RU2547549C2 - Gang saw swinger - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to woodworking, particularly, to reciprocating saw gangs. Saw gang oscillation mechanism comprises saw frame 1 with saws and oscillation drive fitted thereat with the help of homers. The latter are arranged at the frame with the help of friction thrusts. Friction thrusts provide for low forces and moments of friction at notable, up to several tons, saw tension forces and minor, up to several millimetres, of saw displacement relative to the frame in the range of oscillation amplitude. Homers, or stack of saws are directly coupled with oscillation drive. Homers run in solids of revolution 5 including ball and/or roller bearings of linear displacement 3 including multi-row, closed and open sequence of solids of revolution. Saw oscillation drive is composed of at least one lever 4 arranged at saw frame. Said lever, on one side, is coupled with top and bottom homers, or saw stack on the whole. On opposite side, said lever, is coupled with oscillating link fitted at the frame body.

EFFECT: higher efficiency, yield and quality, power saving, decreased losses of wood.

8 cl, 4 dwg

Description

1. The technical field to which the invention relates.

The invention relates to sawmilling, namely, saw frames with reciprocating saws.

2. The level of technology

From numerous studies of the kinematics of saw frames, it is known that one of their significant drawbacks is the inconsistency between the constant feed rate of the material (logs) into the cutting zone and the variable, according to the sine law, the movement of the saws. This leads to a number of negative factors affecting the sawing process. At the beginning and end of the working stroke, this leads to a sharp increase in the thickness of the cut chips and, as a result, to peak loads on the saw teeth. During the reverse (idle) stroke of the saw frame, the teeth cut with the bottom of the saw teeth and, as a result, additional blunting of the cutting edges, energy loss, pressure on the saws from the side of the feed material, worsening the geometry of the lumber and limiting the amount of feed, etc. This forces the use of sufficiently thick saws, which ultimately leads to a decrease in the yield of useful products, an increased number of sawdust, additional energy costs for the cutting process, etc.

To eliminate this drawback, levers use swing mechanisms for the saw frame, which, along with the main movement, provide saw movement within a few millimeters in the direction of supply of the material to be sawed and vice versa. They carry out the removal of saws from the bottom of the cut on the idle (reverse) stroke of the frame and, to one degree or another, smooth out the uneven thickness of the removed chips during the working stroke.

An example is the domestic sawmill P80-1, in which at the end of the working stroke the lower part of the saw frame is retracted by an eccentric mechanism, eliminating the teeth attaching. The disadvantage of this scheme is that it does not eliminate peak loads on the tooth and, therefore, does not fully provide the possibility of using thin saws.

A more progressive solution to the swing mechanism is used in the modern domestic forestry "Morozovka" (patent RU 2329887 C2, published July 27, 2008, also information on the website http: //www.mymoroz.rn). The set of movements of the upper and lower parts of the saw frame during operation ensures the removal of saws from the log at the beginning and end of the working stroke, excluding peak loads on the tooth, as well as the removal of saws from the bottom of the cut when the frame is idle. The movement of the saws, therefore, approaches the ideal mathematical trajectory of the movement of saws (hereinafter BMI), described in the works of A.I. Agapov (see Agapov A.I. Kinematics of sawmills. - M.: Lesn. Prom-st, 1987). This design of the frame provides the use of thin (up to 1.4 mm) saws, which positively affects all the characteristics of the sawing process.

The disadvantages of the applied scheme include the impossibility of changing the swing amplitude depending on the material feed rate, the approximated (approximate) nature of the saw path to the BMI, and the inability to control the path shape during operation depending on the type, size and humidity of the logs, and changes in the feed rate. In addition, this scheme cannot be applied on existing frames as an option without their substantial alteration.

Also a common drawback of the above analogues is that the saws swing together with a massive saw frame, which increases the energy consumption of the process, the level of vibration and load on the nodes and bed of the machine, forcing them to make more massive.

Along with all that has been said, it is desirable to provide in the swing mechanism the possibility of realizing the function of changing the width of the set saws during operation. This can reduce the cost of pre-sorting the logs and the loss of time for the readjustment of equipment. This feature is also absent in the above analogues.

As a prototype we take as the closest analogue sawmill "Morozovka".

3. Disclosure of invention

It is known that rolling bearings, both radial and linear displacement, are able to absorb significant loads and at the same time provide low displacement forces with sufficient durability and reliability.

So, for example, according to GOST 3722-81, the breaking load for a ball with a diameter of 8.731 mm is 4050 kgf, and for a ball with a diameter of 10.716 mm - 6100 kgf. This ensures a coefficient of friction for thrust rolling bearings equal to 0.003. The use of modern technologies and materials can further enhance these characteristics.

Swinging supports (suspensions) are also known, which at small swing angles also meet this condition. These include swinging supports (suspensions) on bodies of revolution, on knives, supports with friction of elasticity.

Thus, by installing homers, tensioning saws in the saw frame, on rolling elements, incl. linear ball or roller bearings, or using swinging suspensions, we will be able to swing the saw package directly, while reducing the set of moving masses by eliminating the mass of the saw frame. Unlike analogues, this will reduce the dynamic loads in the mechanism, the energy costs of the swing process and the vibration level of the machine.

At the same time, by using the swing mechanism, setting the most optimal saw path, you can achieve the ability to change its shape and amplitude directly during the cutting process (without stopping the sawmill), depending on the feed speed and the properties of the log being sawn specifically. This is feasible by changing the corresponding parameters of the swing mechanism during operation. For example, when sawing a log, it is possible to gradually reduce the feed rate with a simultaneous increase in swing swing without increasing the load on thin saws, as its diameter decreases due to natural growth. And for this reason, the possibility of using thinner than the prototype saws is not excluded. This function is not implemented in the given analogues.

The essence of the invention lies in the fact that in order to reduce the energy intensity of the process of swinging the saws and the forces in the system by reducing the aggregate of moving masses, as well as providing the ability to control the shape of the path of movement of the saws during operation, the saw tensioners in the saw frame, the so-called. homers are mounted on a frame on rolling bodies, for example, ball or roller bearings of linear displacement, including multi-row ones.

Also, swinging suspensions mounted on rolling bodies, or having elements with fragments of rolling surfaces on working surfaces, including supports on knives, can be introduced into the composition of homers as elements that reduce friction. Suspensions with friction elasticity can also be used. In all cases, the use of these elements provides low friction forces and moments with significant, up to several tons, saw tension forces and insignificant, up to several. millimeters, the movements of the saw mounted on the homer relative to the frame within the swing amplitude. At the same time, homers, or a package of saws as a whole, are directly associated with the swing drive.

In addition, the installation of homers on the rolling elements contains the potential for the implementation of an important function, especially for sawmills of the first row - changes in the width of the saw set during sawing. To do this, put the assembly, consisting of several homers and their bearings, on a common linear motion ball bearing, moving in the transverse direction and having, in the general case, a closed sequence of rolling bodies. The transverse bearing can be mounted on both shoulders of the cross-member of the saw frame. Moving the assembly is carried out by an additional mechanism.

Thus, it is possible to change the thickness of the carriage (two-edged beam) in the center of the set. This is able to expand the capabilities of the sawmill when sawing logs of various diameters, reduce the amount of sorting of logs and slightly increase the yield of useful products.

One of the positive features contained in the proposed mechanisms, in contrast to the prototype, is the possibility of their use on almost all types of existing saw frames as an option without any significant alteration. It is enough to install the homers of the proposed design and to equip the frame with a swing drive. Thanks to this, thin saws can be used on conventional frames.

4. Brief Description of the Drawings

Figure 1 shows a homer pos.2 with a saw stretched over it, mounted on the cross members of the saw frame pos.1 on a linear ball bearing with a cage. The upper part of the bearing has mobility and is connected with the lever pos.4, mounted at one of its ends on one of the cross members of the frame. The other end of the lever is connected via a roller to a swinging link mounted on the housing. The swing axis of the wings, in addition to swing, has some horizontal movement to ensure the movement of saws along an ideal mathematical path (BMI).

Figure 2 presents a variant with the simultaneous installation of three homers pos.2 on a linear roller bearing with increased load capacity pos.3. The swing drive is carried out using the traction pos.4 from the mechanism mounted on the frame body (not shown conditionally). This option allows you to reduce the distance between the saws. In addition, it allows the installation of a package of saws on a linear motion ball bearing with a closed sequence of rolling elements, pos. 5, moving in the transverse direction. Due to this, there is an additional opportunity to realize the function of changing the width of the saw set during the sawing process, which expands the capabilities of the frame when sawing logs of various diameters.

Figure 3 presents a variant of the swing suspension of the saws. On the lower part, a variant of a homer with roller bearing is conventionally depicted, on the upper part there is a swinging support with one rolling body in the form of a pressed-in finger with high surface hardness, rolling over small saddle angles.

Figure 4 presents a variant with several homers pos.2 installed on one working element pos.3 with fragments of rolling surfaces of large diameter on its working surfaces. The rocking lever pos.4 is connected directly to the working element pos.3.

5. The implementation of the invention

The possibility of carrying out the invention as a whole follows from the previous discussion.

Consider the main features of the invention.

When using rolling bearings, they can be completely enclosed in an elastic boot to protect against dust and grease. Given the small, up to several millimeters, swing amplitudes, the bodies of rotation of the bearings do not have to be closed in a continuous chain consisting of a working and an idle chain.

However, it is necessary to take into account the possibility of displacing bodies of revolution from the working area during operation due to the possible uneven load on the edges of the raceways or in case of their non-parallelism. To eliminate this phenomenon, the bearing should be able to self-align and have protection against the release of rolling elements.

Bearings with linear displacement bearings are most suitable for use in medium- and long-stroke frames with a saw frame stroke of more than 400 mm, where the swing range can reach 10 millimeters or more, and the tension forces of each saw up to 3 tons.

In some short-stroke frames with small feeds per stroke of the frame, the swing range can be of the order of 2-3 mm, and the tension forces of the saw due to its smaller thickness and width do not exceed, as a rule, one ton. In this case, you can use the installation of saws on a swinging suspension, which is part of the homer. This can be a support on a radial rolling bearing, a support on knives, or a suspension on elastic rods (a support with elastic friction). So, when the swinging suspension is deviated by a length of 200 mm by 2 mm, the elongation of the saw, taking into account the two suspensions - the lower and the upper ones involved in the work, will be a negligible amount of the order of 0.02 mm.

Special attention deserves the option presented in figure 2. It allows you to simultaneously install several homers pos.2 on a linear linear bearing pos.3, which due to its width and the possibility of using long rollers enclosed in a separator, can provide increased load capacity and durability. It is advisable to make a collar on the upper surface of the bearing, positioning the homers parallel to the axis of the log feed. It is advisable to cover the rollers with the cuff from dirt. This option also allows you to reduce the distance between the saws due to the possibility of using relatively thin homers.

In addition, this design contains the potential for the implementation of an important function - changing the width of the set of saws during the sawing process. For this, as shown in Fig. 2, it is necessary to put an assembly consisting of homers and a roller bearing on a linear motion ball bearing, item 5, moving in the transverse direction and having, in general, a closed sequence of rolling bodies. (In this embodiment, the transverse bearing is mounted on both shoulders of the cross-member of the saw frame and also has cuffs to protect it from dirt.) Symmetrical movement of both halves of the set relative to the middle of the frame can be done, for example, with a lead screw with a right-left thread associated with an additional rotation drive.

When designing the swing mechanism, it is necessary to strive to provide the smallest possible mass additionally hung on the frame. This task is generally achievable given the fact that reducing the thickness of the saw by 1 mm facilitates its weight by 1.3 kg. In addition, thin saws require less tension, which allows some lightening of the design of the saw frame.

Considering the mobility of the saw package, attention should be paid to its side crimping during assembly and the adjustment of the position of the saws. Usually, saws are dialed into the set through spacers - the so-called. "Separation", determining the thickness of the boards. Further, the saws are clamped with studs mounted on the frame. However, they must be strictly parallel to the feed direction.

In this case, a different approach is necessary, since a rigid connection with the frame will prevent the saws from swinging. The following option is possible - to tighten the saw blade with studs only among themselves without communication with the frame, and check the parallelism with the help of an attachment, for example. with an indicator of the clock type at the base points on the bed (or frame). Another option is to preload the sides of the frame with emphasis also through linear ball bearings.

It is important to note that if you control separately the swing of the right and left sides of the saw package, you can control the parallelism of the saw position in the log feed direction to a small extent.

Consider the general design options for the swing drive.

Saw swing drive can be implemented (Fig. 1) in the form of one, two or four levers (two at the top, two at the bottom) mounted on a saw frame. The levers are connected on one side with homers (or a package of saws), and on the other hand, with the help of a slider or a roller, with a swinging link mounted on the frame body and setting the swing path. The shape of the trajectory can be controlled during operation by changing the swing swing of the wings in conjunction with the shift of the swing axis. In this way, the most optimal saw path can be ensured. The angle of inclination of the saws does not play a big role in this case, unlike analogues. But even with separate levers in the upper and lower parts of the frame, it can be changed during operation, if necessary.

Instead of the wings, you can use, for example, a swinging rod (figure 2), one end of which is connected with a lever on the frame, and the other is connected with a mechanism on the frame body, which sets the desired trajectory. The development of such mechanisms relates to the well-known problems of the synthesis of plane mechanisms and is not particularly difficult.

Using modern visualization tools, e.g. laser pointers, you can implement a real display of the current path of the saws on the operator screen to control the process.

Claims (8)

1. The swing mechanism of the saws of the saw frame, including a saw frame with saws mounted on it with the help of homers and a swing drive, characterized in that the homers are mounted on the frame with the use of friction bearings, providing low friction forces and moments with significant, up to several tons, forces tension of the saw and minor, up to a few millimeters, movements of the saws relative to the frame within the swing amplitude, while homer, or the package of saws as a whole, are directly related to the swing drive. 2. The swing mechanism according to claim 1, characterized in that the homers are mounted on bearings with rolling bodies, including ball or roller bearings of linear displacement, including multi-row ones, with both a closed and an open sequence of rolling bodies. 3. The swing mechanism according to claim 1, characterized in that the swing bearings on the rolling elements, including radial rolling bearings, or having working elements with fragments of the rolling surfaces on the working surfaces, including supports on knives, are used as friction bearings . 4. The swing mechanism according to claim 1, characterized in that the swing rod pendants with elastic friction are used as friction bearings. 5. The swing mechanism according to claim 1, characterized in that the swing drive of the saws is made of at least one lever mounted on the saw frame and connected on the one hand to the upper and lower homers, or the package of saws as a whole, and on the other hand with a swinging curtain mounted on the frame body and defining a swing path, including a variable during operation due to changes in the swing swing characteristics. 6. The swing mechanism according to claim 1, characterized in that the swing drive is made in the form of a swinging rod, one end of which is connected with a lever on the saw frame, or with a saw package, and the other end is connected with a mechanism on the sawmill housing, which sets the desired trajectory of movement drank. 7. The swing mechanism according to claim 2, characterized in that the linear displacement bearing has a substantial width with the possibility of installing several homers on it at the same time. 8. The swing mechanism according to claim 2, characterized in that in order to ensure the possibility of changing the set of saws during operation, the linear motion bearing with one or more homers installed on it is mounted on another linear motion bearing, which in turn is mounted on the saw the frame is movable in a direction perpendicular to the swing of the saws and has its own drive movement.

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