阅读说明：本技术 螺旋榨油机榨膛压力监测装置 (Pressure monitoring device for barrel of screw oil press ) 是由 葛梦思 刘晔 陆建戈 李云雁 宋光森 张垒 任占冬 于 2021-05-13 设计创作，主要内容包括：一种压力监测装置,用于监测螺旋榨油机榨膛压力,其包括：固定机构,位于压力监测装置后端部,用于将压力检测装置可拆卸地固定在榨膛径向外侧的榨笼板之间；测力机构,包括：力传导片,位于压力监测装置前端部,用于向前沿径向插入榨膛排油缝隙,测力元件,位于力传导片后侧,用于感测力传导片传导的榨膛压力；以及限位机构,包括从固定机构的前端向前侧延伸的至少两个限位臂,以将力传导片和测力元件保持于其间,其中限位臂的前端部用于滑动地夹持力传导片。在不改变榨油机自身结构的前提下,可完成压力监测装置的安装及对榨膛压力的实时监测。(The utility model provides a pressure monitoring device for monitor screw oil press presses thorax pressure, it includes: the fixing mechanism is positioned at the rear end part of the pressure monitoring device and is used for detachably fixing the pressure monitoring device between the squeezing cage plates on the radial outer side of the squeezing chamber; a force measuring mechanism comprising: the force transmission piece is positioned at the front end part of the pressure monitoring device and is used for being inserted into the oil discharge gap of the barrel along the radial direction, and the force measuring element is positioned at the rear side of the force transmission piece and is used for sensing the barrel pressure transmitted by the force transmission piece; and a limit mechanism including at least two limit arms extending from a front end of the fixing mechanism to a front side to hold the force conducting chip and the load cell therebetween, wherein front end portions of the limit arms are used to slidingly clamp the force conducting chip. The installation of the pressure monitoring device and the real-time monitoring of the pressure of the pressing chamber can be completed on the premise of not changing the structure of the oil press.)

1. The utility model provides a pressure monitoring device for monitor screw oil press presses thorax pressure, it includes:

the fixing mechanism is positioned at the rear end part of the pressure monitoring device and is used for detachably fixing the pressure monitoring device between the squeezing cage plates on the radial outer side of the squeezing chamber;

a force measuring mechanism comprising:

the force transmission piece is positioned at the front end part of the pressure monitoring device and is used for being inserted into the oil discharge gap of the barrel along the radial direction, and the force measuring element is positioned at the rear side of the force transmission piece and is used for sensing the barrel pressure transmitted by the force transmission piece; and

and a limiting mechanism comprising at least two limiting arms extending from the front end of the fixing mechanism to the front side to hold the force conducting chip and the load cell therebetween, wherein the front end portions of the limiting arms are used for slidably clamping the force conducting chip.

2. The pressure monitoring device of claim 1, the securing mechanism comprising a bracket having an end plate, the limiting mechanism being connected to the end plate; and two side walls for removably securing to opposite sides of two adjacent cage plates.

3. The pressure monitoring device of claim 1, further comprising a return spring having a front end attached to a rear side of the force conducting blade and a rear end extending towards the load cell for abutting against the load cell, wherein the rear end of the force conducting blade for abutting against the sensing location of the load cell is located within a cavity of the return spring.

4. A pressure monitoring device as claimed in any one of claims 1 to 3, further comprising an insulating ring disposed on the front side of the load cell, which is outside the press chamber of the oil press when the pressure monitoring device is in use, and which has a through hole allowing the rear side of the force transmitting plate to pass through and abut the sensing location of the load cell.

5. The pressure monitoring device of claim 1, further comprising a locating pin extendable forward through the securing mechanism into the space between the retaining arms to tighten the load cell forward.

6. The pressure monitoring device of claim 4, wherein the at least two retaining arms are a pair of opposed L-shaped retaining arms, the load cell and the heat isolating ring are held between straight arms extending in front and back directions, and the opposed lateral arms are plate-shaped and coplanar with the force transmitting plate, and are configured to slidably hold both sides of the force transmitting plate and to be inserted into the oil drain gap together.

7. The pressure monitoring device of claim 2, wherein the bracket is secured between two adjacent plates by bolts passing through the two side walls and nuts at opposite ends of the bolts.

8. The pressure monitoring device of claim 6, further comprising a spacing cylinder held between the straight arms, the load cell being disposed within the spacing cylinder, the load cell having an insulating ring overlying the front face thereof.

9. The pressure monitoring device of claim 6, wherein the opposing cross-arm portions define slots through which the force conducting plate slidably passes to provide sliding support on both sides of the force conducting plate.

10. The pressure monitoring device of claim 6, further comprising gap limiting tabs attached to the sides of the opposing cross arm portions to provide sliding support to the sides of the force conducting tabs.

Technical Field

The invention relates to a barrel pressure monitoring device of a screw oil press

Background

The production and life of human beings can not be kept from the oil. The edible oil serves as a necessity of daily life of people and provides energy and nutrient substances for health of human bodies. The processing technology of vegetable oil mainly has two paths, namely mechanical pressing oil preparation and solvent leaching oil preparation.

Screw oil presses and hydraulic oil presses are two types of mechanical pressing oil-making equipment commonly used in the industry. Among them, the screw oil press is a mainstream oil manufacturing equipment because of its continuous operation capability and high automation degree. The core structure of a screw oil press is a barrel, which is composed of a pressing cage (a cylindrical space formed by a series of continuous pressing bars or pressing rings) and a pressing screw (a screw rod with gradually increased diameter and gradually reduced screw pitch). The oil is pushed into a series of continuously reduced spaces from a feed inlet to a cake outlet by the rotation of a pressing screw, namely, the clearance between the pressing screw and a barrel is continuously reduced, so that the oil is uneven in the high-pressure barrel and has continuously increased friction resistance, and the oil is gathered into oil drops to flow out of an oil discharge gap (a pressing strip gap or a pressing ring gap). Therefore, the size, distribution and pressurization rate of the barrel pressure are one of the core parameters affecting the oil extraction efficiency, and are also important bases for the design and operation of the oil press. The barrel pressure comprises radial pressure, axial pressure and tangential pressure to which the materials in the barrel are pressed. The pressure monitoring target of the screw oil press is mainly the radial pressure of a barrel.

Currently, researchers have proposed related researches on the testing method for obtaining the barrel pressure data, and the methods are mainly divided into three categories, namely a direct measurement method, an indirect measurement method and a simulation calculation method.

The direct measurement method is to directly obtain the pressure data of the barrel by using a pressure sensor, but the installation of the pressure sensor is difficult due to the limitation of the barrel structure, the barrel structure needs to be adjusted or modified, and the method for directly and effectively obtaining the pressure data of the barrel is to open a hole on the barrel or to install the pressure sensor by adopting a special-shaped pressing strip to replace a standard pressing strip. However, the barrel is a high-pressure, high-oil and strong-friction environment, and the direct pressure measuring sensor or the special barrel or the strip pressing structure thereof can be rapidly failed due to abrasion, so that the barrel cannot work continuously.

The indirect measurement of the pressure of the barrel is mostly realized by measuring the strain or displacement of the press strips and converting the strain or displacement into pressure data according to force analysis. In such a method, because the stress condition of the pressing strip is very complicated, the relation between the deformation amount and the pressure value is difficult to standardize, and therefore, the accuracy and the reliability of the measurement result are difficult to guarantee. The direct pressure measuring sensor and the strip pressing strain sensor are simultaneously arranged in the same area of the barrel, and direct pressure measuring data and strip pressing strain data can be associated under the pressing working condition, so that the calibration of indirect pressure measuring data is realized. However, as the press bars wear in operation, their strain behavior will deviate from the calibration relationship and thus a long-term stable measurement cannot be achieved.

The analog calculation method is to utilize computer software to simulate and assume the structure of the barrel and the properties of the material to be pressed, and establish a pressure model of the oil material in the barrel to obtain the influence of barrel parameters on the pressure change rule.

The Chinese invention patent of application publication No. CN110172371A discloses a pressure detection device for barrel of screw oil press and barrel equipped with the device, the invention replaces a plurality of pressing strips on the barrel of oil press with a pressure detection device with a radial through hole on the base, a pressure sensor is arranged in the radial through hole, the sensor is directly contacted with the material to be measured, and the pressure in the barrel is directly measured. According to the method, part of standard pressing strips in the barrel of the oil press need to be replaced by special pressing strips for detection, so that the installation is complicated, the strength of the special pressing strips is reduced due to the arrangement of the through holes, the special pressing strips are easy to wear in the high-temperature, high-pressure and high-friction environment of the barrel, and the replacement cost is high.

The invention discloses a Chinese patent with application publication number CN108007616A, which discloses a pressure monitoring device for a barrel of a screw oil press, and the pressure monitoring device leads out pressure through an elastic conduction mechanism and acts on a pressure sensor to acquire pressure data. In the method, because the force transmission effect is closely related to the mechanical property of the material of the elastic conduction mechanism, only a small pressure measurement range can be obtained by adopting common materials, and high-performance materials are difficult to obtain, so that the practical application is limited.

In summary, there is no reliable way to obtain the magnitude, distribution and dynamic law of the barrel pressure (especially radial pressure) of the screw oil press, which leads to the operation and design of the oil press being still experience-based.

Therefore, in order to make a good development of the oil-pressing industry, it is necessary to develop a device capable of directly measuring the radial pressure of the barrel.

Disclosure of Invention

Aiming at the problems that the existing test method for measuring the radial pressure of the barrel is complicated, the calibration of the pressing strip is difficult, the barrel structure needs to be changed, the accuracy of obtained data cannot be guaranteed and the like, the invention aims to provide the pressure monitoring device which is convenient to assemble and disassemble, simple in test and high in universality, can realize the off-line calibration of the pressing strip and can obtain accurate barrel radial pressure data on the premise of not changing the structure of an oil press.

The invention relates to a pressure monitoring device, which is used for monitoring the pressure of a barrel of a screw oil press and comprises: the fixing mechanism is positioned at the rear end part of the pressure monitoring device and is used for detachably fixing the pressure monitoring device between the squeezing cage plates on the radial outer side of the squeezing chamber; a force measuring mechanism comprising: the force transmission piece is positioned at the front end part of the pressure monitoring device and is used for being inserted into the oil discharge gap of the barrel along the radial direction, and the force measuring element is positioned at the rear side of the force transmission piece and is used for sensing the barrel pressure transmitted by the force transmission piece; and a limit mechanism including at least two limit arms extending from a front end of the fixing mechanism to a front side to hold the force conducting chip and the load cell therebetween, wherein front end portions of the limit arms are used to slidingly clamp the force conducting chip.

According to an embodiment of the pressure monitoring device, the fixing mechanism comprises a bracket, a limiting mechanism and a fixing device, wherein the bracket is provided with an end plate, and the limiting mechanism is connected to the end plate; and two side walls for removably securing to opposite sides of two adjacent cage plates.

The pressure monitoring device according to an embodiment, further comprising a return spring, the front end being attached to a rear side of the force conducting blade, the rear end extending towards the load cell for abutting against the load cell, wherein the rear end of the force conducting blade for abutting against the sensing location of the load cell is located within a cavity of the return spring.

According to an embodiment, the pressure monitoring device further comprises a heat insulation ring arranged on the front side of the force measuring element, when the pressure monitoring device is used, the heat insulation ring is arranged on the outer side of a barrel of the oil press, and the through hole of the pressure monitoring device allows the rear side part of the force transmission piece to penetrate through and abut against the sensing part of the force measuring element.

The pressure monitoring device can complete the installation of the device and the real-time monitoring of the pressure of the pressing chamber on the premise of not changing the self structure of the oil press, and the installation and the measurement of the device are not influenced by the replacement of the pressing strips. In addition, the main structural components of the pressure monitoring device can be obtained by means of simple cutting, bending and the like according to the required size by utilizing easily available plates, and can be assembled and installed in simple and flexible connection modes such as bolting and the like.

Drawings

Figure 1a shows part of an oil press on which a pressure monitoring device is mounted.

Fig. 1b and 1c show the pressure monitoring device in the installed state, with its front end inserted into the oil discharge gap of the oil press.

FIG. 2 is an exploded view of the barrel pressure monitoring device of the present invention.

FIG. 3 is a schematic diagram of the pressure monitoring device of the present invention after assembly.

Detailed Description

Fig. 1a shows a part of an oil press, the barrel of which is surrounded by a plurality of bars 12 extending in the axial direction thereof, and a plurality of cage plates 11 perpendicular to the bars for fixing the position of the bars. After the squeezing cage plates are folded, the squeezing strips can form a cavity type structure to form a squeezing chamber. The axial gap formed between every two adjacent squeezing strips 12 is the oil discharge gap. The front end of the front side of the pressure detection device 100 of the present invention is inserted into the oil drain gap in the radial direction of the barrel, and the rear side is fixed between the adjacent cage plates 102 by means of bolt and nut tightening. The pressure monitoring device of the invention is also similarly applicable to the condition that the pressing chamber is surrounded by the pressing ring. Fig. 1b and 1c show the pressure monitoring device in the installed state more clearly, with its rear end fixed between adjacent press plates 11 and its front force-conducting blade 10 inserted radially into the gap between adjacent press strips 12.

FIG. 2 is an exploded view of the barrel radial pressure monitoring device 100 according to the present invention; fig. 3 is an assembled schematic view of the pressure monitoring device, the direction from the back side to the front side of the pressure monitoring device being the up-down direction of the figure. The pressure monitoring device 100 includes a rear side portion as a fixed portion, and a front side portion configured as a detection portion. The fixing portion includes a positioning bracket 3 (U-shaped groove opened in the rear side) having openings for inserting the bolts 2 at both side plate portions thereof. The detection portion includes a stopper member 4, and a gasket 5, a pressure sensor 6, a heat insulating sleeve (heat insulating ring) 7, a force transmitting piece 10, and a coil spring 9 extending rearward from a portion rearward of the force transmitting piece 10, which are held by the stopper member 4 and stacked in this order toward the front side. The limiting member 4 may be fixedly connected with the bottom plate of the U-shaped bracket so as to connect the fixing portion of the rear side and the detecting portion of the front side.

As shown in FIG. 1, the U-shaped bracket and the entire pressure monitoring device 100 are fastened between the two adjacent basket plates 102 on the radially outer side of the barrel by vertically abutting the nut at the end of the adjusting bolt 2 between the two adjacent basket plates 102. The pressure monitoring device 100 may further include a sensor positioning bolt 1 that can penetrate through the bottom plate of the U-shaped bracket and the connecting plate, vertically press the gasket 6 toward the front side to position the pressure sensor 7 stacked on the gasket 6, enable the front end surface of the pressure sensor 7 to closely adhere to the rear end surface of the heat insulating sleeve 8, and enable the front end surface of the heat insulating sleeve 8 to abut against the cross arm portion.

The stop member 4 comprises a web and two opposed L-shaped stop arms extending perpendicularly from the web to the front side. The connecting plate can be bolted with the bottom plate of the U-shaped bracket. The L-shaped stopper arm includes a straight arm portion on the rear side and a lateral arm portion on the front side, and the straight arm portion may be attached to the connecting plate by a bent portion at the rear end thereof and bolted thereto, or may be welded to the connecting plate (the connecting plate may be omitted and the stopper arm may be directly fixed to the bottom plate of the bracket by bolting, welding, or the like). The gasket 6, the pressure sensor 7 and the heat insulation sleeve 8 can be held between the straight arm parts of the two opposite L-shaped limiting arms. The distal edges (end faces) of the two lateral arm portions extending inward from the front ends of the straight arm portions respectively serve to hold the force transmitting piece 10 slidably forward and backward, and the heat insulating sleeve 7 can abut against the rear side (face) of the lateral arm portion. The front end of the return coil spring 8 is connected to the rear end of the force transmitting piece 10, and can extend in the rear direction to abut against the front side surface of the heat insulating sleeve 7 or pass through the central through hole of the heat insulating sleeve 8 to abut against the non-sensing part of the pressure sensor 7. The L-shaped limiting arm is of an integral sheet shape or at least the transverse arm part is of a sheet shape.

When assembled as shown in fig. 3, the force transmitting strips 10 are substantially coplanar with the strip-like cross arm portions on both sides, and have a thickness designed to fit into the oil drainage gap between the press strips 101, depending on the width of the oil drainage gap. The front end of the conductive blade 10 may be flush with or slightly protruding from the front side of the crossbar to receive radial pressure from the barrel and be maximally protected from side-to-side deflection by the crossbar.

The force-transmitting piece 10 may generally have a thickness of 0.5 to 1.5mm and a width of 5 to 20mm, based on a conventional screw oil press; and the length of the hard stainless steel sheet can be 30-50% larger than the radial thickness of the pressing strip/pressing ring. The thickness of the cross arm parts for preventing deviation at both sides of the force transmission piece 10 is substantially the same as that of the force transmission piece 10, and the depth of inserting into the gap of the pressing bar/pressing ring is substantially the same as that of inserting the force transmission piece into the gap of the pressing bar/pressing ring, and is in clearance fit with the force transmission piece 10.

The heat-insulating sleeve 8, which may be a cylinder or ring made of zirconia ceramic, has an outer diameter comparable to that of the pressure sensor 7, and is used for supporting the pressure sensor and reducing the influence of the barrel temperature on the pressure sensor. After the device is assembled, the diameter of the inner channel defined by the heat insulation sleeve 7 can be matched with the width of the force conduction piece 9 to realize clearance fit, so that the device also has a limiting function of preventing the force conduction piece 10 from deflecting. The outer diameter of the insulating sleeve may correspond to the outer diameter of the pressure sensor and its thickness may correspond to the difference between the length of the force-conducting blade and the radial thickness of the squeezer/ring.

The pressure sensor 7, which may be a weighing-type micro pressure sensor, is small in size and low in height, is disposed above the heat insulating sleeve 8, and may be in contact with the rear end of the return spring 9. A sensing portion (e.g., a central stress receiving bump) of the pressure sensor 7 is exposed to the through hole of the heat insulating sleeve 8, and a rear end portion of the force transmitting piece 10 may pass through the through hole of the heat insulating sleeve 8 to be close to the stress receiving bump.

The front end of the return coil spring 9 is connected to the rear side of the force conducting piece 10, for example, sleeved on the rear side of the force conducting piece, and extends in the rear lateral direction to abut against the front side surface of the heat insulating sleeve 8 or pass through the central through hole of the heat insulating sleeve 7 to abut against the non-sensing part of the pressure sensor 8. For example, small diameter thread holes may be formed on both sides of the rear side of the conductive piece 10 for connecting the front end of the return spring 9, and the rear end of the conductive piece 10 for directly contacting the sensing portion of the pressure sensor 6 (e.g., the protruding portion of the rear end of the conductive piece 10) has a small width and is located inside the return spring 9.

When the force transmission piece 10 inserted into the oil discharge gap under the protection of the limiting arm is pushed by the radial pressure from the barrel and then moves in the rear side direction, the force can vertically act on the stressed salient point of the pressure sensor 7. When the radial pressure gradually decreases, the return spring 9 can help the force transmission piece 10 to avoid the situation that the oil discharge gap is blocked by the crude oil cake and the displacement can not be recovered automatically. In the meantime, the return spring 9 is always located outside the barrel because its diameter is much larger than the width of the oil discharge gap, and also plays a role of preventing the force transmission piece 10 connected with it from falling into the oil discharge gap or the barrel.

The U-shaped positioning bracket 3 is provided with a hole for mounting the bolt 2. The bolt 2 is parallel to the barrel or the ring and vertical to the adjacent two-side press cage plates, and is tensioned between the press cage plates by adjusting a nut on the bolt, so that the pressure sensor device can be fixed outside the barrel.

When the pressure monitoring device 100 is installed, the assembled pressure monitoring device 100 is pushed into a gap between the squeezing cage plates, and then the driving force conduction piece 10 and the limiting arms (the cross arms) protected at two sides extend into the gap between the squeezing strips/squeezing rings, and the extension amounts of the driving force conduction piece and the limiting arms in the squeezing chamber are not more than the inner surface of the squeezing chamber. The front side surface of the heat insulation sleeve 8 abutting against the rear side edge of the transverse arm part can play a role of limiting the insertion depth, and the insertion depth of the limiting arm does not exceed the front-back width of the transverse arm part. The relative positions of the device and the barrel and the plate are then fixed by means of the bolts 2 and nuts (for example, by tightening the nuts at the two ends of the bolts 2 between two adjacent plates by screwing them out). Finally, the pressing degree of the pressure sensor 7 and the outer surface of the squeezing strips is adjusted through the sensor positioning bolt 1.

According to the embodiments described above, the main structural components of the pressure monitoring device of the present invention, such as the U-shaped bracket, the connecting plate of the limiting component, the L-shaped limiting arm, the force transmitting piece, etc., can be obtained by very simple cutting, bending, etc., according to the required size using readily available plates, and can be assembled and installed by simple and flexible bolting, etc., connection means.

Various features of the above embodiments may be modified.

The connecting plate of the position limiting part 4 can be omitted, and the L-shaped position limiting arm is jointed and bolted on the bottom plate of the U-shaped bracket by utilizing the bent plate part at the rear end of the L-shaped position limiting arm, or is directly welded on the bottom plate.

A spacing cylinder 5 may be added between the spacing arms to facilitate stacking of shims, pressure sensors, heat-insulating sleeves, gaskets, etc. during the stacking, as shown in fig. 2 and 3. In this case, the front end of the limiting cylinder or the front side of the heat insulation sleeve can play a role in limiting the depth of the force transmission piece and the limiting arm inserted into the oil discharge gap. The gasket and sleeve define an internal passage having a diameter close to the width of the force transmitting blade, which also reduces deflection of the force transmitting blade.

The thickness of the cross arm part of the limiting arm is usually equal to or slightly larger than that of the force transmission piece. Therefore, gap limiting plates may be attached (e.g., pasted) to both side surfaces defined by the opposite lateral arms, which may be located on the side surfaces of the lateral arm portions of the two limiting arms (i.e., both side surfaces of the force transmitting piece), and may be closely attached to both side surfaces of the lateral arm portions to form a gap fit with the side surfaces of the force transmitting piece so as to prevent the force transmitting piece from deflecting in the thickness direction. Therefore, in the pressure monitoring process, the force conduction piece is more stably kept in the circumferential closed or semi-closed narrow gap formed by the two transverse arm parts and the thin sheets on the two sides, so that the force conduction piece can slide back and forth, but the force conduction piece does not transversely deflect to influence the accurate conduction of the radial pressure of the barrel. The thickness of the clearance limiting plate can be 0.5-1mm, and the depth of the clearance limiting plate inserted into the gap of the pressing strip/pressing ring is 20-50% less than that of the force transmission piece inserted into the gap of the pressing strip/pressing ring.

When the thickness of the arm portion for holding the force transmitting piece is large, the slit may be formed by forming a groove extending forward and backward on the inner side of the arm portion, so that the force transmitting piece can be held more stably in the opposed groove.

The pressure monitoring device of the invention has the main advantages that:

(1) on the premise of not changing the structure of the oil press, the installation of the device and the real-time monitoring of the pressure of the pressing chamber can be completed. The device of the invention utilizes the oil discharge gap of the pressing strip as a guide channel of the pressure of the pressing chamber, and utilizes the pressing cage plate as a fixed installation foundation, thereby being widely matched with the general structure and the standardized components of the mainstream industrial oil press. The barrel of the industrial oil press is formed by combining the standard pressing strips, the service life of the pressing strips is limited, the pressing strips generally have different degrees of abrasion after continuously working for 200 hours, the pressing strips which cannot normally work need to be replaced at the moment, and the installation and measurement of the device do not influence the conventional operation of replacing the pressing strips.

(2) The device can be wholly separated from the oil press, pressure measurement data are accurately calibrated on the material testing machine, and then the device is integrally installed on the oil press to collect measured data. The pressure is estimated without depending on a complex stress-strain relation of the pressing strip or the pressure is calibrated by depending on other direct pressure measuring devices like an indirect measuring mode.

(3) The device is provided with the heat insulation ring, so that the pressure sensing device is isolated from the environment of the press chamber, and the problems of inaccurate measurement result, low service life and the like of the sensor caused by high temperature in the press chamber can be effectively avoided; moreover, the pressure conduction mechanism is provided with a return spring, and after the oil press finishes working, the return spring can overcome the blocking effect of the pressed materials in the oil discharge gap to push out the force conduction sheet, so that the force conduction sheet is separated from the pressure sensor element to protect the sensor; finally, the pressure conduction piece of the device is cheap and easy to obtain, is convenient to install and is easy to replace even if the pressure conduction piece is worn. Thereby ensuring the long-term stable monitoring of the pressure of the barrel.

(4) The main structural components of the pressure monitoring device, such as the U-shaped bracket, the L-shaped limiting arm of the limiting component, the force conduction sheet and the like, can be obtained by means of simple cutting, bending and the like according to the required size by utilizing easily available plates, and can be assembled and installed by simple and flexible connecting modes such as bolting, welding and the like.