421A (enrdf_load_stackoverflow) 1970-09-30
GB1258770A (enrdf_load_stackoverflow) 1971-12-30
FR2040033A5 (enrdf_load_stackoverflow) 1971-01-15

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