DE2419411A1 - CLAMPING DEVICE FOR A BAND SAW - Google Patents

Description

Patent attorneys
Dipl.-Chem. I. SCHULZE ue Heidelberg ι

Gaisbergstrasse 3

Dipl.-Ing. E. GUTSCHER telephone 23269

Γ Paragraph Dipl.-Chem. I. Schulze, Dipl.-Ing. E. Gutscher. Patent attorneys Π OUR REFERENCE: 2675 S07 Heidelberg, GalsbergstraBe 3 _{| HR ZE (CHEN} .

Applicant: Letson and Burpee Ltd., 172 Alexander Street, Vancouver, B.C. Canada, v6A 1B7

Clamping device for a band saw

The invention relates to a clamping device for a band saw for loading the saw.

The known band saws have a pair of spaced coplanar wheels which support a band saw. One of one Force exerted by the clamping device pushes the wheels apart and puts the band saw under a certain tension, therein Called band saw tension, so that a tension is exerted on the saw which is known as tensioning the saw.

Many band saws use a load weight lever as a tensioning device which works through a knife edge arrangement. This species has been used successfully for many years, however it does not always work satisfactorily and has disadvantages

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on. Fluctuations in the cutting load create excessive tension in the saw, reducing its life and quality the cut is adversely affected. Excessive tension and tension is likely to result in slow response of the clamping system in order to quickly absorb additional forces on the saw and to adapt to them. These are forces that result, for example, from lateral deformation and bending of the saw. The slow response of the system is due to friction that occurs at the cutting edges and other bearing points as well on inertia of the load weight lever. High-tension band saws create smaller cuts and give a more precise one Cut, but have an unfavorable influence on friction and Inertia, which is particularly pronounced in such high-tension band saws.

Four main parameters for the performance of a band saw are:

(i) When a saw through irregularities in the wood, for example Knots, cuts, the saw bends out of the cutting plane, which means that it is subjected to increased local tension ο Such bending occurs suddenly, d. H. it works over a short period of time and affects the cutting accuracy and the lifespan of the saw. When moving sideways the saw reacts the clamping device and acts against it, whereby the lever arm only moves after a certain time interval, after the side force is applied to the saw. Due to the friction inherent in the clamping system and Inertia is the time interval between the application of the lateral force and the initial work of the clamping arm are extended, but this time interval determines the speed of response the jig. The faster the clamping system responds,

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the better the stability of the saw blade is maintained.

(H) The time it takes for the saw blade to look after a sudden Getting into its equilibrium state of tension is called the damping time and this corresponds to it the natural response of the saw blade / band saw system as a puncture of time,

(iii) When additional tension energy is applied to a tensioned band saw and then removed, it should be noted that only a fraction of the additional energy is restored. The remaining energy is lost in friction. This Energy loss is referred to herein as hysteresis energy loss. Generally speaking, a tensioning system in which metal springs are bent has a high hysteresis energy loss, while a system in which a fluid is compressed has lower hysteresis energy loss. These Losses occur in the work done when a force is applied in such systems.

(iv) Another measure of a tensioning system is the amount of force required to overcome static friction. It deals This is a minimal additional force that is required for a noticeable increase in the unit of tension on one side of the saw as a result of a small increase in the amount applied to the tensioning mechanism Tension. Such a force is a measure of the sensitivity of the clamping system to changes in the specified Tension and applied tension.

These four parameters are to some extent dependent on the friction and inertia of the fixture. If, therefore, friction and

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Inertia are reduced, the work of the clamping device should be improved »

The object of the invention is to provide a clamping device for a To create a band saw in which the disadvantages of the known devices are eliminated and inertia and friction are largely eliminated are reduced.

This is achieved in that instead of the load weight lever and the cutting device, the force through a Air spring is applied.

In one embodiment of the band saw, spaced apart, coplanar wheels, referred to as first and second wheels, are provided which support and drive an endless saw. The wheels rotate about axes that rotate coplanar with a central longitudinal plane, which in turn is perpendicular to diametrical ones Levels of the wheels runs. The clamping device is carried by a column in the band saw and they. moves the first Wheel within the longitudinal plane in relation to the second wheel to tension the saw. The clamping device has a first Section in which a bracket assembly, a sleeve, a Lifting device, a support arm and an air spring is arranged. The bracket assembly consists of a hinge part and a in the column sliding guide.

A lock acts together with the bracket assembly and limits their movement so that it is parallel to the longitudinal plane with negligible rotation with respect to the column emotional. The lifting device extends between the column and the bracket assembly and moves the latter with respect to it on the column, for example when the saw is changed. The lifting device has a central axis within the longitudinal

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level of the band saw to reduce the bending forces on the support arm. The support arm is the holder for the pin of the first wheel and has an articulated section that
complements the hinge portion of the bracket assembly. The hinge portions form a hinge to pivot the support arm on the bracket assembly to allow the support arm to rotate with respect to the bracket assembly. The air spring extends between the support arm and the yoke assembly and communicates with a pressurized supply of gas. The air spring serves as an expandable and contractible element to allow rotation of the support arm and the
To clamp the saw, as well as to form a substantially friction-free, resilient mount in order to absorb deviations and fluctuations in the saw load.

In one embodiment, the air spring has a central reference plane when it is in a central stroke position
is located. The joint is provided with a central axis about which the support arm rotates and the first wheel journal has a central axis about which the wheel rotates. When the air spring
assumes a central stroke position, the central axes of the joint and the pin are within the central reference plane of the air spring.

The invention is based on the drawings, in which preferred Embodiments are shown, explained in more detail. Show it:

Fig. 1 is a partial side view of a band saw according to the invention, in which some parts are omitted to the To illustrate individual parts inside;

Fig. 2 is a partial perspective view of an upper one
Wheel of the band saw according to FIG. 1;

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Fig.;> A perspective partial view in section, the Parts of an embodiment of a band saw represents associated air spring;

Fig. 4 is a partial diagram showing the devices for lifting and tilting of the upper wheel journal illustrated;

5 shows a horizontal band saw according to the invention;

6 shows a simplified partial side view of a section of a modified clamping device according to the invention, another embodiment of an air spring shows;

FIG. 7 shows a simplified plan view of a further modification of the device according to FIG. 6;

FIG. 8 is a simplified partial sectional view taken along line 8-8 in FIG. ₃ illustrating part of a modified embodiment of the hinge; FIG.

9 is a partial perspective view of a modified one Embodiment of a pin wedging; and

Fig. 10 is a partial diagram of a modified embodiment the locking of a plunger.

The band saw 10 according to the invention (Fig = l) has an upper Wheel 11, referred to as the first wheel, and a lower wheel 12, referred to as the second wheel. These wheels are designed to that they have an endless saw 14 (shown in dashed lines) carry and drift. The upper wheel 11 rotates about the pin and the lower wheel 12 rotates about the pin 17. The axles (not shown) the tenons are coplanar with a central longitudinal plane of the band saw that is perpendicular to diametrical Levels of the wheels runs. The central longitudinal plane 19 (dashed in Fig. 1) intersects the center points of the pins 16 and 17. The lower wheel 12 is driven by a motor 21 via a common drive 22 (shown in dashed lines),

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Common saw guides 24 and 25 cooperate with the saw 14 to keep the saw within a selected cutting plane to keep. The piece of wood to be sawed (not shown) passes through the sawing plane in a parallel to the longitudinal plane 19 trending plane. The band saw has a column 27 protruding from a base 29, which has a recess at the upper end 30 for the top wheel. In this way, the portions of the upper end 30 are sufficiently removed to allow the To spread wheel 11 (Fig. 2). The band saw is arranged essentially symmetrically about a central vertical plane which perpendicular to the longitudinal plane 19 and coplanar with central diametrical planes of the wheels 11 and 12.

The band saw 10 is provided with a clamping device 32, which cooperates with the upper or first wheel 11. It moves the wheel 11 within the longitudinal plane with respect to the second wheel 12 to tension the saw. The tensioner 52 is shown in greater detail in Figure 2 and has two similar ones Sections of which only section 33 is described. A carrier aritfi that carries the pin 16 of the wheel 11, is provided at one end with a hinge part that connects it to a hinge 35 on a bracket arrangement 36 (Figs. 1 and 2) connects. At the other end of the support arm 34 is an air spring 38 provided. This extends between the support arm 34 and the bracket assembly 36 and is extendable and retractable, to rotate the support arm with respect to the bracket assembly with the "saw cocked and a substantially smooth one." Attachment is created to accommodate the fluctuations in the saw load to catch.

On the column 27, between the column and the bracket arrangement 36, a lifting device 39 is arranged which is adapted to move the bracket assembly with respect to the column

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to lower and raise the wheel when changing the saw. From the bracket assembly ^ 6, a plunger or a guide 41 protrudes downward and protrudes into a bore of the. Column 27 in which it can be moved. In this way, the movement of the bracket arrangement is controlled parallel to the longitudinal plane I9 = a cotter pin or wedge 40 is attached to the tappet, which cooperates with a notched groove 44 in the column ZJ to largely prevent the rotation of the tappet with respect to the column. The axis 42 of the plunger 4l runs parallel to the longitudinal plane 19 and the plunger is guided in several bearings 4 ^ which are arranged concentrically with the bore and allow an exact axial displacement of the plunger. The cotter pin or key and the notch groove serve as a detent or arrest which cooperates with the bracket arrangement J> 6 in order to move the bracket arrangement parallel to the longitudinal plane I9 and to allow only negligible rotation with respect to the column «means (not shown), to limit the rotation of the arm 54 with respect to the bracket assembly J56 are described in conjunction with FIG.

The lifting device J> 9 has a (not designated) central one Longitudinal axis that runs coplanar to the longitudinal plane I9 of the band saw “In this way, the force from the lifting device acts in one plane on the pin and generates low bending forces on the bracket assembly so that the plunger 41 is not jammed in the bearings by off-axis forces. When the axis the lifting device were moved so that it is not directly under the pin, there is a risk that the The hoop arrangement now swings the lifting device, as a result of which off-axis forces were generated on the plunger 41.

The air spring communicates via a pressure line 46 with a pressurized gas that is in a tank 45

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™ "j / ■"

closed 1st. The pressure line 46 is guided through a central bore (not shown) of the plunger 4l and opens into a passage channel in the air spring (Figo 1). In the line 46 a valve 47 is arranged and a pressure gauge 48 indicates the pressure in tank 45. The accuracy of the

The pressure gauge is about 0.014 kg / cm. The tank 45 is preferably pressurized with nitrogen gas, the maximum pressure being about 14 kg / cm ". The valve 47 is normally open to allow gas to enter air spring 38. The tank 45 is via a pressure regulator (not shown) with a source of pressurized gas, such as a gas cylinder (not shown) connected. The valve on the gas cylinder is only opened when it is necessary Refill gas in tank 45. A thermostatically controlled heater (not shown) holds the tank 45 above the Outside temperature, so that a change in this outside temperature has no effect on the pressure in the tank and therefore a setting the amount of gas is not required to maintain the desired pressure.

The pin l6 is a stationary pin, the end 51 of which is inserted in a bore 50 of the support arm 34 (FIG. 2). The opposite end 52 engages in a bore 53 of a similar carrier arm 54, the wheel 11 being arranged between the two carrier _{arms 0} The carrier arm 5 ^ is rotatably mounted in a bracket arrangement 56, which in turn is operatively connected to a lifting device 57 and by a ram or a guide 59 is forced into an axial movement. An air spring (not shown) similar to air spring 38 extends between yoke assembly 56 and support arm 54 and is adapted to extend or retract simultaneously with air spring 38 to prevent rotation of the arms about the yoke assemblies

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Support arm 54 and bracket assembly 56 belong to one second section 55 of the clamping device, which corresponds essentially to the first section and is connected to it is and works together. This second section is therefore not described in detail.

The support arm J> k has an inner end 60 and an outer end 61, the outer end 61 cooperating with the air spring ^ 8 and the inner end being hinged to the bracket assembly. The bracket arrangement ^ 6 consists of a bracket carrier 62, from the underside of which the plunger 41 protrudes and is inserted into the bore of the column. The bracket support 62 cooperates with the lifting device j59 which is inserted between the column and the bracket assembly. The bracket assembly further includes a bracket member 63 with a pair of vertically protruding articulation parts 65 and 66 that are spaced apart from one another. The spacing is chosen so that the inner end 60 of the support arm J4 fits inside. In the articulation parts 65 and 66 , a hinge pin 67 is arranged, which is provided with a ball sliding bearing 69 which is inserted through the inner end and rotatably supports it - the ball sliding bearing allows a limited rolling of the support arm ^ 4 about a longitudinal axis (not shown), with simultaneous pivoting of the hinge pin about a horizontal axis (not shown) which runs essentially perpendicular to the central longitudinal plane 19. The inner end 60 of the support arm J4 and the hinge parts 65 and 66 serve as hinge sections that cooperate with the hinge pin 67.

The bracket assembly 63> is releasably attached to the bracket support 62, for example by bolts 68 which are screwed into threaded holes in the bracket member 63. Oval slots (not shown) In the bracket support the screws take on urid allow one

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- li -

some movement between the temple member 63 and the temple support 62 for a substantially continuous adjustment range to accomplish. The screws and slots serve as adjustment and adjustment elements to move the bracket member 65 to allow with respect to the bracket support 62 and thereby the pin of the first wheel with the pin of the Set the width of the wheel in alignment.

As already mentioned above, the support arm 54 is provided with a bore 50 into which the end 51 of the pin is inserted o gripping or clamping elements 70 work together with the bore to clamp the pin firmly and non-positively in the bore of the carrier arm 54. A cotter pin or key 76 fits into complementary keyways in the bore of the support arm 54 and in the end 51 of the pin. Splint or wedge and keyways serve as wedging to control the rotation of the pin with respect to the carrier to prevent as in a conventional Totzapfen _o The splint 76 is a relatively wide wedge which extends across about 60 of the dispensing sheet, so that the bearing region is increased in order to reduce the possibilities of slight relative movement between the wedge, the pin or the support arm and only negligible bending or relative movement occurs between the pin and the support arms. A bridge 71 cooperates with the end 51 of the pin 16 and has a pair of feet 75 and 74 (FIG. 2) which are pressed against a side wall of the support arm 54 »A common screw part 75 which is inserted through the bridge 71 and an end surface of the end 51 contacts, is used - together with a similar bridge cooperating with the end 52 of the pin and a screw part (not shown) - for the axial displacement of the pin in order to

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align the wheels in the central vertical plane. Before the adjustment, the gripping or clamping elements 70 are loosened and tightened again after the adjustment. For the axial adjustment of the pin 16 can other means can also be used. For example, the upper wheel can be adjusted as in a conventional band saw and be aligned.

The air spring J8 communicates with a top end 78 (Fig. 2) of the pressure line 46 (Fig. 1), which is through a bore (not shown) in the top wall of the bracket member 65 passes through. As already mentioned above, the pressure line 46 goes through the central bore of the plunger 4l and opens into the pressure tank 45 (Fig. 1).

In order to limit the rotational movement of the support arm ~ jk with respect to the bracket assembly, a threaded shaft 80 is provided, which is inserted through a bore in the support arm ^. 4 The inner end 81 of this shaft 80 is attached to the bracket member 63 and the outer end of the shaft has an adjustable stop 82, for example a pair of secured nuts. The stop cooperates with the support arm J4 and limits the upward rotation of the support arm. Downward rotation can be limited by a similar pair of locknuts (not shown) or by a detent attached to the bracket assembly.

The air spring 58 (FIG. 5) consists of a first section 85 which is movable with respect to a second section 86. The underside 88 of this second section 86 is at the Top of the bracket member 65 (shown only in Fig. 2) attached The second portion 86 has an inner side wall 90 forming a cylinder and a threaded bore that has a

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Inlet 89 forms into which the upper end 78 of the conduit 46 is inserted · The bottom wall of the cylinder has a protruding Sprue 91 on. In the first section 85, a piston 93 is provided on which an inner disk 95 and an outer disc 96 are arranged. Between the panes 95 and 96 is the inner area 97 of an elastic membrane 98, the edge area 99 of which is between a Z-shaped cross-section Annular flange 100 is held, which in turn is attached to the second section 86 of the air spring 38. The membrane and. the cylinders enclose a chamber 101 within the air spring. A panel 102 of the diaphragm extends between the cylindrical side wall 90 and the piston 93 and allows axial movement of the piston with respect to the cylinder along the central axis 105. This axis is an arcuate section, as before is explained in more detail. The piston 93 consists of a piston rod 105, at the inner end of which the disks 95 and 96, the membrane 98 and the hub 105 are fastened by a nut screw 106 are. The outer end I07 of the piston rod 105 is on outer end 6l of the support arm 34 attached so that the rotating support arm 34 moves the piston 93 in the cylinder. Between the There is sufficient clearance in the piston and cylinder to prevent the arcuate movement of the piston caused by the rotation of the Carrier arm 34 originates to catch. The axis 103 is a Part of an arc, the radius of which is equivalent to the support arm 34 and it is centered on a hinge pin 67 (Fig. 2) »The movement of the piston is small compared to the radius, so that the axis 103 is approximated to a straight line which is essentially runs parallel to the longitudinal plane of the band saw.

The flange 100, which is Z-shaped in section, has an inner lip 112 on and the outer disc 96 is provided with an upwardly projecting flange 113, for which the lip 112 a forms upper stop, whereby the upward movement of the piston 93 is limited. The lower limit of movement of the piston

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1st reached when the head of the nut screw 106 hits the stop 91 touched. The stroke of the piston 93 within the cylinder is approximately 2.54 cm, a distance sufficient to To accommodate fluctuations in the support arm due to the changes in the sawing forces.

In order to show the operator the position of the piston within the air spring, there is a remote indicator (not shown) intended for the air spring. This position indicator can be a potentiometer, for example. It can be divided into three main zones, identified by four points, while a fifth point is one Indicates the middle position of the piston stroke. A top and a bottom point each shows the outermost top and extreme lower limit of movement of the piston, d. H. when it touches the locks. An inner upper point and an inner lower point indicates the corresponding limits of the normal working range of the piston. These inner points are chosen to lie on a linear portion of the spring characteristic and they are in the same Distance, about 6.35 now arranged from the center of the piston stroke The outer points are preferably located outside a range of movement of the support arm 34. This movement is limited by the upper and lower detents on the shaft 80. In this way the piston reaches its top and lower limit of movement not, as this is protected by the locks of the shaft 80.

The location of the pin on the support arm 34 and the removal of the The pin and the air spring of the joint are chosen so that a distance of 1.27 cm for a certain size of the band saw on the air spring causes the centerline of the pin to move approximately 0.32 cm, a distance that is within normal Movement of the tenon occurs when the saw cuts. If the

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If the air pressure is set correctly, there is little risk of the support arm J4 during normal operation the upper or the lower detent of the shaft 80 touches. It has been found that a suitable voltage ratio is about 0.07 kg / cm air pressure is given in the air spring, which creates a tension of about II3 to 114 kg on the saw.

The piston and the diaphragm thus form a roller-diaphragm-air cylinder, similar to the cylinder supplied by Bellofram Corporation, Massachussetts, USA »This WaIz membrane air cylinder can be used instead of the air spring. On the other hand, there can be similar roll-membrane-air cylinders or cylinder or siphon-type air springs made by Firestone Industrial Products Company, Nobleswille, Indiana, USA, “Other equivalent embodiments and appropriate types of air springs can be selected to adjust the arcuate movement of the support arm 54.

The lifting devices 39 and 57 (Figo 4) are on one device that can perform two separate movements that occur with most band saws. They include:

(i) Raise and lower the upper wheel while keeping the pin 16 parallel to the lower wheel pin as when changing a saw and adjusting the saw tension,

(ii) Raising and lowering only one end of the pin, while the position of the other end remains unchanged remains so that the tenon is inclined to maintain the center track of the saw on the wheel.

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The lifting devices 39 and 57 consist of shafts 120 and 121, which are each driven by a chain and sprocket assembly, which is shown in dashed lines at 123 and 124, respectively. The chain and sprocket assemblies 123 and 124 become driven by sprockets 126 and 127, which at a Shaft 129 are arranged, which in turn goes across the band saw. Only the center line of this wave is shown 129. A hand wheel 131 is provided for fine adjustment of the position of the wheel in order to achieve the desired sawing tension and also to incline the tenon. The handwheel I3I has a Manual coupling with a pin 132 which can be pulled out of a recess in a coupling part 134, to release one of the drives of the lifting device.

The fine adjustment of the wheel spacing to set the tension is done by turning the handwheel 131 * whereby the Pin 132 is held in the recess for both lifting devices to drift at the same time. The upper wheel 11 is by pulling out and releasing the pin I32 from the Engage clutch 134 and turn handwheel 131 inclined, which only actuates the shaft 121. A motor 136 drives the shaft 129 through a sprocket and chain assembly 137 and is used to quickly lower and raise the wheels when changing the saw. Another sprocket and chain combination 139 drives a rotating limit switch l40, which with the motor is connected in series so that when the top or bottom limit of movement of the lifting devices is reached, the engine is switched off automatically. This serves to protect the lifting devices and their movement limits are outside the movement limits of the wheel. , Other means of raising and lowering the wheel can also be used.

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If no saw is used, the air spring 38 can be used at normal working pressure. In this state, the support arm J54 is tensioned against the upper detent. When a saw is to be fitted into the system, the upper wheel 11 is driven by the sprocket and chain assembly driven by the motor 136 lowered. After the saw is fitted to the wheels, the top wheel is powered by motor 136 and the sprocket-chain arrangement is raised until an upper limit of movement of the wheel is approximately reached. As well as at the beginning Voltage is applied to the saw, the remote position indicator of the piston shows when it is off the upper position starts moving downwards. The indicator is provided with indicating means which are actuated when the piston approaches a central position of its stroke at which the motor is automatically switched off the handwheel IJl rotated, the in the coupling element 13 ^ engaging pin 132 both lifters at the same time actuated. The saw voltage increases until the piston 93 reaches approximately the middle position of its stroke, as by the indicator is displayed. The motor 21 of the band saw can then be switched on and sawing begins. When a stray the saw is displayed, the pin 132 is pulled out of the coupling element 134 and the handwheel 131 in such Direction rotated that the shaft 121 of the lifting device 57 is rotated so that it inclines the wheel so that the aberration the saw is corrected.

As has already been stated, during sawing, the saw voltage increases instantaneously due to fluctuations in the load on the saw, as a result of which small, essentially vertical movements of the pin 16 about an equilibrium position occur. First, the pin moves downward, and for example with a transverse movement of the saw due to a node in HoIz ₀ This movement corresponding to the load increase,

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rotates the support arm 34 about the hinge pin 67, whereby the piston 95 is pushed down in the air spring 38. The movement or the response of the Trägerarines occurs rapidly after the increase of the load, since a negligible friction and a relatively low inertia is present "friction loss occurs ara Gj hinge pin, while the frictional losses are negligible in the air spring. The inertia of the wheel 11 and the support arm;? 4 is relatively low, since there are no counterweights. The carrier arm quickly goes up again and establishes the position of equilibrium, since the carrier arm hardly swings around this position of equilibrium. In this way, only a short damping time is given, which is due to the low inertia of the system, which in turn is due to the fact that counterweights are not provided. Since the tensioner uses compressed gas as a spring, hysteresis energy losses are relatively small compared to a mechanical spring. The tensioning device is extremely sensitive to a small increase in tension. For example, the band saw can be designed so that an increase of 0.07 kg / cm in the air spring causes a theoretical increase in tension of 112 to 114 kg, depending on the tension ratio.

In the case of the band saw shown in FIGS. 1 and 2, this is the case upper wheel located approximately in the middle of the wheel journal, while the opposite ends of the journal in the support arms are stored »Consequently, the wheel is arranged between the support arms. Another embodiment of a band saw is used a flying wheel in which the upper wheel journal is cantilevered from a support arm. The top wheel is mounted adjacent to the end of the tenon. With appropriate modifications, the clamping device according to the invention

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be placed in such a band saw and in this way their advantages of low friction and low inertia can be used »A band saw of this type only needs part of the tensioning device, i.e. an air spring and the associated components. The difficulties that arise in such an arrangement when using high tension Band saws are used are known and special care must be taken that the pin and support arm are sufficient are strong and rigid to withstand the stresses caused by the saw tension.

Another embodiment is a horizontally mounted band saw, as shown schematically in FIG. 5 at 145. This horizontal band saw 145 has coplanarly arranged wheels 146 and 14-7 which drive the saw 148. Adjacent to one As conventional, saw guides 149 and 150 are provided for the cutting portion of the saw. The first wheel 146 rotates about a pin 151, which is mounted in a support arm 155. The top end the support arm 155 is rotatable in a bracket arrangement 155 and the lower end of this support arm works together with a balanced air spring 157. This air spring extends between the bracket assembly 155 and the support arm 155, similar to the air spring 38, but at 90 ° opposite the position shown in Figs. A jack 158 and a ram 159 operate similarly to that Lifting device 59 and the plunger 4l according to FIG. 1. The changes these arrangements relate to the air spring balancing and can cooperate with a substantially horizontal central axis.

Another modified embodiment of the invention Clamping device I65 (FIGS. 6 and 7) consists of a support arm I60, with an inner end | oil and an outer end 162. The inner end I6I is provided with a hinge part I6j5, the

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the support arm on one designed for this embodiment Bracket arrangement 164 links "The bracket arrangement 164 consists from a bracket base 166, from which a plunger or a guide 167 extends, and from a hinge part 168, which Joint part of the support arm 160 added (Fig. 8). The hinge parts form a portion of the hinge I69 around the support arm 160 to articulate on the bracket assembly 164, such that the support arm can rotate with respect to this bracket assembly. A lifting device I70 (shown in dashed lines), similar the lifting device 39 according to FIG. 1 extends between the column 27 (Fig. 1) and the bracket assembly 164 (Fig. 6) and is designed to move bracket assembly 164 with respect to the column. The plunger I67 slides in the column and there are measures taken to force the movement of the bracket assembly parallel to the longitudinal plane and that only one negligible rotation with respect to the column occurs. The device provided for this is shown together with Fig. described.

The support arm I60 supports a pin 172 of the first or upper wheel. This first wheel carries a saw together with a second or lower wheel. Wheels and saw are similar the wheels 11 and 12, as well as the saw 14 according to FIG. 1 and are therefore in connection with the embodiment according to FIG. 6 and 7 not shown.

Similar to the lifting device 59 (FIG. 1), the lifting device 170 has a central longitudinal axis 17I, which runs coplanar to the longitudinal plane 19 <Ser band saw, in which the central axes the wheel journals lie. The support arm 160 is provided with a bore 174 into which one end of the pin. I72 inserted is. Corresponding key assemblies I76 cooperate with bore 174 and pin 172 to provide rotation to prevent the pin in relation to the support arm (Fig. 9)

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Similar to the pin 16, the pin 172 is also a fixed one Journal and has a central axis I8j5 about which the wheel 16 rotates. A bridge and screw assembly 173, similar to the bridge 71 and the element 75 according to FIG. 1, enable aligning the pin 172 with respect to the support arm. A corresponding lock 177 consists of a boom 178, which starts from the support arm ΙβΟ and with a bore 179 is provided, the one of the base 166 outgoing bolt I80 is inserted. An adjusting nut 181 or I82 is screwed onto the upper and lower end of the bolt, which form the upper and lower catches that spread the boom to prevent the rotation of the support arm I60 with respect to the bracket assembly 164 to limit.

A modified embodiment of an air spring I85 extends between the outer end 162 of the support arm 160 and the yoke assembly 164 and communicates with a pressurized gas supply (not shown) via an inlet connected to a pressure line I87. The air spring 185 performs a similar function to the air spring (FIG. 1), but is constructed differently from it. The air spring I85, the support arm I60, the lifting device I70 and the yoke assembly 164 are housed in a first section 188 of the modified embodiment of the tensioning device and are designed so that the first wheel is moved within the longitudinal plane with respect to the second wheel, similar to that of FIG Section 23 in Fig. 3.

A substantially identical second section (not shown) of the tensioner is operatively connected to the first section. The pin 172 is inserted with its ends in the corresponding section and the first wheel is arranged between the support arms. The sections are connected together and are operated by a chain and sprocket arrangement similar to the arrangement shown in Figure 4 _o,

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to raise and lower the upper wheel and tilt the pin 172.

The air spring 185 has a central axis 189 and in a first section 186 is a piston 190 and in a second section 191 a cylinder I92 is arranged. Between The two sections are provided with a margin so that the sections can suffer from negligible frictional losses are movable with respect to each other. A flexible diaphragm I93 is with its inner area 194 on the piston and attached to the cylinder with its peripheral edge 195 surrounding the inner area. A membrane fold 197 extends between the piston and the cylinder to provide limited, substantially axial movement between the sections To ensure negligible membrane tension. The air spring has a similar structure and works like that a roller diaphragm air cylinder. The air spring 185 has a central reference plane 200, which is delimited by a portion of the piston when this is in a central Lift position (as shown). In the middle position, the axis 183 of the pin I72 lies within the reference plane, as will be explained in more detail below.

The piston has a reference surface 201 within the reference plane 200 and the portion 194 of the diaphragm is on the Reference surface 201 is sealingly attached by a round cap 202 and screws. The cylinder consists of two concentrically aligned rings 203 and 204 with the same Holes on the adjacent end faces, coplanar to Reference surface 201 are connected to one another. The outer peripheral edge 195 of the membrane is between the adjacent, Above-mentioned end faces placed and sealingly attached to them in order to have a gas passage between the membrane and the cylinder to prevent. The adjacent face of the ring

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204 serves as a reference surface 206 of the cylinder so that these cylinders reference surface surrounding the piston reference surface and substantially coplanar with the piston surface, when the air spring in a hub-center position is _o The ring 203 is secured to the support arm ΙβΟ at the outer end I62 and by a wedged into a centering lug 208 fitted into a bore at this end 162. The piston rod 210 of the piston is provided with a bore 211, the inner end 212 of which protrudes inwardly from the piston surface and serves as an inlet port, while the outer end 215 of the piston rod over the conduit I87 is connected to the pressurized gas supply. Adjacent to the inner portion 194 193, the membrane has a bore 215 which communicates with the inner end 212 of the bore in the piston rod and a bore is not marked in the cap 202 "Through these holes gas enters a chamber 217" by the Diaphragm and the cylinder is limited. The piston rod is provided with a thread at the outer end 219, onto which a centering ring 220 with a cylindrical alignment section is screwed. The alignment ring is drawn continuously in the lower position and dashed in the upper position 220.1. A plate 222 for aligning the piston is provided with a threaded hole into which end 219 is screwed. The plate 222 has a pair of oppositely arranged elongated holes 225 and 224, which are shown in dashed lines in Pig. 7 are shown. These elongated holes run parallel to the pin axis 185. The base of the bracket arrangement has a piston support 227 with a bore 228 for receiving the outer end 215 of the piston rod 210. The support 227 is also provided with a pair of identical elongated holes 225 and 226 which run perpendicular to the pin axis I85 and of which parts are aligned with the elongated holes 225 and 224. The plate 222 is fastened to the support 227 'by a nut screw 250 or 251, each through the aligned parts of the elongated holes

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is plugged. The elongated hole pairs work together with the nut screws 230 and 231 so that the piston is transversely in can be moved with respect to the cylinder in any direction perpendicular to the axis 189, concentric about the piston and cylinder to be able to adjust.

The cylinder I92 comes with a rectangular cylinder end plate 254, which is secured by screws 236 and 257 on Cylinder 192 is attached. The end plate 234 is arranged with a concentric to the axis I89 of the air spring I85 Bore 239 provided, the diameter of which is sufficient to Take up alignment section 221 with a snug fit when the centering ring 220 is in the upper position 220.1. If the Alignment section 221 is arranged concentrically with the piston rod 210 and the bore 239 is arranged concentrically with the cylinder I92 the piston rod can be centered with the cylinder when the centering ring 220 is in the upper position 220.1. Nut bolts 230 and 231 are loosened in thanks the elongated holes to allow transverse movement of the piston so that it can be adjusted concentrically to the cylinder can. After adjustment, the nut bolts 230 and 231 tightened again and place the end plate 222 on the support 227 fixed. The centering ring 220 is then screwed down so that the piston can be moved through the bore 239. This movement is approximately axial, but slightly arcuate due to the rotation of the support arm 160 about the joint l69o

From the cylinder goes an arm 242 with a pointer 243 (Fig. 6) which sweeps across a scale 244 attached to the piston. This way the position of the piston is within of the cylinder with respect to the reference plane of the air spring. Limit switches (not shown) can be installed in this way that they are then "when the piston has reached the extreme limits of movement, are actuated. Operate the limit switches

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Warning lights arranged in a console (not shown).

The joint 169 (FIG. 8) has a joint pin 249 a central axis 250 and an eccentric 251 between coaxially aligned outer ends 253 and 254 of the Hinge pin is arranged. One end 254 is provided with opposing flats 255 which are a Allow rotation of the pivot pin about the axis 250. The hinge portion I68 of the base of the bracket assembly has two spaced-apart joint members 256 and 257 with aligned bores into which the outer ends 253 or 254 are plugged in and are sufficiently spaced are to spread the eccentric 251. The joint section 163 of the support arm has a hinge bore. 260 which complements the eccentric. The hinge hole and the eccentric mount the support arm in a rotatable manner (Fig. 8).

The hinge bore 260 is partial with an inner one spherical bearing surface is provided which is centered on a hinge axis 263 and has a low friction Covering is coated. This covering can, for example, be made of the polymer known under the trademark Teflon Tetrafluoroethylene exist. The eccentric 251 has a partially spherical bearing bushing 262, the bearing surface of which the Hinge drilling added. The two surfaces form a ball bearing 264 with a limited arc to prevent tilting of the trunnion to allow. This is done in that one end of the pin 16 is raised with respect to the other end to the central To maintain the track of the saw on the wheel, namely by means of the lifting device according to FIG. 4.

40 9 8 50/07 4 2.

A gap 265 between the axis 250 of the pivot pin 249 and the axis 26j5 of the ball bearing 264 of the Eccentric 25I limits the deflection of the joint. The eccentric 251 is shown in Fig. 8 in a central position, the is referred to as the centered joint position. In this, the axis 265 is perpendicular at a distance above the Axis 250, allowing limited rotation of the pivot pin 249 about the axis in any direction the axis 263 moved substantially horizontally with respect to axis 250. As a result, the carrier arm is moved to a limited extent essentially perpendicular to the central longitudinal plane I9 of the band saw. That The joint thus has an eccentric adjustment device to effect limited movement of the support arm and to enable the alignment of the wheel. It's an alternative to the limited movement between the Bracket support 62 and the bracket member 63 according to FIG. 2. After a such an adjustment the piston rod must be centered with respect to the cylinder. The carrier arm rotates around the axis 263. It must be noted that when centering the joint the axis 263 within the central reference plane 200 of FIG Air spring is, as will be explained in more detail below.

Thus, when the joint is centered and the piston is in the central stroke position, the axes are 16j5 of the joint 169 and the axis 18j5 of the pin I72 coplanar and within the central reference plane 200 of the air spring. During normal operation of the band saw causes a substantially vertical Movement of the pin on a centered on the axis 263 Arch an enlarged similar movement of the cylinder in the air spring, a movement that hardly exceeds about 1.27 om. Since the movement on the arch is small compared to the radius of the arm, it can be viewed as an approximately straight-line movement are designated. Such a move, due in part

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of the 'abovementioned coplanar axes, acts in an im essentially the same movement of the palte 197 in all positions on the perimeter of the palte, between the upper and lower limit of the piston stroke. As a result, almost optimal working conditions for the membrane are achieved. The rotation of the pivot pin for aligning the wheel has a slight drop in the pivot axis with respect to the central reference plane 200 result. This drop changes the above-mentioned optimal conditions, but only to a negligible extent Frame.

As already stated above, the pin 172 is a fixed one or dead peg and is locked by the wedge arrangement I76 against rotational movement with respect to the support arm I60. The wedge assembly 176 consists of a wedge 27I with a flat contact surface 275 and a convex surface 275 (Fig. 9) · The surfaces are in part shared by, at a distance arranged, parallel side edges 277 and 278 limited. The surface 275 is also defined by spaced, parallel ones inner and outer end edges 28I and 282 and the face through spaced, parallel inner and outer Edges 285 and 284 bounded. The distance between the side edges 277 and 278 determine the pitch length 286 and the distance between the end edges 28I and 282 determines the axial length 287. The wedge 271 is a segment of a cylinder with a radius 288 which corresponds essentially to the radius of an outer end 289 of the wheel journal 172 (shown in dashed lines). The wedge 271 is provided with a carrier 290 which has two spaced holes 291 and 292 through the bolts (Fig. 6) are inserted to attach this carrier to the carrier arm. Adjacent to the bore 174 (Fig. 6) of the carrier arm " 160 a recess is provided which is adapted to the carrier 290 and cooperates with this in order to allow the rotation to prevent the wedge in relation to the support arm. The outer

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The end 289 of the pin has a flat face 293 provided, the pitch length and axial length of which corresponds essentially to the pitch and axial length of the wedge. The wedge complements the outer end of the pin 172 so that it is inside of a cylindrical shell of the pin I72 is when the flat face of the pin is the contact surface 273 of the wedge touched. The cylindrical jacket surrounding the wedge and the pin is inserted into the bore 174 of the support arm ΙβΟ, so that when the wedge is attached to the support arm, the pin is locked against rotation with respect to the support arm is. Since the opposite support arm is attached to the pin in a similar manner, it is solid and rigid in section H-shaped arrangement created.

Such an arrangement facilitates the manufacture of the pin because there is a keyway within the pin and within the bore the column is not required. In this way, relatively large tolerances are possible when adapting, with however, a firm and rigid arrangement is achieved.

As has also already been stated, the plungers that protrude downward from the bracket base are against rotating with respect to the pillars locked. The tappet I67 is at a distance from and parallel to the corresponding tappet 298 (Pig. 10) of the second section the clamping device (not shown) arranged. The wheel (indicated by dashed lines) is between the tappets 1Ö7 and 298 and arranged at a distance from them. The tappets are mounted in bearings (indicated as fragments) so that they can move axially. A modified one Jamming device or detent 300 has a connecting member 301 which extends between the lower ends of the Plunger 167 and 298 extends and has a crank or a crank piece 302 in its center. The link 301 is a flat strip which is sufficiently rigid in the horizontal plane not to be affected by forces from the rams to be bent. However, it springs sufficiently in the vertical plane.

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accordingly to a limited axial movement of a plunger in with respect to the other tappet to allow the first wheel journal to be inclined. The crank or the crank piece 502 of the link 30I ensures sufficient Adaptation to normal independent movements of the slide. The cooperating with the plunger according to FIG Wedge arrangement is not required, which simplifies manufacture and maintenance.

The work of the embodiment of the support arm I60 equipped band saw corresponds to the work of the band saw, in which the support arm; 54 according to Pig. I is built in.

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Claims (1)

1.! Clamping device for a band saw with spaced and coplanar arranged first and second wheels for supporting and driving an endless saw, in which the wheels are mounted on pins and rotate about axes that rotate coplanar to a central longitudinal plane perpendicular to diametrical planes of the wheels, a clamping device is arranged on a column, which is used to move the first wheel within the longitudinal plane with respect to the second wheel and tensioning the saw is designed, characterized in that the tensioning device has a first section (j5j5; 188) in which (a) a bracket arrangement (36; 164) with a guide (41; I67) slides in the column (27), a locking device or locking device (40, 44, '350O) is assigned to the bracket arrangement and forces it into a movement parallel to the longitudinal plane (19) with negligible rotation with respect to the column, and the bracket arrangement has a hinge part (65, 66 ₃ I68), (b) between the column (27) and the bracket assembly (j56; 164) a lifting device (j59; 170) is provided and the bracket assembly is assigned and this moves with respect to the column, (c) the pin (16; 172) of the first wheel (11) is attached to a support arm (54; 16g) which has a joint part (60; I63) which complements the joint part (65, 66, I68) of the bracket arrangement and forms a joint (35; I69) with it, by which the support arm is articulated to the bracket arrangement and thereby the support arm with respect to the bracket arrangement is rotatable, (d) between the support arm (34; 160) and the bracket assembly (36; 164) an air spring (38; I85) is provided, which with is connected to a pressurized gas supply (45) and as an extendible and retractable member for rotating the 409850/0742 Support arm with respect to the bracket assembly for tensioning the saw is used and an essentially frictionless arrangement for absorbing fluctuations in the saw load creates. 2. Clamping device according to claim 1, characterized in that (i) the lifting device (39; 170) has a central longitudinal axis has within the longitudinal plane (I9) of the band saw. 3 «clamping device according to claim 1 or 2, characterized in that
(i) the pin (16; 172) on the support arm (34; I60) in one Position between the joint (60; 65; 66) and the air spring (38; 185) is arranged. ' 4. Clamping device according to claim 1, 2 or 3 * characterized in that that (i) the clamping device (32; 165) has a second section (55) which is essentially identical to the first section, which cooperates with the first section (33), and that (ii) each end (5I; 52) of the pin (16; I72) in one corresponding support arm (34; 54; "I60) attached and the first wheel (11) arranged between the support arms is. ' 5. Clamping device according to claim 1, characterized in that that (i) on the column (27) bearings (43) are provided which are concentric are arranged on an axis running parallel to the longitudinal plane (19) of the band saw (10), (ii) the guide (4.1) of the bracket arrangement (36) in the column '(27) consists of a plunger whose axis (42) is parallel 409850/0742 runs to the longitudinal plane (19) of the band saw (10), the ram slides in the bearings of the column, (iii) the jamming device or detent consists of a wedge (40) attached to the plunger, in the column a keyway (44) complementing the wedge (4o) is provided in which the wedge engages and the rotation of the plunger in relation on the column, and (iv) the air spring (38) can be extended and retracted on an axis (I03) which runs essentially parallel to the longitudinal plane (19) of the band saw (10) and which is on one side of the pin (16 ) is arranged at a distance from and apart from the joint part (65, 66) of the bow arrangement (36). Clamping device according to claim 1, characterized in that the bracket arrangement (36) (i) has a bracket support (62) on which the guide (41) is arranged and which cooperates with the lifting device (39), which is provided between the column (27) and the bracket assembly (^ 6), and (ii) further comprises eiri bracket member (65) on which the hinge part (65, 66) is arranged and which is releasably attached to the bracket support (62) and is provided with an adjusting device (68) which is used to limit the movement of the bracket member in relation is designed on the bracket support and for aligning the pin (l6) of the first wheel (11) with the pin (17) of the second wheel (12). Clamping device according to claim 1, characterized in that (i) the hinge (35) that holds the bracket assembly (36) on the support arm (34) articulates, has a ball bearing (69) with a limited arcuate section for inclining the pin (16). 409850/0742 8. Clamping device according to claim 1, characterized in that that the air spring (58) (i) a first section (85th, 186) with a piston (93, 190), and
(ii) has a second section (86, I91) with a cylinder (90, 192), the two sections (85, 86, I86, 191) can be moved with respect to one another with negligible frictional losses, (iii) an elastic membrane (98, 19j5) with its interior Area (97, 194) attached to the piston and the outer peripheral edge (99, 195) surrounding the inner area is attached to the cylinder, the diaphragm and the cylinder a chamber (101, 217) within the air spring include, the diaphragm between the piston and the cylinder forms a fold (102, I97) which is a delimited essentially axial movement between the parts with negligible membrane tension ensured, and that (iv) an inlet (89, 212) the chamber (101, 217) with the pressurized gas supply (45) connects. 9. Clamping device according to claim 1, characterized in that (i) a second section (55) identical to the first section is provided, which has a lifting device (57) which is releasably connected to the lifting device (59; 170) of the first section (33; 186), a guide (59 ) is arranged parallel to the guide of the first section, (ii) the first wheel journal (I6j 172) is guided with its outer ends (51, 52, 189) in a corresponding carrier arm (3 ² I-, 54, I60) and the first wheel (11) is arranged between the carrier arms, and each support arm 04, 54, 160) 4098S0 / 07A2 (iii) is rotatably mounted with its inner end (60, 16l) in a corresponding bracket arrangement (56, 164) by ball bearings (69, 264), while the outer end (61, I62) with a corresponding air spring (38, I85) cooperates, a section between the ends of the support arm is provided with a bore (50, 55, 174) into which the outer end (51, 52, -289) of the pin (16, 172) of the first wheel is inserted,
(iv) clamping bolts (70, 175) cooperate with the bore of the support arm (34, 160) and clamp the corresponding outer end (51, 286) of the pin (16, 172) firmly in the bore of the support arm, and (v) a key assembly (76, I76) with the bore of the pin to prevent rotation of the pin with respect to the support arm Support arm cooperates and connects the support arms and the pin to form a rigid unit. 10. Clamping device according to claim 1, characterized in that the bracket arrangement (164) (i) has a bracket base (I66), of which the joint part (I68) and the guide (I67) and the lifting device arranged between the column (27) and bracket arrangement (164) go out (170) cooperates, (ii) the joint (I69) has an adjusting eccentric (251), that to limit the movement of the support arm in a direction perpendicular to the central longitudinal plane (I9) of the band saw (10) and for aligning the wheels (11, 12) is designed. 11. Clamping device according to claim 1 and 10, characterized in that that (i) the joint (I69) is provided with a pivot pin (249), between its coaxially aligned ends (255 * 254) and im 409850/0742 The eccentric (251) with its hinge axis (265) is arranged at a distance from these, (ii) the hinge part (168) of the bracket base (I66) with two spaced apart arranged joint members (256, 257) is provided, which have aligned bores into which the outer ends (253, 254) of the pivot pin (249) are inserted and which, for spreading the eccentric, are arranged at a distance from one another, and (iii) the joint part (163) of the support arm (I60) one of the eccentric (251) essentially has a supplementary hinge bore (260) which is concentric to the hinge axis (263) is arranged and the support arm is rotatably mounted by the eccentric, wherein the rotation of the hinge pin rotates the eccentric about the hinge axis of the support arm with respect to the hinge part of the Move the bracket base. 12. Clamping device according to claim 11, characterized in that (i) the eccentric (251) has a bearing bush (2β2) with a running surface and
(ii) the hinge bore (2βθ) of the carrier arm (ΙβΟ) is provided with an inner, partially spherical running surface which complements the eccentric and forms a ball bearing with a limited arcuate section which permits the inclination of the pin. 15. Clamping device according to claim 1, 10 and 11, characterized in that
(i) the air spring (185) has a central reference plane (200) in its central position, (ii) the hinge axis (263) of the eccentric is at the same time the axis of the hinge (Ιβ9) around which the support arm rotates and which is approximately within the central reference plane (200) 409850/0742 of the air spring (I85) is when the joint is centered in is mounted with respect to the bracket assembly (164), and (iii) the pin (172) of the first wheel (11) has a central axis (I85) about which the wheel rotates and which approximately lies within the central reference plane (200) of the air spring (185) when it is in a central position. 14. Clamping device according to claim 8 and 13, characterized in that that (i) the piston (I90) the air spring (I85) a reference surface (201) has within the central reference plane (200) of the air spring when it is in a central position and the inner region (194) of the diaphragm (193) is attached to the reference surface of the piston, (ii) the cylinder (I92) of the air spring (I85) also has a reference surface (206) which surrounds the reference surface (201) of the piston and which is substantially coplanar with the The reference surface of the piston is arranged when the air spring is in the middle position, the edge area (195) of the membrane (193) is attached to the reference surface (206) of the cylinder, (iii) with the joint (169) in the centered position with respect to the Bracket arrangement (164) the central axis (263) of the joint essentially within the central reference plane (200) the air spring (I85) lies, and (iv) the pin (172) of the first wheel (11) has a central axis (183) about which the wheel rotates and which is in the middle position the air spring (I85) lies within the central reference plane (200) of this air spring. 15. Clamping device according to claim 14, characterized in that that (i) the piston (190) has a piston rod (210) with a bore (211), the inner end (212) of this bore as 409850/0742 2413411 Inlet serves and protrudes inwardly from the reference surface (201) of the piston and the outer end (213) of the bore is connected to the pressurized gas supply (45), and (ii) the diaphragm (195) adjacent its inner region ( 19 ² O has a bore (215) which communicates with the inner end (212) of the bore (211) in the piston rod (210) and the gas passage into one through the membrane (193) and the cylinder (192) of the air spring ( I85) delimited chamber (217) forms. 16. Clamping device according to claim 9 *, characterized in that the wedge arrangement (I76) (i) A wedge (271) in the form of a segment of a cylinder with a flat contact surface (273) and a convex one Surface (275) consists, the surfaces by common, spaced, parallel side edges (277, 278) and are limited by spaced, parallel inner and outer end edges (28l, 282, 283, 284), the distance between the side edges or between the end edges the pitch length (286) or the axial length (287) of the surfaces determine, the convex surface has a radius (288) which is substantially the radius of the outer end (289) of the Wheel journal corresponds to the wedge (271) adjacent to the outer end edge of the surface is provided with a support (290) which is connected to the support arm to prevent the rotation of the Wedge cooperates, (ii) the outer end (289) of the pin (172) has a flat face (293), whose pitch length and axial length are essentially the pitch length or the axial length of the Corresponding to the wedge, the wedge complements the outer end of the pin in such a way that it is inside a cylindrical jacket of the pin is when the flat face of the pin touches the contact surface of the wedge, the cylindrical jacket encloses the wedge and the pin 4Q985Q / 0742 in the bore (17 ² O of the support arm (l60) is inserted, such ₃ that with a fixed wedge on the support arm (l60) and a fixed clamping bolt (175), the pin is locked against rotation with respect to the support arm and a non-positive unit is formed. 17. Clamping device according to claim 1 or 10, characterized in that that (i) the second section of the tensioning device (I65) is a lifting device (57) which is detachably connected to the lifting device (I70) of the first section (I88), (ii) the pin (172) of the first wheel (11) with its outer ends (289) in a respective support arm (ΙβΟ) of the first Wheel (11) is inserted, which is arranged between the support arms, (iii) each column (27) has bearings (43) arranged concentrically with an axis that is parallel to the longitudinal plane (19) the band saw (10) runs, (iv) each guide (167, 298) consists of a tappet whose Axis runs parallel to the longitudinal plane (19) of the band saw, the plungers are arranged parallel to one another and in the Slide bearings (43) of the corresponding column, (v) the jamming device or lock (300) from a connecting link (301), which extends between the tappets of the guides (I67, 298) and is designed so that it follows the same movements of the tappets and prevents rotation of the tappets with respect to the columns (27) and that further comprises a crank or a crank piece (302) and a limited axial movement of a plunger in relation on the other tappet and thus an inclination of the journal of the first wheel is permitted » 18. Clamping device according to claim 1 and / or 10, characterized in that that 403850/0742 (e) also upper and lower locking devices (82, 18l, 182) are provided with the support arm (54, l6o) for Limit the rotation of the support arm with respect to the bracket assembly cooperate. 19. Clamping device according to claim 8, 14 or 15, characterized in that that the air spring (I85) consists of two sections (I86 and I91), one section (I86) for the purpose of concentric adjustment of the two sections to each other, with respect to the other section (19I) is movable. 20. Clamping device according to claim 8, 14 or 15, characterized in that that the air spring has an indicator (245) for indicating the position of the piston with respect to the cylinder. 409850/0742 HO Blank page