CA1198885A - Method for manufacturing wood poles - Google Patents
Method for manufacturing wood polesInfo
- Publication number
- CA1198885A CA1198885A CA000415096A CA415096A CA1198885A CA 1198885 A CA1198885 A CA 1198885A CA 000415096 A CA000415096 A CA 000415096A CA 415096 A CA415096 A CA 415096A CA 1198885 A CA1198885 A CA 1198885A
- Authority
- CA
- Canada
- Prior art keywords
- sections
- side faces
- tube
- central cavity
- glued
- 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.)
- Expired
Links
Landscapes
- Chemical And Physical Treatments For Wood And The Like (AREA)
Abstract
ABSTRACT
In the manufacturing of wood poles a number of sections are glued together along abutting side surfaces (7, 8) so that a tubular pole (19) with a central cavity is formed. The side surfaces (7, 8) which have been provided with glue are brought into intimate con-tact with each other so as to give a tube (19). Sealing covers (20, 21) of the like are placed at both ends of the tube so that these are sealed, whereafter air is pumped out from the central cavity (23) through one or both of the said covers so as to give a vacuum in the cavity in comparison with the external pressure, whereby the contact pressure between the abutting side surfaces increases. The vacuum is maintained until the glued joints (31) have been fixed.
In the manufacturing of wood poles a number of sections are glued together along abutting side surfaces (7, 8) so that a tubular pole (19) with a central cavity is formed. The side surfaces (7, 8) which have been provided with glue are brought into intimate con-tact with each other so as to give a tube (19). Sealing covers (20, 21) of the like are placed at both ends of the tube so that these are sealed, whereafter air is pumped out from the central cavity (23) through one or both of the said covers so as to give a vacuum in the cavity in comparison with the external pressure, whereby the contact pressure between the abutting side surfaces increases. The vacuum is maintained until the glued joints (31) have been fixed.
Description
`~ ~
METHOD FOR MANUFACTURING WOOD POLES
TECHNICAL SCOPE
The invention relates to a method for manufacturing wood poles consisting of a number of sections which are glued toge-ther along abutting side surfaces so that a tubular pole with central cavity is formed. Poles of this type can be used primarily as power line poles but also as rnasts of various types, columns for buildings, bridges etc.
STATE OF THE ARI' For many years power lines have been constructed using natural poles made from pressure-impregnated pine. Because of developments in modern forestry however there has been a drastic reduction in the availability of full-grown timber and hence also of natural poles having the requisite dimensions. Because of -this poles of glued -timber have been developed which are designed to replace natural poles. Examples of such designs are shown in DE 665 210, GB 745 540, FR 2 348 345 and WO ?30/02709.
In spite of the urgent demand for glued poles and in spite oE the fact that a plurality of glued pole designs have been produced in past years, the tubular glued timber pole has not as yet however been widely employed for power lines and simi]ar demanding applications. One reason for this is tha-t fro-m the production viewpoint these poles give rise to a number of problems which have not been satisfactorily solved using available tech-niques. These problems concern both the jointing and the gluing of the individual sections, also the requi,site impregnation of the glued construction, ~.~
~ 2 DESCRIPTION OF THE INVENTION
According to one aspect of the inven-tion a method for manufacturing wood poles as of -the type cornprising a number of sections glued together along abutting side Eaces so as -to form a tubular pole with a central cavity comprises:
the steps of providing a number of sections having a trapezoidal shape, each section having side faces abuttable with side faces of other sections, providing the side faces with glue to provlde glue-bearing side faces, and bringing the glue-bearing side faces into intimate contact with each other to provide a tube in which the sections define a central cavity, placing seal-ing means at both ends of the tube for sealing the ends of the tube, pumping air out of the central cavity through one or both of the sealing means to provide a vacuum in the central cavity in comparison to the external pressure, so that contact pressure between abutting side faces increases, and maintaining the vacuum until glued joints are formed to hold the sections together.
Sealing devices may be arranged between the central cav-ity and the glued joints to prevent communication between the central cavity and the glued joints wlile -the glue is curing.
The abuttable side faces may be provided with circular tongues and grooves.
The number of sections is preferably more than 10.
Each of the sections may be made up of 2-~ pieces of timber layers~ which are glued together with the sapwood facing a base of the -trapezoidal shape.
The tubular pole may be subjected to an external posi--~L~9~
2a-tive pressure as compared with surrounding pressure, whereby the contact pressure between abutting side faces is further increased.
The tube may be hea-ted during gluing of the sections together by hot air in the cen-tral cavity or by hot air ex-ternally of the tube.
According to another aspect of the invention a method for manufacturing wood poles comprising sections glued together along abutting side surfaces so as to form a tubular pole with a central cavity comprises:
the steps of providing a number of sections having a txapezoidal shape, each section having side faces abuttable with side faces of other sections, gluing the sections together along the side faces to provide a tube with a central cavity, placing sealing means a-t both ends of the tube for sealing the ends of the tube, pumping air out of the central cavity through one or both of the sealing means to generate a reduced pressure in the tube, whereby contact pressure between abutting side surfaces increases, and maintaining the reduced pressure until glued joints are formed to hold the sections together.
Further characteristics and advantages of the invention are outlined in the patent claims and are illustrated by the following description of a preferred embodiment.
~RIEF DESCRIPTION OF DIAGRAMS
In the following description of a preferred embodiment reference will be made to the appended drawings in which Figure 1 is a perspective view of a section of the type from which the pole is to be manufactured in accordance with the ,3j D
invention.
Figure 2 is a perspective view which illustrates pole manufacture.
Figure 3 illustrates the same feature as Figure 2, in side elevation.
Figure 4 is a section on the line IV-IV in Figure 3.
Figure 5 is a section on the line V-V in Figure 3.
Figure 6 illustrates the conditions prevailing in the glued joint.
DESCRIPTION OF PREFERRED EMBODIMENT
With reference initially to Figure 1 a section Eor manu-facture of the pole in accordance with the invention is generally designa-ted as 1. The section 1 has a profile shaped like an isosceles parallel trapezoid and is made up of three glued lamin-ations 2, 3 and 4. The base surface of the section is designated as 5, its top surfaces as 6 and its two side surfaces as 7 and 8.
The two side surfaces 7 and 8 are provided with tongues and grooves in the form of grooves , . .
,/
~3~9~
9 and tongues 10. During assembly the sections 1 are arranged so that the side faces 7 on adjacent sections are placed against each other, whereby the tongues 10 fit into the grooves 9. lhe base surfaces 5 form the outside and the top surfaces 6 form the inside of the finished pole. The tongue and groove 9, 10 are parallel with the edge lines 11, 12 between the side surfaces 7, 8 and the top surface 6. In accordance with the embodiment illustrated tbe section 1 is a~solutely uniform, i.e. has the same cross sectional area along its entire length, so that the tongue and groove 99 10 are also parallel with the lower edge lines 13, 1~, but it is also possible to plalte the base surface 5 so that the section 1 tapers.
This has been indicated by the dashed line 13' which in this case is not parallel with the tongue and groove 9, 10. The three lamina-tions 2, 3, and 4 are further sawn and laid in such a way that the sapwood faces towards the base surfaces 5, i.e. towards the outside in the finished pole. The laminations 2, 3 and 4 are furthermore composed appropriately, in a manner which forms part of the state of the art, of finger-jointed sections, so that the desired length can always be obtained. Fig. 1 shows also that the tongue and groove 9, 10 is placed considerably closer to the edge lines 11, 12 than to the edge lines 13, 14 so that the base surface 5 can be planed down, if so required, without cutting the tongue and groove at the narrow-est end.
About 2mm from the edge line 12 the side surface 8 is also provided with a small projection in the form of a "mini-tongue" 30 t~hich extends along the entire length of section 1. The mini-tongue 30 is about 1mm wide and ~ to 1mm in height. Its function is to provide a seal for the glue in the glued joints 31, Fig. 6, so that the glued joint cannot communicate with the cavity 23. In Fig. 6 the thickness of the glued joint 31 has been exaggerated for the sa~e of clarity.
During jointing the side surfaces 7 and 8 are provided with glue and are then pla-ced in a fixture 15; Fig. 2 and Fig. 3, with semi-circular-shaped support 16~ First of all a numher of sections 1 are ~L~98~5 placed in this support 16, the sections being orientated with respect to each other in the desired manner by means of the rQund tongues and grooves 9, 10. Then a vertical ring 17 is placed at both ends, after which the layer is completed by adding further sections 1. Some straps 18 are then wound around the whole assembly and tightened so that the side faces 7, 8 are pressed firmly against each other. The two ends of the tube 19 thus formed are cut off so that the end faces are absolutely even~ after which the ends are sealed by a pair of covers 20 and 21.
The covers 20, 21 consist of plates 22, the outsides of which are domed so that they can withstand an external overpressure relative to the central cavity 23 of the tube 19. On the inside the covers 20, 21 are~ absolutely flush and provided with a ringshaped fairly ~ide rubber packing 24. One cover 20 is provided with an extraction pipe 25 which is connected with the cavity 23, whilst the other cover 21 is provided in a corresponding manner with a manometer 26 for measuring the pressure in the cavity 23. Thus when the covers 20, 21 with packings 24 have been placed against both ends of the tube 19 and are pressed against the ends at a certain pressure, the air in the cavity 23 is pumped out through the pipeline 25. Until the vacuum produced in the cavity 23 is so great that the covers 20, 21 are sucked firmly in place1 the covers 20, 21 can be held in position manually. The pumping out of the air then continues until the pressure in the cavity 23 has dropped to the desired level, appropriately to about 0.1 kplcm2. Subsequently this same pressure difference is maintained between the pressure in the cavity 23 and the surrounding pressure until the glued joints 31 in the tube 19 have become fixed.
During the assembly of the sections the mini-tongues 30 are pressed against the opposing side face 7 and to some extent are also pressed into this. Hence the tongues 30 function as a seal which effec~ively cuts off the glue in the glued joint 31 from the cavity 23. When the air is pumped out of the cavity 23, the glue in the glued joints 31 is consequently not sucked into the cacity 23 and the glue does not start to bail because of the pressure reduction in the cavity 23.
When the glue in the glued joints 31 has hardened so that the joints have become fixed, the straps 1~ are removed together with the covers 20, 21 and the supporting rings 17. For this purpose the latter can be provided with a pair of clamps 27. The pole 19 can then be transferred to store for su~sequest curing. Finally the pole 19 is impregnated with creosote oil both from the outside and from the inside in a known manner. As the sapwood faces the outside of the pole and the grain is orientated in the manner indicated in the diagrams, this greatly iacilitates the penetration of the impreg.
nation agent.
To increase the gluing pressure it is feasible and possible in accordance with the invention to subject the outside of the pole l9 to an overpressure, whilst at the same time a vacuum is produced in the cavity 23. The ent~re structure illustrated in Fig. 2 and Fig. 3 is tl1en placed in a pressure vessel in which a positive pressure is brought about by means of compressors, whilst the air is simul~aneously pumped out through the pipe 25. To shorten the gluing time it is also possible to heat up the residual air in the cavity 23. For this purpose a further connecting pipe 28 can be pro-vided so that hot air is made to circulate through the cavity 23 so that the pole is heated up from the inside before the air is pumped out. Even whilst the vacuum is maintained in the cavity 23, it is possible to allow certain quantities of hot air to circulate within the cavity. I~ a positive pressure is also applied to the outside, it is possible in the same way to heat the air in the pressure vessel so as to obtain a temp~rature rise also from the outside with a view to shortening the gluing time. Whilst the glue is curing, the pressure in the cavity is checked continuously so that it is maintained at the desired level~
The gluing pressure ~or vacuum gluing in accordance with the inven-tion9 possibly combi~ed with positive pressure treatment~ ls cal-culated as follows.
-7 ~
t . D _ r where
METHOD FOR MANUFACTURING WOOD POLES
TECHNICAL SCOPE
The invention relates to a method for manufacturing wood poles consisting of a number of sections which are glued toge-ther along abutting side surfaces so that a tubular pole with central cavity is formed. Poles of this type can be used primarily as power line poles but also as rnasts of various types, columns for buildings, bridges etc.
STATE OF THE ARI' For many years power lines have been constructed using natural poles made from pressure-impregnated pine. Because of developments in modern forestry however there has been a drastic reduction in the availability of full-grown timber and hence also of natural poles having the requisite dimensions. Because of -this poles of glued -timber have been developed which are designed to replace natural poles. Examples of such designs are shown in DE 665 210, GB 745 540, FR 2 348 345 and WO ?30/02709.
In spite of the urgent demand for glued poles and in spite oE the fact that a plurality of glued pole designs have been produced in past years, the tubular glued timber pole has not as yet however been widely employed for power lines and simi]ar demanding applications. One reason for this is tha-t fro-m the production viewpoint these poles give rise to a number of problems which have not been satisfactorily solved using available tech-niques. These problems concern both the jointing and the gluing of the individual sections, also the requi,site impregnation of the glued construction, ~.~
~ 2 DESCRIPTION OF THE INVENTION
According to one aspect of the inven-tion a method for manufacturing wood poles as of -the type cornprising a number of sections glued together along abutting side Eaces so as -to form a tubular pole with a central cavity comprises:
the steps of providing a number of sections having a trapezoidal shape, each section having side faces abuttable with side faces of other sections, providing the side faces with glue to provlde glue-bearing side faces, and bringing the glue-bearing side faces into intimate contact with each other to provide a tube in which the sections define a central cavity, placing seal-ing means at both ends of the tube for sealing the ends of the tube, pumping air out of the central cavity through one or both of the sealing means to provide a vacuum in the central cavity in comparison to the external pressure, so that contact pressure between abutting side faces increases, and maintaining the vacuum until glued joints are formed to hold the sections together.
Sealing devices may be arranged between the central cav-ity and the glued joints to prevent communication between the central cavity and the glued joints wlile -the glue is curing.
The abuttable side faces may be provided with circular tongues and grooves.
The number of sections is preferably more than 10.
Each of the sections may be made up of 2-~ pieces of timber layers~ which are glued together with the sapwood facing a base of the -trapezoidal shape.
The tubular pole may be subjected to an external posi--~L~9~
2a-tive pressure as compared with surrounding pressure, whereby the contact pressure between abutting side faces is further increased.
The tube may be hea-ted during gluing of the sections together by hot air in the cen-tral cavity or by hot air ex-ternally of the tube.
According to another aspect of the invention a method for manufacturing wood poles comprising sections glued together along abutting side surfaces so as to form a tubular pole with a central cavity comprises:
the steps of providing a number of sections having a txapezoidal shape, each section having side faces abuttable with side faces of other sections, gluing the sections together along the side faces to provide a tube with a central cavity, placing sealing means a-t both ends of the tube for sealing the ends of the tube, pumping air out of the central cavity through one or both of the sealing means to generate a reduced pressure in the tube, whereby contact pressure between abutting side surfaces increases, and maintaining the reduced pressure until glued joints are formed to hold the sections together.
Further characteristics and advantages of the invention are outlined in the patent claims and are illustrated by the following description of a preferred embodiment.
~RIEF DESCRIPTION OF DIAGRAMS
In the following description of a preferred embodiment reference will be made to the appended drawings in which Figure 1 is a perspective view of a section of the type from which the pole is to be manufactured in accordance with the ,3j D
invention.
Figure 2 is a perspective view which illustrates pole manufacture.
Figure 3 illustrates the same feature as Figure 2, in side elevation.
Figure 4 is a section on the line IV-IV in Figure 3.
Figure 5 is a section on the line V-V in Figure 3.
Figure 6 illustrates the conditions prevailing in the glued joint.
DESCRIPTION OF PREFERRED EMBODIMENT
With reference initially to Figure 1 a section Eor manu-facture of the pole in accordance with the invention is generally designa-ted as 1. The section 1 has a profile shaped like an isosceles parallel trapezoid and is made up of three glued lamin-ations 2, 3 and 4. The base surface of the section is designated as 5, its top surfaces as 6 and its two side surfaces as 7 and 8.
The two side surfaces 7 and 8 are provided with tongues and grooves in the form of grooves , . .
,/
~3~9~
9 and tongues 10. During assembly the sections 1 are arranged so that the side faces 7 on adjacent sections are placed against each other, whereby the tongues 10 fit into the grooves 9. lhe base surfaces 5 form the outside and the top surfaces 6 form the inside of the finished pole. The tongue and groove 9, 10 are parallel with the edge lines 11, 12 between the side surfaces 7, 8 and the top surface 6. In accordance with the embodiment illustrated tbe section 1 is a~solutely uniform, i.e. has the same cross sectional area along its entire length, so that the tongue and groove 99 10 are also parallel with the lower edge lines 13, 1~, but it is also possible to plalte the base surface 5 so that the section 1 tapers.
This has been indicated by the dashed line 13' which in this case is not parallel with the tongue and groove 9, 10. The three lamina-tions 2, 3, and 4 are further sawn and laid in such a way that the sapwood faces towards the base surfaces 5, i.e. towards the outside in the finished pole. The laminations 2, 3 and 4 are furthermore composed appropriately, in a manner which forms part of the state of the art, of finger-jointed sections, so that the desired length can always be obtained. Fig. 1 shows also that the tongue and groove 9, 10 is placed considerably closer to the edge lines 11, 12 than to the edge lines 13, 14 so that the base surface 5 can be planed down, if so required, without cutting the tongue and groove at the narrow-est end.
About 2mm from the edge line 12 the side surface 8 is also provided with a small projection in the form of a "mini-tongue" 30 t~hich extends along the entire length of section 1. The mini-tongue 30 is about 1mm wide and ~ to 1mm in height. Its function is to provide a seal for the glue in the glued joints 31, Fig. 6, so that the glued joint cannot communicate with the cavity 23. In Fig. 6 the thickness of the glued joint 31 has been exaggerated for the sa~e of clarity.
During jointing the side surfaces 7 and 8 are provided with glue and are then pla-ced in a fixture 15; Fig. 2 and Fig. 3, with semi-circular-shaped support 16~ First of all a numher of sections 1 are ~L~98~5 placed in this support 16, the sections being orientated with respect to each other in the desired manner by means of the rQund tongues and grooves 9, 10. Then a vertical ring 17 is placed at both ends, after which the layer is completed by adding further sections 1. Some straps 18 are then wound around the whole assembly and tightened so that the side faces 7, 8 are pressed firmly against each other. The two ends of the tube 19 thus formed are cut off so that the end faces are absolutely even~ after which the ends are sealed by a pair of covers 20 and 21.
The covers 20, 21 consist of plates 22, the outsides of which are domed so that they can withstand an external overpressure relative to the central cavity 23 of the tube 19. On the inside the covers 20, 21 are~ absolutely flush and provided with a ringshaped fairly ~ide rubber packing 24. One cover 20 is provided with an extraction pipe 25 which is connected with the cavity 23, whilst the other cover 21 is provided in a corresponding manner with a manometer 26 for measuring the pressure in the cavity 23. Thus when the covers 20, 21 with packings 24 have been placed against both ends of the tube 19 and are pressed against the ends at a certain pressure, the air in the cavity 23 is pumped out through the pipeline 25. Until the vacuum produced in the cavity 23 is so great that the covers 20, 21 are sucked firmly in place1 the covers 20, 21 can be held in position manually. The pumping out of the air then continues until the pressure in the cavity 23 has dropped to the desired level, appropriately to about 0.1 kplcm2. Subsequently this same pressure difference is maintained between the pressure in the cavity 23 and the surrounding pressure until the glued joints 31 in the tube 19 have become fixed.
During the assembly of the sections the mini-tongues 30 are pressed against the opposing side face 7 and to some extent are also pressed into this. Hence the tongues 30 function as a seal which effec~ively cuts off the glue in the glued joint 31 from the cavity 23. When the air is pumped out of the cavity 23, the glue in the glued joints 31 is consequently not sucked into the cacity 23 and the glue does not start to bail because of the pressure reduction in the cavity 23.
When the glue in the glued joints 31 has hardened so that the joints have become fixed, the straps 1~ are removed together with the covers 20, 21 and the supporting rings 17. For this purpose the latter can be provided with a pair of clamps 27. The pole 19 can then be transferred to store for su~sequest curing. Finally the pole 19 is impregnated with creosote oil both from the outside and from the inside in a known manner. As the sapwood faces the outside of the pole and the grain is orientated in the manner indicated in the diagrams, this greatly iacilitates the penetration of the impreg.
nation agent.
To increase the gluing pressure it is feasible and possible in accordance with the invention to subject the outside of the pole l9 to an overpressure, whilst at the same time a vacuum is produced in the cavity 23. The ent~re structure illustrated in Fig. 2 and Fig. 3 is tl1en placed in a pressure vessel in which a positive pressure is brought about by means of compressors, whilst the air is simul~aneously pumped out through the pipe 25. To shorten the gluing time it is also possible to heat up the residual air in the cavity 23. For this purpose a further connecting pipe 28 can be pro-vided so that hot air is made to circulate through the cavity 23 so that the pole is heated up from the inside before the air is pumped out. Even whilst the vacuum is maintained in the cavity 23, it is possible to allow certain quantities of hot air to circulate within the cavity. I~ a positive pressure is also applied to the outside, it is possible in the same way to heat the air in the pressure vessel so as to obtain a temp~rature rise also from the outside with a view to shortening the gluing time. Whilst the glue is curing, the pressure in the cavity is checked continuously so that it is maintained at the desired level~
The gluing pressure ~or vacuum gluing in accordance with the inven-tion9 possibly combi~ed with positive pressure treatment~ ls cal-culated as follows.
-7 ~
t . D _ r where
2 . m m = wa]l thickness, cm t - vacuum ~ possible overpressure, kp/cm D = external diameter of tubular pole, cm T = gluing prcssure, kp/cm2, in glued joint 31 The dimensions of the pole can be varied wi-thin wide limits. For practical reasons the upper limit can be taken as 40 m,whilsta lower economic limit is about 0.5 m. Ihe external diameter can also be varied within wide limits. For efficient handling only a restricted number of dimensions for the sections 1 should be employed. But even with a very restricted number of section sizes the external diameter can be varied between circa 350 and 1 300 mm, which gives a wall thickness range between circa 50 and circa 225 mm.
For manufacturing it is best to use a glue which is made and marketed by the Norwegian company Dyno A/S under the tradename Dynosol S 204, together with the hardener recommended for this Dynosol H 627 which requires a gluing pressure of circa 2.0 kp/cm2. With the method in accordance with the invention this gluing pressure can be achieved for all the dimensions encountered in prac~ice without it being necessary to apply a positive pressure.
If the vacuum amounts ~o 0.9 kp/cm2 ~0.1 atmospheres gauge) in an assumed example where D = 48 cm and m = 9 cm the following gluing pressure is obtained:
D = 0 9 48 = 2.4 kp/cm2 2 . 9 ~"~
For manufacturing it is best to use a glue which is made and marketed by the Norwegian company Dyno A/S under the tradename Dynosol S 204, together with the hardener recommended for this Dynosol H 627 which requires a gluing pressure of circa 2.0 kp/cm2. With the method in accordance with the invention this gluing pressure can be achieved for all the dimensions encountered in prac~ice without it being necessary to apply a positive pressure.
If the vacuum amounts ~o 0.9 kp/cm2 ~0.1 atmospheres gauge) in an assumed example where D = 48 cm and m = 9 cm the following gluing pressure is obtained:
D = 0 9 48 = 2.4 kp/cm2 2 . 9 ~"~
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Method for manufacturing wood poles comprising a number of sections glued together along abutting side faces so as to form a tubular pole with a central cavity, said method comprising:
providing a number of sections having a trapezoidal shape, each of said sections having side faces abuttable with side faces of other said sections;
providing said side faces with glue to provide glue-bearing side faces, and bringing said glue-bearing side faces into intimate contact with each other to provide a tube in which said sections define a central cavity;
placing sealing means at both ends of said tube for seal-ing said ends of said tube;
pumping air out of said central cavity through one or both of said sealing means to provide a vacuum in said central cavity in comparison to the external pressure so that contact pressure between abutting side faces increases;
maintaining said vacuum until glued joints are formed to hold said sections together.
providing a number of sections having a trapezoidal shape, each of said sections having side faces abuttable with side faces of other said sections;
providing said side faces with glue to provide glue-bearing side faces, and bringing said glue-bearing side faces into intimate contact with each other to provide a tube in which said sections define a central cavity;
placing sealing means at both ends of said tube for seal-ing said ends of said tube;
pumping air out of said central cavity through one or both of said sealing means to provide a vacuum in said central cavity in comparison to the external pressure so that contact pressure between abutting side faces increases;
maintaining said vacuum until glued joints are formed to hold said sections together.
2. A method as claimed in claim 1, wherein sealing devices are arranged between said central cavity and said glued joints so as to prevent communication between said central cavity and said glued joints while said glue is curing.
3. Method as claimed in claim 1, wherein said abuttable side faces are provided with circular tongues and grooves.
4. Method as claimed in claim 1, wherein the number of sections is more than 10.
5. Method as claimed in claim 1, wherein each of said sec-tions is made up of 2-4 pieces of timber layers which are glued together with the sapwood facing a base of said trapezoidal shape.
6. Method as claimed in claim 1, wherein said tubular pole is subjected to an external positive pressure as compared with surrounding pressure, whereby said contact pressure between abut-ting side faces is further increased.
7. Method as claimed in claim 1, wherein said tube is heated during gluing of said sections together by hot air in said central cavity or by hot air externally of the tube.
8. Method for manufacturing wood poles comprising sections glued together along abutting side surfaces so as to form a tub-ular pole with a central cavity, said method comprising:
providing a number of sections having a trapezoidal shape, each of said sections having side faces abuttable with side faces of other of said sections;
gluing said sections together along said side faces to provide a tube with a central cavity;
placing sealing means at both ends of said tube for sealing said ends of said tube;
pumping air out of said central cavity through one or both of said sealing means to generate a reduced pressure in said tube, whereby contact pressure between abutting side surfaces increases;
maintaining said reduced pressure until glued joints are formed to hold said sections together.
providing a number of sections having a trapezoidal shape, each of said sections having side faces abuttable with side faces of other of said sections;
gluing said sections together along said side faces to provide a tube with a central cavity;
placing sealing means at both ends of said tube for sealing said ends of said tube;
pumping air out of said central cavity through one or both of said sealing means to generate a reduced pressure in said tube, whereby contact pressure between abutting side surfaces increases;
maintaining said reduced pressure until glued joints are formed to hold said sections together.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000415096A CA1198885A (en) | 1982-11-08 | 1982-11-08 | Method for manufacturing wood poles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000415096A CA1198885A (en) | 1982-11-08 | 1982-11-08 | Method for manufacturing wood poles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1198885A true CA1198885A (en) | 1986-01-07 |
Family
ID=4123906
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000415096A Expired CA1198885A (en) | 1982-11-08 | 1982-11-08 | Method for manufacturing wood poles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1198885A (en) |
-
1982
- 1982-11-08 CA CA000415096A patent/CA1198885A/en not_active Expired
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