94 results about "Maximum diameter" patented technology

This application discloses an insulated torsion bar spline, comprising a straight section, a recessed section, a tapered section, and a bottom section arranged sequentially from top to bottom. The maximum diameter of the recessed section, tapered section, and bottom section is less than or equal to the diameter of the straight section. The total height of the insulated torsion bar spline is defined as L, the height of the straight section as L1, the height of the recessed section as L2, the height of the tapered section as L3, and the height of the bottom section as L4, satisfying the following conditions: 10%L≤L1≤15%L, 38%L≤L2≤43%L, 45%L≤L3≤49%L, and L4≤1%L. The diameter of the straight section is defined as D, and the maximum depth of the recessed section is 2%~4%D. The insulated torsion bar spline is made of metal, and the straight section, recessed section, tapered section, and bottom section are connected as a single structure. This application's insulated torsion bar spline, through optimization of its shape and dimensions, effectively improves the torque of the insulated torsion bar.

This invention discloses a method, apparatus, equipment, and storage medium for detecting annular flow pressure drop in wellbore. The method includes: fitting acquired electrical logging data of the well diameter of the target well; processing an irregularly enlarged well section into a concave arc-shaped wellbore to be tested; obtaining the maximum diameter and concave height of the concave arc-shaped wellbore; determining the diameter enlargement factor of the concave arc-shaped wellbore based on the maximum diameter and the pre-acquired drill bit diameter of the target well; and inputting the diameter enlargement factor, the concave height, and the drilling data of the target well into a pre-constructed model of an irregular wellbore annular flow pressure drop in a reference well for calculation to obtain the annular flow pressure drop of the target well. This method enables rapid detection of the annular flow pressure drop of the target well based on the annular flow pressure drop of the reference well, improving the detection efficiency of annular flow pressure drop in irregular wellbore annulus.

This utility model discloses a floating material trough structure and a buffer paper pad winding device for winding buffer paper pads. The floating material trough structure includes a material trough, a rotating shaft, a limiting plate, a driving mechanism, and a resetting component. The end of the material trough is provided with a flange, allowing the material trough to swing from a horizontal state to a non-horizontal state. The driving mechanism drives the limiting plate to swing around the rotating shaft as the swing center. The resetting component ensures that the material trough maintains a tendency to swing from a non-horizontal state to a horizontal state. The buffer paper pad winding device includes a winding mechanism and the floating material trough structure. With this utility model's floating material trough structure, regardless of whether the wound buffer paper pad roll has the minimum or maximum diameter, the material trough remains tightly attached to the outer periphery of the buffer paper pad roll, ensuring adequate tightness. The diameter of the buffer paper pad roll wound by the buffer paper pad winding device can vary between the minimum and maximum diameters, and it ensures that the tape is firmly adhered and wrapped around the outer periphery of the buffer paper pad roll, preventing the buffer paper pad roll from unraveling.

The invention provides a conical barrel clamping piece anchorage device for mechanical connection of building components, which comprises a conical barrel, a sleeve, clamping piece anchors, a component at one end and a component at the other end, two sets of clamping piece anchorage devices are respectively sleeved on the component at one end and the component at the other end, and the conical barrel is integrally formed and comprises an equal-diameter section and a variable-diameter section; the tail end of the equal-diameter section is fixedly connected with the maximum-diameter end of the variable-diameter section, the head end of the equal-diameter section is provided with internal threads, the two ends of the sleeve are provided with external threads, and the two conical barrels penetrate through a component at one end and a component at the other end respectively. The variable-diameter sections are arranged on the clamping piece anchorage devices arranged at the connecting end of the component at one end and the connecting end of the component at the other end in a sleeving mode respectively, and the minimum diameter of the variable-diameter sections of the conical cylinder is matched with the sum of the diameter of the building component and the thickness of the clamping piece anchorage devices. The invention further discloses a method for connecting building components through the cone clamping piece anchorage device type connecting device. The method has the advantages of simple structure, simplicity and convenience in construction, shortened construction period and wide application range.

A polyester-resin-coated seamless can including a reduced diameter portion obtained by neck processing within a distance of 0% to 15% from a can body uppermost portion with respect to a total height of the can from the can body uppermost portion to a can bottom of the can. A ratio Im / Iu is 1.0 or more, where Iu (cps / μm) is calculated by dividing a maximum peak intensity in a range satisfying 15°≤2Θ≤19° of an outer-surface coating in a maximum reduced diameter portion of the reduced diameter portion by a thickness of the coating at the measurement site, and Im (cps / μm) is calculated by dividing a maximum peak intensity in a range satisfying 15°≤2Θ≤19° of outer-surface coating at a measurement site within a distance of 45% to 60% from the can body uppermost portion by a thickness of the outer-surface coating at the measurement site.

The application provides an outer wall protection device for a socket metal pipe, the outer wall protection device is a ring segment with the same center as the socket metal pipe to be protected, a hollow cylinder is formed by more than two ring segments, the socket metal pipe is sleeved in the hollow cylinder, the outer diameter of the hollow cylinder is greater than or equal to the outer diameter of the pushing flange and smaller than the maximum diameter of the socket segment sleeved in the hollow cylinder; the outer wall protection device comprises a first ring segment and a third ring segment; the first ring segment is adjacent to the reinforcing support during installation, and the third ring segment is matched with the socket segment. The application eliminates the longest curing process in the production of nodular cast iron pipes, shortens the pouring link in the preparation process of the nodular cast iron pipes, forms the required structure of the outer wall and the socket metal pipe in stages, and thus improves the production efficiency of the metal pipe.

To provide a container that can restrict movement of stored articles during transportation and can prevent damage to the container and the articles as much as possible.SOLUTION: A container 1 includes a bottom wall 2 and a side wall 3, and is box-shaped and open upward. The bottom wall 2 includes: a flat, non-porous general portion 31; and a large protrusion 32 and a small protrusion 33 provided in the entire upper surface of the general portion 31. The large protrusion 32 has a height from the general portion 31 to an apex and the maximum diameter in a planar view larger than the small protrusion 33. Each of the protrusions 32 and 33 has a generally circular shape in a planar view and a curved cross-section, with the large protrusion 32 and the small protrusion 33 arranged alternately. The rounded shape of each of the protrusions 32 and 33 minimizes damage to the articles stored in the container 1 and the protrusions during transportation. Furthermore, the articles are supported not only by the large protrusion 32 but also by the small protrusion 33, effectively restricting their movement.SELECTED DRAWING: Figure 1

The invention provides a grinding method for a roller and a grinding machine, and relates to the technical field of machining. The grinding method for the roller comprises the following steps that a groove is formed in the roller face of the end of the roller to be machined, and a first roller is obtained; acquiring a surface profile curve of the first roller; based on grinding treatment parameters, grinding treatment is conducted on the first roller, and a second roller is obtained; wherein the grinding treatment parameters comprise grinding current, and the grinding current is used for representing the maximum limiting current determined on the basis of the surface profile curve. The grooves are formed in the roller surface of the end of the roller, the maximum diameter change value of the surface of the roller is increased, the surface profile curve of the roller is made to change, then the grinding machine control system improves the maximum limiting current set value, traditional grinding current limitation is broken through, the grinding process can be stably operated under the higher current condition, and the grinding efficiency is improved. The material removal efficiency is improved; and the processing time is shortened.

The present invention relates to a drill bit and a method of manufacturing a perforated article. In the case where the rigidity of the main shaft of a perforating machine is sufficient, it goes without saying, but even in the case where perforation is performed using a hand-held tool rotation device or the rigidity of the main shaft of the perforating machine is low, a workpiece composed of a composite material or a metal or the like can be perforated with high accuracy. The drill bit of the embodiment has a first cutting edge formed on the leading end side in such a manner that the leading end angle is continuously or discontinuously reduced from the leading end side to the trailing end side, and on the other hand, the clearance angle is continuously or discontinuously reduced from the leading end side to the trailing end side, and is used to perforate a workpiece to form a pilot hole; a second cutting edge formed by being positioned away from the first cutting edge toward the trailing end side, and used to perform finishing of the pilot hole, and having a clearance angle at the maximum diameter position; and a vibration-damping portion formed between the first cutting edge and the second cutting edge, and reducing vibration of the second cutting edge by being inserted into the pilot hole processed by the first cutting edge.

To provide a ball bearing which can optimize the diameters of a plurality of balls with different sizes as a roller and which can contribute to reduction in rotation torque and increase in acceptable load.SOLUTION: A representative configuration of a ball bearing 100 includes: an outer ring 110; an inner ring 120; and a plurality of balls that roll between the outer ring and the inner ring. As the balls, balls with different diameters are regularly aligned. When a parameter γ representing an internal configuration of the bearing is indicated by the following formula: γ=(Da / PCD)*cosα (where Da is the diameter of the ball, PCD is a pitch circle diameter, and α is a contact angle), a maximum ball diameter difference ΔDa between a ball with the largest diameter (largest-diameter ball 132) and a ball with the smallest diameter (smallest-diameter ball 134) is within a range of (7.52×10-4γ+8.91×10-4)*Da≤ΔDa≤(6.43×10-3γ+7.62×10-3)*Da when γ≤0.09, and (-9.65×10-4γ+1.05×10-3)*Da≤ΔDa≤(-8.25×10-3γ+8.98×10-3)*Da when γ>0.09.SELECTED DRAWING: Figure 2

Aspects of the disclosure relate to a package, a carrier (90) for packaging one or more articles (B, B1, B2) and a blank (10; 110; 210; 310A, 310B) for forming the carrier. The package comprises an article carrier and one or more articles. The carrier comprises a main panel (14) having at least two article retention structures for receiving and securing the main panel to a respective article. Each of the at least two article retention structures comprises a center. The center C of the at least two article retention structures is spaced apart from the center of an adjacent one of the at least two article retention structures by a distance. The distance is greater than the maximum diameter of each of the at least two articles.

The high-sensitivity and large-stroke air spring mechanism comprises an air spring body and a pressure storage bin, the air spring body comprises an elastic telescopic part and a sealing plate, the elastic telescopic part comprises a plurality of telescopic units connected in sequence, each telescopic unit comprises a disc-shaped sleeve and an annular edge plate, and the disc-shaped sleeve is connected with the sealing plate. The middle of the side wall of the dish-shaped sleeve is concaved inwards to form a V shape, an inner hole in the middle of the dish-shaped sleeve comprises conical hole sections located on the two end sides and a middle hole section, the dish-shaped sleeve can stretch and deform when subjected to axial force, when the dish-shaped sleeve is in a natural state, the diameter of the maximum diameter position of each conical hole section is D2, the diameter of each middle hole section is D1, and D1 / D2 is smaller than or equal to 1 / 4. Annular edge plates are fixedly arranged at the two ends of the dish-shaped sleeve correspondingly, the annular edge plates of every two adjacent telescopic units are fixedly connected, and sealing plates are connected to the two end sides of the elastic telescopic part correspondingly. And the pressure storage bin is communicated with a spring air cavity in the air spring body through a pipeline.

The utility model relates to a novel blank punching tool which comprises a die body, a forming cavity and a limiting cavity which sequentially extend in the vertical direction are formed in the middle of the die body, and the forming cavity is communicated with the limiting cavity. The base assembly comprises a leakage plate pad and an insert, the leakage plate pad is embedded in the limiting cavity, a first through hole extending in the vertical direction is formed in the middle of the leakage plate pad, a limiting part is formed in the position, located at the top end of the first through hole, of the leakage plate pad, the insert abuts against the limiting part, and a second through hole extending in the vertical direction is formed in the middle of the insert; the maximum diameter of the second through hole is smaller than or equal to the minimum diameter of the first through hole; and the outer peripheral surface of the punch assembly can be connected with the hole wall of the second through hole in a sliding manner. The utility model provides a novel blank punching tool with high efficiency and high yield through the die body, the drain plate, the insert and the punch assembly, and the novel blank punching tool has the advantages of good interchangeability, reduction of the cost of forgings and guarantee of the product quality.

This invention proposes a mold steel with uniformly distributed inclusions and a low deformation rate, and its manufacturing method. The steel plate composition, by weight percentage, is as follows: C: 0.45%–0.55%, Si: 0.20%–0.30%, Mn: 0.20%–0.40%, P≤0.015%, S≤0.015%, Cr: 3.0%–4.0%, Mo: 3.0%–3.5%, V: 0.70%–0.80%, Ni: 0.80%–0.90%, Sc: 0.02%–0.03%, Zn: 0.03%–0.05%, wherein Ni / V = 1.125–1.145, Sc+Zn = 0.06%–0.07%, and the balance is Fe and unavoidable impurities. The steel plate production method includes smelting, continuous casting, slab heating, rolling, straightening, slow cooling, normalizing + annealing pretreatment, and quenching and tempering. The number of inclusions per unit area in the microstructure of the mold steel of this invention is (192-205) inclusions / mm. 2 The average particle size is 1.75μm to 1.85μm, fine and uniformly dispersed. The ratio of the maximum diameter to the minimum diameter of the inclusions is 1.69 to 1.78, approximately spherical. The thickness of the mold steel of this invention is 30 to 180 mm; the hardness of the steel plate is 46 to 48 HRC, and the hardness difference between the thickness and the cross-section is ≤2 HRC; the unnotched room temperature transverse impact toughness of the core is 220 to 230 J; the wear volume at 800℃ is (25 to 26) × 10⁻¹⁰. ‑3 mm 3 It has high thermal conductivity at high temperatures, with a thermal conductivity of (35~36) W·m at 800℃. ‑1 ·K ‑1 .

A cylindrical side-wall core is acquired from an inner circumferential surface of a well at a predetermined depth from a ground surface. First, second and third measurement cross sections spaced apart in a longitudinal direction of the core are set. In each cross section, the length of the maximum diameter of the cross section where the amount of distortion relative to the diameter of a standard circle is largest and the length of the minimum diameter where the amount of distortion relative to the diameter of the standard circle is smallest are measured. Six independent components among stress tensors for defining three-dimensional stress elements are obtained using an equation representing a difference between maximum and minimum stresses acting on the side-wall core along each cross section and another equation representing the angle between the well excavation direction and the action direction of the maximum stress on each cross section.

The extrusion equipment for SPC floor production comprises a machine barrel, a pair of conical screws with opposite rotating directions, a driving device in transmission connection with the pair of conical screws and a confluence core installed at a discharging port of the machine barrel, and each conical screw comprises a conical rod body extending from front to back and a thread spirally extending around the conical rod body; the bottom diameter of the conical rod body is gradually reduced from front to back, the outer diameter of the threads is gradually reduced from front to back, the maximum diameter of the conical screw rod is 200-250 mm, and the minimum diameter of the conical screw rod is 100-150 mm; the conical rod body is sequentially provided with a feeding section, a first mixing section, a second mixing section, a first metering section, an exhaust section and a second metering section from front to back, the threads are double-end threads on the feeding section, the first mixing section and the second mixing section, the threads are single-end threads on the first metering section, the threads are four-end threads on the exhaust section, and the threads are three-end threads on the second metering section; the extrusion device can efficiently and stably extrude materials in a low-consumption and high-quality mode, and is particularly suitable for production of SPC plates.

The invention belongs to the field of abrasive grinding tools, and particularly relates to a wafer thinning grinding wheel and a preparation method thereof.The wafer thinning grinding wheel comprises a base plate 1, an abrasive coating 11 is fixed to the end face of the base plate 1, abrasive particles are arranged in the abrasive coating 11, and the abrasive particles comprise first abrasive particles 12 located at the bottom of the abrasive coating 11 and close to the end face of the base plate 1; the abrasive material further comprises second abrasive particles 13 arranged in a layer above the first abrasive particles 12, the average diameter of the first abrasive particles 12 is 110%-140% of the diameter of the second abrasive particles 13, and the minimum diameter of the first abrasive particles 12 is not lower than 70% of the maximum diameter.

The utility model discloses a special-shaped drill bit, which relates to the technical field of construction drilling equipment, can be arranged in a pile casing in a penetrating manner, and structurally comprises a sleeve, one end of the sleeve is used for being connected with a drill rod, and the other end of the sleeve is provided with a slag outlet; the special-shaped protective ring is fixedly arranged on the outer side of the sleeve in a sleeving mode, one side of the special-shaped protective ring is of an inwards-concave structure, and the maximum diameter of the special-shaped protective ring is smaller than the inner diameter of the protective cylinder. And the conical cutting edge is obliquely connected between the inner side of the special-shaped retainer and the side wall of the sleeve. According to the special-shaped drill bit, the drill bit can smoothly pass through a deformation area of a pile casing, the diameter of a follow-up drill hole meets the requirement, cost is low, and safety is high.

The invention discloses a self-centering tip measuring radius detection device and method, and belongs to the technical field of detection tools.The device comprises a base and a core rod, a center hole is formed in the center of the base, the core rod comprises a first rod body and a second rod body, the first rod body is cylindrical, the diameter of the first rod body is D1, the first rod body is in clearance fit with the center hole, and the second rod body is in clearance fit with the center hole; the second section of rod body is a trapezoidal cylinder, the maximum diameter of the second section of rod body is smaller than D1, a first measuring rod and a second measuring rod are arranged on the base, a first through hole is formed in the workpiece, the inner diameter of the first through hole is D2, the first measuring rod is located at the upper limit position of the tooth-shaped part measuring tip radius of the workpiece, and the second measuring rod is located at the lower limit position of the tooth-shaped part measuring tip radius of the workpiece. The upper limit and the lower limit of the workpiece are judged to have uniqueness; and the first section of rod body moves up and down in the central hole to play a guiding role and self-center the workpiece to be detected, so that the problem that the workpiece is difficult to center due to large tolerance of the through hole is solved.

To solve the problem that a handle grip of a spinning reel is easily damaged when the spinning reel is placed on a floor surface, etc., and its appearance and commercial value are lowered. Further, the handle grip is often made of metal, resin, or the like, and is slippery, so that a fish caught during fishing may be missed. To improve the touch of a handle grip and enable comfortable fishing.SOLUTION: A hollow handle grip cover made of an elastic material having a hole at the approximate center of each hemispherical part when an approximately spherical thin-walled handle grip cover is assumed to be divided into two hemispherical parts, and at least one of the holes is extended to a size capable of passing the maximum diameter part of the handle grip without damaging it, is freely exchangeably put on and mounted. The spinning reel to which the handle grip cover is previously attached in a production stage, etc., is made available to a purchaser.SELECTED DRAWING: Figure 1

The name of the utility model is a scratch-proof platinum crucible transportation device. Belongs to the technical field of optical glass platinum crucible transportation and placement. The device mainly solves the problems that the platinum crucible is easy to deform and scratch during installation and transportation and the structure of the platinum crucible is easy to damage during hoisting. The device is mainly characterized by comprising a support ring and a support ring support frame, the diameter of the support ring is smaller than the maximum diameter of the outer upper part of the platinum crucible; the space of the inner side of the supporting ring supporting frame is larger than the space occupied by the platinum crucible. According to the device, a platinum crucible is placed on the inner wall of the supporting ring, a platinum tube is fixed in the supporting clamping groove, therefore, the platinum crucible is prevented from being scratched and deformed due to shaking in the transportation and placement process, the transportation risk is reduced, it is guaranteed that the structure is not damaged, in addition, the supporting ring is sleeved with glass fiber cotton, and the situation that stainless steel is attached and rubbed with the platinum crucible due to high hardness is avoided. The device is mainly used for transporting and placing the platinum crucible.

To form a plating film with good continuity on a baked film that serves as the base in an external conductor disposed on the outer surface of a component element.SOLUTION: An outer conductor 11 includes, from the component body side, at least a baked film 13 and a plating film 14 in contact with the baked film 13, and the baked film 13 includes silver 22 and glass 23. A glass floating portion 21 derived from the glass 23 is exposed on the surface of the baked film 13 in contact with the plating film 14, and the maximum diameter of the glass floating portion 21 is 4.8 μm or less. This 4.8 μm can be considered the critical value for the maximum diameter of the glass floating portion 21 at which the continuity of the plating film 14 on the underlying baked film 13 can be maintained.SELECTED DRAWING: Figure 5

Device (10) for holding a component (20) to be encased in plastic, wherein the device (10) has a retaining element (11) for generating a releasable mechanical positive connection with a fastening area (21) of the component (20), characterized in that the retaining element (11) has a plug-and-turn locking element (12), wherein the retaining element (11) has a mandrel (13) extending along an axial direction (100), wherein the mandrel (13) has a cylindrical first sub-section (13') and a cuboid second sub-section (13''), wherein the maximum diameter of the second sub-section (13'') is smaller than the maximum diameter of the first sub-section (13'), and wherein the plug-and-turn locking element (12) is formed in an end region of the second sub-section (13'') and comprises at least one positive locking element (14),wherein at least one positive locking element (14) projects from the mandrel (13) along a transverse direction (101) perpendicular to the axial direction (100) of the mandrel (13).

The utility model discloses a ceramic fiber tube forming die which comprises two groups of die bodies, a first connecting block and a second connecting block are respectively fixed on two sides of the die bodies. Compared with the prior art, due to the split type mold body structural design, the risk of structural damage during demolding of the ceramic fiber pipe is remarkably reduced, the first connecting block and the second connecting block arranged on the two sides of the mold body are accurately engaged through a step structure and anti-skid lines and are matched with the first bolt for locking, and the sealing performance and stability of the forming cavity are ensured; the mold core is of a gradually-changed taper structure, the maximum-diameter end is fixed to the connecting flange, contact resistance between a fiber pipe and the mold core during demolding is effectively reduced, the pressure relief opening releases redundant gas in the initial forming stage to avoid the bubble defect, the supporting spring pushes the sealing plate to close the air hole to maintain forming pressure in the later stage, and the rejection rate is greatly reduced; and meanwhile, the split type die body design simplifies the die maintenance process, and the production cost is reduced.

The present invention addresses the problem of providing a vacuum suction pad capable of reliable and stable suction regardless of the shape and orientation of an egg. As the means for solving the problem, the present invention is a vacuum suction pad (10) that suctions a prescribed egg (E), is formed in a cylindrical shape, and can expand and contract along the direction of an axis (12) of the cylindrical shape. The vacuum suction pad comprises: a first contact part (16) that is formed as an opening (14) and has a first tapered shape; a second contact part (18) that is formed closer to an intake side than the first contact part (16) and has a second tapered shape; and a first bellows part (20) that is formed between the first contact part and the second contact part and protrudes outward. The maximum diameter (X1) of the first contact part (16) is 0.6-1.2 times the lateral dimension of the egg (E), the maximum diameter (X3) of the second contact part (18) is smaller than the minimum diameter (X2) of the first contact part (16) and 0.3-0.7 times the lateral dimension of the egg (E), and the egg (E) is suctioned by the first contact part (16) and the second contact part (18).

The objective is to provide a thermally conductive sheet that offers superior insulation properties in addition to thermal conductivity. [Solution] The material comprises a reinforcing material and a resin layer laminated on the front and back surfaces of the reinforcing material, wherein the resin layer contains resin and agglomerated boron nitride, and in particles of the agglomerated boron nitride with an area circle equivalent diameter in the range of 20 to 100 μm, the codispersion between the area circle equivalent diameter and the maximum Ferret diameter is 275 μm. 2 The following is a heat dissipation sheet.

A foam molded body provided with a foam layer and a skin layer covering the foam layer, the foam molded body being characterized in that: the maximum diameter of air bubbles in the foam layer is 0.90 mm or less; a method for producing a foam molded article or a method for suppressing appearance defects, the method comprising an injection step and a foaming step, the foam molded article after molding being provided with a foam layer and a skin layer covering the foam layer, the skin layer having an average thickness of 0.3 mm to 0.7 mm, expanding the volume of the cavity includes withdrawing the mold such that the thickness of the foam molded body after molding is within + / -0.2 mm with respect to a preset target thickness.

A casting roller shape design method for cooperative control of thermal convexity compensation and edge reduction is suitable for improving casting strip section defects caused by large thermal convexity of a casting roller in the thin strip casting and rolling process and comprises the steps that a casting roller body curve is divided into a middle area and an edge area according to the thermal expansion distribution condition of the casting roller, the middle area plays a key role in the overall section contour shape of the casting strip, and the edge area adjusts the rolling reduction to avoid the edge crack defect of the casting strip. A cosine curve of the middle area is designed based on the preset maximum-diameter roller shape height and the casting roller thermal convexity; then superposing two sections of cosine curves to obtain an edge curve; and further, in combination with continuous and smooth connection conditions of the curve, a roll shape curve of the whole roll body is finally obtained. According to the method, the roll shape of the casting roll is designed based on the piecewise function, the hot convexity compensation principle is followed, meanwhile, the edge pressing control of the casting strip is considered, the problem that the section shape of the casting strip is poor due to thermal expansion of the casting roll is effectively solved, and the probability of the edge crack defect of the casting strip is reduced.

The application provides a variable-diameter pipeline connecting piece and a variable-diameter connecting method. The variable-diameter pipeline connecting piece is designed with a connecting piece body with bendable teeth, realizes the variable-diameter function of the pipeline connecting piece, can adapt to the pipeline connecting requirements of different pipe diameters, effectively reduces pipeline connecting nodes, reduces the occurrence of leakage hidden dangers, reduces the workload of maintenance, saves construction efficiency, reduces material consumption. The structural design of the teeth makes the variable-diameter process simple and stable, the setting of the maximum diameter and the minimum diameter ensures that the connecting piece can cover a wide range of pipe diameters, improves the degree of freedom of pipeline connection, saves larger diameter pipelines, optimizes the size of the floor sleeve, and improves the construction effect of fireproof plugging.

The invention relates to a print head (10) for a 3D printer (1), comprising a feed zone (11) with a feeder (12) for a starting material (21) with variable viscosity, a plasticizing zone (14) with a heater (15) and an outlet opening (16) for the liquid phase (22) of the starting material (21), and a conveying device (30) for conveying the starting material (21) from the feed zone (11) to the plasticizing zone (14), wherein the conveying device (30) comprises a piston (31) that can be inserted into the feed zone (11), wherein the piston (31) has a first piston section (5) facing the plasticizing zone (14) with a guide surface (9) through which the piston (31) is guided in a recess (7) of the print head (10), wherein the piston (31) is connected by a positive locking connection of the first piston section (5) is secured against radial rotation by the recess (7) of the printhead (10). It is characterized by the fact that the first piston section (5) and the recess (7) of the print head (10) form a cross-sectional area (F), wherein a maximum diameter (d1) of the cross-sectional area (F) is formed by a circle (2) and the cross-sectional area (F) has rotationally symmetric circular segment-shaped recesses (3).