Fixing device for welding LED lamp light source module
Technical Field
The invention relates to the technical field of LED lamps, in particular to a fixing device for welding an LED lamp light source module.
Background
The LED lamp light source module is a light source formed by welding individual patches or plug-in type LED lamps on a circuit board and packaging, the batch production of a factory utilizes mechanical equipment to weld, not only the efficiency is high, but also the accuracy is high, but the operation cannot be carried out by a machine when the maintenance or the manual welding is carried out by oneself, however, the welding of the LED lamp light source module is particularly inconvenient by one person, the LED lamp light source module cannot be accurately fixed, so that the phenomenon of insufficient welding or infirm welding is easy to occur during the welding, and the height adjustment cannot be carried out according to the environment used by a welder, so that the welder carries out uncomfortable welding positions for a long time, the welder generates great physical fatigue, and the fixing device cannot be rotated, so that the welder needs to continuously adjust the position of the welder according to the welding requirements, moreover, the traditional welding and fixing device can only fix and weld the light source module with a single size, the applicability is low, when a single person welds, the LED lamp light source module is difficult to stick up for welding, so that the plug-in type LED lamp is difficult to weld, and people urgently need a fixing device for welding the LED lamp light source module to solve the problems.
Disclosure of Invention
The invention aims to provide a fixing device for welding an LED lamp light source module, which aims to solve the problems in the prior art.
In order to achieve the purpose, the invention provides the following technical scheme: a fixing device for welding an LED lamp light source module comprises a base, a lifting adjusting assembly, a lifting rotating assembly and a welding fixing box;
a lifting adjusting component is fixedly arranged above the base through welding and used for adjusting the height of the whole fixing device, so that the height of the fixing device can be suitable for different welding environments and crowds, a rotary adjusting component is fixedly arranged above the lifting adjusting component through welding, the rotary adjusting component can adjust the direction of the whole fixing device, so that the rotary adjusting component can be adjusted according to actual requirements during welding, a welding fixing box is fixedly arranged above the rotating and fixing component through welding, the welding fixing box is used for fixedly welding the LED lamp light source module to be welded, welding fixed case top is rotated through the rotation axis and is installed welding fixed plate for can adjust the position of LED lamp light source module according to actual demand at the welded in-process, for example: can be adjusted to vertical state by the horizontality, conveniently weld, the welding mouth has been seted up at the welding fixed plate middle part, the welding mouth is used for welding LED lamp light source module, the centre gripping subassembly is installed in the inside embedding of welding mouth for carry out centre gripping and fixed to LED lamp light source module, rotation axis one end is located the welded fastening case outside and installs the fixed subassembly of regulation, is used for adjusting and fixing the angle of welding fixed plate.
As a preferred technical scheme, the lifting adjusting assembly comprises a first lifting pipe, a second lifting pipe and a lifting air bag;
the first lifting pipe is connected with the base in a welding way, the outer side of the first lifting pipe is sleeved with a second lifting pipe, the diameter of the first lifting pipe is smaller than that of the second lifting pipe, a lifting air bag is embedded in the first lifting pipe, the lifting air bag is used for expanding and contracting to push the second lifting pipe to ascend and descend so as to realize lifting, so that the lifting height can be adjusted more accurately, moreover, the air bag can play a certain role in shock absorption in the welding process of the LED lamp light source module, and do not need electric power to adjust, more environmental protection, simultaneously, the mode of regulation is more comfortable, the equal fixed mounting in the first fall way top outside and second fall way bottom inboard has the echelonment snap ring, makes things convenient for the block of first fall way and second fall way, avoids taking place to rock between first fall way and the second fall way and leads to whole fixing device unstable.
As a preferred technical scheme, an air inlet pipe is installed at one end of the bottom end of the lifting air bag and used for sending gas into the lifting air bag to realize expansion and contraction of the lifting air bag, a check valve is installed in the middle of the air inlet pipe and used for ensuring that gas can enter the lifting air bag from one end of the air inlet pipe to avoid gas leakage, an extrusion air inlet balloon is installed at one end, away from the lifting air bag, of the air inlet pipe and is a rubber component and used for sending gas into the lifting air bag through the air inlet pipe, one end of the extrusion air inlet balloon is also connected with an air inlet hose, one end of the air inlet hose is also provided with the check valve, the check valve is oriented towards the lifting air bag from the extrusion air inlet balloon, an exhaust pipe is installed at the other end of the bottom end of the lifting air bag and used, and then realize the decline of lift adjustment subassembly, the gas vent has been seted up to blast pipe one end.
The rotary adjusting assembly comprises a rotary seat, a rotary groove, a rotary bearing, a rotary column and a mounting plate;
be integrated into one piece structure between roating seat and the first fall way, the roating groove is installed to the inside embedding of roating seat, the roating groove is inside to rotate through the swivel bearing and to be installed the column spinner, the column spinner is used for whole fixing device's rotation, column spinner top fixed mounting has the mounting panel, pass through welded connection between mounting panel and the welded fastening case.
As preferred technical scheme, be located the column spinner outside fixed mounting in the mounting panel below, the column spinner outside has the slip snap ring through spacing spout slidable mounting, avoids the slip snap ring to appear rotating the phenomenon at gliding in-process, the slip snap ring is the component of a steel material, fixed magnet is used for fixing the slip snap ring, the roating seat top laminating column spinner position department has seted up fixed slot, the slip snap ring below corresponds fixed slot position department and installs fixed fixture block, mutual block between fixed slot and the fixed fixture block can effectually avoid taking place to rotate by oneself under the circumstances that need not carry out the pivoted to fixing device, has guaranteed the stability among the welding process.
According to a preferable technical scheme, the clamping assembly comprises a clamping plate, a slow-acting spring, a clamping groove, a sliding groove and a fastening rod;
the clamping plate is embedded in the welding port, the clamping plate is connected with the inner wall of the welding port through the slow-acting spring, the slow-acting spring not only can adjust the position of the clamping plate, but also can utilize the elasticity of the slow-acting spring to realize the slow adjustment of the clamping plate, the clamping phenomenon of the clamping plate in the moving process is avoided, the LED lamp light source module is not firmly clamped or is excessively firmly damaged due to the clamping phenomenon, one end of the clamping plate, which is far away from the slow-acting spring, is provided with a clamping groove, the clamping groove is used for clamping and fixing the LED lamp light source module, the upper surfaces of two ends of the welding port are respectively provided with a sliding groove, one end of the upper surface of the clamping plate is provided with a fastening rod through threads at the position corresponding to the sliding groove, the middle part of the fastening rod is fixedly provided with a fastening disc, and the fastening disc is used for fixing, avoid the grip block to appear rocking at the welded in-process and lead to the centre gripping unstable, fastening rod top fixed mounting has the knob, the knob is used for rotating the fastening rod, realizes the fixed to the grip block.
As preferred technical scheme, the roll pearl is all installed in the embedding of grip block both sides, the roll pearl is used for reducing the frictional force between grip block and the welding fixed plate for more smooth and easy when the grip block slides, also avoid appearing the card pause phenomenon, the laminating of sliding tray upper surface limit portion has the rubber pad, the rubber pad is used for increasing the frictional force between fastening disc and the welding fixed plate, makes the fixed more firm and stable of grip block.
As a preferred technical scheme, the adjusting and fixing assembly comprises a driven gear, a driving gear, a rotating rod, a fixing groove, a fixing ring and a fixing column;
rotation axis one end is located the fixed mounting in the welded fastening case outside and has driven gear, driven gear rotates the below and installs the driving gear, the meshing is connected between driving gear and the driven gear, the driving gear is kept away from welded fastening case one side and is connected through articulated and install the dwang for the manual drive driving gear rotates, dwang one end is run through and is seted up the fixed slot, the laminating of driving gear outside has solid fixed ring at welded fastening case fixed surface, gu fixed ring is concentric with the driving gear, gu fixed ring one side fixed surface installs a plurality of fixed column, fixed column and fixed slot are used for fixing the driving gear to realize fixing to welded fastening board turned angle.
As a preferred technical scheme, the fixed columns are installed at equal intervals, and the distance between the fixed columns and the circle center of the driving gear is smaller than the length of the rotating rod, so that the fixed grooves can be clamped into the fixed columns.
As a preferred technical scheme, the pin collection box is slidably mounted inside the bottom end of the welding fixing box, arc-shaped grooves are formed in two sides of the pin collection box, so that a welding fixing plate cannot be blocked when rotating, a drawing plate is fixedly mounted in the middle of one end of the pin collection box and used for drawing the pin collection box out from the inside of the welding fixing box, collected pins are subjected to unified recovery processing, sponge cushion rings are fixedly bonded on the edge portions of the top end of the welding fixing box and used for protecting corners, and the LED lamp light source module is more comfortable when being welded by using a fixing device.
Compared with the prior art, the invention has the beneficial effects that:
1. be provided with the lift adjustment subassembly, utilize the extrusion to advance the balloon to the inside air that fills of lift gasbag, make the inflation of lift gasbag, utilize the inflation extrusion second fall way of lift gasbag, make the second fall way upwards slide in the first fall way outside, the realization is to the lift of whole fixing device, utilize the lift gasbag to go up and down, not only practice thrift the electric energy, and can carry out accurate artificial control to the height of going up and down, and simultaneously, can also play certain cushioning effect to whole fixing device, utilize the echelonment snap ring, can make mutual block between first fall way and the second fall way, avoid taking place to rock and lead to fixing device unstable.
2. Be provided with the rotation regulation subassembly, utilize the roating seat, swivel bearing and column spinner, can realize the rotation to fixing device, make can rotate the fixed case of welding according to actual demand, make more comfortable to the welding of LED lamp light source module, and simultaneously, utilize fixed slot and the mutual block of fixed fixture block, can effectually avoid when need not rotating the fixed case of welding, the rotation that proper motion appears in the fixed case of welding leads to influencing the normal welding operation of LED lamp light source module, and simultaneously, utilize fixed magnet to fix the slip snap ring, make fixed fixture block break away from fixed slot, make can rotate and adjust the fixed case of welding, welded suitability has been increased.
3. Be provided with the centre gripping subassembly, utilize slow-moving spring not only can adjust the position of grip block, the elasticity that can also utilize slow-moving spring realizes the slow regulation to the grip block, avoid the grip block to appear blocking phenomenon at the in-process that removes and lead to the insecure or too firmly lead to LED lamp light source module to damage to the block of LED lamp light source module, and simultaneously, utilize fastening disk and rubber pad, can make the grip block fixed more stable and firm, avoid appearing not hard up phenomenon at the in-process of centre gripping, be provided with the roll pearl, make the grip block more smooth and easy at the in-process that removes, blocking phenomenon can not appear.
4. Be provided with and adjust fixed subassembly, the rotation that utilizes the dwang drives the driving gear and rotates, the rotation that utilizes the driving gear drives driven gear and rotates, thereby it rotates to drive welding fixed plate, make can adjust the angle of welding fixed plate, can become vertical state by the horizontality with LED lamp light source module at the welded in-process, make it to weld LED lamp light source module alone to be convenient for more, more convenient and practical, utilize fixed column and fixed slot, can fix driving gear pivoted position, make after adjusting welding fixed plate's inclination, can fix it, do not need to hold by hand, more convenience.
5. Utilize the pin to collect the box, can collect the pin of cutting short to the welding in-process, avoid piling up the influence welding on the welding fixed plate surface, simultaneously, utilize the sponge backing ring, can be so that when the welding, can play the effect of a support to welder's hand, avoid the hand block to lead to the welder uncomfortable on the welding fixed box surface.
Drawings
FIG. 1 is a schematic structural diagram of a fixing device for welding an LED lamp light source module according to the present invention;
FIG. 2 is a schematic view of a combined structure of a lifting adjusting assembly and a rotating adjusting assembly of a fixing device for welding an LED lamp light source module according to the present invention;
FIG. 3 is a cross-sectional view of a fixing device lifting adjusting assembly for welding an LED lamp light source module according to the present invention;
FIG. 4 is a cross-sectional view of a fixing device rotation adjusting assembly for welding an LED lamp light source module according to the present invention;
FIG. 5 is a schematic structural view of a clamping plate of a fixing device for welding an LED lamp light source module according to the present invention;
FIG. 6 is a schematic structural view of an area A in FIG. 1 of a fixing device for welding an LED light source module according to the present invention;
FIG. 7 is a schematic structural view of a fixing device adjusting and fixing assembly for welding an LED lamp light source module according to the present invention;
fig. 8 is a schematic structural view of a pin collection box of a fixing device for welding an LED light source module according to the present invention.
1. A base;
2. a lift adjustment assembly; 201. a first elevator tube; 202. a second elevator tube; 203. a lifting air bag; 204. a stepped snap ring; 205. an air inlet pipe; 206. extruding into a balloon; 207. a one-way valve; 208. an exhaust pipe; 209. an exhaust port;
3. a rotation adjustment assembly; 301. a rotating base; 302. a rotating tank; 303. a rotating bearing; 304. a spin column; 305. mounting a plate; 306. fixing the clamping groove; 307. a sliding snap ring; 308. fixing the fixture block; 309. fixing a magnet; 310. a limiting chute;
4. welding a fixed box; 5. a rotating shaft; 6. welding a fixed plate; 7. welding the opening;
8. a clamping assembly; 801. a clamping plate; 802. a slow-acting spring; 803. clamping a clamping groove; 804. a sliding groove; 805. a fastening rod; 806. a rotation knob; 807. rolling the beads; 808. a rubber pad;
9. adjusting the fixing component; 901. a driven gear; 902. a driving gear; 903. rotating the rod; 904. fixing grooves; 905. a fixing ring; 906. fixing a column;
10. a pin collection box; 11. an arc-shaped slot; 12. a drawing plate; 13. a sponge backing ring.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example (b): as shown in fig. 1, a fixing device for welding an LED lamp light source module comprises a base 1, a lifting adjusting assembly 2, a lifting rotating assembly 3 and a welding fixing box 4;
a lifting adjusting component 2 is fixedly arranged above the base 1 by welding, the lifting adjusting component 2 is used for adjusting the height of the whole fixing device, so that the height of the fixing device can be suitable for different welding environments and crowds, the rotary adjusting component 3 is fixedly arranged above the lifting adjusting component 2 through welding, the rotary adjusting component 3 can adjust the direction of the whole fixing device, so that the welding device can be adjusted according to actual requirements during welding, a welding fixing box 4 is fixedly arranged above the rotary fixing component 3 through welding, the welding fixing box 4 is used for fixedly welding the LED lamp light source module to be welded, a welding fixing plate 6 is rotatably arranged at the top end of the welding fixing box 4 through a rotating shaft 5, make can adjust the position of LED lamp light source module according to actual demand at the welded in-process, for example: can be adjusted to vertical state by the horizontality, conveniently weld, weld joint 7 has been seted up at 6 middle parts of welded fastening board, weld joint 7 is used for welding LED lamp light source module, the inside embedding of weld joint 7 installs centre gripping subassembly 8, be used for carrying out centre gripping and fixing to LED lamp light source module, 5 one end of rotation axis is located the 4 outsides of welded fastening case and installs regulation fixed subassembly 9, be used for adjusting and fixing the angle of welded fastening board 6, 4 top limit portions of welded fastening case all fix bonding have sponge backing ring 13, be used for protecting the corner, make more comfortable when using fixing device to weld LED lamp light source module.
As shown in fig. 2-3, the lift adjustment assembly 2 includes a first elevator tube 201, a second elevator tube 202, and a lift balloon 203;
the first lifting pipe 201 is connected with the base 1 by welding, the second lifting pipe 202 is sleeved outside the first lifting pipe 201, the diameter of the first lifting pipe 201 is smaller than that of the second lifting pipe 202, the lifting air bag 203 is embedded in the first lifting pipe 201 and used for expanding and contracting, the second lifting pipe 202 is pushed to ascend and descend to realize lifting, so that the adjustment of the lifting height is more accurate, moreover, the air bag can play a certain role in shock absorption in the welding process of the LED lamp light source module, and do not need electric power to adjust, more environmental protection, simultaneously, the mode of regulation is more comfortable, and the equal fixed mounting in the outside of first fall way 201 top and the inboard second fall way 202 bottom has echelonment snap ring 204, makes things convenient for the block of first fall way 201 and second fall way 202, avoids taking place to rock between first fall way 201 and the second fall way 202 and leads to whole fixing device unstable.
An air inlet pipe 205 is installed at one end of the bottom end of the lifting air bag 203, the air inlet pipe 205 is used for sending air into the lifting air bag 203 to realize expansion and contraction of the lifting air bag 203, a check valve 207 is installed in the middle of the air inlet pipe 205, the check valve 207 ensures that the air can enter the lifting air bag 203 from one end of the air inlet pipe 205 to avoid air leakage, an extrusion air inlet ball 206 is installed at one end, away from the lifting air bag 203, of the air inlet pipe 205, the extrusion air inlet ball 206 is a rubber component and is used for sending the air into the lifting air bag 203 through the air inlet pipe 205, an air inlet hose is further connected to one end of the extrusion air inlet ball 206, a check valve is also installed at one end of the air inlet hose, the direction of the check valve is that the extrusion air inlet ball 206 is towards one end of the, further, the lifting adjusting assembly 2 is lowered, and an exhaust port 209 is opened at one end of the exhaust pipe 208.
As shown in fig. 4, the rotation adjusting assembly 3 includes a rotary base 301, a rotary groove 302, a rotary bearing 303, a rotary column 304, and a mounting plate 305;
be integrated into one piece structure between roating seat 301 and the first fall way 201, roating groove 302 is installed to the inside embedding of roating seat 301, and inside the roating groove 302 is rotated through swivel bearing 303 and is installed column spinner 304, and column spinner 304 is used for whole fixing device's rotation, and column spinner 304 top fixed mounting has mounting panel 305, passes through welded connection between mounting panel 305 and the welded fastening case 4.
Mounting panel 305 below is located the rotating column 304 outside fixed mounting and has fixed magnet 309, there is slip snap ring 307 in the rotating column 304 outside through spacing spout 310 slidable mounting, avoid slip snap ring 307 to appear rotating the phenomenon at gliding in-process, slip snap ring 307 is the component of a steel material, fixed magnet 309 is used for fixing slip snap ring 307, roating seat 301 top laminating rotating column 304 position department has seted up fixed slot 306, fixed slot 306 can be four also can be for six or eight, slip snap ring 307 below corresponds fixed slot 306 position department and installs fixed fixture block 308, mutual block between fixed slot 306 and the fixed fixture block 308, can effectually avoid taking place to rotate by oneself under the condition that need not rotate fixing device, stability among the welding process has been guaranteed.
As shown in fig. 5-6, the clamping assembly 8 includes a clamping plate 801, a slow-acting spring 802, a clamping slot 803, a sliding slot 804 and a fastening bar 805;
the clamping plate 801 is embedded in the welding port 7, the clamping plate 801 is connected with the inner wall of the welding port 7 through the slow moving spring 802, the slow moving spring 802 not only can adjust the position of the clamping plate 801, but also can utilize the elasticity of the slow moving spring 802 to realize the slow adjustment of the clamping plate 801, the clamping phenomenon of the clamping plate 801 in the moving process is avoided, the LED lamp light source module is not firmly clamped or is too firmly damaged due to the clamping phenomenon, the clamping plate 801 is provided with a clamping groove 803 at one end far away from the slow moving spring 802, the clamping groove 803 is used for clamping and fixing the LED lamp light source module, the upper surfaces of two ends of the welding port 7 are provided with sliding grooves 804, a fastening rod 805 is arranged at the position, corresponding to the sliding groove 804, of one end of the upper surface of the clamping plate 801 through threads, a fastening disc 806 is fixedly arranged in the middle of the fastening disc 806, and the clamping plate 801 and the welding fixing plate 6, avoid grip block 801 to appear rocking at the welded in-process and lead to the centre gripping unstable, fastening rod 805 top fixed mounting has knob 807, and knob 807 is used for rotating fastening rod 805, realizes the fixed to grip block 801.
All the embedding in grip block 801 both sides is installed and is rolled pearl 808, rolls pearl 808 and is used for reducing the frictional force between grip block 801 and the welded fastening board 6 for grip block 801 is more smooth and easy when sliding, also avoids appearing the card pause phenomenon, and sliding tray 804 upper surface limit portion laminating has rubber pad 809, and rubber pad 809 is used for increasing the frictional force between fastening disc 806 and the welded fastening board 6, makes grip block 801 fixed more firmly and stable.
As shown in fig. 7, the adjusting and fixing assembly 9 includes a driven gear 901, a driving gear 902, a rotating rod 903, a fixing groove 904, a fixing ring 905 and a fixing column 906;
5 one end of rotation axis is located 4 outside fixed mounting of welded fastening case and has driven gear 901, driven gear 901 below is rotated and is installed driving gear 902, the meshing is connected between driving gear 902 and the driven gear 901, driving gear 902 is kept away from 4 one sides of welded fastening case and is connected through articulated and install dwang 903, be used for manual drive driving gear 902 to rotate, dwang 903 one end is run through and has been seted up fixed slot 904, the laminating in the driving gear 902 outside has solid fixed ring 905 at 4 fixed surface of welded fastening case, gu fixed ring 905 is concentric with driving gear 902, gu fixed ring 905 one side fixed surface installs a plurality of fixed column 906, fixed column 906 and fixed slot 904 are used for fixing driving gear 902, thereby realize 6 turned angle.
The fixing posts 906 are equidistantly arranged, and the distance between the fixing posts 906 and the circle center of the driving gear 902 is smaller than the length of the rotating rod 903, so that the fixing grooves 904 can be clamped into the fixing posts 906.
As shown in fig. 8, the pin collecting box 10 is slidably mounted inside the bottom end of the welding fixing box 4, the arc-shaped grooves 11 are formed in two sides of the pin collecting box 10, so that the welding fixing plate 6 cannot be blocked when rotating, the drawing plate 12 is fixedly mounted in the middle of one end of the pin collecting box 10 and used for drawing the pin collecting box 10 out of the welding fixing box 4, and the collected pins are subjected to uniform recovery processing.
The working principle of the invention is as follows: firstly, a circuit board which needs to be maintained and welded with an LED lamp light source module is clamped in a welding port 7, the position of a clamping plate 801 is adjusted by sliding a fastening rod 805 in a sliding groove 804, so that the circuit board is clamped in a clamping groove 803, the clamping plate 801 can move more smoothly by using a slow-moving spring 802 and a rolling ball 808, the phenomenon of blocking is avoided, after the clamping position of the circuit board is confirmed, a rotating button 807 is rotated, a fastening disc 806 is in contact with a rubber pad 809, and the position of the clamping plate 801 is fixed by using the friction force between the fastening disc 806 and the rubber pad 809;
after the circuit board is fixed, the height of the fixing device needs to be adjusted according to actual use requirements, at the moment, the air inlet balloon 206 is held by hand and is pressed continuously, so that outside air enters the lifting air bag 203 through the air inlet pipe 208, the lifting air bag 203 is expanded continuously, the lifting air bag 203 jacks the second lifting pipe 202, the second lifting pipe 202 slides outside the first lifting pipe 201, after the fixing device is lifted to a specified height, the pressing of the air inlet balloon 206 is stopped, the height of the fixing device is determined, and when the height needs to be lowered, only the air outlet 209 needs to be opened;
then a surface-mounted LED lamp or a plug-in type LED lamp is required to be welded on a circuit board to form an LED lamp light source module, at the moment, welding is carried out by using an electric iron, when the welding position needs to be adjusted, the sliding clamping ring 307 is upwards slid by using the limiting sliding groove 310, the sliding clamping ring 307 is adsorbed by using the fixed magnet 309, so that the fixed clamping block 308 is separated from the inside of the fixed clamping groove 306, at the moment, the welding fixing box 4 can be rotated, after the corresponding angle is rotated, the sliding clamping ring 307 is downwards slid again, so that the fixed clamping block 308 is clamped into the fixed clamping groove 306 again, the welding fixing box 4 can be fixed again, the phenomenon that the welding fixing box is automatically rotated in the welding process to influence welding is avoided, when pins on the back side of the circuit board need to be welded, the rotating rod 903 is rotated, so that the driving gear 902 drives the driven gear, when adjusting corresponding angle, go into fixed column 906 card inside the fixed slot 904, can carry out block and fixed to driving gear 902, can realize the fixed of welding fixed plate 6, can weld and fix the reverse side of circuit board, and the pin after the shearing is collected through pin collection box 10, carries out unified recovery processing.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.