JP2006259540A - Heating roller, fixing device provided with the heating roller, image forming apparatus provided with the fixing device, and manufacturing method of core bar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating roller without the need of using a thick pipe stock even in the case that a thin heating roller of a small diameter is demanded and without the risk of breaking a core bar when in use. <P>SOLUTION: The heating roller with a built-in heat source 55 in which an endless fixing belt 45 provided with a skew stop member on the inner periphery is disposed together with a fixing roller comprises: a metal cylindrical pipe 41b provided with a body part 41c and a shaft part 41d in which the diameter of both ends of the body part 41c is reduced; a ring-like member 411 provided coaxially with the metal cylindrical pipe 41b on the shaft part 41d of the metal cylindrical pipe 41b and engaged with the skew stop member 452; and a projection part provided on the shaft part 41d on the outer side of the ring-like member 411 by plastic deformation for positioning the ring-like member 411 toward the body part 41c. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing type fixing device for fixing a toner image formed on transfer paper or the like by heating and pressing in an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and a heating roller used in the fixing device. It is.

  FIG. 6 is a schematic diagram showing a basic configuration of a conventional image forming apparatus and an image forming apparatus to which the present invention can be applied. FIG. 6 schematically shows the configuration of a four-color tandem full-color printer. This printer has four sets of electrophotographic systems for forming four color toner images of yellow, magenta, cyan, and black on the surfaces of the corresponding photosensitive drums 1Y, 1M, 1C, and 1Bk (image carrier). Image forming units 10Y, 10M, 10C, and 10Bk (image forming means).

  Below these image forming units 10Y, 10M, 10C, and 10Bk, a conveying belt 20 is stretched to convey a sheet (recording material) through each image forming unit. The photosensitive drums 1Y, 1M, 1C, and 1Bk of the image forming units 10Y, 10M, 10C, and 10Bk are respectively arranged in contact with the conveyance belt 20, and the sheet (recording material) is electrostatically applied to the surface of the conveyance belt 20. Adsorbed.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk have substantially the same structure. Therefore, here, the yellow image forming unit 10Y disposed on the most upstream side in the sheet conveyance direction will be described as a representative, and the other color image forming units 10M, 10C, and 10Bk are denoted by the same reference numerals. Detailed description is omitted.

  The image forming unit 10Y has a photosensitive drum 1Y that is in contact with the conveyance belt 20 at a substantially central position. Around the photosensitive drum 1Y, a charging device 2Y for charging the surface of the photosensitive drum 1Y to a predetermined potential, the charged drum surface is exposed based on the color-separated image signal, and the surface of the drum is electrostatically charged. An exposure device 3Y that forms a latent image, a developing device 4Y that supplies yellow toner to the electrostatic latent image formed on the drum surface and develops it, and a developed toner image on a sheet that is conveyed via the conveyance belt 20 A transfer roller 5Y (transfer device) for transferring, a cleaner 6Y for removing residual toner remaining on the drum surface without being transferred, and a charge eliminating lamp for removing electric charge remaining on the drum surface (not shown) are provided in the rotational direction of the photosensitive drum 1Y. Are disposed in order.

  A paper feed mechanism 30 for feeding paper onto the transport belt 20 is disposed on the lower right side of the transport belt 20 in the drawing. A fixing device according to the present invention, which will be described in detail later, can be disposed on the left side of the conveying belt 20 in the drawing. The paper transported by the transport belt 20 is transported through a transport path continuously extending from the transport belt 20 through the fixing device 40 and passes through the fixing device 40.

  The fixing device 40 heats and pressurizes the conveyed paper, that is, the paper on which the toner images of the respective colors are transferred. Then, the toner images of the respective colors are melted and permeated into the paper to be fixed. In addition, the paper is discharged to the downstream side of the conveyance path of the fixing device 40 via a paper discharge roller.

  In an image forming apparatus as shown in FIG. 6, conventionally, a heat fixing method using heat and pressure is generally used as a method for fixing a toner image formed on transfer paper.

  Specifically, the toner image formed on the recording paper (same as the transfer paper) is passed along with the transfer paper between a fixing roller having a heating source inside and a pressure roller facing the toner, Heat is applied to cause melting, and at the same time, the toner image is fixed on the transfer paper by the pressure between both rollers.

  In recent years, colorization and rise time of the image forming apparatus have been further advanced. First, coloration increases the amount of toner to be fixed (latent images are formed using four-color toners of Y yellow, M magenta, C cyan, and B black), so that there is a gap between the fixing roller and the pressure roller (nip portion). ), The adhesion of the melted toner to the roller has become a problem. As a result, wrapping of the transfer paper is likely to occur due to the toner offset to the roller.

  As a countermeasure, a belt fixing system as shown in FIG. 7 is mainly used. In this belt fixing method, the fixing roller is not directly heated but is passed through the nip portion via the indirectly heated fixing belt 45 in contrast to the above-described roller fixing method using the fixing roller and the pressure roller. Immediately after the molten toner is cooled, the viscosity of the toner is lowered, so that adhesion to the surface can be prevented. Further, the rubber hardness on the side of the pressure roller 43 with respect to the fixing roller 42 is made harder, and the nip surface is set on the side of the pressure roller, so that the direction of discharge of the transfer paper after passing through the nip is set on the pressure roller side (generally By taking it to the “downward nip”), the separability can be improved.

  In the fixing device using the fixing belt, as a means for heating the fixing belt 45, in many cases, a roller having a heating source such as a halogen heater 55 installed therein, that is, a heating roller 41 is used.

In order to shorten the rise time, it is necessary to heat the fixing belt 45 to a predetermined temperature more quickly with a fixing device using the fixing belt 45. As the means, the thickness of the heating roller 41 is reduced, the winding amount of the fixing belt 45 is increased, the outer diameter of the heating roller 41 is reduced, and the distance from the halogen heater 55 as an internal heat source is shortened. A method is conceivable.
JP 2000-1237 A JP 2002-182501 A JP 2002-126824 A JP 2002-126904 A Japanese Patent Laid-Open No. 10-221993

  Here, the shape of the heating roller 41 in the belt fixing method will be described with reference to FIG.

  In the fixing device 40, a fixing belt 45 is disposed on a body portion of the heating roller 41, and a bearing member 54 such as a bearing is attached to a shaft portion (hereinafter referred to as a journal portion).

  Therefore, the heating roller 41 is rotatably held and is configured to be rotated along with the rotational movement of the fixing belt 45. Further, a detent member 452 is bonded to the inner surface end of the fixing belt 45 as means for preventing the fixing belt 45 from shifting. The detent member 452 has a thickness of about 2 mm in order to obtain the effect, and when viewed from the inner surface of the fixing belt 45, it can be seen that it has a guide shape with a height of about 2 mm.

  The detent member 452 naturally moves together with the fixing belt 45, but when the detent member 452 comes into strong contact with the end of the body portion of the heating roller 41, a climbing phenomenon occurs and the fixing belt 45 moves away from the heating roller 41. As a result (generally, “belt shift phenomenon”), heat may not be sufficiently transferred from the heating roller 41 to the fixing belt 45, or in the worst case, the fixing belt 45 may be damaged. In order to avoid such a situation, it is necessary to suppress the shift so that it does not meander when the fixing belt 45 rotates and moves in an appropriate shape so as not to run over the end portions of the locking member 452 and the heating roller 41. . Further, the journal portion outer diameter is smaller than the inner peripheral diameter of the detent member 452, that is, a gap is required between the detent member 452 and the journal portion outer diameter so that the detent member 452 does not protrude.

  Accordingly, when the positional relationship with the fixing belt 45 in the vicinity of the end of the body portion of the heating roller 41 is viewed, the outer diameter dimension of the journal portion side facing the detent member 452 is one side of the outer diameter of the body portion of the heating roller 41. A step portion having a small diameter of about 2 mm and a diameter of about 4 mm is required.

Here, the prevention measures against the above-mentioned “belt slip phenomenon” will be described.
The prior art described in Patent Document 1 and Patent Document 2 is a basic technology described in the text, and is a disclosure of a technique for preventing meandering during rotation movement of the fixing belt by attaching the above-described detent member to the fixing belt. is there. However, in these conventional techniques, a step portion is required to guide the detent member at the end of the body portion of the heating roller that is driven and rotated as described above. Can not be realized, that is, energy saving (rise time is shortened).

  Here, the cross-sectional shape of the heating roller 41 will be described. In the inner diameter part of the heating roller 41, the body thickness is reduced in order to shorten the rise time, the cylinder is tubular, and the halogen heater is provided inside. The heating source 55 must be held. Therefore, it is necessary to form the body portion and the journal portion with a constant thickness.

  First, the manufacturing process of the journal part of the cored bar 41a used for the heating roller 41 will be described with reference to FIG.

  As described in Patent Document 3 and Patent Document 4 previously disclosed by the present applicant, the barrel portion of the core bar 41a before processing (hereinafter also referred to as a blank tube or a metal cylindrical tube) is fixed by a collet chuck 103 or the like. This is a spinning method in which the journal portion is drawn while the drawing tool 101 is brought into contact with, pressed against, and moved on the outer peripheral surface of the raw tube 41a in a state of being gripped and rotated.

  Both ends of the raw tube are similarly reduced in diameter to form a journal portion, and the journal portion is cut to finish a predetermined shape dimension. After that, in order to complete the heating roller 41, the outer diameter of the body portion is cut to ensure dimensional accuracy, and then a surface layer is formed on the surface layer of the body portion by a release material made of fluororesin or the like, an alumite treatment, or the like.

  Since it is difficult to ensure the accuracy of the shape by a single spinning process, the predetermined amount is formed by adjusting the push-in amount and position and dividing the process into several times. In addition, since it can be dry-processed and does not use processing oil, it is a construction method that does not require a cleaning process.

  Next, the shape of the end portion of the body portion of the heating roller 41 will be described.

  Although the present invention is directed to the fixing device 40 using the fixing belt 45, a roller fixing device that does not use the fixing belt 45 will be described for comparison. Since the fixing belt 45 is not used, the configuration is as follows.

  The fixing roller 141 in which a heating source 55 such as a halogen heater is installed is generally a hard roller having no elastic layer such as silicone rubber in the surface layer portion, and is responsible for both heating and fixing. For easy discrimination, this hard roller is called a heat fixing roller 141.

  In the heat fixing roller 141 (see FIG. 11) used in the roller fixing device that does not use the fixing belt 45, for example, if the outer diameter of the body portion of the heat fixing roller 141 is 30 mm and the outer diameter of the journal portion is 20 mm, The step of the body is 5 mm on one side, and since the fixing belt 45 is not used, the detent member 452 does not exist, there is nothing that contacts the body end of the heat fixing roller 141, and the shape of the body end There is no problem even if it has a slope. Therefore, it is easy to maintain and secure the required wall thickness by performing a process of giving an inclination by spinning process (see FIG. 11).

  On the other hand, in the fixing device 40 using the fixing belt 45 described in the present invention, contact (interference) with the detent member 452 positioned at the end portion of the inner peripheral surface of the fixing belt 45 becomes a problem. As a means for avoiding this, it is necessary to make the inclination of the end portion of the body portion and the journal portion at right angles as described above.

  Also in the prior art described in Patent Document 2, the shape of the end portion of the body portion of the heating roller on the side that suppresses meandering during rotation of the fixing belt relative to the fixing roller (see reference numeral 4 in Patent Document 2) (in Patent Document 2) I think that it can be seen from the point that the reference numeral 3) is a right angle.

  FIG. 10 shows an ideal shape, but in the current spinning process, the gripping force of the collet chuck 103 that holds the body of the element tube 41a and the rigidity of the element tube 41a itself counter the processing force of the spinning process. For this reason, if the shoulder shape angle at the time of drawing is abruptly bent, the rigidity of the raw tube is lost and sagging occurs. (See Figure 12)

  Sagging due to spinning occurs in two places as shown in FIG. The sagging part A is not a problem because most of the sagging part A is removed when the body part is cut. On the other hand, the sagging part B is an important part related to how much thickness is secured at the base of the journal part after cutting of the journal part.

  When the curvature of the sag portion B is large, the wall thickness td remaining at the time of cutting is thin, so that it is desired to have a curvature as small as possible, but it cannot be partially bent. As a result, the only way to ensure the thickness after cutting is to increase the thickness remaining in the sag portion B by using a thick-walled tube. In addition to this, the smaller the dimensional difference between the outer diameter of the body portion and the outer diameter of the journal portion, the smaller the amount of bending, making it difficult to make a sag portion with a small curvature.

  As another means for forming the journal part, swaging is one of the most frequently used methods. The cross section of the journal portion obtained by this swaging process is as shown in FIG. 13, but since it has a large curvature as in the case of FIG. 12, the thickness of the raw tube 41a is ensured in order to ensure the thickness. There is no choice but to deal with thickness.

  That is, in order to ensure the durability (strength) of the core metal 41a even when a thin core metal having a body thickness t of 0.6 mm or less is necessary as the heating roller 41, that is, to secure a desired thickness of the sag section. In order to do this, it is necessary to manufacture from a tube thickness of 2 mm or more because of the above-described workability, and a thickness of 50% or more will be discarded as chips.

  For this reason, not only is the material cost high because of the thick-walled tube (thickness of 2 mm or more), but the number of cuttings increases, resulting in a decrease in productivity.

  Accordingly, the present invention provides a heating roller that does not require the use of a thick-walled tube even when a thin-walled and small-diameter heating roller is required, and that does not cause a core metal breakage during use. For the purpose. It is another object of the present invention to shorten the rise time by a fixing device using the heating roller and to save energy.

The invention according to claim 1 is a heating roller including a heat source in which an endless fixing belt provided with a detent member on the inner periphery is stretched together with a fixing roller.
A metal cylindrical tube having a body part and a shaft part whose diameters are reduced at both ends of the body part;
A ring-shaped member that is provided coaxially with the metal cylindrical tube at the shaft portion of the metal cylindrical tube and is engaged with the detent member;
A heating roller comprising: a convex portion provided by plastic deformation on the shaft portion outside the ring-shaped member, which positions the ring-shaped member toward the body portion.

  The invention according to claim 2 is characterized in that the convex portion is formed between the concave portion and the ring-shaped member by forming a concave portion adjacent to the outside of the convex portion. It is a heating roller as described in above.

  The invention according to claim 3 is the heating roller according to claim 1 or 2, wherein the ring-shaped member is made of a material having a smaller thermal expansion coefficient than a metal material used for the metal cylindrical tube. .

Invention of Claim 4 is a manufacturing method of the metal core used for the heating roller of Claim 1 or 2,
Both ends of a metal cylindrical tube made of an aluminum alloy are reduced in diameter by drawing to form a shaft,
In a state where another ring member is inserted into the shaft portion, a convex portion is formed by plastic working on the outside where the shaft ring member is inserted again by drawing,
The ring-shaped member is supported in a state in which the ring-shaped member cannot move with respect to the metal cylindrical tube.

According to a fifth aspect of the present invention, there is provided an endless fixing belt stretched between a fixing roller and a heating roller having a built-in heat source, a detent member provided on an inner periphery of the fixing belt, and the fixing belt. A fixing device for fixing through a recording material carrying an unfixed toner image in a nip portion between the fixing belt and the pressure roller.
The heating roller is a metal cylindrical tube having a body part and a shaft part whose both ends of the body part are reduced in diameter,
A ring-shaped member that is provided coaxially with the metal cylindrical tube at the shaft portion of the metal cylindrical tube and is engaged with the detent member;
A fixing device comprising: a convex portion provided by plastic deformation on the shaft portion outside the ring-shaped member for positioning the ring-shaped member toward the body portion.

  According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising the fixing device according to the fifth aspect.

  According to the first, second, or fourth aspect of the present invention, even when a thin and small-diameter heating roller is required, the present invention does not require the use of a thick-walled tube, and the core in use. It is possible to provide a heating roller that is free from gold damage.

  According to the third aspect of the invention, the “loosening” can be prevented by the occurrence of the difference in thermal expansion, and a stronger fixation becomes possible.

  According to the invention according to claim 5 or 6, the rise time can be shortened and energy saving can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In order to achieve the above object, according to the present invention as shown in FIG. 1, a ring-shaped member 411 is provided between a body portion 41c of a cored bar 41a for a heating roller 41 and a journal portion 41d on which a bearing is supported. .

[First embodiment]
FIG. 7 is a diagram showing a basic configuration of a fixing device 40 using the heating roller 41 of the present invention. As a configuration, a fixing belt 45 is sandwiched between the fixing roller 42 and the heating roller 41, and a pressure roller 43 is supported at a position opposite to the fixing roller 42.

  Inside the heating roller 41, a halogen heater 55 as a heating source is held without contacting the heating roller 41. Although not shown in FIG. 7, the halogen heater 55 may be disposed inside the pressure roller 43. In this fixing device, the toner s on the transfer paper S is inserted between the fixing roller 42 and the pressure roller 43 and passed therethrough, thereby fixing the toner s.

  FIG. 1 is a sectional view showing a basic configuration of a heating roller 41 used in the present invention.

  The structure is composed of a cored bar 41a and a surface layer (not shown). The metal core 41a is a metal cylindrical tube made of an aluminum alloy, and the body part 41c has a thin wall thickness because the outer diameter of the body part is 25 mm and the rise time is important as the heating roller 41, and the body part thickness t is 0.4 mm.

  The journal portions at both ends have an outer diameter of 20 mm and a wall thickness of t1 mm or more to ensure strength. The ring-shaped member 411 of the present invention is held in the vicinity of the end of the body portion of the journal portion 41d.

  The inner surface of the metal core is coated with black paint (not shown) in order to enhance heat absorption, and the outer surface of the metal core is a mold release material to prevent wear due to contact with the fixing belt 45 combined. A surface layer (not shown) made of fluororesin or the like, or a coating layer (substitute for the surface layer) is formed on the entire surface of the heating roller by alumite treatment.

  The method of providing the ring-shaped member 411 in the journal portion described in the present invention will be described below.

  First, the journal part is formed by the spinning process described above. However, as described above, the step between the end portion of the trunk portion and the journal portion as shown in FIG. 10 shown in the conventional example, that is, the shape of the end portion is not in a nearly right angle state, but in a shape having an inclination as shown in FIG. Good.

  For this reason, the thickness of the shoulder portion is not reduced by plastic processing such as spinning, and can be processed in a state where t = 1 mm or more, which is substantially the same as that in the raw pipe, is secured.

  Next, after spinning the journal part, an end face (centering) process as a process reference is performed later. As a result, center references (in this embodiment, the center angle is 60 degrees, but may be an angle that forms a pair with both side center jigs 104 of the NC lathe described later) are provided at both ends.

  Further, in this state, the reference surface of the ring-shaped member 411 is processed in the journal portion while the core bar 41a is gripped by the center jig 104 with an NC lathe. (See FIGS. 3A to 3C.)

  Here, the core bar 41a is once removed from the NC lathe, the ring-shaped member 411 is inserted into a desired position (see FIG. 3D), and is gripped by the center jig 104 again (see FIG. 3E). ).

  In this state, a roller tool 105 shown in FIG. 3 (F) is used to push into a predetermined position on the end side of the ring-shaped member 411 to form a groove which is a recess by plastic working. As a result, the surface can be raised when the groove is formed, and a convex portion 412 is formed as shown in FIG. 3 (F) and as shown in FIG. 4, and the ring-shaped member 411 is integrated with the cored bar 41a in a state where it cannot move. It is formed.

  As a result of the above processing, a bulge (inner surface rib 413) is formed by plastic processing on the inner peripheral surface at the same position in the cross-sectional shape by groove processing. Therefore, there is no decrease in rigidity due to the thinning of the groove portion, and it can be easily fixed.

  In this grooving, the roller tool 105 rotates with the rotation of the cored bar 41a. In this case, the rotational speed of the cored bar 41a is 350 rpm. The pushing speed at the time of pushing was set to φ0.1 mm / rev.

  Next, the convex portion 412 is formed by groove processing, and the groove portion is cut to a predetermined outer diameter by cutting the outer diameter of the journal portion to eliminate the groove. In this case, there is no groove when finished, but a considerable amount of swell (inner rib 413) is formed on the inner peripheral surface by groove processing at the inner diameter portion (see FIG. 2).

  Further, the body can be used as the heating roller 41 by cutting the outer diameter of the body into a desired shape with a cutting tool such as a diamond tool (see FIG. 3G). Finally, the surface of the cored bar 41a is painted to complete the heating roller 41.

  As a result, the shoulder thickness can secure a desired strength, and can suppress the climbing of the detent member 452 of the fixing belt 45.

  Here, supplementation of the method of forming the convex portion 412 that integrally fixes the ring-shaped member 452 is the same processing method as the reinforcing rib 414 that is performed using the roller tool 105 described in Patent Document 3 and Patent Document 4.

  Further, the cross-sectional shape of the convex portion 412 to be formed does not need to be particularly defined because stress concentration due to pressure deformation is not applied as described in Patent Document 5. That is, any shape that can integrally fix the ring-shaped member 411 in a non-movable state may be used.

  Here, the ring-shaped member 411 will be described. As shown in FIG. 5, the ring-shaped member 411 is formed of an aluminum alloy having an outer diameter φ = 25 mm, an inner diameter φ = 22 mm, and a wall thickness t = 2 mm.

  Although the heat capacity as the cored bar 41a is slightly increased by installing the ring-shaped member 411, there is no problem because it is formed in the journal part instead of the body part for fixing the toner s. Furthermore, it is possible to cope with the light distribution adjustment of the halogen heater 55. Since the heat capacity is increased at the end portion of the body portion, there is no problem in the characteristics at the time of rising. Conversely, an increase in heat capacity on the end side is advantageous for a drop in temperature during continuous paper feeding.

[Second Embodiment]
Next, in the above description, the convex portion 412 is formed by groove processing, and the groove portion is cut to a predetermined outer diameter by cutting the outer diameter of the journal portion to eliminate the groove, but the roller tool is more than in the case of the first embodiment. The groove depth to be formed may be deepened by deeply pushing 105. In this case, there is a groove when finished, but since a considerable amount of swell (inner surface rib 413) is formed on the inner peripheral surface by groove processing in the inner diameter portion, sufficient rigidity can be obtained without lowering the strength. (See FIG. 4).

[Third embodiment]
Further, the ring-shaped member 411 is made of a SUS material having a different thermal expansion from that of the raw tube material (aluminum alloy in the first and second embodiments), specifically having a low thermal expansion coefficient. As a result, when the heating roller 41 is heated to a predetermined temperature (generally around 170 ° C.) to fix the toner s, “loosening” can be prevented due to the occurrence of a difference in thermal expansion, and a stronger fixation can be achieved. It becomes possible.

  Of course, the outer diameter and inner diameter of the ring-shaped member 411 as shown in FIG. 5 are defined by the component layout of the fixing device 40 to be used. Satisfied. Further, it is well known that the inner diameter is appropriately set depending on the shape of the journal portion.

  Further, the thickness t = 2 mm is also set appropriately on the component layout if sufficient rigidity can be obtained in order to suppress the deviation of the fixing belt 45.

  Finally, through the first to third embodiments, as the cross-sectional shape of the body core of the heating roller 41, a reinforcing rib 414 as shown in Patent Document 3 and Patent Document 4 previously disclosed by the present applicant is provided. It may be done, of course, no problem.

[Embodiment]
An embodiment of the fixing device 40 using the heating roller 41 according to the present invention will be described below.

  Reference numeral 40 denotes a fixing device of a heat fixing system, reference numeral 41 denotes a heating roller according to the present invention, reference numeral 55 denotes a heating source (halogen heater) provided on the axis of the heating roller 41, and reference numeral 54 denotes a support not shown. A bearing 44 that rotatably supports the heating roller 41 on a frame or the like, a reference numeral 44 is a tension roller that applies a tension force F to the fixing roller 42 and the fixing belt 45 stretched around the heating roller 41.

  Further, a cleaning roller 56 (not shown) that removes the toner s that is offset from the surface of the fixing belt 45 and a transfer sheet S that is fixed with the toner s (not shown) are wound around the fixing belt 45 on the paper discharge side. In such a case, a separation claw 53 that contacts the surface of the fixing belt 45 on the downstream side of the sheet passing may be provided in order to forcibly peel off.

  For controlling the temperature of the heating roller 41, the heating roller control temperature sensor 51 is in contact with the outer peripheral surface of the fixing belt that is in contact with the heating roller 41, and the pressure roller control temperature sensor 52 is in contact with the pressure roller 43. . Generally, a thermistor is used for the temperature sensors 51 and 52.

  The fixing belt 45 has an elastic layer formed of a silicone rubber having a thickness of 200 to 300 μm on a PI (polyimide) film, and a thin film layer made of a fluororesin layer is coated on the surface layer. At both ends of the fixing belt 45, a detent member 452 having a thickness of 2 mm and a width of 3 mm and a hardness of about 60 degrees (Asker C) is bonded.

  The heating roller 41 includes a metal core 41a made of an aluminum alloy, and a resin layer (not shown) provided on the outer surface of the metal core 41a. The core bar 41a has a schematic shape formed of an aluminum alloy A6063 as a base, and has an outer diameter of 25 mm, a length of 350 mm, and a wall thickness of t0.4 mm. The inner peripheral surface of the cored bar 41a is coated with an inner surface coating (not shown) with a black paint.

  In the evaluation of the heating roller 41, the rise time under the fixing conditions of the medium speed machine class with a linear speed of 162 mm / s and a fixing temperature of 160 ° C. was evaluated. In the fixing device 40 used in this embodiment, the total power of the halogen heater 55 on the heating roller 41 side is 800 W, and the halogen heater 55 on the pressure roller 43 side is 400 W. Other parts are common.

  The temperature measurement point was measured at the site before the nip. For temperature measurement, a contact temperature sensor (E-type thermocouple) is brought into contact, and the rise time is defined as the time required to raise the temperature at the center of the paper passing area to the temperature required for fixing (fixing temperature = 160 ° C.). .

  As a result, when the outer diameter φ30 mm of the heating roller 41 as shown in FIG. 8 and the wall thickness t1.0 mm as shown in FIG. 8 is 99 seconds, the rising time is 99 seconds in the heating roller 41 described in the present invention. The seconds have been shortened.

  Here, the actual machine target has a rise time of 60 seconds or less, and the conventional technology cannot achieve the target.

  Next, the shifting state of the fixing belt 45 was confirmed. The evaluation method is to set the control temperature of the heating roller 41 to 200 ° C. (overshoot upper limit temperature assumed in the actual machine) in order to accelerate the shift state, rotate for 2 minutes at a linear speed of 162 mm / sec, and stop for 10 seconds. It repeated with the period of. When this operation was performed for 260 hours (calculated from the actual machine life), it was confirmed whether or not the fixing belt 45 was shifted.

  Specifically, the evaluation results are shown in the following Table 1. Table 1 is a comparison table of evaluation results of the fixing device 40 using the heating roller 41 according to the embodiment of the present invention.

  In addition, in the above, the imaginary line in sectional drawing of FIGS. 10-13, FIG. 2 represents the outline of the raw material outer peripheral surface after spinning processing, and the continuous line represents the outline after cutting. In addition, this invention is not limited to the said embodiment or Example. That is, various modifications can be made without departing from the scope of the present invention.

FIG. 9 is a cross-sectional view showing a heating roller according to an embodiment of the present invention, and is a cross-sectional view along the axial direction of the fixing device of FIG. It is an expanded sectional view which shows the positioning state of the ring-shaped member with which the heating roller of FIG. 1 is equipped. It is explanatory drawing which showed the manufacturing method of the core metal used for the heating roller of FIG. 1 in time series. It is a figure which shows the shape of a trunk | drum edge part among the manufacturing methods of the metal core used for the heating roller of FIG. It is an external view of the ring-shaped member with which the heating roller of FIG. 1 is equipped, (A) is a front view, (B) is sectional drawing. It is a schematic diagram showing a basic configuration of a conventional image forming apparatus and an image forming apparatus to which the present invention can be applied. FIG. 7 is a cross-sectional view illustrating a fixing device provided in the image forming apparatus of FIG. 6. (A) shows a conventional heating roller, and is a cross-sectional view along the axial direction along the line AA of the fixing device of FIG. 2, and (B) is an enlarged view of a detent portion. It is a schematic diagram which shows the spinning process which forms the journal part of the heating roller used also by one Embodiment concerning this invention. It is sectional drawing which shows the ideal shape regarding the trunk | drum edge part of the conventional heating roller. It is sectional drawing which shows the shape regarding the trunk | drum edge part of the conventional hard roller (heat-fixing roller). It is sectional drawing which shows the shape regarding the trunk | drum edge part of the conventional heating roller. It is sectional drawing which shows the shape of the trunk | drum edge part of the heating roller by a prior art.

Explanation of symbols

40 Fixing device (belt fixing method)
41 Heating roller 41b Metal cylindrical tube (element tube)
41c trunk 41d shaft (journal part)
42 Fixing roller 43 Pressure roller 45 Fixing belt 55 Halogen heater (heat source)
411 Ring-shaped member 412 Convex part 415 Concave part 452 Side stop member

Claims (6)

In a heating roller with a built-in heat source in which an endless fixing belt provided with a detent member on the inner periphery is stretched together with a fixing roller,
A metal cylindrical tube having a body part and a shaft part whose diameters are reduced at both ends of the body part;
A ring-shaped member that is provided coaxially with the metal cylindrical tube at the shaft portion of the metal cylindrical tube and is engaged with the detent member;
A heating roller comprising: a convex portion provided by plastic deformation on the shaft portion outside the ring-shaped member, which positions the ring-shaped member toward the body portion.   The heating roller according to claim 1, wherein the convex portion is formed between the concave portion and the ring-shaped member by forming a concave portion adjacent to the outside of the convex portion.   The heating roller according to claim 1 or 2, wherein the ring-shaped member is made of a material having a smaller thermal expansion coefficient than a metal material used for the metal cylindrical tube. In the manufacturing method of the metal core used for the heating roller according to claim 1 or 2,
Both ends of a metal cylindrical tube made of an aluminum alloy are reduced in diameter by drawing to form a shaft,
In a state where another ring member is inserted into the shaft portion, a convex portion is formed by plastic working on the outside where the shaft ring member is inserted again by drawing,
A method of manufacturing a metal core, wherein the ring-shaped member is supported so as not to move with respect to the metal cylindrical tube. An endless fixing belt stretched between a fixing roller and a heating roller having a built-in heat source, a detent member provided on the inner periphery of the fixing belt, and a press contact with the fixing roller via the fixing belt In a fixing device having a pressure roller, and performing fixing through a recording material carrying an unfixed toner image in a nip portion between the fixing belt and the pressure roller,
The heating roller is a metal cylindrical tube having a body part and a shaft part whose both ends of the body part are reduced in diameter,
A ring-shaped member that is provided coaxially with the metal cylindrical tube at the shaft portion of the metal cylindrical tube and is engaged with the detent member;
A fixing device comprising: a convex portion provided by plastic deformation on the shaft portion outside the ring-shaped member for positioning the ring-shaped member toward the body portion.   An image forming apparatus comprising the fixing device according to claim 5.

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