905 results about "Screw head" patented technology

The invention relates to the technical field of floor heating, and discloses an assembly type prefabricated floor heating module which comprises an upper prefabricated slab and a lower prefabricated slab matched with the upper prefabricated slab, second connecting strips are embedded into the left end and the right end of the upper prefabricated slab and the left end and the right end of the lower prefabricated slab, and first connecting strips are embedded into the front end and the rear end of the upper prefabricated slab and the front end and the rear end of the lower prefabricated slab. The first connecting strip comprises a square pipe, and a lead screw is arranged in the square pipe. The first connecting strip and the second connecting strip are embedded between the upper prefabricated slab and the lower prefabricated slab which are adjacent to each other, and are meshed in the splicing screw holes in the upper prefabricated slab and the lower prefabricated slab through the screw heads on the first connecting strip and the second connecting strip, so that the prefabricated floor heating modules are spliced together; after the prefabricated floor heating module is laid, the first connecting strip and the second connecting strip cannot be seen from the outside, only one hole needs to be formed between every two adjacent upper prefabricated plates, and therefore the neatness and attractiveness of the prefabricated floor heating module are guaranteed.

The invention discloses motor assembling equipment and an automobile motor assembling method capable of automatically screwing, and relates to the field of motor assembly.The motor assembling equipment comprises a feeding module and a screwing module, the screwing module comprises a mounting plate and a plurality of screwing assemblies, the screwing assemblies are all mounted on the mounting plate, and the screwing assemblies can vertically move; the screwing assembly comprises a screwing head, a screwing bit and a transmission rod, the transmission rod can drive the screwing bit to rotate, the feeding module can convey a screw into the screwing head, and after the screwing head descends to abut against a workpiece, the transmission rod descends and rotates in the screwing head. The position of the mounting block can be adjusted on the plane of the mounting plate, so that the flexibility of the equipment is greatly enhanced, the equipment can adapt to the change of screw hole spacing on workpieces with different specifications, the connecting rod is connected with the transmission rod through the universal joint, and even if the position of the transmission rod is changed due to the movement of the screwing head, the transmission rod can be fixed. And the rotating power can still be effectively transmitted to the transmission rod, so that the screwing function is ensured to be realized.

This invention relates to a treatment device suitable for combined operative procedure of vertebroplasty and pediculoplasty. A treatment device includes a cylindrical driver capable of driving a screw into bone, an inner sleeve capable of being inserted into the driver, and a guide pin capable of being inserted into the inner sleeve, and is configured as follows. The screw includes on an outer wall (outer circumference) a thread that can tap into bone or cement, and a through hole that allows the inner sleeve to pass from a head to a tip. The driver can fit onto the head of the screw and when moved along the central axis and be joined to the screw, so as to transmit torque about the central axis to the screw. The inner sleeve includes a notch which protrudes, when the inner sleeve is inserted from the distal end of the driver in a state in which the screw and the driver are joined together, protrudes more proximally than a tip of the screw, preventing removal of the screw.

To provide a lens device that suppresses performance variation caused by positional changes of an optical element accompanying attachment / detachment of an optical element unit, and ensures replacement workability of the optical element unit.SOLUTION: In a lens device 1 in which an optical unit 100 having a second optical element 2 is attachable to and detachable from a base lens barrel unit 200 having a first optical element 1000, the optical unit 100 includes: a fixing screw 3 that fixes the base lens barrel unit 200 and the optical unit 100; a screw accommodating portion 101 that accommodates the fixing screw 3; and a fixing screw operation hole 13b communicating with the screw accommodating portion 101. A depth of a spot-facing portion 19a provided in the screw accommodating portion 101 is shorter than a total length of the fixing screw 3, and an inner diameter of the fixing screw operation hole 13b is smaller than a diameter of a screw head of the fixing screw 3.SELECTED DRAWING: Figure 4

A safety device is disclosed, consisting of a screw body with a screw head, which is connected to the screw body in one piece and forms a rotary-drive part, and with a thread, which is connected to the screw head in one piece and forms a securing part, and also with a rupture device, which is arranged in a channel of the screw body, wherein a sight glass is accommodated entirely within the channel of the screw body, together with the rupture device, and forms an inspecting device for assessing the state of the rupture device.

A bone fixation system for reconstruction and / or trauma treatment of bones, the bone fixation plate comprising: a bone fixation plate configured and dimensioned for application to a patient's bone, the bone fixation plate comprising an in-use upper surface and an in-use lower surface with at least one opening formed on the upper and lower surfaces to form a passage extending from the upper surface to the lower surface; each passage being defined by inner walls extending from the upper surface to the lower surface, the inner walls having a height extending between the upper surface and the lower surface, the inner wall further comprising: a threaded inner wall portion extending from the upper surface towards the lower surface, the threaded inner wall portion having threads with a thread pitch (PW); and a non-threaded lower inner wall portion extending from a lower part of the threaded inner wall portion towards the lower surface of the bone fixation plate; and at least one bone screw with a threaded screw head having threads with a thread pitch (PH) for engaging and interfacing with the threaded inner wall for variable angle anchoring of the threaded screw head during use.

Implantable devices and assemblies that provide a friction fit between a receiver and a fastener, such as a bone screw. A frictional force is applied between the screw head and both a retention ring and a pressure insert, maintaining and stabilizing the orientation of the receiver relative to the screw head before being fixed by a set screw. This mechanism prevents drooping or slipping of the receiver out of alignment when implanted. Additionally, the devices allow for modular assembly before or during spinal fixation, enabling bottom-side loading of the screw head into the receiver. Various screws with different characteristics can be coupled to the receiver body before or after implantation. The frictional force may be facilitated by one or more ridges on the receiver body that engage the pressure insert, which is resiliently urged against the screw head, providing a spring-like compression force.

An abutment for dental build-up. The abutment is lockable to an implant body. The abutment has an opening with an introduction end and an exit end. A fixing screw in introducible via the introduction end. The screw portion of the fixing screw projects from the exit end. The screw portion is screwable with the implant body for locking. The opening has a tapering from the introduction end towards the exit end. In the locked state, the upper end of the screw head is at a distance from the introduction end. The abutment has a threaded portion. A locking element has a mating thread corresponding to the threaded portion for releasably connecting the locking element to the abutment. The locking element can be introduced into the opening via the introduction end and is releasably connectable to the threaded portion via the mating thread.

A spinal fixation system including: a pedicle screw including a screw head, a screw tip opposite to the screw head, a screw body extending from the screw head to the screw tip, and a channel extending from a first opening defined in the screw head to a second opening defined at a side of screw body; a tulip head defining a cavity configured to accommodate the screw head, and defining a slot configured to accommodate a fixation rod; a nail including a nail head, a nail tip, and a nail body extending from the nail head to the nail tip, the nail body including a curved portion that is flexible; and an inserter for the nail configured to cooperate with the tulip head.

The utility model belongs to the technical field of disassembly and assembly tools, and particularly relates to an electric wrench which comprises a wrench body, an open gear, a driving assembly and a reverse torque wrench. The wrench main body is provided with an imbedding opening communicated with the cavity of the wrench main body; an opening in the open gear communicates with an inner ring of the open gear to form a first jaw, and the open gear is rotationally arranged in the cavity. The driving assembly is in transmission connection with the opening gear; a second jaw is arranged on the reverse torque wrench, the reverse torque wrench is arranged outside the wrench body, and the opening direction of the second jaw is the same as the opening direction of the placing opening. According to the electric wrench, a first jaw on an open gear and a second jaw on a reverse torque wrench can be clamped on a screw head and / or a nut connected to a pipeline respectively, and the open gear can be driven by a driving assembly to rotate, so that the screw head and the nut connected to the pipeline rotate relatively, and the screw head and the nut are tightened or loosened; disassembly and assembly of the screw head and / or the nut can be rapidly completed, and therefore the maintenance efficiency of a pipeline is improved.

The utility model discloses a pneumatic screwing device, which relates to the technical field of screwing equipment and comprises a base, a screwing mechanism mounted at the top of the base, a driving mechanism mounted at the top of the base and used for driving the screwing mechanism to lift, and a clamping mechanism mounted at the top of the base and used for clamping a pipe fitting to be screwed, the screwing mechanism comprises a movable seat movably arranged on the top of the base, a rotating air cylinder fixedly installed in the movable seat and a screwing head fixedly installed at the bottom end of the rotating air cylinder. The pneumatic screwing device is driven by the motor and matched with the threaded rod to rotate, parts such as the rotating air cylinder can be driven to ascend and descend, the screwing head can be driven to twist by matching with rotation of the rotating air cylinder, the nut can be screwed on a clamped automobile pipe fitting through the screwing head after the screwing head ascends and descends and rotates, pneumatic screwing is carried out, and compared with manual screwing, the pneumatic screwing device is more labor-saving and convenient to use, and the working efficiency is improved. And the consumption of human resources is reduced, and the installation and working efficiency is improved.

The utility model provides a firmly installed and adjustable support, which comprises a circular fixed disc and a fixed rod, the fixed disc is fixedly connected with a square tube through a bolt I, a threaded hole is formed in the fixed rod, the fixed rod is in threaded connection with a connecting rod capable of extending into the square tube, and the connecting rod is abutted against two side walls of the square tube to share the load at the joint of the fixed disc. And the length can be adjusted to adapt to different square tubes. The front end of the fixing rod is provided with a connecting hole and connected with the round pipe through a second bolt and a second nut, the second bolt is sleeved with the positioning pipe, and an arc-shaped positioning groove in one end of the positioning pipe is matched with the round pipe in radius to achieve positioning and supporting of the round pipe. The connecting groove and the containing groove in the fixing rod are used for installing the positioning pipe and containing the two screw heads of the bolt correspondingly. According to the support, through multiple connecting and positioning structures, the connecting firmness is effectively enhanced, stable installation of square pipes and round pipes of different specifications is achieved, and the applicability and the bearing capacity are improved.

The invention discloses an electricity leading device and an electron accelerator, the electron accelerator comprises an accelerating tube device, the accelerating tube device comprises an insulating tube, the insulating tube is provided with a plurality of electricity leading holes, the accelerating tube device comprises a plurality of electrode plate devices, the electricity leading device comprises an electricity leading screw, a screw head and a sealing ring, and the sealing ring is provided with a sealing ring. An annular groove is formed in the front side of the screw head, a sealing ring is installed in the annular groove, the electricity leading screw penetrates through the electricity leading hole to be in threaded connection with the electrode slice device, and the screw head presses the sealing ring on the outer side of the electricity leading hole in the outer surface of the insulating tube. According to the electricity leading device, the connection effect of the electrode plate and the anode resistor can be achieved, meanwhile, the position of the electrode plate device can be fixed, the electricity leading device can further seal the accelerating tube of the electron accelerator, the accelerating tube is convenient and rapid to assemble, and the production speed is increased.

A screw insertion system has a screw having a threaded shaft and a head. The head has a conically tapered outer surface, the taper increasing in distance from a central longitudinal axis of the screw from a free end of the head towards a larger diameter adjacent the connection between the head and the threaded shaft. The conically tapered head outer surface has preferably two helically extending partially rounded threads. The head has a drive element for engaging a driver. A tubular screw holder has an outer surface and internal bore extending between a leading end and a trailing end for receiving the screw. The leading end having a conically tapered inner threaded portion for engaging the conically tapered outer thread of the screw head. The tubular screw holder outer surface having a diameter less than or equal to the maximum diameter of the conically tapered head.

The utility model discloses a sensor used for air compressor detection, comprising a dismounting screw head, the center of the lower end of the dismounting screw head is connected with a temperature sensing head, the center of the upper end of the dismounting screw head is connected with a connecting wire harness, the outer side of the lower end of the dismounting screw head is connected with an installation threaded sleeve, and the installation threaded sleeve is sleeved on the upper side of the outer part of the connecting wire harness. The temperature sensing head is arranged in the mounting and dismounting screw head and can be replaced according to the type of a connecting hole of the air compressor, a limiting clamping groove is formed in the outer side of the lower end of the mounting and dismounting screw head, a plurality of positioning strips are connected to the upper side of the outer wall of the temperature sensing head, and the upper ends of the positioning strips are located in the limiting clamping groove and connected to the inner wall of the upper end of the limiting clamping groove. According to the utility model, rapid replacement can be carried out according to the inner diameter sizes and thread specifications of different air compressor connecting holes, the universality and adaptability of the sensor are improved, the problem that a traditional sensor cannot be installed due to mismatching of the thread specifications is avoided, and the use cost is reduced.

The invention discloses a quick evacuating and plugging device for an explosion-proof opening of a shell of a vacuum heat-insulation cryogenic container, and belongs to the technical field of evacuating operation of an interlayer of the vacuum heat-insulation cryogenic container. The quick evacuating and plugging device comprises a valve body I, a valve body lower flange is fixedly connected to the valve body I, and a valve rod limiting groove is formed in the valve body I; a valve rod limiting groove is formed in the valve body lower flange, a valve rod mechanism is slidably connected to the valve rod limiting groove, a hand wheel is fixedly connected to the upper end of the valve rod mechanism, a valve body upper flange is arranged on the valve body lower flange, a valve rod fixing screw head is arranged on the valve body upper flange, and a polytetrafluoroethylene gasket is arranged at the upper end of the valve rod fixing screw head. The explosion-proof opening of the shell is used for carrying out interlayer vacuumizing action and plugging is carried out after vacuumizing is completed, vacuumizing operation can be completed without installing a vacuum valve, use of the vacuum valve is reduced, the manufacturing cost of equipment is reduced, the cryogenic container is more economical on the premise that the function is guaranteed, the production cost of an enterprise is reduced, and the production efficiency of the enterprise is improved. And the market competitiveness of the product is improved.

The utility model relates to the technical field of agricultural planting, and discloses a polygonatum sibiricum planting land disease and pest prevention device which comprises four first telescopic rods, adjusting knobs are arranged in the middles of one sides of the four first telescopic rods, a protection mechanism is arranged above the first telescopic rods, a pest killing mechanism is arranged below the protection mechanism, and the pest killing mechanism is arranged above the first telescopic rods. The protection mechanism comprises a fixing disc, the middle of the lower surface of the fixing disc is fixedly connected to the top of the first telescopic rod, a threaded head is fixedly connected to the middle of the upper surface of the fixing disc, and an insect-proof net is arranged above the threaded head. The top of the first telescopic rod is connected with the fixing disc, the bottom of the threaded head is perpendicularly connected to the middle of the upper surface of the fixing disc, the threaded head can penetrate through the interior of the through hole, the first telescopic rod is covered with the insect-proof net, the nut can be screwed outside the threaded head, the insect-proof net is limited, and pests are blocked; therefore, the effect of preventing the pesticide from damaging the rhizoma polygonati can be achieved.

This utility model discloses an internal hexagonal head screw, including a screw head, a screw rod, and an expansion assembly. The screw head is hexagonal with an internal hexagonal turning groove at the top. A screw rod is fixed to the bottom of the screw, and an expansion assembly is fitted around the screw rod. The expansion assembly consists of an upper fixing ring, a lower fixing ring, and arc-shaped strips. Both the upper and lower fixing rings are fitted around the screw rod, with the upper fixing ring positioned above the lower fixing ring. Several outwardly protruding arc-shaped strips connect the upper and lower fixing rings, and the upper fixing ring is fixed to the screw head. This utility model, by fitting an outwardly expanding expansion assembly around the screw rod, allows the expansion assembly to expand outward during tightening, increasing the friction between the screw and the connected components. This results in excellent anti-loosening performance after tightening, making the screw less prone to loosening.

The utility model relates to the field of automation, in particular to an adjustable motor screw heading device. The utility model provides an adjustable motor screw heading device which comprises a cabinet, a screw heading machine, an electric turntable, a mounting frame, a screw rod, a guide rod and the like, the screw heading machine is mounted at the top of the cabinet, the electric turntable is mounted at the top of the cabinet, the mounting frame is mounted at the top of the cabinet, and the screw rod is rotatably connected in the mounting frame. Guide rods are connected to the mounting frame in a bilateral symmetry mode. The guide ring can be adjusted to the position suitable for the size of a workpiece through the lead screw, so that the clamping distance of the fixing frames is accurately adjusted, then in the rotating process of the electric rotating disc, the second rolling wheel makes contact with the inclined face of the guide ring, and the two fixing frames automatically move towards the inner side through the synergistic effect of the guide ring, the first rolling wheel and the second rolling wheel; the workpiece is firmly clamped, the stability and precision of the workpiece in the screw driving process are ensured, manual intervention is not needed, and the automation level and the operation efficiency are improved.

This invention discloses a spinal endoscopic screw-rod fixation system, belonging to the field of medical device technology. The system includes screws, locking pins, and connecting rods. The screw head has a fixing hole with internal threads on the inner wall and a driving hole at the bottom. The proximal end of the screw forms an arc-shaped mating surface around the fixing hole. The locking pin has external threads matching the internal threads, and a spherical clamping surface is formed on the side of the clamping head facing the connecting block. This invention, through the arc-shaped mating between the screw, locking pin, and connecting block, allows the connecting block to adapt to the screw at multiple angles, facilitating insertion and locking in spinal endoscopy or minimally invasive small-incision environments. The flip-handle mechanism facilitates tightening the locking pin in confined operating spaces and prevents arbitrary disassembly of the locking pin, improving the operational convenience and safety of the fixation system.

The invention relates to a screw (1) comprising a screw head (2) and a screw shaft (3) which has a threaded section B with a thread (6). A measuring device (8) with an extensible measuring strip (9) is arranged along or in the interior of the screw shaft (3). In the process, the extensible measuring strip (9) is arranged in the threaded section B and detects a compression of the screw shaft (8).

The invention relates to a component arrangement for a medical device comprising a first component with an outer surface, an inner surface and at least one recess extending between the outer surface and the inner surface, a second component comprising at least one screw boss with a longitudinally extended boss shaft and a bore, wherein the second component is arranged on the outer surface of the first component, the boss shaft projecting axially into the recess, and wherein an end face of the boss shaft does not project axially beyond the inner surface of the first component, and at least one screw with a screw shaft and a screw head, wherein the screw shaft is screwed into the bore and the screw head is axially supported on the inner surface of the first component, wherein the first component is subjected to compression between the screw head and the second component and the boss shaft is subjected to axial tension.which means that the first component is screwed to the second component.

The invention discloses a parallel counter-rotating double-screw structure for gunpowder processing, which is composed of two screws which are arranged in parallel and have opposite thread directions, and the thread arrangement structures of the two screws are consistent; each screw sequentially comprises a screw head, a feeding section, a mixing and shearing section, an exhaust section and a metering section from front to back, the depths of screw grooves of all threaded sections are consistent, the screw head is of a conical structure, the length of the screw head is 0.5 times of the diameter of the screw, the length of the feeding section is 4-6 times of the diameter of the screw, and the metering section is of a conical structure. The mixing shearing section is composed of a front shearing section and a rear shearing section with different screw pitches, the total length of the mixing shearing section is 4-7 times of the diameter of the screw rod, the length of the exhaust section is 2-4 times of the diameter of the screw rod, and the length of the metering section is 3-5 times of the diameter of the screw rod. According to the parallel counter-rotating double-screw structure, stable conveying, efficient mixing and extrusion forming of high-viscosity and high-solid-content gunpowder are achieved.

The utility model discloses a hinge combination structure. The hinge combination structure comprises a pile head and a glasses leg connected with the pile head through a hinge assembly, the hinge assembly comprises a screw and a screw sleeve, one end of the pile head is provided with an upper connecting part and a lower connecting part, one end of the glasses leg is rotatably arranged between the upper connecting part and the lower connecting part, the upper connecting part and the lower connecting part are respectively provided with an upper hole and a lower hole, the glasses leg is provided with a middle hole coaxial with the upper hole and the lower hole, and the screw sleeve extends into the middle hole from the lower hole. The screw extends into the middle hole from the upper hole and is in threaded connection with the thread sleeve, an upper shaft sleeve is arranged between the screw and the inner wall of the upper hole, a lower shaft sleeve is arranged between the thread sleeve and the inner wall of the lower hole, an upper gasket is arranged between the upper shaft sleeve and the glasses leg, a lower gasket is arranged between the lower shaft sleeve and the glasses leg, and a gasket is arranged between a screw head of the screw and the upper shaft sleeve; the lower end of the threaded sleeve is provided with a limiting flange extending towards the periphery and abutting against the lower end of the lower shaft sleeve. The glasses are simple and reliable in structure, the hinge structure is not easy to loosen, fall off and the like, and the service life of the glasses can be remarkably prolonged.

The utility model relates to the technical field of electric power iron accessories, in particular to an electric power iron accessory locking mechanism convenient to disassemble and assemble, which comprises a first arc-shaped seat and a second arc-shaped seat, the first arc-shaped seat and the second arc-shaped seat are identical in structure and opposite in direction, and butt joint assemblies are arranged at the upper ends and the lower ends of the first arc-shaped seat and the second arc-shaped seat. Limiting assemblies are arranged on the side faces of the first arc-shaped base and the second arc-shaped base correspondingly. Through the arrangement of the first arc-shaped seat, the second arc-shaped seat, the telescopic connecting seat, the overhead seat, the screwing seat, the screwing screw sleeve, the threaded rod, the screwing head, the telescopic rubber sleeve and the telescopic spring piece, the equipment can be used as an electric iron accessory locking mechanism, the disassembly, assembly and use operation are more convenient and more stable, and in the actual use process, the use is more convenient. A worker can integrally sleeve and mount the first arc-shaped seat and the second arc-shaped seat at a mounting position, and at the moment, the contraction joint seats at the upper and lower ends of the first arc-shaped seat and the second arc-shaped seat are arranged.

The utility model relates to hand formula screw sorting device for solving the technical problem of time -consuming and troublesome artificial screening. Including storage mechanism, feeding mechanism, screening mechanism and collection mechanism, from upstream to downstream each fixed plate and each movable plate's upper end is in turn higher, movable step board includes transmission block and interval fixed on transmission block many movable plates, movable plate and fixed plate one -to -one cross sliding fit, transmission block drives and linear reciprocating motion along the up-down direction through cam mechanism, the upper end surface of fixed plate and movable plate all are the inclined plane that tilts downward to the downstream direction, screening mechanism and feeding mechanism butt joint, including the multiple screening unit that interval sets along the up-down direction, screening unit includes the screening inclined slide that sets down to the downstream inclination, screening inclined slide has the width of unloading channel, the width of unloading channel is less than the diameter of corresponding screw head and is greater than the outer diameter of next level screw head, the width of unloading channel of each screening unit decreases from top to bottom.

Construction of an integrally formed liquid collection container (10), comprising an integrally formed liquid collection container (10), a screw (40), and a leak-proof sealing ring (50), wherein a projecting part (20) with a liquid injection opening (30) is integrally formed on an inner wall surface of the liquid collection container (10), wherein the liquid injection opening (30) has an internally threaded hole (31) and a stepped hole (32) for receiving a screw head (41) of the screw (40) and the leak-proof sealing ring (50), wherein the internally threaded hole (31) is connected to an interior of the liquid collection container (10), wherein the stepped hole (32) is connected to the internally threaded hole (31) and the outside of the liquid collection container (10), and wherein the leak-proof sealing ring (50) is located between the screw head (41) of the screw (40) and an inner end face (A) of the is arranged in a stepped hole (32),wherein the screw (40) is screwed into the internal threaded hole (31), wherein when the screw (40) is tightened the leak-proof sealing ring (50) is pressed in by the screw head (41), so that the leak-proof sealing ring (50) is deformed and clamped between the screw head (41) and the inner end face (A) of the stepped hole (32) to prevent leakage.

The utility model discloses a bolt hole sand dirt cleaning device which comprises a stud matched with the inner wall of a bolt hole in shape, the stud is of a hollow shell structure, the side wall of the stud is provided with a first dirt discharging groove penetrating through the inside and the outside of the side wall of the stud, and the top of the stud is connected with a twisting head. The bolt is simple and convenient to operate, as the stud is of the hollow shell structure and the first dirt discharge groove penetrating through the inside and the outside of the side wall of the stud is formed in the side wall of the stud, sand dirt on the hole wall of the bolt hole can be collected into the stud from the first dirt discharge groove by rotating the screwing head manually or through a wrench, and the sand dirt in the bolt hole is convenient to clean; the problem of insufficient buckling pressure of the fastener caused by sand accumulation in the bolt hole is solved, the risk of rail breakage is greatly reduced, the time for cleaning the sand in the bolt hole is short, and the operation efficiency is high.

Fastening arrangement (10) comprising: - a screw (12) having a screw head (14) and a shaft section (16) provided with an external thread; and - a cylinder head cover (18) having a through-hole (20), wherein the through-hole (20) has an inner diameter dimensioned such that it allows axial passage of the externally threaded shaft section (16) through it, wherein the screw head (14) has a dimension extending transversely to a central axis (A-A') of the screw (12) which exceeds the inner diameter of the through-hole (20) so that the screw head (14) is restrained against axial passage through the through-hole (20);- a plurality of spring-elastic deformable engagement elements (22) provided on the cylinder head cover (18), wherein the plurality of spring-elastic deformable engagement elements (22) project radially inwards from an inner wall (21) of the through-bore (20); - wherein the screw (12) comprises at least one detent projection (24) formed on the externally threaded shaft section (16); - wherein, upon axial insertion of the externally threaded shaft section (16) through the through-bore (20), the at least one detent projection (24) engages with the plurality of spring-elastic deformable engagement elements (22) and deflects the plurality of spring-elastic deformable engagement elements (22) to allow axial passage of the at least one detent projection (24) through the plurality of spring-elastic deformable engagement elements (22);- wherein, after the axial passage of the at least one detent projection (24) through the plurality of spring-elastic deformable engagement elements (22), the plurality of spring-elastic deformable engagement elements (22) return to their undisplaced initial shape and thereby prevent a reverse axial movement of the screw (12) relative to the cylinder head cover (18), so that the screw (12) and the cylinder head cover (18) together form a pre-assembled unit which can be handled manually as a single component before installation in a cylinder head (28);- and wherein the plurality of spring-elastic deformable engagement elements (22) has a bending flexibility index (FI) in the range of 0.005 to 40,000.;