GB2267248A - Loudspeaker cabinet - Google Patents

Loudspeaker cabinet Download PDF

Info

Publication number
GB2267248A
GB2267248A GB9211562A GB9211562A GB2267248A GB 2267248 A GB2267248 A GB 2267248A GB 9211562 A GB9211562 A GB 9211562A GB 9211562 A GB9211562 A GB 9211562A GB 2267248 A GB2267248 A GB 2267248A
Authority
GB
United Kingdom
Prior art keywords
blowing agent
cabinet
skin
thermoplastics material
loudspeaker cabinet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9211562A
Other versions
GB2267248B (en
GB9211562D0 (en
Inventor
Mouldings Limited Rotational
Peter Godfrey Knowles
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ROTATIONAL MOULDINGS Ltd
Original Assignee
ROTATIONAL MOULDINGS Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ROTATIONAL MOULDINGS Ltd filed Critical ROTATIONAL MOULDINGS Ltd
Priority to GB9211562A priority Critical patent/GB2267248B/en
Publication of GB9211562D0 publication Critical patent/GB9211562D0/en
Publication of GB2267248A publication Critical patent/GB2267248A/en
Application granted granted Critical
Publication of GB2267248B publication Critical patent/GB2267248B/en
Priority to HK6696A priority patent/HK6696A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
    • B29C44/12—Incorporating or moulding on preformed parts, e.g. inserts or reinforcements
    • B29C44/14—Incorporating or moulding on preformed parts, e.g. inserts or reinforcements the preformed part being a lining
    • B29C44/146—Shaping the lining before foaming
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C41/22—Making multilayered or multicoloured articles
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/02—Casings; Cabinets ; Supports therefor; Mountings therein
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C41/04—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Mechanical Engineering (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Abstract

A loudspeaker cabinet 22 formed by a rotational moulding technique comprises an outer skin 20 of thermoplastics material and an inner skin 21 of thermoplastics material incorporating a blowing agent. The outer skin 20 is formed first, then a charge of thermoplastics material incorporating a blowing agent is introduced to the mould while the outer skin is still hot. Typically the outer skin 20 has a thickness of 2 to 3 mm, and the inner skin 21 a thickness of 1 cm. Preferably the thermoplastic used is polyethylene, and the blowing agent is diphenyloxide-4,4'-disulphohydrazide. Holes 23 may be cut in the cabinet after moulding to allow fitting of loudspeakers. <IMAGE>

Description

LOUDSPEAKER CABINET This invention concerns a loudspeaker cabinet.
The choice of materials from which loudspeaker cabinets are made has a critical and not entirely understood influence on the quality of sound output.
Certain woods are much favoured but have the disadvantage of requiring costly fabrication processes.
Attempts to mould a loudspeaker cabinet in polyethylene using a rotational moulding technique have produced cabinets of relatively low cost but with disappointing acoustic properties.
The present invention is based on the results of research conducted by the Applicant to overcome the problem aforesaid.
According to the invention there is provided a loudspeaker cabinet formed by a rotational moulding technique and comprising an outer skin of thermoplastics material and an inner skin of thermoplastics material incorporating a blowing agent.
The thermoplastics material may be a polyethylene material.
The blowing agent may be Diphenyloxide-4,4' disulphohydrazide.
The invention will be further apparent from the following description, which concerns, by way of example only, the manufacture of one form of loudspeaker cabinet embodying same, and with reference to the figures of the accompanying drawing.
Of the drawing Figure 1 shows a cross-section through a mould in which the cabinet is formed; Figure 2 shows a perspective view of the loudspeaker cabinet; and Figure 3 shows a fragmentary cross-section through the wall of the cabinet on an enlarged scale.
Referring first to Figure 1, it will be seen that the mould, generally indicated at 10 is in two halves 11 and 12 which can be secured together at mating flanges 13. A vent tube 14 extends through a wall 15 of the mould half 12 at a position where one speaker is to be secured in the finished cabinet.
A charge of polyethylene powder is introduced into the mould 10 through the vent tube 14 and the mould in mounted on a rotational moulding machine to form a fused skin 20 over the mould surface. Whilst the skin 20 is still hot a further charge of polyethylene powder incorporating a blowing agent is introduced into the mould. Moulding is continued to form a further skin 21 of porous polythylene over the skin 20.
A suitable blowing agent is Diphenyloxide-4,4' disulphohydrazide available as Genitron (Registered Trade Mark) from Schering Industrial Chemicals, which may be added to the polyethylene at 1-5% and typically 2% by volume.
The mould 10 is opened and the cabinet 22 removed and finished by cutting apertures 23 in its front wall at the locations which are to receive the loudspeakers.
The outer solid skin 20 of the cabinet wall will have a typical thickness of about 2-3 mm whilst the porous inner skin 21 will have a typical thickness of about 1 cm.
Tests have shown that the cabinet has exceptionally good acoustic qualities comparable with the best of traditional cabinets.
It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible, without departing from the scope thereof.

Claims (3)

1. A loudspeaker cabinet formed by a rotational moulding technique and comprising an outer skin of thermoplastics material and an inner skin of thermoplastics material incorporating a blowing agent.
2. A loudspeaker cabinet according to claims 1, wherein the thermoplastics material is a polyethylene material.
3. A loudspeaker cabinet according to claims 1 or claim 2, wherein the blowing agent is Diphenyloxide-4,4' - disulphohydrazide.
GB9211562A 1992-05-30 1992-05-30 Loudspeaker cabinet Expired - Lifetime GB2267248B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9211562A GB2267248B (en) 1992-05-30 1992-05-30 Loudspeaker cabinet
HK6696A HK6696A (en) 1992-05-30 1996-01-11 Loudspeaker cabinet

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9211562A GB2267248B (en) 1992-05-30 1992-05-30 Loudspeaker cabinet

Publications (3)

Publication Number Publication Date
GB9211562D0 GB9211562D0 (en) 1992-07-15
GB2267248A true GB2267248A (en) 1993-12-01
GB2267248B GB2267248B (en) 1995-05-31

Family

ID=10716327

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9211562A Expired - Lifetime GB2267248B (en) 1992-05-30 1992-05-30 Loudspeaker cabinet

Country Status (2)

Country Link
GB (1) GB2267248B (en)
HK (1) HK6696A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2739741A1 (en) * 1995-10-04 1997-04-11 Rotational Mouldings Ltd SPEAKER SPEAKER
GB2305886A (en) * 1995-10-04 1997-04-23 Rotational Mouldings Ltd Loudspeaker cabinet formed by rotational moulding
GB2307994A (en) * 1995-12-08 1997-06-11 M A International Ltd Clock housing
GB2310160A (en) * 1996-01-11 1997-08-20 Columbus Plastics Ltd Loudspeaker Components
GB2317138A (en) * 1996-09-13 1998-03-18 Rotational Mouldings Ltd Rotational moulding of an acoustic hood
FR2758760A1 (en) * 1997-01-24 1998-07-31 Allibert Equipement Rapid process forming moulding with walls and foam core in same plastic

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1427670A (en) * 1974-03-28 1976-03-10 Rotoplas Ltd Rotational moulding
GB2245450A (en) * 1990-06-19 1992-01-02 Canon Kk Speaker for use in a sound output system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1427670A (en) * 1974-03-28 1976-03-10 Rotoplas Ltd Rotational moulding
GB2245450A (en) * 1990-06-19 1992-01-02 Canon Kk Speaker for use in a sound output system

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2739741A1 (en) * 1995-10-04 1997-04-11 Rotational Mouldings Ltd SPEAKER SPEAKER
GB2305886A (en) * 1995-10-04 1997-04-23 Rotational Mouldings Ltd Loudspeaker cabinet formed by rotational moulding
GB2307994A (en) * 1995-12-08 1997-06-11 M A International Ltd Clock housing
GB2307994B (en) * 1995-12-08 2000-01-12 M A International Ltd Clock
GB2310160A (en) * 1996-01-11 1997-08-20 Columbus Plastics Ltd Loudspeaker Components
GB2317138A (en) * 1996-09-13 1998-03-18 Rotational Mouldings Ltd Rotational moulding of an acoustic hood
FR2758760A1 (en) * 1997-01-24 1998-07-31 Allibert Equipement Rapid process forming moulding with walls and foam core in same plastic

Also Published As

Publication number Publication date
GB2267248B (en) 1995-05-31
GB9211562D0 (en) 1992-07-15
HK6696A (en) 1996-01-19

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Legal Events

Date Code Title Description
PE20 Patent expired after termination of 20 years

Expiry date: 20120529